The electronic speed controller and motor are off the shelf components that are controlled by the Atheris control board. The electronic speed controller handles all of the power management for the motor. IR Four IR sensors (2x Sharp GP2Y0A02YK0F and 2x Sharp GP2D120) were used to provide mid to short range obstacle detection. Figure . Detail of IR sensors Although the datasheet described the sensors as having a maximum range of 150cm, the sensors actually were useful for roughly half of that range. Additionally, the sensors were virtually useless in daylight or for detecting black surfaces due to heavy interference from the former and almost complete absorption in the latter. Some characteristic that proved critical for the robot were the low speed and noisiness of the sensors the robot moved fast enough that it would collide with an – obstacle while it was being detected or before the sensors could it. “see” A Hall effect sensor, coupled with magnets embedded in the rear wheel, provided a means of calculating the velocity of the robot. It was connected to the input capture peripheral, which in turn was clocked from a real time clock, so as to provide an accurate measurement of the time take for a revolution of the rear wheel. Only two magnets were used, and they were placed on opposite ends of a diameter of the rear tire and in opposite polar configurations so that they would set and unset the Hall effect sensor over the course of one revolution. An ADXL345 digital 3-axis accelerometer was used for collision detection in the robot. It features tap and double tap detection, which were used to detected acceleration impulses arising from collision events. The tap and double tap detection were also used as option means of arming and starting the robot. High torque, digital servo (TRA2070) was used for steering. A wireless XBee module provided a means of meshed networking, untethered debugging, and a master override. A general purpose payload bay allowed simple reconfiguration of the robot to fit different mission requirements. The payload was a GPS module and compass monitored via a custom Propeller-based PCB.
The electronic speed controller and motor are off the shelf components that are controlled by the Atheris control board. The electronic speed controller handles all of the power management for the motor. IR Four IR sensors (2x Sharp GP2Y0A02YK0F and 2x Sharp GP2D120) were used to provide mid to short range obstacle detection. Figure . Detail of IR sensors Although the datasheet described the sensors as having a maximum range of 150cm, the sensors actually were useful for roughly half of that range. Additionally, the sensors were virtually useless in daylight or for detecting black surfaces due to heavy interference from the former and almost complete absorption in the latter. Some characteristic that proved critical for the robot were the low speed and noisiness of the sensors – the robot moved fast enough that it would collide with an obstacle while it was being detected or before the sensors could “see” it. A Hall effect sensor, coupled with magnets embedded in the rear wheel, provided a means of calculating the velocity of the robot. It was connected to the input capture peripheral, which in turn was clocked from a real time clock, so as to provide an accurate measurement of the time take for a revolution of the rear wheel. Only two magnets were used, and they were placed on opposite ends of a diameter of the rear tire and in opposite polar configurations so that they would set and unset the Hall effect sensor over the course of one revolution. An ADXL345 digital 3-axis accelerometer was used for collision detection in the robot. It features tap and double tap detection, which were used to detected acceleration impulses arising from collision events. The tap and double tap detection were also used as option means of arming and starting the robot. High torque, digital servo (TRA2070) was used for steering. A wireless XBee module provided a means of meshed networking, untethered debugging, and a master override. A general purpose payload bay allowed simple reconfiguration of the robot to fit different mission requirements. The payload was a GPS module and compass monitored via a custom Propeller-based PCB.
Devron_Lee.docx