In assistive robotics applications, the human limb is attached intimately to the robotic
exoskeleton. The coupled dynamics of the human-exoskeleton system are highly nonlinear
and uncertain, and effectively appear as uncertain load-torques at the joint actuators of the
exoskeleton. This uncertainty makes the application of standard computed torque
techniques quite challenging. Furthermore, the need for safe human interaction severely
limits the gear ratio of the actuators. With small gear ratios, the uncertain joint load-torques …