Robust tracking of the light-exoskeleton for arm rehabilitation tasks
- Post by: System
- 27 November 2019
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It is well known that the application of advanced nonlinear control techniques enable more efficient and precise tracking than linear ones in real models. However, for some critical applications nonlinear schemes are not an option but a requirement, for instance for exoskeleton robots wherein human is wearing the robot and the human is tightly coupled to the powered mechanical linkage. In this paper, we deal with the nonlinear control design of an exoskeleton performing arm rehabilitation on patients with poor neural and motor capabilities. Since this fixed frame man-forearm light exoskeleton presents unknown coupling perturbations, which can neither be neglected nor modeled, a robust and fast controller is desired. To this end, a chattering-free second order sliding mode nonlinear controller is proposed. The closed-loop guarantees fast and robust tracking, whilst rejecting unmodeled bounded dynamics like nonlinear friction and user perturbations. The performance of the closed loop system using Light Exoskeleton renders arm rehabilitation subject to complex trajectories patterns on the basis of the minimum-jerk criterion. Preliminary experimental results show the functionality and validity of the proposed system.