Trajectory generation of CPM device for the elbow joint considering constraint caused by joint disorder

Continuous passive motion (CPM) is an orthopedic treatment or a physiotherapy after surgery. After surgery to injury of ulna collateral ligament (UCL) in the elbow, excessive extension of the UCL aggravates the injury, and reaction force at hand of patient increases excessively near the end of the range of motion due to increased stiffness. It is known that controlling pro-/supination is effective to suppress the reaction force, but the UCL may be extended excessively by the pro-/supination. In this paper, we focus on the treatment after the surgery to UCL and propose the trajectory generation method to control the pro-/supination in order to suppress both the reaction force and the UCL extension based on skeleton model. Finally, experimental results with simulated patient show the effectiveness of the proposed method.