A Hierarchical Approach to the Control of a Prosthetic Arm

A hierarchical method combining analytical techniques from control theory and heuristic techniques from artificial intelligence is presented and applied to the decentralized control of a prosthetic arm. The dynamic model of the arm is derived, and two complementary performance criteria are suggested for the kinematic and the dynamic evaluation for the system response. The "principle of minimum interaction" is used to decompose the prosthetic system into seven subsystems, one per mechanical degree of freedom. A "suboptimal" control structure for nonlinear systems is proposed in conjunction with a performance adaptive self-organizing control algorithm. Syntactic pattern classification is used for the dynamic coordination of the subsystems. The syntax of the man-machine commands is also examined as part of the function of highest level of the hierarchy, the organizer.