Task Tags Position Control

This task demonstrates how to move the subject’s arm smoothly while using the Position Controller block. It will move the subject’s arm alternatively between 4 target locations.

Forces/torques will be commanded to the Kinarm as soon as the task starts, and will continue throughout the entire task (i.e. the Position Controller is always on). There is a different sample task “Position controller enable/disable” which demonstrates how to turn the Position Controller on/off smoothly within a trial, for tasks that need to alternate between free movement and positioning the arm.

In the Trajectory subsystem/Create_Trajectory subsystem, a bell-shaped velocity profile is calculated between where the hand was at the start of the trial and the destination target. Using Stateflow, the virtual trajectory is sent point by point to the Position Controller block to create a smooth motion.

This task works on both Endpoint and Exoskeleton Kinarm labs.

Compiled for Dexterit-E 3.7, MATLAB 2013a.

This task is a slightly more complex version of the position control demo. In the original position control demo the position controller comes on at the start of the task and remains on throughout. This version of the position controller demo shows how to enable and disable the position controller smoothly – i.e. no sudden jerks as the controller goes on and off. This demo is a good place to start if you plan to have a task where you drag the subject back to a starting location after they have completed a movement.

Each trial in this task starts with the position controller off (i.e. free movement). Once the initial target is reached and held for a short time the position controller is ramped on. Once the position controller is at full strength you will be moved to a destination target. After the destination is reached the position controller is ramped off.

This task is saved as MATLAB 2013a and compiled for Dexterit-E 3.6.2