ON THE FORCE AND POSITION CONTROL OF HUMAN PROSTHESIS SYSTEMS

摘要

The final goals of prosthesis research are to develop artificial limbs which are naturally controlled by the amputees' motor intents and are functionally responsive like natural limbs. However, most prostheses in present use are still far from the goals in spite of recent advanced technologies for robot manipulators. In human prosthesis systems, amputees' motor intents must be transmitted through the remaining functions. Therefore, information transmission is largely restricted and the control properties of human prosthesis systems are inferior to these of regular man-machine systems. Improvement of the control properties requires development of more cybernetic interface between an amputee and an artificial limb. In this paper, the force and position controls of human prosthesis systems are analyzed from the view point of their dynamic property. First, to analyze the force control, tracking tests controlled by myoelectric signals were performed. Open loop describing functions show good characteristics and it was shown that one of the most important problems in the force control of human prosthesis systems is the influence of sensory force feedback to control characteristics. A human prosthesis interface with bilinear structure is proposed. The bilinear structure makes it possible to control the mechanical impedance about the joint. The test results of tracking performance demonstrate that the position control could be largely improved by adding the bilinear structure to the interfaces in human prosthesis systems.