Adaptive trajectory control based robotic rehabilitation device

Abstract

One of the main objectives of a successful lower limb robotic rehabilitation device is to obtain a smooth human machine interaction in different phase of gait cycle. The new concept in robotics rehabilitation is a “cooperative patient strategy” meaning patient's voluntary efforts are taken into account rather than imposing any predefined movements or inflexible strategies. The term cooperative is defined to include compliance of robot as it behaves soft and gentle. It only reacts to muscular effort, interactive because there is a bidirectional exchange of energy and information between robot and patient. The control of trajectory is shared by robot and patient to complete gait cycle. In this paper an effort has been made to establish a control law to tune the inertia, damping and stiffness which in turn produce the desired trajectory impedance for smooth human machine interaction. The gain margin and phase margin in bode plot of our system is positive and hence a stable system.