A myosignal-based powered exoskeleton system

Integrating humans and robotic machines into one system offers multiple opp ortunities for creating assistive technologies that can be used in biomedic al, industrial, and aerospace applications, The scope of the present resear ch is to study the integration of a human arm with a powered exoskeleton (o rthotic device) and its experimental implementation in an elbow joint, natu rally controlled by the human. The Human-Machine interface was set at the n euromuscular level, by using the neuromuscular signal (EMG) as the primary command signal for the exoskeleton system. The EMG signal along with the jo int kinematics were fed into a myoprocessor (Hill-based muscle model) which in turn predicted the muscle moments on the elbow joint. The moment-based control system integrated myoprocessor moment prediction with feedback mome nts measured at the human arm/exoskeleton and external load/exoskeleton int erfaces. The exoskeleton structure under study was a two-link, two-joint me chanism, corresponding to the arm limbs and joints, which was mechanically linked (worn) by the human operator. In the present setup the shoulder join t was kept fixed at given positions and the actuator was mounted on the exo skeleton elbow joint, The operator manipulated an external weight, located at the exoskeleton tip, while feeling a scaled-down version of the load. Th e remaining external load on the joint was carried by the exoskeleton actua tor. Four indices of performance were used to define the quality of the hum an/machine integration and to evaluate the operational envelope of the syst em, Experimental tests have shown that synthesizing the processed EMG signa ls as command signals with the external-load/human-arm moment feedback, sig nificantly improved the mechanical gain of the system, while maintaining na tural human control of the system, relative to other control algorithms tha t used only position or contact forces. The results indicated the feasibili ty of an EMG-based power exoskeleton system as an integrated human-machine system using high- level neurological signals.