Enhanced performance of lower limb robotic system based on PSO algorithm.

The control technique for Lower Limb Rehabilitation Robot (LLRR) is complicated and requires the consideration of numerous internal and external elements. This paper presents the controller design of a lower limb Knee-Ankle-Foot Orthosis (KAFO) rehabilitation robot to restore mobility and assist Spinal Cord Injury (SCI) and brain stroke Patients. The framework of the KAFO system is made of two Degree-Of-Freedom (DOF) for the knee and ankle joints. In this study, the nonlinear differential equations have been linearized using Jacobean's method. Then, the feedback linearization method is used to facilitate the controller design. The Computed Torque Control (CTC) based on PD (CTC-PD) has been developed based on PD control (CTC-PD). A comparison with an optimal state feedback control strategy of Linear Quadratic Regulator (LQR) control has also been carried out using the linearized system model. The comparison is carried out based on evaluating the Root Mean Square Error (RMSE) function. Meanwhile, the Particle Swarm Optimization (PSO) algorithm has been implemented in order to further improve the gain values for the implemented controller. Finally, simulation results have revealed that the CTC-PD controller can give reliable estimations and control, where the CTC-PD RMSE has improved by 99.9% than LQR for the first link and second link. Besides, the CTC-PD method has claimed to reduce external disturbance and random noise and it is the most effective when compared to the LQR controller. [ABSTRACT FROM AUTHOR]