Impedance control of CPM device with flex-/extension an pro-/supination of upper limbs

Continuous passive motion (CPM) is an orthopedic treatment or physiotherapy after injury or operation. Most of CPM devices used for treatment of the elbow joint have one degree of freedom in flex-/extension. This causes that the patients are limited in pro-/supination of the forearm with flex- /extension of the elbow joint due to the movement of CPM device. In this paper, a novel impedance control scheme of pro- /supination is proposed for CPM device with flex-/extension and pro-/supination. Impedance control is designed for the reference trajectory measured from normal subject, and the parameters for impedance control are determined in order to suppress the excessive force at the end of the range of motion. The effectiveness of the proposed scheme is evaluated by experiments.