Mechanism and Control of Powered Prosthesis with Bi-articular Muscle-Type Hydraulic Bilateral Servo Actuator

Abstract

For person with bilateral shoulder disarticulation, powered prosthesis is highly needed. In late years, some experimental trials using electrically multi articulated powered prostheses has been achieved. However, these electrically powered prostheses are not so practical and hold unsolved problems such as its mechanism and control, fundamentally. To improve the functions, in this study, hydraulic-electric powered system were developed for a wearable prosthesis with 5 degrees of freedom. The wearable prosthesis can be supplied by the remaining functions of the human trunk to retain full workspace. In addition, this prosthesis can be used as a desktop mounted robot arm using an external attachment. This prosthesis have hydraulic bilateral servo actuator which combines the controllability of electric motor control and the high output of hydraulics. The joint mechanism is highly rigid mechanism without the use of speed reduction gear mechanism. A bi-articular muscle-type hydraulic bilateral servo actuator is used on the upper arm. Simultaneous and independent drive of the shoulder and elbow are possible with the one actuator. The mechanism and control of its upper arm with the bi-articular muscle-type hydraulic bilateral servo actuator are described in this study, in addition, sensor system using hydraulic pressure sensors which detect and avoid disturbance force is considered in this study for the safety control.