Design and control of a powered knee orthosis for gait assistance

A powered knee orthosis named Assistive Knee Brace (AKB) is designed for the elderly and patients with knee dysfunctions to gain external support at their knee joints during gait. Safety, light-weight and user-friendly interface are the emphasis of system design. In the assistive controller design, gait analysis method based on Finite State Machine is developed for gait pattern estimation, with state estimated through fuzzy inference. Based on the gait pattern estimated online, reference gait pattern is generated as assistive control input of the powered knee orthosis to adjust the wearer's abnormal motion with torque support to track the normal pattern. To verify the assistive function of AKB, gait experiments under control are conducted on healthy subjects simulating certain limited mobility. Results show that with proper assistive torque from the AKB, wearers can perform motions in good patterns.