A DYNAMIC-MODEL FOR SIMULATING MOVEMENTS OF THE ELBOW, FOREARM, AND WRIST

We developed a dynamic model of the upper extremity to simulate forear m and wrist movements. The model is based on the skeletal structure of the arm and is capable of elbow flexion/extension, forearm pronosupin ation, and wrist flexion/extension and radial/ulnar deviation movement s. Movements are produced by activation of a Hill-type model of muscle , and limits on joint motion are imposed by passive moments modeled af ter experimental results. We investigated the muscle output force sens itivity, as well as wrist flexion/extension motion sensitivity to para meter variations. The tendon slack length and muscle fiber length were found to have the greatest influence on muscle output and flexion/ext ension wrist motion. The model captured the direction of the moment ve ctors at the wrist well, but predicted much higher moments than were m easured by stimulating the paralyzed muscles of one tetraplegic subjec t. Copyright (C) 1996 Elsevier Science Ltd.