Evaluation of an assistive controller for reaching following brain injury

The authors evaluated an assistive control law for reaching along a mechanical guide by three individuals with brain-injury. The controller compensated for passive properties of the arm, including its weight and passive tissue stiffness, as a function of arm configuration. The authors found that such “counterpoise assistance” improved the subject´s active range of motion during reaching along the guide, but did not enable subjects to move fully through their available passive range of motion. These results suggest that brain-injured individuals exhibit position-dependent weakness that will constrain future designs of assistive devices for reaching