Optimal cascade hydraulic control for a parallel robot platform by PSO

A new cascade load force control design for a parallel robot platform is proposed. A parameter search for a proposed cascade controller is difficult because there is no methodology to set the parameters and the search space is broad. A parameter search based on particle swarm optimization (PSO) is suggested to effectively search the parameters of the cascade controller. We used a unified mathematical model of a hydraulic actuator of parallel robot platform. These equations are readily applicable to various types of proportional valves, and they unify the cases of critical center, overlapped, and underlapped valves. These unified model equations are useful for nonlinear controller design. Simulation results show the advantages of the proposed optimal tuned cascade controller to solve the formulated tracking problem in relation to the classical proportional–integral (PI) controller.