Development of computer-based environment for simulating the voluntary upper-limb movements of persons with disability

Upper-limb orthotic systems have been designed for restoring the upper-limb functions of individuals with disabilities resulting from spinal cord inju ry (SCI), stroke and muscular dystrophy. These systems employ either functi onal electrical stimulation or external power. It is proposed that, instead of time-consuming and complicated monitoring using sensors and motion anal ysis, a software simulator with both angular displacement and acceleration parameters can facilitate the design of a control strategy for an orthosis. Reaching movements of three cervical SCI subjects are used to verify the s imulator. A motion analysis system is used to measure the range of motion a nd joint angles during hand reaching. Results indicate that quaternion and spline curve techniques are suitable for interpolation of the hand reaching movements. The information needed for good simulation only compress the sh oulder and elbow joint angles in a few key postures. Stimulated acceleratio n signals on the upper-arm segment have a high correlation coefficient (> 0 .9) and a small root mean squared error (< 0.11 g) with a real bi-axial acc elerometer.