Firefly optimised PID control for upper extremity rehabilitation robot

This paper proposes a meta-heuristic technique to optimize controller parameters for upper extremity rehabilitation robot. The exoskeleton used in this study is a three-degrees-of-freedom system facilitating shoulder and elbow joint movements. The robot exoskeleton is designed for facilitating shoulder abduction/ adduction, extension/ flexion, horizontal external/ internal rotation and elbow extension/ flexion. Zeigler-Nichols is a conventional technique for setting the PID parameters produces large overshoots, high rise-time and settling-time in the system. To address such issues nature-inspired Firefly optimization algorithm for the parameterizing 2-DOF-PID controller has been proposed. A comparative analysis between two algorithms has been done for a 3-DOF upper extremity rehabilitation robot. For analysis, four different objective functions ISE (integral square error), ITSE (integral time square error), IAE (integral absolute error) and ITAE (integral time absolute error) have been used. The results of the analysis showed that Firefly algorithm with ITAE as objective functions performs better in terms of overshoot, rise-time and settling-time

Sliding mode control for 2 degrees of freedom upper limb rehabilitation robotics system under uncertainties

rehabilitation of patients suffering from post-stroke injuries via robots in now adapted world widely. The aim of this therapy is to restore and improve the dysfunction and the performance of the affected limbs doing repetitive tasks with the help of rehabilitation robots, as robots are best way to perform repetitive task without and monotony failure, Control of these rehabilitation robots is an important part to consider because of nonlinear sliding mode controller (SMC) for controlling a 2 degrees of freedom (DOF) upper limb robotic manipulators. Sliding mode control is able to handle system uncertainties and parametric changes, One drawback of using SMC is high frequency osculations called layer techniques. This chattering can be reduced by using boundary layer techniques. Experiments have been carried our under perturbed conditions and results have been shown that SMC performance well and remain stable and thus proves to robust controller for upper limb robotic manipulator