Collaborative Position Control of Pantograph Robot Using Particle Swarm Optimization

This article presents the design and real-time implementation of an optimal collaborative approach to obtain the desired trajectory tracking of two Degree of Freedom (DOF) pantograph end effector position. The proposed controller constructively synergizes the Proportional Integral Derivative (PID) and Linear Quadratic Regulator (LQR) by taking their weighted sum. Particle Swarm Optimization (PSO) algorithm is proposed to optimally tune the gains of PID, weighting matrices of LQR, and their ratio of contributions. Initially, the PID and LQR controller parameters are optimally tuned using PSO. In order to enhance the control effort and to provide more optimal performance, the weightages of each controller are optimally tuned and are kept constant. The collaborative position control strategy is tested against the PID and the LQR controllers via hardware in loop trials on a robotic manipulator. Experimental results are provided to validate the accurate trajectory tracking of the proposed controller. Results demonstrate that the optimal combination renders a significant improvement of 10% in steady-state response and about 37% in transient response over the PID and LQR schemes.