Fuzzy Force Field Control Design for Lower Limb Rehabilitation Robot

In this paper, an intelligent powerful control scheme is presented for a lower-limb rehabilitation robot. The focus of this study is on maintaining patient safety, focusing on the concept of assist as needed to improve the efficacy of robotic rehabilitation exercises and intelligent controller behavior. The proposed control scheme is consists of force field control and fuzzy logic control. Gravity compensation, friction forces, and interaction torque have been considered to the dynamic model of the system. The force field control method creates a virtual wall along the desired trajectory in the sagittal plane that can guide the patient's gait. Force field control parameters are selected using the fuzzy logic control rules o improve the concept of assist as needed for the rehabilitation robot in order to make a freedom of action for the patient. Therefore, the fuzzy logic control algorithm was proposed to improve the behavioral quality of the rehabilitation robot depending on the patient's ability in the gait process. In this regard, the proposed control scheme has been implemented for the lower-limb rehabilitation robot system. Simulation results show the efficiency of the proposed controller to improve the quality of motorized gait training.