Development of knee joint robot for students becoming therapist — Design of prototype and fundamental experiments

The authors are developing a knee joint robot as an educational tool for students becoming physical therapist (PT) or occupational therapist (OT). The robot can simulate some problems of a knee joint, such as range of motion trouble, contracture, rigidity, spasticity and so on. The robot has a knee joint mechanism to realize not only flexion/extension movement but also inner/outer rotation movement, which is based on the idea of rolling, sliding and coming off movement. In addition the robot has the wire drive system to control the knee joint passive movement. In this paper we design optimal arrangement of four pulleys in the wire drive system by introducing performance indices. In addition we design control algorithms to imitate two kinds of knee joint troubles and verify the effectiveness by fundamental experiments.