DEVELOPMENT OF ELECTROHYDRAULIC CONTROLLED ABOVE-KNEE PROSTHESES

In this study, a four-bar linkage above-knee (AK) prosthesis with an e lectrohydraulic controller was developed. A microcomputer was employed to regulate the puppet valve of the hydraulic control system. To obta in a reliable design, a test rig was also designed for evaluation of t he knee controller performance. The rig had a variable-speed alternate -current servomotor for simulating the angular displacement of the hip joint at different walking speeds. A proportional+derivative (PD) con troller was employed to regulate the knee torque of the above-knee pro sthesis. Experimental results revealed that the controller can produce a knee joint trajectory close to that of a normal person or a designe d one. Use of the electrohydraulic controller can be expected to impro ve the amputee swing phase gait.