Designing a self-tuning regulator controller for a non-linear and MIMO Exoskeleton system assist test setup with adaptive decoupling

Abstract

The assistive exoskeleton robots are designed in order to help immobile patients and augment healthy individual s muscle power. Assistive robots help humans with control algorithms and providing the needed power for users walking. The control algorithm must be in a manner that provides a share of the torque the person requires for walking and consequently, the force the person needs to endure in order to walk will reduce. Considering the integration of the robot to the human, it is essential to assure the safety and practicality of the control algorithm before implementing it on a real user. In this paper, a new test setup is designed and built for simulating human joints and implementing the assistive control algorithm on the robots provided with the series elastic actuator. In this test setup incorporation of a set of motor and gearbox along with a series elastic actuator for simulating motion and torques exerted to human joints is used. A series elastic actuator is considered as an actuating system for the robot and for implementing the assistive control algorithm. This test setup includes a non-linear and multiple inputs-multiple outputs (MIMO) system. Considering the complexities of MIMO non-linear control methods, in this paper after linearization, the test setup is decoupled. Subsequently, an adaptive control method for the trajectories and actuator torques is employed. The proposed control method is immune to systems parameters uncertainty and is able to adapt to the system parameters varying. In the end, the practicality of the proposed controller is shown in comparison with the PD controller.