based on performance first the object manipulator 211 will orient the object interface 213 and adjust the forces applied in the interface 213 to simulate the weight of a bottle as if the bottle is not held by the object manipulator 211 each task is defined by parameters such as object position orientation in 3d space distance of movement speed torque and force compensation to be applied etc a display 218 will then instruct the user to reach and lift the bottle for a doorknob turning task a trial is a success if the user turns the doorknob at or beyond a pre determined target angle for a jar opening closing task the trial is a success if the subject closes the jar lid at or beyond a pre determined angle for the doorbell pushing task the trial is a success if the pushing force is higher than a threshold force because a patient 39 s performance will presumably improve over the course of rehabilitation tasks that were initially challenging become less so with more practice thus adapting the tasks to each patient continuously will improve motor learning the adaptive performance based task scheduling and adaptive difficulty allows each user to perform the task within their capabilities while being constantly optimally challenged as the user 39 s performance improves heuristics may be used to modify adaptively the position of the end effector and the force needed to move or rotate the object optimal challenge will be assessed by the movement times and by the successful completion of tasks if for instance the controller 212 determines that the user cannot reach a bottle 30 cm away then the bottle will be brought incrementally closer inversely if the.