< position_i_min  >-1</  position_i_min  >


        traj_msg_external_point_ptr_.reset();
        traj_msg_external_point_ptr_.initRT(set_hold_position());
      }
      // else, run another cycle while waiting for outside_goal_tolerance
      // to be satisfied (will stay in this state until new message arrives)
      // or outside_goal_tolerance violated within the goal_time_tolerance
    }
  }


* SDF file:


1) Velocity mode: This mode lets the user control the desired joint velocity
directly.


< geometry  >


< mass  >0.6</  mass  >


void JointTrajectoryController::topic_callback(
  const std::shared_ptr<trajectory_msgs::msg::JointTrajectory> msg)
{
  if (!validate_trajectory_msg(*msg))
  {
    return;
  }
  // http://wiki.ros.org/joint_trajectory_controller/UnderstandingTrajectoryReplacement
  // always replace old msg with new one for now
  if (subscriber_is_active_)
  {
    add_new_trajectory_msg(msg);
    rt_is_holding_.writeFromNonRT(false);
  }
};


id: 12


Sign in to reply to author


< axis  >


![](JointController.png)


Show original message


controller_interface::CallbackReturn JointTrajectoryController::on_shutdown(
  const rclcpp_lifecycle::State &)
{
  // TODO(karsten1987): what to do?


subscriber_is_active_ = false;


PLUGINLIB_EXPORT_CLASS(
  joint_trajectory_controller::JointTrajectoryController, controller_interface::ControllerInterface)


command_joint_names_ = params_.command_joints;


Sign in to report message


    trajectory_msg->points[index].accelerations =
      remap(trajectory_msg->points[index].accelerations, mapping_vector);


            traj_msg_external_point_ptr_.reset();
            traj_msg_external_point_ptr_.initRT(set_hold_position());
          }
        }
      }
      else if (tolerance_violated_while_moving && *(rt_has_pending_goal_.readFromRT()) == false)
      {
        // we need to ensure that there is no pending goal -> we get a race condition otherwise
        RCLCPP_ERROR(get_node()->get_logger(), "Holding position due to state tolerance violation");


< joint_name  > j1  </  joint_name  >


</  box  >


Maximally allowed deviation from the goal (end of the trajectory) for a given
joint.


< parent  > world  </  parent  >


        feedback->actual = state_current_;
        feedback->desired = state_desired_;
        feedback->error = state_error_;
        active_goal->setFeedback(feedback);


</  model  >


name  =  "gz::sim::systems::JointTrajectoryController"  >


< position_cmd_max  >20</  position_cmd_max  >


###  mfr...@vt.edu


limit_lower: -inf


Show original message


> Oh, two more things, that I cannot explain at the moment:
>
>  When I have a look at the process_value entry in the
> JointVelocityController state message, this should be the actual/current
> joint velocity, right?
>  This value is retrieved directly from the HardwareInterface/GazeboHandle
> joint_->getVelocity(),right?
>


    if (valid_point)
    {
      const rclcpp::Time traj_start = traj_external_point_ptr_->time_from_start();
      // this is the time instance
      // - started with the first segment: when the first point will be reached (in the future)
      // - later: when the point of the current segment was reached
      const rclcpp::Time segment_time_from_start = traj_start + start_segment_itr->time_from_start;
      // time_difference is
      // - negative until first point is reached
      // - counting from zero to time_from_start of next point
      double time_difference = time.seconds() - segment_time_from_start.seconds();
      bool tolerance_violated_while_moving = false;
      bool outside_goal_tolerance = false;
      bool within_goal_time = true;
      const bool before_last_point = end_segment_itr != traj_external_point_ptr_->end();


The code that does this is here:


void JointTrajectoryController::fill_partial_goal(
  std::shared_ptr<trajectory_msgs::msg::JointTrajectory> trajectory_msg) const
{
  // joint names in the goal are a subset of existing joints, as checked in goal_callback
  // so if the size matches, the goal contains all controller joints
  if (dof_ == trajectory_msg->joint_names.size())
  {
    return;
  }


Sign in to forward


< sphere  >


  // Check if only allowed interface types are used and initialize storage to avoid memory
  // allocation during activation
  joint_command_interface_.resize(allowed_interface_types_.size());


sec: 1


Reply to author


Let's see a detailed description of each of them and an example usage to help
users select the right joint controller for their usage.


< pose  relative_to  =  "RR_position_control_link0"  >0 0 0 0 0 0</  pose  >


  // get degrees of freedom
  dof_ = params_.joints.size();


points {


void JointTrajectoryController::goal_accepted_callback(
  std::shared_ptr<rclcpp_action::ServerGoalHandle<FollowJTrajAction>> goal_handle)
{
  // mark a pending goal
  rt_has_pending_goal_.writeFromNonRT(true);


name  =  "gz::sim::systems::JointController"  >


    // TODO(anyone): How to halt when using effort commands?
    if (has_effort_command_interface_)
    {
      joint_command_interface_[3][index].get().set_value(0.0);
    }
  }


< specular  >0.8 0.8 0.8 1</  specular  >


> \- What we are currently trying to do is figure out good PIDs for each
> revolute joint separately (separate controllers with separate yaml files) by
> making all but the current joint a fixed joint in the URDF.
>


to Felix Meßmer, ros-sig-ro...@googlegroups.com, Michael Francis


  auto interface_has_values = [](const auto & joint_interface)
  {
    return std::find_if(
             joint_interface.begin(), joint_interface.end(), [](const auto & interface)
             { return std::isnan(interface.get().get_value()); }) == joint_interface.end();
  };


< diffuse  >0.8 0 0 1</  diffuse  >


< cylinder  >


    update_pids();
  }


void JointTrajectoryController::update_pids()
{
  for (size_t i = 0; i < dof_; ++i)
  {
    const auto & gains = params_.gains.joints_map.at(params_.joints[i]);
    if (pids_[i])
    {
      // update PIDs with gains from ROS parameters
      pids_[i]->setGains(gains.p, gains.i, gains.d, gains.i_clamp, -gains.i_clamp);
    }
    else
    {
      // Init PIDs with gains from ROS parameters
      pids_[i] = std::make_shared<control_toolbox::Pid>(
        gains.p, gains.i, gains.d, gains.i_clamp, -gains.i_clamp);
    }
    ff_velocity_scale_[i] = gains.ff_velocity_scale;
  }
}


< mass  >0.1</  mass  >


Report message


Finally, JointTrajectoryController can be used for hybrid control (e.g. In
manipulator robots) where value from position PID, velocity PID, and commanded
force value are summed up and applied.


filename  =  "gz-sim-joint-trajectory-controller-system"


  return true;
}


</  joint  >


2) Sending joint position command.


< iyy  >0.032</  iyy  >


  for (size_t index = 0; index < dof_; ++index)
  {
    if (has_position_command_interface_)
    {
      joint_command_interface_[0][index].get().set_value(
        joint_command_interface_[0][index].get().get_value());
    }


</  axis  >


</  scene  >


1) Save the SDF file in the desired directory or create one


  // Update the active goal
  RealtimeGoalHandlePtr rt_goal = std::make_shared<RealtimeGoalHandle>(goal_handle);
  rt_goal->preallocated_feedback_->joint_names = params_.joints;
  rt_goal->execute();
  rt_active_goal_.writeFromNonRT(rt_goal);


  return CallbackReturn::SUCCESS;
}


</  visual  >


< diffuse  >0.8 0 0 1</  diffuse  >


maintain current configuration as hold position") Mar 31, 2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [ christophfroehlich ](/christophfroehlich) closed this
Mar 31, 2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [ christophfroehlich ](/christophfroehlich) mentioned
this pull request  Mar 31, 2023
[ JTC: maintain current configuration as hold position  #531  ](/ros-
controls/ros2_controllers/pull/531)
Closed
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [ christophfroehlich ](/christophfroehlich) mentioned
this pull request  Apr 8, 2023
[ [JTC] Reject trajectories with nonzero terminal velocity  #567  ](/ros-
controls/ros2_controllers/pull/567)
Merged
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [ christophfroehlich ](/christophfroehlich) reopened
this  Apr 27, 2023
[ ![@github-actions](https://avatars.githubusercontent.com/in/15368?s=40&v=4)
](/apps/github-actions) [ github-actions ](/apps/github-actions) bot
requested review from [ aprotyas  ](/aprotyas) , [ DasRoteSkelett
](/DasRoteSkelett) and [ VX792  ](/VX792) April 27, 2023 11:18
[ ![@codecov-
commenter](https://avatars.githubusercontent.com/u/65553080?s=80&u=1e9e0de760ac0083c86dab588f627a0468cd714e&v=4)
](/codecov-commenter)
Copy link
###
**[ codecov-commenter ](/codecov-commenter) ** commented  Apr 27, 2023  •
edited
##  [ Codecov ](https://app.codecov.io/gh/ros-
controls/ros2_controllers/pull/558?src=pr&el=h1&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls) Report
> Merging [ #558 ](https://app.codecov.io/gh/ros-
> controls/ros2_controllers/pull/558?src=pr&el=desc&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
> controls) ( [ ` 0e82010 ` ](https://github.com/ros-


controller_interface::CallbackReturn JointTrajectoryController::on_activate(
  const rclcpp_lifecycle::State &)
{
  // update the dynamic map parameters
  param_listener_->refresh_dynamic_parameters();


< constant  >0.9</  constant  >


< inertia  >


< position_cmd_min  >-10</  position_cmd_min  >


time_from_start {


  for (size_t index = 0; index < trajectory_msg->points.size(); ++index)
  {
    trajectory_msg->points[index].positions =
      remap(trajectory_msg->points[index].positions, mapping_vector);


Send feedback to Google


` [ [JTC] Explicitly set hold position (backport ](/ros-
controls/ros2_controllers/commit/5b4b662bf7d717efaa7990024824370f890a0019
"\[JTC\] Explicitly set hold position \(backport #558\)") [ #558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ ) ](/ros-
controls/ros2_controllers/commit/5b4b662bf7d717efaa7990024824370f890a0019
"\[JTC\] Explicitly set hold position \(backport #558\)") `
` [ 5b4b662 ](/ros-
controls/ros2_controllers/commit/5b4b662bf7d717efaa7990024824370f890a0019) `
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [ christophfroehlich ](/christophfroehlich) mentioned
this pull request  Mar 21, 2024
[ [JTC] Deprecate ` start_with_holding ` (backport #1076)  #1086  ](/ros-
controls/ros2_controllers/pull/1086)
Closed
[ Sign up for free ](/join?source=comment-repo) **to join this conversation on
GitHub** . Already have an account? [ Sign in to comment
](/login?return_to=https%3A%2F%2Fgithub.com%2Fros-
controls%2Fros2_controllers%2Fpull%2F558)
Reviewers
[ ![@bmagyar](https://avatars.githubusercontent.com/u/3524577?s=40&v=4)
](/bmagyar) [ bmagyar  ](/bmagyar) [ ](/ros-
controls/ros2_controllers/pull/558/files/bb1de716ba3e35117548f8817eba05ac37f86ae5)
bmagyar approved these changes
[ ![@anfemosa](https://avatars.githubusercontent.com/u/22676337?s=40&v=4)
](/anfemosa) [ anfemosa  ](/anfemosa) Awaiting requested review from anfemosa
[ ![@homalozoa](https://avatars.githubusercontent.com/u/21300069?s=40&v=4)
](/homalozoa) [ homalozoa  ](/homalozoa) Awaiting requested review from
homalozoa
[ ![@mcbed](https://avatars.githubusercontent.com/u/83034299?s=40&v=4)
](/mcbed) [ mcbed  ](/mcbed) Awaiting requested review from mcbed
[
![@peterdavidfagan](https://avatars.githubusercontent.com/u/42982057?s=40&v=4)
](/peterdavidfagan) [ peterdavidfagan  ](/peterdavidfagan) Awaiting requested
review from peterdavidfagan
[ ![@progtologist](https://avatars.githubusercontent.com/u/2506743?s=40&v=4)
](/progtologist) [ progtologist  ](/progtologist) Awaiting requested review
from progtologist
[ ![@aprotyas](https://avatars.githubusercontent.com/u/34530011?s=40&v=4)
](/aprotyas) [ aprotyas  ](/aprotyas) Awaiting requested review from aprotyas


You do not have permission to delete messages in this group


to ros-sig-ro...@googlegroups.com, mfr...@vt.edu, adolfo.r...@pal-robotics.com


Delete


controller_interface::return_type JointTrajectoryController::update(
  const rclcpp::Time & time, const rclcpp::Duration & period)
{
  if (get_state().id() == lifecycle_msgs::msg::State::PRIMARY_STATE_INACTIVE)
  {
    return controller_interface::return_type::OK;
  }
  // update dynamic parameters
  if (param_listener_->is_old(params_))
  {
    params_ = param_listener_->get_params();
    default_tolerances_ = get_segment_tolerances(params_);
    // update the PID gains
    // variable use_closed_loop_pid_adapter_ is updated in on_configure only
    if (use_closed_loop_pid_adapter_)
    {
      update_pids();
    }
  }


In Development


< length  >0.2</  length  >


w: 1


< pose  >0.0 0.0 0.0 0 0 0</  pose  >


**Note** : All the plugins discussed here should be between ` <model> ` and `
</model> ` tags. Ideally just before the ` </model> ` tag for better
readability.


  // Check if only allowed interface types are used and initialize storage to avoid memory
  // allocation during activation
  // Note: 'effort' storage is also here, but never used. Still, for this is OK.
  joint_state_interface_.resize(allowed_interface_types_.size());


</  sphere  >


Jul 11, 2014, 1:10:18 AM  7/11/14


</  geometry  >


Report message


P.S. This thread has diverged significantly from its subject. Since very
interesting discussions are taking place here, it would be nice for others to
easily find them. I appreciate it if we create a new thread with an
appropriate title the next time the subject strays from the original post.
Smaller, focused threads are easier to find.


Sign in to reply to author


</  cylinder  >


        traj_msg_external_point_ptr_.reset();
        traj_msg_external_point_ptr_.initRT(set_hold_position());
      }
      else if (
        !before_last_point && !within_goal_time && *(rt_has_pending_goal_.readFromRT()) == false)
      {
        RCLCPP_ERROR(get_node()->get_logger(), "Exceeded goal_time_tolerance: holding position...");


> \- Now we are trying to find the PIDs using Ziegler-Nichols strategy for
> each joint controller separately and then hope that it still works when me
> make all joints revolute again. Would you say this approach is feasible? Are
> there any other suggestions?
>


< diffuse  >0.5 0.5 0.5 1</  diffuse  >


        // store the previous command. Used in open-loop control mode
        last_commanded_state_ = state_desired_;
      }


  }
  else
  {
    state.accelerations.clear();
  }


</  collision  >


![](JointTrajectoryController.gif)


unread,


Commanded position(cmd_pos) can be published or subscribed at the topic: `
/model/<model_name>/joint/<joint_name>/<joint_index>/cmd_pos ` by default.


  return CallbackReturn::SUCCESS;
}


Show original message


  // prepare hold_position_msg
  init_hold_position_msg();


< ixx  >2.501</  ixx  >


< i_max  >1</  i_max  >


###  Felix Meßmer


#include <string>
#include <vector>


[ ![](https://gazebosim.org/assets/doxygen/gazebo_logo.svg) ](index.html)


You already asked this question, the original answer still holds:


Reply to author


We tune our hardware PIDs using frequency-domain tools. We've so far been more
heuristic when tuning our simulation gains, definitely something to improve.


Sign in to report message


Sign in to forward


</  geometry  >


< i_min  >-1</  i_min  >


` [ 4665580
](/christophfroehlich/ros2_controllers/commit/46655807a6e64bc9c3d5011a19c981e4c84fc979)
`
[ christophfroehlich ](/christophfroehlich) added a commit to
christophfroehlich/ros2_controllers that referenced this pull request  Nov 30,
2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
` [ [JTC] Explicitly set hold position (backport
](/christophfroehlich/ros2_controllers/commit/8c428370e27f49375636fab707c40ceb17a06ccd
"\[JTC\] Explicitly set hold position \(backport #558\)") [ ros-controls#558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ )
](/christophfroehlich/ros2_controllers/commit/8c428370e27f49375636fab707c40ceb17a06ccd
"\[JTC\] Explicitly set hold position \(backport #558\)") `
` [ 8c42837
](/christophfroehlich/ros2_controllers/commit/8c428370e27f49375636fab707c40ceb17a06ccd)
`
[ christophfroehlich ](/christophfroehlich) added a commit to
christophfroehlich/ros2_controllers that referenced this pull request  Dec 5,
2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
` [ [JTC] Explicitly set hold position (backport
](/christophfroehlich/ros2_controllers/commit/4abddd59ab8758d7d319b226c1dac44d3f6756eb
"\[JTC\] Explicitly set hold position \(backport #558\)") [ ros-controls#558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ )
](/christophfroehlich/ros2_controllers/commit/4abddd59ab8758d7d319b226c1dac44d3f6756eb
"\[JTC\] Explicitly set hold position \(backport #558\)") `
` [ 4abddd5
](/christophfroehlich/ros2_controllers/commit/4abddd59ab8758d7d319b226c1dac44d3f6756eb)
`
[ bmagyar ](/bmagyar) pushed a commit that referenced this pull request  Dec
6, 2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [
![@bmagyar](https://avatars.githubusercontent.com/u/3524577?s=40&v=4)
](/bmagyar)


Sign in to reply to author


Maybe the gains are not set correctly.


  return CallbackReturn::SUCCESS;
}


</  link  >


For controlling joints one would require adding the Gazebo's joint controller
plugin to the existing ` <model_name>.sdf ` file.


unread,


If a joint is part of a chain, it's dynamics will be affected by the dynamic
coupling with upstream and downsteam links. That is, as the robot changes
configuration, it's mass distribution will also change, as well as the joint
accelerations. In the absence of a controller that compensates dynamics, as in
pure PID control, these dynamic effects are disturbances the PID must be
effective at rejecting. If you tune a joint PID in a fixed configuration, you
could be underestimating the disturbances it must reject. If your robot does
not do very dynamic motions, you can probably get a good starting point by
using the most demanding fixed configurations (eg. tune a shoulder joint with
the arm stretched, oriented for max gravity load).


![Adolfo Rodríguez Tsouroukdissian's profile
photo](https://lh3.googleusercontent.com/a/default-user=s40-c)


You do not have permission to delete messages in this group


Using the safety controller specification is not mandatory.


Forward


< iyy  >2.501</  iyy  >


< dynamics  >


The controller expects at least position feedback from the hardware. Joint
velocities and accelerations are optional. Currently the controller does not
internally integrate velocity from acceleration and position from velocity.
Therefore if the hardware provides only acceleration or velocity states they
have to be integrated in the hardware-interface implementation of velocity and
position to use these controllers.


Skip to first unread message


###  mfr...@vt.edu


#  Configuring the controller.yaml file to use a velocity controller


< xyz  >1 0 0</  xyz  >


Sign in to reply to author


points {


**You're reading the documentation for a version of ROS 2 that has reached its
EOL (end-of-life), and is no longer officially supported. If you want up-to-
date information, please have a look at[ Iron
](../../../../../iron/doc/ros2_controllers/joint_trajectory_controller/doc/userdoc.html)
. **


  // effort is always used alone so no need for size check
  if (
    has_effort_command_interface_ &&
    (!has_velocity_state_interface_ || !has_position_state_interface_))
  {
    RCLCPP_ERROR(
      logger,
      "'effort' command interface can only be used alone if 'velocity' and "
      "'position' state interfaces are present");
    return CallbackReturn::FAILURE;
  }


</  plugin  >


< radius  >0.01</  radius  >


< izz  >0.00012</  izz  >


This returns the progress of the commanded trajectory which is a value between
(0,1].


< geometry  >


Copy link


< izz  >0.000005</  izz  >


Rate to monitor status changes when the controller is executing action
(control_msgs::action::FollowJointTrajectory).


bool JointTrajectoryController::read_commands_from_command_interfaces(
  JointTrajectoryPoint & commands)
{
  bool has_values = true;


> > To unsubscribe from this group and stop receiving emails from it, send an
> email to  ros-sig-robot-control+unsub...@googlegroups.com  .


< sphere  >


Forward


< ambient  >0.4 0.4 0.4</  ambient  >


##  Hardware interface type  


< child  > rotor  </  child  >


to Michael Francis, ros-sig-ro...@googlegroups.com


< box  >


bool JointTrajectoryController::reset()
{
  subscriber_is_active_ = false;
  joint_command_subscriber_.reset();


    state_publisher_->unlockAndPublish();
  }
}


< ixx  >0.0003358</  ixx  >


###  Adolfo Rodríguez Tsouroukdissian


* Velocity mode


On Thu, Jul 10, 2014 at 7:10 PM,  < [ mfr...@vt.edu ]() > wrote:


< position_i_gain  >0.2</  position_i_gain  >


< link  name  =  "RR_position_control_link2"  >


< pose  >0 0 0 0 -3.14159 0</  pose  >


< length  >0.2</  length  >


</  light  >


Delete


gz topic -e -t /world/default/model/joint_controller_demo/joint_state


Sign in to report message


Forward


gz topic -t "/topic_name" -m gz.msgs.Double -p "data: -1.0"


Append the following lines before ` </model> ` tag in the SDF file.


  if (trajectory.points.empty())
  {
    RCLCPP_ERROR(get_node()->get_logger(), "Empty trajectory received.");
    return false;
  }


</  collision  >


namespace joint_trajectory_controller
{
JointTrajectoryController::JointTrajectoryController()
: controller_interface::ControllerInterface(), dof_(0)
{
}


  }
  response->position = state_requested.positions;
  response->velocity = state_requested.velocities;
  response->acceleration = state_requested.accelerations;
}


Main menu


        traj_msg_external_point_ptr_.reset();
        traj_msg_external_point_ptr_.initRT(set_hold_position());
      }


</  geometry  >


1) Launching gazebo simulation.


This is how the model will look:


[ Master ](../../../../../master/doc/ros2_controllers/joint_trajectory_controller/doc/userdoc.html)


__ [ ROS2_Control: Galactic ](../../../../index.html)


// Copyright (c) 2021 ros2_control Development Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


positions: 0


4) Checking the progress of the commanded trajectory.


  has_position_state_interface_ =
    contains_interface_type(params_.state_interfaces, hardware_interface::HW_IF_POSITION);
  has_velocity_state_interface_ =
    contains_interface_type(params_.state_interfaces, hardware_interface::HW_IF_VELOCITY);
  has_acceleration_state_interface_ =
    contains_interface_type(params_.state_interfaces, hardware_interface::HW_IF_ACCELERATION);


  // if there is only velocity or if there is effort command interface
  // then use also PID adapter
  use_closed_loop_pid_adapter_ =
    (has_velocity_command_interface_ && params_.command_interfaces.size() == 1 &&
     !params_.open_loop_control) ||
    has_effort_command_interface_;


Jul 7, 2014, 5:04:56 PM  7/7/14


Values: position (mandatory) [velocity, [acceleration]]. Acceleration
interface can only be used in combination with position and velocity.


< plugin


  // set flag, otherwise tolerances will be checked with holding position too
  rt_is_holding_.writeFromNonRT(true);


< pose  >0 0 -0.5 0 0 0</  pose  >


< ambient  >0.2 0.8 0.2 1</  ambient  >


Controller for executing joint-space trajectories on a group of joints.
Trajectories are specified as a set of waypoints to be reached at specific
time instants, which the controller attempts to execute as well as the
mechanism allows. Waypoints consist of positions, and optionally velocities
and accelerations.


Show original message


  try
  {
    // Create the parameter listener and get the parameters
    param_listener_ = std::make_shared<ParamListener>(get_node());
    params_ = param_listener_->get_params();
  }
  catch (const std::exception & e)
  {
    fprintf(stderr, "Exception thrown during init stage with message: %s \n", e.what());
    return CallbackReturn::ERROR;
  }


###  Adolfo Rodríguez Tsouroukdissian


Forward


</  cylinder  >


unread,


</  collision  >


< material  >


velocity: 8.1005154347602952e-09


to Michael Francis, ros-sig-ro...@googlegroups.com


Delete


constraints (structure)


Close search


</  inertial  >


position: 44282.754868627489


Jul 4, 2014, 2:49:55 PM  7/4/14


---|---|---
[ ...ontroller/test/test_load_diff_drive_controller.cpp
](https://app.codecov.io/gh/ros-
controls/ros2_controllers/pull/558?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls#diff-
ZGlmZl9kcml2ZV9jb250cm9sbGVyL3Rlc3QvdGVzdF9sb2FkX2RpZmZfZHJpdmVfY29udHJvbGxlci5jcHA=)
|  ` 11.11% <0.00%> (ø) ` |
[ ...ive_controller/test/test_diff_drive_controller.cpp
](https://app.codecov.io/gh/ros-
controls/ros2_controllers/pull/558?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls#diff-
ZGlmZl9kcml2ZV9jb250cm9sbGVyL3Rlc3QvdGVzdF9kaWZmX2RyaXZlX2NvbnRyb2xsZXIuY3Bw)
|  ` 12.66% <7.81%> (ø) ` |
[ diff_drive_controller/src/odometry.cpp ](https://app.codecov.io/gh/ros-
controls/ros2_controllers/pull/558?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls#diff-ZGlmZl9kcml2ZV9jb250cm9sbGVyL3NyYy9vZG9tZXRyeS5jcHA=) |  `
42.16% <11.11%> (ø) ` |
[ diff_drive_controller/src/speed_limiter.cpp ](https://app.codecov.io/gh/ros-
controls/ros2_controllers/pull/558?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls#diff-ZGlmZl9kcml2ZV9jb250cm9sbGVyL3NyYy9zcGVlZF9saW1pdGVyLmNwcA==) |
` 46.55% <11.11%> (ø) ` |
[ ...iff_drive_controller/src/diff_drive_controller.cpp
](https://app.codecov.io/gh/ros-
controls/ros2_controllers/pull/558?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls#diff-
ZGlmZl9kcml2ZV9jb250cm9sbGVyL3NyYy9kaWZmX2RyaXZlX2NvbnRyb2xsZXIuY3Bw) |  `
47.13% <46.94%> (ø) ` |
[ ...de/diff_drive_controller/diff_drive_controller.hpp
](https://app.codecov.io/gh/ros-
controls/ros2_controllers/pull/558?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls#diff-
ZGlmZl9kcml2ZV9jb250cm9sbGVyL2luY2x1ZGUvZGlmZl9kcml2ZV9jb250cm9sbGVyL2RpZmZfZHJpdmVfY29udHJvbGxlci5ocHA=)
|  ` 100.00% <100.00%> (ø) ` |
[ ...troller/include/diff_drive_controller/odometry.hpp
](https://app.codecov.io/gh/ros-
controls/ros2_controllers/pull/558?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls#diff-
ZGlmZl9kcml2ZV9jb250cm9sbGVyL2luY2x1ZGUvZGlmZl9kcml2ZV9jb250cm9sbGVyL29kb21ldHJ5LmhwcA==)
|  ` 100.00% <100.00%> (ø) ` |


time_from_start {


If you're using the MoveitSimpleControllerManager (the most common usecase),
then a effort_controller/JointVelocityController (from the ros_controllers
project) will not do. The expected controller interface should implement a
follow_joint_trajectoy action server. See [1] for more details. In
ros_controllers, there's the joint_trajectory_controller that implements this
interface. Position and effort interfaces are already supported, and velocity
interfaces have an open PR [2], that is pending some validation.

[1] [ http://moveit.ros.org/wiki/Executing_Trajectories_with_MoveIt
](http://moveit.ros.org/wiki/Executing_Trajectories_with_MoveIt) !
[2] [ https://github.com/ros-controls/ros_controllers/pull/64
](https://github.com/ros-controls/ros_controllers/pull/64)


Either email addresses are anonymous for this group or you need the view
member email addresses permission to view the original message


</  material  >


to ros-sig-ro...@googlegroups.com, mfr...@vt.edu


< static  > true  </  static  >


Gazebo provides three joint controller plugins which are ` JointController ` ,
` JointPositionController ` , and ` JointTrajectoryController ` .


< ambient  >0 0.5 0.5 1</  ambient  >


< pose  relative_to  =  "RR_position_control_joint2"  >0 0 0.1 0 0 0</  pose
>


You do not have permission to delete messages in this group


##  ROS/Orocos Robot Control Special Interest Group


joint {


controller_interface::CallbackReturn JointTrajectoryController::on_configure(
  const rclcpp_lifecycle::State &)
{
  const auto logger = get_node()->get_logger();


<!-- Models -->


  auto assign_point_from_interface =
    [&](std::vector<double> & trajectory_point_interface, const auto & joint_interface)
  {
    for (size_t index = 0; index < dof_; ++index)
    {
      trajectory_point_interface[index] = joint_interface[index].get().get_value();
    }
  };


To change the topic name add the following line before ` </plugin> ` tag in
the SDF file.


Joint Controllers


< parent  > RR_position_control_link1  </  parent  >


  // create subscriber and publishers
  joint_command_subscriber_ =
    get_node()->create_subscription<trajectory_msgs::msg::JointTrajectory>(
      "~/joint_trajectory", rclcpp::SystemDefaultsQoS(),
      std::bind(&JointTrajectoryController::topic_callback, this, std::placeholders::_1));


###  ROS2 interface of the controller  


to ros-sig-ro...@googlegroups.com


`
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [ christophfroehlich ](/christophfroehlich) mentioned
this pull request  Nov 6, 2023
[ [JTC] Need for ` start_with_holding ` option?  #816  ](/ros-
controls/ros2_controllers/issues/816)
Closed
[ christophfroehlich ](/christophfroehlich) added a commit to
christophfroehlich/ros2_controllers that referenced this pull request  Nov 11,
2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
` [ [JTC] Explicitly set hold position (backport
](/christophfroehlich/ros2_controllers/commit/786202419b1bd1e471e6fadf6fb4861cc282c3cb
"\[JTC\] Explicitly set hold position \(backport #558\)") [ ros-controls#558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ )
](/christophfroehlich/ros2_controllers/commit/786202419b1bd1e471e6fadf6fb4861cc282c3cb
"\[JTC\] Explicitly set hold position \(backport #558\)") `
` [ 7862024
](/christophfroehlich/ros2_controllers/commit/786202419b1bd1e471e6fadf6fb4861cc282c3cb)
`
[ christophfroehlich ](/christophfroehlich) added a commit to
christophfroehlich/ros2_controllers that referenced this pull request  Nov 15,
2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
` [ [JTC] Explicitly set hold position (backport
](/christophfroehlich/ros2_controllers/commit/661cf82fde2220f8b475da6a03f362ec6cf68c92
"\[JTC\] Explicitly set hold position \(backport #558\)") [ ros-controls#558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ )
](/christophfroehlich/ros2_controllers/commit/661cf82fde2220f8b475da6a03f362ec6cf68c92
"\[JTC\] Explicitly set hold position \(backport #558\)") `
` [ 661cf82
](/christophfroehlich/ros2_controllers/commit/661cf82fde2220f8b475da6a03f362ec6cf68c92)
`
[ christophfroehlich ](/christophfroehlich) added a commit to
christophfroehlich/ros2_controllers that referenced this pull request  Nov 17,


< world  name  =  "default"  >


</  axis  >


State interfaces provided by the hardware for all joints.


Copy link


  // TODO(destogl): why is this here? Add comment or move
  if (!reset())
  {
    return CallbackReturn::FAILURE;
  }


>   * position_controllers::JointTrajectoryController \- Input: position,
> [velocity, [acceleration]] \- Output: position
>
>   * position_velocity_controllers::JointTrajectoryController \- Input:
> position, [velocity, [acceleration]] \- Output: position and velocity
>
>   * position_velocity_acceleration_controllers::JointTrajectoryController \-
> Input: position, [velocity, [acceleration]] \- Output: position, velocity
> and acceleration
>
>


< izz  >0.000005</  izz  >


std::shared_ptr<trajectory_msgs::msg::JointTrajectory>
JointTrajectoryController::set_success_trajectory_point()
{
  // set last command to be repeated at success, no matter if it has nonzero velocity or
  // acceleration
  hold_position_msg_ptr_->points[0] = traj_external_point_ptr_->get_trajectory_msg()->points.back();
  hold_position_msg_ptr_->points[0].time_from_start = rclcpp::Duration(0, 0);


\--
Adolfo Rodríguez Tsouroukdissian
Senior robotics engineer
[ adolfo.r...@pal-robotics.com ]()
[ http://www.pal-robotics.com ](http://www.pal-robotics.com/)

PAL ROBOTICS S.L
c/ Pujades 77-79, 4º4ª
08005 Barcelona, Spain.
Tel. [ +34.93.414.53.47 ](tel:+34%20934%2014%2053%2047)
Fax. [ +34.93.209.11.09 ](tel:+34%20932%2009%2011%2009)
Skype: adolfo.pal-robotics
[ Facebook ](http://www.facebook.com/palrobotics1) \- [ Twitter
](http://twitter.com/#%21/palrobotics) \- [ PAL Robotics YouTube Channel
](http://www.youtube.com/user/PALRobotics)

AVISO DE CONFIDENCIALIDAD: Este mensaje y sus documentos adjuntos, pueden
contener información privilegiada y/o confidencial que está dirigida
exclusivamente a su destinatario. Si usted recibe este mensaje y no es el
destinatario indicado, o el empleado encargado de su entrega a dicha persona,
por favor, notifíquelo inmediatamente y remita el mensaje original a la
dirección de correo electrónico indicada. Cualquier copia, uso o distribución
no autorizados de esta comunicación queda estrictamente prohibida.  `

` CONFIDENTIALITY NOTICE: This e-mail and the accompanying document(s) may
contain confidential information which is privileged and intended only for the
individual or entity to whom they are addressed. If you are not the intended
recipient, you are hereby notified that any disclosure, copying, distribution
or use of this e-mail and/or accompanying document(s) is strictly prohibited.
If you have received this e-mail in error, please immediately notify the
sender at the above e-mail address.


  if (use_closed_loop_pid_adapter_)
  {
    pids_.resize(dof_);
    ff_velocity_scale_.resize(dof_);
    tmp_command_.resize(dof_, 0.0);


> It did this by connecting and registering a
> "hardware_interface::EffortJointInterface jnt_pos_interface" object to a
> array named cmd[ ] (This is all from this tutorial). The cmd array had only
> one value for each joint, that being the relative position. Adolfo am I
> correct in assuming that? Or is the value being sent something different?
>
>


  * Joint controller which can be attached to a model with a reference to a single joint.
  * Currently, only the first axis of a joint can be actuated.


unread,


© Copyright 2024, ros2_control Development Team.


</  visual  >


![Felix Meßmer's profile photo](//lh3.googleusercontent.com/a-/ALV-UjXo2aXfAk-
du0bo7Rk6_qcY5MZE8BRzAtLvSi33j1VJUTXvhQ=s40-c)


Jul 11, 2014, 10:38:21 PM  7/11/14


< visual  name  =  "base_visual"  >


Delete


< geometry  >


void JointTrajectoryController::add_new_trajectory_msg(
  const std::shared_ptr<trajectory_msgs::msg::JointTrajectory> & traj_msg)
{
  traj_msg_external_point_ptr_.writeFromNonRT(traj_msg);
}


Clear search


[ https://github.com/ros-simulation/gazebo_ros_pkgs/blob/hydro-
devel/gazebo_ros_control/src/gazebo_ros_control_plugin.cpp#L117
](https://github.com/ros-simulation/gazebo_ros_pkgs/blob/hydro-
devel/gazebo_ros_control/src/gazebo_ros_control_plugin.cpp#L117)

You can additionally decide to skip doing work on a per-controller basis if
you want, say to run a controllers computations every n controller_manager
updates.


open_loop_control (boolean):


< joint  name  =  "world_fixed"  type  =  "fixed"  >


Report message


< child  > RR_position_control_link2  </  child  >


Copy link


I am also working with the effort_controller/JointVelocityController.
We are currently trying to figure out good PID gains for a 7DoF robot arm. I
will post our experiences here, once we are done.

I just have a few questions:
\- Isn't the effort_controller/JointVelocityController a single joint
controller? Thus only capable of having one joint being set in the joint tag?
\- What we are currently trying to do is figure out good PIDs for each
revolute joint separately (separate controllers with separate yaml files) by
making all but the current joint a fixed joint in the URDF.
\- Another thing that we recognized is that the JointVelocityController only
publishes state information only every 10th time update() is called ( [
https://github.com/ros-controls/ros_controllers/blob/indigo-
devel/effort_controllers/src/joint_velocity_controller.cpp#L140
](https://github.com/ros-controls/ros_controllers/blob/indigo-
devel/effort_controllers/src/joint_velocity_controller.cpp#L140) ). For our
initial PIDs the rqt_plots looked quite ok/smooth, but the arm kept dropping
and was totally unstable. When I then published to the state topic every
update(), I found the controller heavily oscillating changing sign every
message. By only publishing every even message, you did not see this...;-)
\- Now we are trying to find the PIDs using Ziegler-Nichols strategy for each
joint controller separately and then hope that it still works when me make all
joints revolute again. Would you say this approach is feasible? Are there any
other suggestions?


On Fri, Jul 4, 2014 at 2:30 PM, Felix Meßmer  < [ felixm...@gmail.com ]() >
wrote:


< iyz  >0</  iyz  >


#include "angles/angles.h"
#include "builtin_interfaces/msg/duration.hpp"
#include "builtin_interfaces/msg/time.hpp"
#include "controller_interface/helpers.hpp"
#include "hardware_interface/types/hardware_interface_return_values.hpp"
#include "hardware_interface/types/hardware_interface_type_values.hpp"
#include "joint_trajectory_controller/trajectory.hpp"
#include "lifecycle_msgs/msg/state.hpp"
#include "rclcpp/logging.hpp"
#include "rclcpp/qos.hpp"
#include "rclcpp/time.hpp"
#include "rclcpp_action/create_server.hpp"
#include "rclcpp_action/server_goal_handle.hpp"
#include "rclcpp_lifecycle/state.hpp"
#include "urdf/model.h"


< visual  name  =  "visual"  >


  * [ Getting Started ](../../../getting_started/getting_started.html)
  * [ Architecture ](../../../getting_started/getting_started.html#architecture)
  * [ Hardware Components ](../../../getting_started/getting_started.html#hardware-components)
  * [ API Documentation ](../../../ros2_control/doc/index.html)
  * [ Core functionalities ](../../../ros2_control/doc/index.html#core-functionalities)
  * [ ros2_controllers ](../../doc/controllers_index.html)
    * [ Nomenclature ](../../doc/controllers_index.html#nomenclature)
    * [ Controllers ](../../doc/controllers_index.html#id1)
    * [ Guidelines and Best Practices ](../../doc/controllers_index.html#guidelines-and-best-practices)
      * [ Writing a new controller ](../../doc/writing_new_controller.html)
      * [ Available Controllers ](../../doc/controllers_index.html#available-controllers)
        * [ Differential Drive ](../../diff_drive_controller/doc/userdoc.html)
        * [ Forward Command ](../../forward_command_controller/doc/userdoc.html)
        * Joint Trajectory
          * Trajectory representation
          * Hardware interface type
          * Other features
          * Using Joint Trajectory Controller(s)
            * Details about parameters
            * ROS2 interface of the controller
          * Specialized versions of JointTrajectoryController (TBD in …)
        * [ Position Controllers ](../../position_controllers/doc/userdoc.html)
        * [ Velocity Controllers ](../../velocity_controllers/doc/userdoc.html)
        * [ Effort Controllers ](../../effort_controllers/doc/userdoc.html)
      * [ Available Broadcasters ](../../doc/controllers_index.html#available-broadcasters)
  * [ Command Line Interface ](../../../ros2_control/ros2controlcli/doc/userdoc.html)
  * [ Differences to ros_control (ROS1) ](../../../differences_to_ros1/differences_to_ros1.html)
  * [ Migration Guide to ros2_control ](../../../differences_to_ros1/differences_to_ros1.html#migration-guide-to-ros2-control)
  * [ Demos ](../../../ros2_control_demos/doc/index.html)
  * [ Resources ](../../../resources/resources.html)
  * [ Pull Requests ](../../../contributing/contributing.html)
  * [ Rules for the repositories and process of merging pull requests ](../../../contributing/contributing.html#rules-for-the-repositories-and-process-of-merging-pull-requests)
  * [ Writing documentation ](../../../contributing/contributing.html#writing-documentation)
  * [ Repository structure and CI configuration ](../../../contributing/contributing.html#repository-structure-and-ci-configuration)
  * [ Project Ideas for GSoC 2022 ](../../../project_ideas.html)
  * [ Acknowledgements ](../../../acknowledgements/acknowledgements.html)


< iyy  >0.0003358</  iyy  >


limit_lower: -inf


  Reply all


  // get parameters from the listener in case they were updated
  params_ = param_listener_->get_params();


>
>  For more options, visit [ https://groups.google.com/d/optout
> ](https://groups.google.com/d/optout) .
>


bool JointTrajectoryController::contains_interface_type(
  const std::vector<std::string> & interface_type_list, const std::string & interface_type)
{
  return std::find(interface_type_list.begin(), interface_type_list.end(), interface_type) !=
         interface_type_list.end();
}


bool JointTrajectoryController::validate_trajectory_msg(
  const trajectory_msgs::msg::JointTrajectory & trajectory) const
{
  // If partial joints goals are not allowed, goal should specify all controller joints
  if (!params_.allow_partial_joints_goal)
  {
    if (trajectory.joint_names.size() != dof_)
    {
      RCLCPP_ERROR(
        get_node()->get_logger(),
        "Joints on incoming trajectory don't match the controller joints.");
      return false;
    }
  }


* SDF file:


velocity: 1.0000051832309742


You can find some doc in the PR2 pages, which has not been migrated to the
ros_control wiki:

[ http://wiki.ros.org/pr2_controller_manager/safety_limits
](http://wiki.ros.org/pr2_controller_manager/safety_limits)


![mfr...@vt.edu's profile photo](//lh3.googleusercontent.com/a-/ALV-
UjXLZw18gFzZHa2C4A0mrLpZ13blWBOpMeCRZ4tYXUaxAYg45w=s40-c)


Sign in to forward


< joint_name  > j1  </  joint_name  >


< link  name  =  "base_link"  >


  // Assign values from the command interfaces as state. Therefore needs check for both.
  // Position state interface has to exist always
  if (has_position_command_interface_ && interface_has_values(joint_command_interface_[0]))
  {
    assign_point_from_interface(state.positions, joint_command_interface_[0]);
  }
  else
  {
    state.positions.clear();
    has_values = false;
  }
  // velocity and acceleration states are optional
  if (has_velocity_state_interface_)
  {
    if (has_velocity_command_interface_ && interface_has_values(joint_command_interface_[1]))
    {
      assign_point_from_interface(state.velocities, joint_command_interface_[1]);
    }
    else
    {
      state.velocities.clear();
      has_values = false;
    }
  }
  else
  {
    state.velocities.clear();
  }
  // Acceleration is used only in combination with velocity
  if (has_acceleration_state_interface_)
  {
    if (has_acceleration_command_interface_ && interface_has_values(joint_command_interface_[2]))
    {
      assign_point_from_interface(state.accelerations, joint_command_interface_[2]);
    }
    else
    {
      state.accelerations.clear();
      has_values = false;
    }


Default: 50.0


Jul 9, 2014, 1:53:14 AM  7/9/14


Sign in to reply to author


Sign in to report message


< plugin


Reply to author


I think not, and I couldn't find


< material  >


Forward


</  attenuation  >


Skip to content
Toggle navigation
[ ](https://github.com/)
[ Sign in ](/login?return_to=https%3A%2F%2Fgithub.com%2Fros-
controls%2Fros2_controllers%2Fpull%2F558)
  * Product
    * [ Actions  Automate any workflow  ](/features/actions)
    * [ Packages  Host and manage packages  ](/features/packages)
    * [ Security  Find and fix vulnerabilities  ](/features/security)
    * [ Codespaces  Instant dev environments  ](/features/codespaces)
    * [ Copilot  Write better code with AI  ](/features/copilot)
    * [ Code review  Manage code changes  ](/features/code-review)
    * [ Issues  Plan and track work  ](/features/issues)
    * [ Discussions  Collaborate outside of code  ](/features/discussions)
Explore
    * [ All features ](/features)
    * [ Documentation  ](https://docs.github.com)
    * [ GitHub Skills  ](https://skills.github.com/)
    * [ Blog  ](https://github.blog)
  * Solutions
For
    * [ Enterprise ](/enterprise)
    * [ Teams ](/team)
    * [ Startups ](/enterprise/startups)
    * [ Education  ](https://education.github.com)
By Solution
    * [ CI/CD & Automation ](/solutions/ci-cd/)
    * [ DevOps ](/solutions/devops/)
    * [ DevSecOps  ](https://resources.github.com/devops/fundamentals/devsecops/)
Resources
    * [ Learning Pathways  ](https://resources.github.com/learn/pathways/)
    * [ White papers, Ebooks, Webinars  ](https://resources.github.com/)
    * [ Customer Stories ](/customer-stories)
    * [ Partners  ](https://partner.github.com/)
  * Open Source
    * [ GitHub Sponsors  Fund open source developers  ](/sponsors)
    * [ The ReadME Project  GitHub community articles  ](/readme)
Repositories
    * [ Topics ](/topics)
    * [ Trending ](/trending)


< link  name  =  "rotor"  >


< collision  name  =  "RR_position_control_link1_collision_0"  >


</  cylinder  >


</  geometry  >


name  =  "gz::sim::systems::JointPositionController"  >


Similarly to the trajectory representation case above, it’s possible to
support new hardware interfaces, or alternative mappings to an already
supported interface (eg. a proxy controller for generating effort commands).


time_from_start {


Conversations


< radius  >0.01</  radius  >


< diffuse  >0 0.8 0.8 1</  diffuse  >


  * [ List ](namespaces.html)
  * [ Members ](namespacemembers.html)
  * [ Functions ](namespacemembers_func.html)
  * [ Typedefs ](namespacemembers_type.html)
  * [ Variables ](namespacemembers_vars.html)
  * [ Enumerations ](namespacemembers_enum.html)
  * [ Enumerator ](namespacemembers_eval.html)


2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
` [ [JTC] Explicitly set hold position (backport
](/christophfroehlich/ros2_controllers/commit/170bfa41321cf382088d2ec905dc4d5c7498383f
"\[JTC\] Explicitly set hold position \(backport #558\)") [ ros-controls#558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ )
](/christophfroehlich/ros2_controllers/commit/170bfa41321cf382088d2ec905dc4d5c7498383f
"\[JTC\] Explicitly set hold position \(backport #558\)") `
` [ 170bfa4
](/christophfroehlich/ros2_controllers/commit/170bfa41321cf382088d2ec905dc4d5c7498383f)
`
[ christophfroehlich ](/christophfroehlich) added a commit to
christophfroehlich/ros2_controllers that referenced this pull request  Nov 27,
2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
` [ [JTC] Explicitly set hold position (backport
](/christophfroehlich/ros2_controllers/commit/fe5763f2c44673cb205a52b8878731062b854c55
"\[JTC\] Explicitly set hold position \(backport #558\)") [ ros-controls#558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ )
](/christophfroehlich/ros2_controllers/commit/fe5763f2c44673cb205a52b8878731062b854c55
"\[JTC\] Explicitly set hold position \(backport #558\)") `
` [ fe5763f
](/christophfroehlich/ros2_controllers/commit/fe5763f2c44673cb205a52b8878731062b854c55)
`
[ christophfroehlich ](/christophfroehlich) added a commit to
christophfroehlich/ros2_controllers that referenced this pull request  Nov 29,
2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
` [ [JTC] Explicitly set hold position (backport
](/christophfroehlich/ros2_controllers/commit/46655807a6e64bc9c3d5011a19c981e4c84fc979
"\[JTC\] Explicitly set hold position \(backport #558\)") [ ros-controls#558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ )
](/christophfroehlich/ros2_controllers/commit/46655807a6e64bc9c3d5011a19c981e4c84fc979
"\[JTC\] Explicitly set hold position \(backport #558\)") `


  rclcpp::Duration previous_traj_time(0ms);
  for (size_t i = 0; i < trajectory.points.size(); ++i)
  {
    if ((i > 0) && (rclcpp::Duration(trajectory.points[i].time_from_start) <= previous_traj_time))
    {
      RCLCPP_ERROR(
        get_node()->get_logger(),
        "Time between points %zu and %zu is not strictly increasing, it is %f and %f respectively",
        i - 1, i, previous_traj_time.seconds(),
        rclcpp::Duration(trajectory.points[i].time_from_start).seconds());
      return false;
    }
    previous_traj_time = trajectory.points[i].time_from_start;


Reply to author


![](JoinControllerForceMode.gif)


z: 1


---

All reactions
Sorry, something went wrong.
[ christophfroehlich ](/christophfroehlich) added a commit to
christophfroehlich/ros2_controllers that referenced this pull request  Oct 21,
2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
` [ [JTC] Explicitly set hold position (
](/christophfroehlich/ros2_controllers/commit/e01f5979a1670faa3a024335effeba2793302124
"\[JTC\] Explicitly set hold position \(#558\)") [ ros-controls#558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ )
](/christophfroehlich/ros2_controllers/commit/e01f5979a1670faa3a024335effeba2793302124
"\[JTC\] Explicitly set hold position \(#558\)") `
` [ e01f597
](/christophfroehlich/ros2_controllers/commit/e01f5979a1670faa3a024335effeba2793302124)
`
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [ christophfroehlich ](/christophfroehlich) mentioned
this pull request  Oct 21, 2023
[ [JTC] Backport recent changes  #801  ](/ros-
controls/ros2_controllers/pull/801)
Merged
[ christophfroehlich ](/christophfroehlich) added a commit to
christophfroehlich/ros2_controllers that referenced this pull request  Oct 21,
2023
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
` [ [JTC] Explicitly set hold position (backport
](/christophfroehlich/ros2_controllers/commit/975cf2fb140d18a792c3f9b35bdf56b404d5ed06
"\[JTC\] Explicitly set hold position \(backport #558\)") [ ros-controls#558
](https://github.com/ros-controls/ros2_controllers/pull/558) [ )
](/christophfroehlich/ros2_controllers/commit/975cf2fb140d18a792c3f9b35bdf56b404d5ed06
"\[JTC\] Explicitly set hold position \(backport #558\)") `
` [ 975cf2f
](/christophfroehlich/ros2_controllers/commit/975cf2fb140d18a792c3f9b35bdf56b404d5ed06)


![](JointTrajectoryController.png)


Sign in to reply to author


    // Enter hold current position mode
    add_new_trajectory_msg(set_hold_position());
  }
  return rclcpp_action::CancelResponse::ACCEPT;
}


  // Assign values from the command interfaces as command.
  if (has_position_command_interface_)
  {
    if (interface_has_values(joint_command_interface_[0]))
    {
      assign_point_from_interface(commands.positions, joint_command_interface_[0]);
    }
    else
    {
      commands.positions.clear();
      has_values = false;
    }
  }
  if (has_velocity_command_interface_)
  {
    if (interface_has_values(joint_command_interface_[1]))
    {
      assign_point_from_interface(commands.velocities, joint_command_interface_[1]);
    }
    else
    {
      commands.velocities.clear();
      has_values = false;
    }
  }
  if (has_acceleration_command_interface_)
  {
    if (interface_has_values(joint_command_interface_[2]))
    {
      assign_point_from_interface(commands.accelerations, joint_command_interface_[2]);
    }
    else
    {
      commands.accelerations.clear();
      has_values = false;
    }
  }
  if (has_effort_command_interface_)
  {
    if (interface_has_values(joint_command_interface_[3]))


< material  >


child: "rotor"


Forward


**Note** : by default velocity and position control are disabled if one wants
to use this mode, they must specify the PID gains value according to usage.


< length  >0.2</  length  >


positions: -1.5708


A detailed description and related parameter of JointTrajectoryController can
be found [ here ](classgz_1_1sim_1_1systems_1_1JointTrajectoryController.html)
.


</  link  >


< visual  name  =  "RR_position_control_link2_visual"  >


< attenuation  >


joint_names: "RR_position_control_joint2"


Search


< specular  >0.2 0.2 0.2 1</  specular  >


###  Adolfo Rodríguez Tsouroukdissian


> Adolfo
>
>  Thank you soo much for the link, it really helped me break down the
> confusion :). My next question then is if the effort controller is outputing
> a position that uses the position error, and velocity error, how can I
> extract the velocity error? If possible I would like to continue using the
> effort controller and extract the velocity error from the command , so that
> I can control the arm using the velocity error. This way i can use velocity
> to control the arm and use the position error to determine other factors. Or
> should I go another route and use the velocity controller created for the
> joint_trajectory_controllers but still not released( [
> https://github.com/ros- __ controls/ros_controllers/pull/ __ 64
> ](https://github.com/ros-controls/ros_controllers/pull/64) )?
>


< size  >0.25 0.1 0.05</  size  >


  // parse remaining parameters
  default_tolerances_ = get_segment_tolerances(params_);


< iyy  >0.0003358</  iyy  >


All groups and messages


![Adolfo Rodríguez Tsouroukdissian's profile
photo](https://lh3.googleusercontent.com/a/default-user=s40-c)


< use_force_commands  > true  </  use_force_commands  >


Joint names to control.


  has_position_command_interface_ =
    contains_interface_type(params_.command_interfaces, hardware_interface::HW_IF_POSITION);
  has_velocity_command_interface_ =
    contains_interface_type(params_.command_interfaces, hardware_interface::HW_IF_VELOCITY);
  has_acceleration_command_interface_ =
    contains_interface_type(params_.command_interfaces, hardware_interface::HW_IF_ACCELERATION);
  has_effort_command_interface_ =
    contains_interface_type(params_.command_interfaces, hardware_interface::HW_IF_EFFORT);


</  light  >


< child  > RR_position_control_link1  </  child  >


JointPositionController uses a PID controller to reach a desired joint
position.


unread,


](/ros-controls/ros2_controllers/tree/master "ros-
controls/ros2_controllers:master") from  [ christophfroehlich  :
jtc_hold_position
](/christophfroehlich/ros2_controllers/tree/jtc_hold_position
"christophfroehlich/ros2_controllers:jtc_hold_position") Aug 15, 2023
[ Conversation  50  ](/ros-controls/ros2_controllers/pull/558) [ Commits  65
](/ros-controls/ros2_controllers/pull/558/commits) [ Checks  13  ](/ros-
controls/ros2_controllers/pull/558/checks) [ Files changed ](/ros-
controls/ros2_controllers/pull/558/files)
##  Conversation
This file contains bidirectional Unicode text that may be interpreted or
compiled differently than what appears below. To review, open the file in an
editor that reveals hidden Unicode characters. [ Learn more about
bidirectional Unicode characters ](https://github.co/hiddenchars)
[ Show hidden characters ]({{ revealButtonHref }})
[
![christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=60&v=4)
](/christophfroehlich)
Copy link
Contributor
###
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=48&v=4)
**[ christophfroehlich ](/christophfroehlich) ** commented  Mar 31, 2023  •
edited
Using velocity or effort command interface: After canceling a goal (tolerances
or manually by cancelling the action) the movement is not stopped, see [ #514
](https://github.com/ros-controls/ros2_controllers/issues/514) . Thanks to [
@c-rizz ](https://github.com/c-rizz) for proposing a solution fixing [ #514
](https://github.com/ros-controls/ros2_controllers/issues/514)
**Edit:**
The behavior after merging this PR is the following:
  * ` set_hold_position ` is called at
    * Action interface:
      * state tolerance violation
      * goal_time_tolerance violation
      * cancel of action
      * reaching the goal successfully
    * Topic interface:
      * state tolerance violation
    * Activation: (optionally) The position which is read the first time from the hardware is actively held


~/joint_trajectory (input topic) [trajectory_msgs::msg::JointTrajectory]


void JointTrajectoryController::preempt_active_goal()
{
  const auto active_goal = *rt_active_goal_.readFromNonRT();
  if (active_goal)
  {
    auto action_res = std::make_shared<FollowJTrajAction::Result>();
    action_res->set__error_code(FollowJTrajAction::Result::INVALID_GOAL);
    action_res->set__error_string("Current goal cancelled due to new incoming action.");
    active_goal->setCanceled(action_res);
    rt_active_goal_.writeFromNonRT(RealtimeGoalHandlePtr());
  }
}


Default: 0.0 (tolerance is not enforced)


</  sdf  >


You do not have permission to delete messages in this group


w: 1


<!-- RR robot (Red) - Position control -->


< collision  name  =  "base_collision"  >


< cast_shadows  > false  </  cast_shadows  >


Sign in to forward


limit_upper: inf


< pose  relative_to  =  "RR_position_control_link1"  >0 0 0.1 0 0 0</  pose  >


  Reply to author


positions: 0


to Felix Meßmer, ros-sig-ro...@googlegroups.com, Michael Francis


< quadratic  >0.001</  quadratic  >


  // Print output so users can be sure the interface setup is correct
  RCLCPP_INFO(
    logger, "Command interfaces are [%s] and state interfaces are [%s].",
    get_interface_list(params_.command_interfaces).c_str(),
    get_interface_list(params_.state_interfaces).c_str());


![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=80&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
Copy link
Contributor  Author
###
**[ christophfroehlich ](/christophfroehlich) ** commented  Aug 24, 2023
I think I've found a possible issue, do you have set a ` goal_time_tolerance>0
` ? If the time tolerance is exceeded, the PID controller will be deactivated
even in hold position mode.

---

All reactions
Sorry, something went wrong.
[
![@BarisYazici](https://avatars.githubusercontent.com/u/11574709?s=80&u=69837dbce7c726a585a9e0bea0b38baa9626ba83&v=4)
](/BarisYazici)
Copy link
###
**[ BarisYazici ](/BarisYazici) ** commented  Aug 24, 2023
I didn't explicitly set a ` goal_time ` tolerance. So I guess this was not
checked. I used the panda_moveit_config launch file in our franka_ros2 repo to
test the new ` JTC ` . Maybe it's been implicitly set there but I doubt it.

---

All reactions
Sorry, something went wrong.
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=80&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
Copy link
Contributor  Author
###
**[ christophfroehlich ](/christophfroehlich) ** commented  Aug 24, 2023
I checked that now, false alarm. It could happen only if the PID can't hold
the position (wrong tuning, effort limit,..), then it might enter a loop
setting a new hold position again and again.

---


If you want to make this a configurable parameter, as other controller do, I'd
be happy to review a patch.


< cmd_max  >1000</  cmd_max  >


If you have velocity-controlled joints, keep an eye on [
https://github.com/ros-controls/ros_controllers/issues/43
](https://github.com/ros-controls/ros_controllers/issues/43)


Forward


< link  name  =  "RR_position_control_link1"  >


velocity: -2891.1685359866523


position {


< diffuse  >1 1 1 1</  diffuse  >


orientation {


id: 12


[ ![@DasRoteSkelett](https://avatars.githubusercontent.com/u/6168467?s=40&v=4)
](/DasRoteSkelett) [ DasRoteSkelett  ](/DasRoteSkelett) Awaiting requested
review from DasRoteSkelett
[ ![@VX792](https://avatars.githubusercontent.com/u/25421074?s=40&v=4)
](/VX792) [ VX792  ](/VX792) Awaiting requested review from VX792
[ ![@destogl](https://avatars.githubusercontent.com/u/1918204?s=40&v=4)
](/destogl) [ destogl  ](/destogl) Awaiting requested review from destogl
[ ![@erickisos](https://avatars.githubusercontent.com/u/14081477?s=40&v=4)
](/erickisos) [ erickisos  ](/erickisos) Awaiting requested review from
erickisos
[ ![@qiayuanl](https://avatars.githubusercontent.com/u/21256355?s=40&v=4)
](/qiayuanl) [ qiayuanl  ](/qiayuanl) Awaiting requested review from qiayuanl
[ ![@VanshGehlot](https://avatars.githubusercontent.com/u/63863949?s=40&v=4)
](/VanshGehlot) [ VanshGehlot  ](/VanshGehlot) Awaiting requested review from
VanshGehlot
Assignees
No one assigned
Labels
None yet
Projects
None yet
Milestone
No milestone
Development
Successfully merging this pull request may close these issues.
None yet
8 participants
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=52&v=4)
](/christophfroehlich) [ ![@codecov-
commenter](https://avatars.githubusercontent.com/u/65553080?s=52&v=4)
](/codecov-commenter) [
![@saikishor](https://avatars.githubusercontent.com/u/10082428?s=52&v=4)
](/saikishor) [
![@bmagyar](https://avatars.githubusercontent.com/u/3524577?s=52&v=4)
](/bmagyar) [
![@BarisYazici](https://avatars.githubusercontent.com/u/11574709?s=52&v=4)
](/BarisYazici) [
![@destogl](https://avatars.githubusercontent.com/u/1918204?s=52&v=4)
](/destogl) [


All reactions
Sorry, something went wrong.
[
![@BarisYazici](https://avatars.githubusercontent.com/u/11574709?s=80&u=69837dbce7c726a585a9e0bea0b38baa9626ba83&v=4)
](/BarisYazici)
Copy link
###
**[ BarisYazici ](/BarisYazici) ** commented  Aug 24, 2023  •
edited
I think the problem is set_hold_position() is never get called in our case.
When I add this ` else ` condition from [ motified_jtc
](https://github.com/frankaemika/franka_ros2/blob/humble/joint_trajectory_controller/src/joint_trajectory_controller.cpp#L353)
, it works.

---

All reactions
Sorry, something went wrong.
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [ christophfroehlich ](/christophfroehlich) mentioned
this pull request  Aug 24, 2023
[ [JTC] Hold position & goal_time>0: Infinite loop  #757  ](/ros-
controls/ros2_controllers/issues/757)
Closed
[
![@BarisYazici](https://avatars.githubusercontent.com/u/11574709?s=80&u=69837dbce7c726a585a9e0bea0b38baa9626ba83&v=4)
](/BarisYazici)
Copy link
###
**[ BarisYazici ](/BarisYazici) ** commented  Aug 24, 2023
in our case ` goal_time ` is default 0 . And the set_hold_position is never
get called when the robot reaches the target.

---

All reactions
Sorry, something went wrong.
[


< radius  >0.0125</  radius  >


< range  >1000</  range  >


( _Not implemented yet_ ) When using pure ` velocity  ` or ` effort  `
controllers a command is generated using the desired state and state error
using a velocity feedforward term plus a corrective PID term. (#171)


  // current state update
  state_current_.time_from_start.set__sec(0);
  read_state_from_state_interfaces(state_current_);


<?  xml  version  =  "1.0"  ?>


< light  type  =  "directional"  name  =  "sun"  >


< grid  > false  </  grid  >


Delete


filename  =  "gz-sim-joint-state-publisher-system"


Sign in to report message


</  box  >


Jul 4, 2014, 2:24:40 PM  7/4/14


  const auto trajectory_start_time = static_cast<rclcpp::Time>(trajectory.header.stamp);
  // If the starting time it set to 0.0, it means the controller should start it now.
  // Otherwise we check if the trajectory ends before the current time,
  // in which case it can be ignored.
  if (trajectory_start_time.seconds() != 0.0)
  {
    auto trajectory_end_time = trajectory_start_time;
    for (const auto & p : trajectory.points)
    {
      trajectory_end_time += p.time_from_start;
    }
    if (trajectory_end_time < get_node()->now())
    {
      RCLCPP_ERROR(
        get_node()->get_logger(),
        "Received trajectory with non-zero start time (%f) that ends in the past (%f)",
        trajectory_start_time.seconds(), trajectory_end_time.seconds());
      return false;
    }
  }


joint (list(string)):


< topic  > topic_name  </  topic  >


joint_names: "RR_position_control_joint1"


  for (size_t index = 0; index < dof_; ++index)
  {
    {
      if (
        std::find(
          trajectory_msg->joint_names.begin(), trajectory_msg->joint_names.end(),
          params_.joints[index]) != trajectory_msg->joint_names.end())
      {
        // joint found on msg
        continue;
      }
      trajectory_msg->joint_names.push_back(params_.joints[index]);


Internally, when the trajectory is sampled, one has access to the desired
position, velocity and acceleration. For position controlled joints it
suffices to forward the desired position. For effort controlled joints, a PID
around position is implemented (note that we also have access to the current
position and velocity to compute errors).


Show original message


< ambient  >0.5 0 0 1</  ambient  >


Default: 0.0 (not checked)


positions: -1.5708


< collision  name  =  "RR_position_control_link2_collision"  >


< pose  >0 0 0 0 0 0</  pose  >


</  dynamics  >


< ambient  >0.5 0.5 0.5 1</  ambient  >


Report message


Sign in to report message


Forward


</  geometry  >


< mass  >120.0</  mass  >


Sign in to reply to author


< iyz  >0</  iyz  >


##  Using Joint Trajectory Controller(s)  


  // Setup goal status checking timer
  goal_handle_timer_ = get_node()->create_wall_timer(
    action_monitor_period_.to_chrono<std::chrono::nanoseconds>(),
    std::bind(&RealtimeGoalHandle::runNonRealtime, rt_goal));
}


unread,


  for (size_t index = 0; index < allowed_interface_types_.size(); ++index)
  {
    joint_command_interface_[index].clear();
    joint_state_interface_[index].clear();
  }
  release_interfaces();


~/follow_joint_trajectory (action server)
[control_msgs::action::FollowJointTrajectory]


< direction  >-0.5 0.1 -0.9</  direction  >


The following version of the Joint Trajectory Controller are available mapping
the following interfaces:


< damping  >0.25</  damping  >


You do not have permission to delete messages in this group


</  cylinder  >


controller_interface::InterfaceConfiguration
JointTrajectoryController::state_interface_configuration() const
{
  controller_interface::InterfaceConfiguration conf;
  conf.type = controller_interface::interface_configuration_type::INDIVIDUAL;
  conf.names.reserve(dof_ * params_.state_interfaces.size());
  for (const auto & joint_name : params_.joints)
  {
    for (const auto & interface_type : params_.state_interfaces)
    {
      conf.names.push_back(joint_name + "/" + interface_type);
    }
  }
  return conf;
}


> How is it possible to move without being allowed to exceed the effort limit?
> (I saw that the command value in the state message of the
> JointVelocityController has values much higher than the effort limit (which
> seems to be ok, as the documentation for SetForce() says that the commanded
> effort is truncated to the effort limit).
>


    auto it = std::find(params_.joints.begin(), params_.joints.end(), incoming_joint_name);
    if (it == params_.joints.end())
    {
      RCLCPP_ERROR(
        get_node()->get_logger(), "Incoming joint %s doesn't match the controller's joints.",
        incoming_joint_name.c_str());
      return false;
    }
  }


< geometry  >


<!-- Joints -->


  * [ Index ](classes.html)
  * [ List ](annotated.html)
  * [ Hierarchy ](hierarchy.html)
  * [ Members: All ](functions.html)
  * [ Members: Functions ](functions_func.html)
  * [ Members: Variables ](functions_vars.html)
  * [ Members: Typedefs ](functions_type.html)
  * [ Members: Enumerations ](functions_enum.html)
  * [ Members: Enumerator ](functions_eval.html)


</  material  >


> controls/ros2_controllers/commit/0e82010d3e067c88aa30e892ac266ba5790ee0f9) )
> into [ master ](https://app.codecov.io/gh/ros-
> controls/ros2_controllers/commit/e7f99620c17dee0abbdeb49af1e5f52bf5fabbd0?el=desc&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
> controls) ( [ ` e7f9962 ` ](https://github.com/ros-
> controls/ros2_controllers/commit/e7f99620c17dee0abbdeb49af1e5f52bf5fabbd0) )
> will **decrease** coverage by ` 4.90% ` .
>  Report is 352 commits behind head on master.
>  The diff coverage is ` 25.91% ` .
❗ Your organization is not using the GitHub App Integration. As a result you
may experience degraded service beginning May 15th. Please [ install the
Github App Integration ](https://github.com/apps/codecov) for your
organization. [ Read more ](https://about.codecov.io/blog/codecov-is-updating-
its-github-
integration/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls) .

    @@            Coverage Diff             @@
    ##           master     #558      +/-   ##
    ==========================================
    - Coverage   35.78%   30.88%   -4.90%
    ==========================================
      Files         189        7     -182
      Lines       17570      832   -16738
      Branches    11592      505   -11087
    ==========================================
    - Hits         6287      257    -6030
    + Misses        994      133     -861
    + Partials    10289      442    -9847
|  Flag  |  Coverage Δ  |
---|---|---
unittests  |  ` 30.88% <25.91%> (-4.90%) ` |  ⬇

Flags with carried forward coverage won't be shown. [ Click here
](https://docs.codecov.io/docs/carryforward-
flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls#carryforward-flags-in-the-pull-request-comment) to find out more.
[ Files Changed ](https://app.codecov.io/gh/ros-
controls/ros2_controllers/pull/558?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls) |  Coverage Δ  |


< cylinder  >


</  plugin  >


The former produces effort commands that realize the desired trajectory, while
the latter produces position commands that do the same thing. You use one or
the other depending on whether your hardware exposes effort or position
controlled joints.


* Joint trajectory controller, which can be attached to a model with reference to one or more 1-axis joints to follow a trajectory.


    {
      assign_point_from_interface(commands.effort, joint_command_interface_[3]);
    }
    else
    {
      commands.effort.clear();
      has_values = false;
    }
  }


Forward


  return CallbackReturn::SUCCESS;
}


    trajectory_msg->points[index].velocities =
      remap(trajectory_msg->points[index].velocities, mapping_vector);


> When we now command a velocity in the same direction as the effort (e.g.
> send negative velocity in case current effort is -effort_limit), the arm
> move but the current effort still is equal to the previous effort value
> (still -effort_limit).
>


position {


</  geometry  >


RCLCPP_WARN(get_node()->get_logger(), error_string.c_str());


gz topic -e -t /world/default/model/joint_controller_demo/joint_state


2) In this tutorial we will be using the following SDF file (this is just a
slight modification of the original ` joint_controller.sdf ` [ example
](https://github.com/gazebosim/gz-sim/blob/gz-
sim7/examples/worlds/joint_controller.sdf) ).


< visual  name  =  "RR_position_control_link1_visual_1"  >


#include "pluginlib/class_list_macros.hpp"


< linear  >0.01</  linear  >


![Adolfo Rodríguez Tsouroukdissian's profile
photo](//lh3.googleusercontent.com/a-/ALV-
UjWUxHT8qByi6OYKbrEfTiu12v2zMkGSVemC9-iV-3dj6so_yIrg=s40-c)


  auto get_interface_list = [](const std::vector<std::string> & interface_types)
  {
    std::stringstream ss_interfaces;
    for (size_t index = 0; index < interface_types.size(); ++index)
    {
      if (index != 0)
      {
        ss_interfaces << " ";
      }
      ss_interfaces << interface_types[index];
    }
    return ss_interfaces.str();
  };


All the parameters related to this controller can be found [ here
](classgz_1_1sim_1_1systems_1_1JointController.html) .


< pose  >0.0 0.0 0.0 0 0 0</  pose  >


< normal  >0 0 1</  normal  >


Yes
[ https://github.com/ros-controls/ros_controllers/blob/indigo-
devel/effort_controllers/src/joint_velocity_controller.cpp#L146
](https://github.com/ros-controls/ros_controllers/blob/indigo-
devel/effort_controllers/src/joint_velocity_controller.cpp#L146)


Reply to author


void JointTrajectoryController::resize_joint_trajectory_point(
  trajectory_msgs::msg::JointTrajectoryPoint & point, size_t size)
{
  point.positions.resize(size, 0.0);
  if (has_velocity_state_interface_)
  {
    point.velocities.resize(size, 0.0);
  }
  if (has_acceleration_state_interface_)
  {
    point.accelerations.resize(size, 0.0);
  }
}


< radius  >0.01</  radius  >


3) Sending trajectory message (Can also change the topic name).


< joint  name  =  "RR_position_control_joint2"  type  =  "revolute"  >


Report message


I'm not sure. Gazebo's changelog and roadmap don't make much mention of it.
Some time ago it was in the roadmap, but not anymore.


I don't know what can be happening here. I suggest using a debugger and follow
the trail until the unexpected action happens, which can be on how commands
are sent to Gazebo, within Gazebo itself, or on how the state is read from
Gazebo.


"Merge branch 'jtc-features' into jtc_hold_position") `
` [ 6133afd ](/ros-
controls/ros2_controllers/pull/558/commits/6133afd0a0617555af33d55b61be312576564d55)
`
This was referenced  May 11, 2023
[ [JTC] Fix tests and set_hold_position  #607  ](/ros-
controls/ros2_controllers/pull/607)
Closed
[ [JTC] Hold the position after the goal was reached successfully  #608
](/ros-controls/ros2_controllers/pull/608)
Closed
[ christophfroehlich ](/christophfroehlich) added  3  commits  May 12, 2023
20:58
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&v=4)
](/christophfroehlich)
` [ Make hold on startup configurable and add tests ](/ros-
controls/ros2_controllers/pull/558/commits/9bd49b3b8ed872109b941ba0b2cf517db1009e41
"Make hold on startup configurable and add tests") `
` [ 9bd49b3 ](/ros-
controls/ros2_controllers/pull/558/commits/9bd49b3b8ed872109b941ba0b2cf517db1009e41)
`
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&v=4)
](/christophfroehlich)
` [ Update comment ](/ros-
controls/ros2_controllers/pull/558/commits/8755e3783e1622adc57d589ecbf052876fc23da3
"Update comment") `
` [ 8755e37 ](/ros-
controls/ros2_controllers/pull/558/commits/8755e3783e1622adc57d589ecbf052876fc23da3)
`
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&v=4)
](/christophfroehlich)
` [ Cleanup tests ](/ros-
controls/ros2_controllers/pull/558/commits/ac48006565996191dbf889980f3e7a95f769e003
"Cleanup tests") `
` [ ac48006 ](/ros-
controls/ros2_controllers/pull/558/commits/ac48006565996191dbf889980f3e7a95f769e003)
`


< joint_name  > RR_position_control_joint1  </  joint_name  >


</  inertial  >


>
>  For more options, visit [ https://groups.google.com/d/optout
> ](https://groups.google.com/d/optout) .
>


void JointTrajectoryController::init_hold_position_msg()
{
  hold_position_msg_ptr_ = std::make_shared<trajectory_msgs::msg::JointTrajectory>();
  hold_position_msg_ptr_->header.stamp =
    rclcpp::Time(0.0, 0.0, get_node()->get_clock()->get_clock_type());  // start immediately
  hold_position_msg_ptr_->joint_names = params_.joints;
  hold_position_msg_ptr_->points.resize(1);  // a trivial msg only
  hold_position_msg_ptr_->points[0].velocities.clear();
  hold_position_msg_ptr_->points[0].accelerations.clear();
  hold_position_msg_ptr_->points[0].effort.clear();
  if (has_velocity_command_interface_ || has_acceleration_command_interface_)
  {
    // add velocity, so that trajectory sampling returns velocity points in any case
    hold_position_msg_ptr_->points[0].velocities.resize(dof_, 0.0);
  }
  if (has_acceleration_command_interface_)
  {
    // add velocity, so that trajectory sampling returns acceleration points in any case
    hold_position_msg_ptr_->points[0].accelerations.resize(dof_, 0.0);
  }
}


Adolfo.


Copy link


pose {


#include "joint_trajectory_controller/joint_trajectory_controller.hpp"


  if (trajectory.joint_names.empty())
  {
    RCLCPP_ERROR(get_node()->get_logger(), "Empty joint names on incoming trajectory.");
    return false;
  }


97 hidden items  Load more…
[
![@RobertWilbrandt](https://avatars.githubusercontent.com/u/7694551?s=40&v=4)
](/RobertWilbrandt) [ RobertWilbrandt ](/RobertWilbrandt) mentioned this pull
request  Aug 21, 2023
[ ur_controllers build error due to class change in JTC
UniversalRobots/Universal_Robots_ROS2_Driver#778
](/UniversalRobots/Universal_Robots_ROS2_Driver/issues/778)
Closed
[
![@BarisYazici](https://avatars.githubusercontent.com/u/11574709?s=80&u=69837dbce7c726a585a9e0bea0b38baa9626ba83&v=4)
](/BarisYazici)
Copy link
###
**[ BarisYazici ](/BarisYazici) ** commented  Aug 24, 2023
I just had the time to test on our FR3 robot. And it still didn't solve the
hold position issue. I didn't dive deep in debugging, but basically the robot
successfully goes to the goal position and either free falls down or drags
slowly sideways. We are only using effort commands. I will test today again.

---

All reactions
Sorry, something went wrong.
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=80&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich)
Copy link
Contributor  Author
###
**[ christophfroehlich ](/christophfroehlich) ** commented  Aug 24, 2023  •
edited
To ensure that I understand you setup: Are you using effort command with
active feedback gains of the PID controller?

---

All reactions
Sorry, something went wrong.
[


< box  >


On Fri, Jul 4, 2014 at 2:45 PM, Felix Meßmer  < [ felixm...@gmail.com ]() >
wrote:


subscriber_is_active_ = true;


<!-- Controller -->


Sign in to forward


        // Always check the state tolerance on the first sample in case the first sample
        // is the last point
        // print output per default, goal will be aborted afterwards
        if (
          (before_last_point || first_sample) && *(rt_is_holding_.readFromRT()) == false &&
          !check_state_tolerance_per_joint(
            state_error_, index, default_tolerances_.state_tolerance[index],
            true /* show_errors */))
        {
          tolerance_violated_while_moving = true;
        }
        // past the final point, check that we end up inside goal tolerance
        if (
          !before_last_point && *(rt_is_holding_.readFromRT()) == false &&
          !check_state_tolerance_per_joint(
            state_error_, index, default_tolerances_.goal_state_tolerance[index],
            false /* show_errors */))
        {
          outside_goal_tolerance = true;


>
>     controller_manager:
>       ros__parameters:
>         joint_trajectory_controller:
>         type: "joint_trajectory_controller/JointTrajectoryController"
>
>     joint_trajectory_controller:
>       ros__parameters:
>         joints:
>           - joint1
>           - joint2
>           - joint3
>           - joint4
>           - joint5
>           - joint6
>
>         command_interfaces:
>           - position
>
>         state_interfaces:
>           - position
>           - velocity
>
>         state_publish_rate: 50.0
>         action_monitor_rate: 20.0
>
>         allow_partial_joints_goal: false
>         open_loop_control: true
>         constraints:
>           stopped_velocity_tolerance: 0.01
>           goal_time: 0.0
>           joint1:
>             trajectory: 0.05
>             goal: 0.03
>


</  link  >


</  joint  >


gz topic -t "/topic_name" -m gz.msgs.Double -p "data: 10.0"


Sign in to report message


After changing the directory, name the SDF file as ` example.sdf `


< inertial  >


  publish_state(time, state_desired_, state_current_, state_error_);
  return controller_interface::return_type::OK;
}


In case, PID gains are not specified then by default force mode will work.


axis1 {


> When I removed the tag, the controller seems to behave (at least a bit)
> better.


###  mfr...@vt.edu


##  Specialized versions of JointTrajectoryController (TBD in …)  


Reply to author


Jul 11, 2014, 10:57:26 PM  7/11/14


Copy link


#include <chrono>
#include <functional>
#include <memory>


< position_d_gain  >0.5</  position_d_gain  >


  return has_values;
}


> \--
>  You received this message because you are subscribed to the Google Groups
> "ROS/Orocos Robot Control Special Interest Group" group.
>  To unsubscribe from this group and stop receiving emails from it, send an
> email to [ ros-sig-robot-co...@googlegroups.com ]() .
>  For more options, visit [ https://groups.google.com/d/optout
> ](https://groups.google.com/d/optout) .
>


![mfr...@vt.edu's profile photo](//lh3.googleusercontent.com/a-/ALV-
UjXLZw18gFzZHa2C4A0mrLpZ13blWBOpMeCRZ4tYXUaxAYg45w=s40-c)


    const size_t joint_count = trajectory.joint_names.size();
    const auto & points = trajectory.points;
    // This currently supports only position, velocity and acceleration inputs
    if (params_.allow_integration_in_goal_trajectories)
    {
      const bool all_empty = points[i].positions.empty() && points[i].velocities.empty() &&
                             points[i].accelerations.empty();
      const bool position_error =
        !points[i].positions.empty() &&
        !validate_trajectory_point_field(joint_count, points[i].positions, "positions", i, false);
      const bool velocity_error =
        !points[i].velocities.empty() &&
        !validate_trajectory_point_field(joint_count, points[i].velocities, "velocities", i, false);
      const bool acceleration_error =
        !points[i].accelerations.empty() &&
        !validate_trajectory_point_field(
          joint_count, points[i].accelerations, "accelerations", i, false);
      if (all_empty || position_error || velocity_error || acceleration_error)
      {
        return false;
      }
    }
    else if (
      !validate_trajectory_point_field(joint_count, points[i].positions, "positions", i, false) ||
      !validate_trajectory_point_field(joint_count, points[i].velocities, "velocities", i, true) ||
      !validate_trajectory_point_field(
        joint_count, points[i].accelerations, "accelerations", i, true))
    {
      return false;
    }
    // reject effort entries
    if (!points[i].effort.empty())
    {
      RCLCPP_ERROR(
        get_node()->get_logger(), "Trajectories with effort fields are currently not supported.");
      return false;
    }
  }
  return true;
}


>
>  \- Is it possible that a slower update frequency for the
> JointVelocityController might help the problem? Is this update frequency
> parameterizable? Where can I set it? I think the default is the gazebo tick
> rate, isn't it?
>


##  2) JointPositionController


Built with [ Sphinx ](https://www.sphinx-doc.org/) using a [ theme
](https://github.com/readthedocs/sphinx_rtd_theme) provided by [ Read the Docs
](https://readthedocs.org) .


< geometry  >


You do not have permission to delete messages in this group


</  sphere  >


< radius  >0.0125</  radius  >


On Fri, Jul 4, 2014 at 8:24 AM, Felix Meßmer  < [ felixm...@gmail.com ]() >
wrote:


Sign in to reply to author


</  geometry  >


Either email addresses are anonymous for this group or you need the view
member email addresses permission to view the original message


Forward


< material  >


joint given. But looking at the yaml file I see the list of joints?

Thanks
Mike


state_interfaces (list(string)):


< ixz  >0</  ixz  >


###  Felix Meßmer


> If I am correct in my assumption from above what is
> "position_controllers/JointTrajectoryController" for (I havent tried to use
> this controller yet)?
>
>  Also I was wondering does "effort_controllers/JointTrajectoryController"
> use joint_position_controller.cpp located in
> ros_controllers/effort_controllers/src directory? If so does the cmd [ ]
> (mentioned above) use the setCommand() function to get its target position
> data?
>


  RCLCPP_INFO(get_node()->get_logger(), "Accepted new action goal");
  return rclcpp_action::GoalResponse::ACCEPT_AND_EXECUTE;
}


> Thanks for the comments,
>
>  it seems that we are able to find (more or less) good/satisfying PIDs for
> all separate joint respectively following the approach mentioned above.
>  However, as soon as we allow several joints to be revolute again at the
> same time, The behaviour is bad again - as Adolfo already expected for the
> obvious reasons.
>  We again see highly oscillating values in the joint controllers changing
> the sign evey update cycle.
>
>  Some things that we are currently thinking about:
>  \- As we do not know realistic values for damping, friction and so on, so
> far, we tried to use default values (or simply remove the respective tags
> from the URDF or the gazebo extension XACRO). In fact, we currently only set
> the <matrial> in the gazebo extension and use damping=0 and friction=0 in
> the URDF. (Friction is not implemented in Gazebo anyway, isn't it?)
>


controller_interface::CallbackReturn JointTrajectoryController::on_init()
{
  if (!urdf_.empty())
  {
    if (!model_.initString(urdf_))
    {
      RCLCPP_ERROR(get_node()->get_logger(), "Failed to parse URDF file");
    }
    else
    {
      RCLCPP_DEBUG(get_node()->get_logger(), "Successfully parsed URDF file");
    }
  }
  else
  {
    // empty URDF is used for some tests
    RCLCPP_DEBUG(get_node()->get_logger(), "No URDF file given");
  }


Jul 7, 2014, 4:47:35 PM  7/7/14


< size  >5 5</  size  >


< position_i_min  >-1</  position_i_min  >


< link  name  =  "background_plane_link"  >


</  world  >


rclcpp_action::CancelResponse JointTrajectoryController::goal_cancelled_callback(
  const std::shared_ptr<rclcpp_action::ServerGoalHandle<FollowJTrajAction>> goal_handle)
{
  RCLCPP_INFO(get_node()->get_logger(), "Got request to cancel goal");


axis1 {


< cmd_min  >-1000</  cmd_min  >


Delete


Default value for end velocity deviation.


We identify the plant by exciting it with signals of varying frequency, and
then run some frequency-domain tools from Matlab. There are some building
blocks for doing a sine sweep in the control_toolbox package.

[ https://github.com/ros-controls/control_toolbox/tree/indigo-
devel/include/control_toolbox ](https://github.com/ros-
controls/control_toolbox/tree/indigo-devel/include/control_toolbox)


<!-- Links -->


positions: 1.5708


< box  >


This sounds unexpected.


state_publish_rate (double):


rclcpp_action::GoalResponse JointTrajectoryController::goal_received_callback(
  const rclcpp_action::GoalUUID &, std::shared_ptr<const FollowJTrajAction::Goal> goal)
{
  RCLCPP_INFO(get_node()->get_logger(), "Received new action goal");


  // update the dynamic map parameters
  param_listener_->refresh_dynamic_parameters();


</  geometry  >


</  link  >


Releases


e.g.


Show original message


}  // namespace joint_trajectory_controller


joint {


gz topic -t "topic_name" -m gz.msgs.JointTrajectory -p '


< visual  name  =  "background_plane_visual"  >


RCLCPP_INFO(get_node()->get_logger(), "Goal reached, success!");


  * Joint position controller which can be attached to a model with a reference to a single joint.
  * One can mention the axis of the joint they want to control.


< collision  name  =  "RR_position_control_link0_collision_0"  >


void JointTrajectoryController::resize_joint_trajectory_point_command(
  trajectory_msgs::msg::JointTrajectoryPoint & point, size_t size)
{
  if (has_position_command_interface_)
  {
    point.positions.resize(size, 0.0);
  }
  if (has_velocity_command_interface_)
  {
    point.velocities.resize(size, 0.0);
  }
  if (has_acceleration_command_interface_)
  {
    point.accelerations.resize(size, 0.0);
  }
  if (has_effort_command_interface_)
  {
    point.effort.resize(size, 0.0);
  }
}


Delete


... and [ 189 files with indirect coverage changes
](https://app.codecov.io/gh/ros-controls/ros2_controllers/pull/558/indirect-
changes?src=pr&el=tree-
more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-
controls)

All reactions
Sorry, something went wrong.
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&u=98db36351213b952b1c6ce663c1fde4108272539&v=4)
](/christophfroehlich) [ christophfroehlich ](/christophfroehlich) changed the
base branch from  master  to  jtc-features  May 8, 2023 17:47
[ christophfroehlich ](/christophfroehlich) added  3  commits  May 8, 2023
19:48
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&v=4)
](/christophfroehlich)
` [ Merge branch 'jtc-features' into jtc_hold_position ](/ros-
controls/ros2_controllers/pull/558/commits/41a3cd1f10a96892a0c450fdce0ee099fa67a505
"Merge branch 'jtc-features' into jtc_hold_position") `
` [ 41a3cd1 ](/ros-
controls/ros2_controllers/pull/558/commits/41a3cd1f10a96892a0c450fdce0ee099fa67a505)
`
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&v=4)
](/christophfroehlich)
` [ [JTC] Renovate action tests ( ](/ros-
controls/ros2_controllers/pull/558/commits/583b8152e864ec19b67e5d0a7acc303d09cbac03
"\[JTC\] Renovate action tests \(#603\)") [ ros-controls#603
](https://github.com/ros-controls/ros2_controllers/pull/603) [ ) ](/ros-
controls/ros2_controllers/pull/558/commits/583b8152e864ec19b67e5d0a7acc303d09cbac03
"\[JTC\] Renovate action tests \(#603\)") `
` [ 583b815 ](/ros-
controls/ros2_controllers/pull/558/commits/583b8152e864ec19b67e5d0a7acc303d09cbac03)
`
[
![@christophfroehlich](https://avatars.githubusercontent.com/u/3367244?s=40&v=4)
](/christophfroehlich)
` [ Merge branch 'jtc-features' into jtc_hold_position ](/ros-
controls/ros2_controllers/pull/558/commits/6133afd0a0617555af33d55b61be312576564d55


> Sorry for the late response Adolfo,
>
>  First of all thanks for the feedback. I guess what my main concern is how
> can I extract the velocity data being sent through the trajectory msg? I
> started digging around and came to the conclusion that I dont fully
> understand the difference between
> "effort_controllers/JointTrajectoryController" and
> "position_controllers/JointTrajectoryController".
>


        // check abort
        if (tolerance_violated_while_moving)
        {
          auto result = std::make_shared<FollowJTrajAction::Result>();
          result->set__error_code(FollowJTrajAction::Result::PATH_TOLERANCE_VIOLATED);
          result->set__error_string("Aborted due to path tolerance violation");
          active_goal->setAborted(result);
          // TODO(matthew-reynolds): Need a lock-free write here
          // See https://github.com/ros-controls/ros2_controllers/issues/168
          rt_active_goal_.writeFromNonRT(RealtimeGoalHandlePtr());
          rt_has_pending_goal_.writeFromNonRT(false);


  // parse timeout parameter
  if (params_.cmd_timeout > 0.0)
  {
    if (params_.cmd_timeout > default_tolerances_.goal_time_tolerance)
    {
      cmd_timeout_ = params_.cmd_timeout;
    }
    else
    {
      // deactivate timeout
      RCLCPP_WARN(
        get_node()->get_logger(),
        "Command timeout must be higher than goal_time tolerance (%f vs. %f)", params_.cmd_timeout,
        default_tolerances_.goal_time_tolerance);
      cmd_timeout_ = 0.0;
    }
  }
  else
  {
    cmd_timeout_ = 0.0;
  }


</  geometry  >


Adolfo.


![Adolfo Rodríguez Tsouroukdissian's profile
photo](https://lh3.googleusercontent.com/a/default-user=s40-c)


Jul 4, 2014, 8:45:04 PM  7/4/14


name  =  "gz::sim::systems::JointController"  >


positions: 0


>
>
>  @Adolfo:
>  Can you elaborate a bit more on what frequency-domain tools you were using?
> Do you mean Bode-Diagram and stuff like that?
>  So you have a mathematical model for your hardware, right?
>


5) Checking Joint states. Here the state of the joint is obtained using the
Gazeboâs JointStatepublisher plugin. Please visit [
gz::sim::systems::JointStatePublisher
](classgz_1_1sim_1_1systems_1_1JointStatePublisher.html) for more information.


< inertia  >


  // Precondition: Running controller
  if (get_state().id() == lifecycle_msgs::msg::State::PRIMARY_STATE_INACTIVE)
  {
    RCLCPP_ERROR(
      get_node()->get_logger(), "Can't accept new action goals. Controller is not running.");
    return rclcpp_action::GoalResponse::REJECT;
  }


Topic publishing internal states.


z: -0.5


< pose  >5 5 5 0 0 0</  pose  >


positions: -1.5708


![Felix Meßmer's profile photo](//lh3.googleusercontent.com/a-/ALV-UjXo2aXfAk-
du0bo7Rk6_qcY5MZE8BRzAtLvSi33j1VJUTXvhQ=s40-c)


##  3) JointTrajectoryController.


* Add the following lines to the SDF file before ` </model> ` tag:


* Force mode


< position_p_gain  >10</  position_p_gain  >


</  inertial  >


< joint  name  =  "j1"  type  =  "revolute"  >


< sphere  >


< collision  name  =  "collision"  >


Best,

Adolfo.


< pose  relative_to  =  "RR_position_control_joint1"  >0 0 0.2 0 0 0</  pose
>


  Forward


< parent  > RR_position_control_link0  </  parent  >


Either email addresses are anonymous for this group or you need the view
member email addresses permission to view the original message


Delete


  resize_joint_trajectory_point(state_current_, dof_);
  resize_joint_trajectory_point_command(command_current_, dof_);
  resize_joint_trajectory_point(state_desired_, dof_);
  resize_joint_trajectory_point(state_error_, dof_);
  resize_joint_trajectory_point(last_commanded_state_, dof_);


xyz {


HTH,


Copy link


to ros-sig-ro...@googlegroups.com, felixm...@gmail.com, mfr...@vt.edu,
adolfo.r...@pal-robotics.com


  // The controller should start by holding position at the beginning of active state
  add_new_trajectory_msg(set_hold_position());
  rt_is_holding_.writeFromNonRT(true);


< izz  >5</  izz  >


< radius  >0.025</  radius  >


Let's see an example for both modes using a simple model having only one
joint.


  if (params_.state_interfaces.empty())
  {
    RCLCPP_ERROR(logger, "'state_interfaces' parameter is empty.");
    return CallbackReturn::FAILURE;
  }


Show original message


> If you have velocity-controlled joints, keep an eye on [
> https://github.com/ros-controls/ros_controllers/issues/43
> ](https://github.com/ros-controls/ros_controllers/issues/43)
>  This would be the right way to do it.
>


</  inertia  >


</  link  >


<!-- Fix To World -->


unread,


allow_partial_joints_goal (boolean):


>
>  \- We also have had the <safety_controller> tag in our URDF. There were
> values for k_p and k_v, where I don't know where they come from.


###  Modes of JointController


> To unsubscribe from this group and stop receiving emails from it, send an
> email to [ ros-sig-robot-co...@googlegroups.com ]() .


The controller is templated to work with multiple hardware interface types.
Currently joints with position, velocity and effort interfaces are supported.
For position-controlled joints, desired positions are simply forwarded to the
joints; while for velocity (effort) joints, the position+velocity trajectory
following error is mapped to velocity (effort) commands through a PID loop.
Example controller configurations can be found here.


</  joint  >


Google apps


>
>  Finally I just wanted to know if I could use
> "effort_controllers/JointTrajectoryController" and some how grab the
> velocity values coming from the trajectory msg from moveit using it?
>


Reply to author


Forward


Do you get constant high velocities, isolated peaks or noise?.


          traj_msg_external_point_ptr_.reset();
          traj_msg_external_point_ptr_.initRT(set_hold_position());
        }
        // check goal tolerance
        else if (!before_last_point)
        {
          if (!outside_goal_tolerance)
          {
            auto result = std::make_shared<FollowJTrajAction::Result>();
            result->set__error_code(FollowJTrajAction::Result::SUCCESSFUL);
            result->set__error_string("Goal successfully reached!");
            active_goal->setSucceeded(result);
            // TODO(matthew-reynolds): Need a lock-free write here
            // See https://github.com/ros-controls/ros2_controllers/issues/168
            rt_active_goal_.writeFromNonRT(RealtimeGoalHandlePtr());
            rt_has_pending_goal_.writeFromNonRT(false);


How exactly is the effort value calculated?


Command interfaces provided by the hardware interface for all joints.


  return hold_position_msg_ptr_;
}


Message type: [ ` JointTrajectory `
](https://gazebosim.org/api/msgs/7.2/classignition_1_1msgs_1_1JointTrajectory.html)


> I am also working with the effort_controller/JointVelocityController.
>  We are currently trying to figure out good PID gains for a 7DoF robot arm.
> I will post our experiences here, once we are done.
>
>  I just have a few questions:
>  \- Isn't the effort_controller/JointVelocityController a single joint
> controller? Thus only capable of having one joint being set in the joint
> tag?
>


* To check joint state.


</  visual  >


< plane  >