A Nonlinear Adaptive Compliance Controller for Rehabilitation

In the last few decades, the increase in the worldwide elderly population and the progress in the treatment of severe and chronic pathologies have led to a growing demand for rehabilitation therapies. Meanwhile, rehabilitation robotics has started to grow and to evolve, in order to develop suitable robotics devices and control strategies to better assist patients during training and to promote rehabilitation processes. In particular, some control strategies are designed to assist patients in completing the desired movements while applying the minimum force necessary. As a result, an "assist-as-needed" behavior can be achieved. A novel nonlinear adaptive compliance controller, that aims to achieve such "assist-as-needed" behavior, has been developed and is presented in this paper. In addition to promote the active participation of patients, the proposed control also provides a tool to estimate and evaluate patient's state and therapeutic improvements. The proposed controller is obtained...