Precise locomotion controller design for a novel magnetorheological fluid robot based on improved gray wolf optimization algorithm

Spherical magnetorheological fluid (MRF) robots are capable to move in narrow space, which can be used for drug releasing to human stomach; however, the magnetic-controlled rolling movement often generates a large displacement error, which greatly hinders the practical applications of the MRF robots. In order to bridge this research gap, this paper introduces a new MRF robot with a precise locomotion controller. In this control system, a data acquisition system is designed for the MRF robot and an optimal proportion integration differentiation (PID) controller is proposed based on an improved grey wolf optimization algorithm (IGWO). Both simulations and experiments have been performed to verify the performance of the locomotion controller. The simulation results show that the proposed IGWO-PID controller is superior to the conventional PID and GWO PID controller, with faster response output and smaller overshoot. Experimental analysis results demonstrate the proposed MRF robot can move in a complex trace with a speed fluctuation rate below 5.4%. As a result, precise locomotion has been achieved to make the new MRF robot ready for medicine delivery in narrow space.