Joint angle measurements based on omni-directional lower limb rehabilitation platform

A measuring method of hip and knee joint angles based on omni-directional lower limb rehabilitation platform is proposed. Several ultrasonic modules are vertically fixed inside the rehabilitation platform, the relative distances between the ultrasonic modules and surface of each lower limb are detected circularly in walk process, hip and knee joint angles at any time are obtained according to the geometrical relationship. Joint angle patterns of healthy people are acquired by robust fitting and then abnormal gait is effectively evaluated by comparing the pattern differences between lower limb dyscinesia patients and healthy people. The experimental results show that the method can obtain the gait information in walk process and evaluate the abnormal gait effectively.