AbstractThis article presents a hierarchical adaptive algorithm for controlling a human wrist motion simulator (WMS). The WMS is a computer-controlled, electromechanical system that permits the application of desired forces to the tendons of a human cadaver wrist/hand specimen. The proposed control scheme does not require knowledge of the cadaver specimen's dynamic model, and solves on-line the so-called indeterminate problem that arises because the wrist possesses more actuators than degrees of freedom. Computer simulation results are given for a wrist/hand system under adaptive control, and demonstrate that any desired normal wrist motion can be accurately tracked with the proposed algorithm. Additionally, these simulations indicate that the controller resolves the indeterminate problem redundancy in a physiologic manner and show that the control scheme is robust to parameter uncertainty, actuator and sensor bias and noise, and incomplete state feedback.