Robotic excavator swing control using fuzzy rotating sliding mode

This paper presents the design of fuzzy rotating sliding mode controllers with an application to the swing control problem of electro-hydraulic servo systems of a robotic excavator. By introducing the integral of differential pressure as an auxiliary state, the dynamic model of an electro-hydraulic servo system can be cast as a second-order coupled nonlinear system. Using a successive loop closure procedure, the differential pressure is first considered as the control input for position tracking. The servo-valve command voltage required to track the desired differential pressure is then computed. Fuzzy rotating sliding surfaces are applied to achieve fast tracking and robustness to uncertainties. The validity and advantage of the proposed technique are verified through simulation of the cab swing electro-hydraulic servo system of a robotic excavator. Control implementation and experimental results are provided. The results obtained Indicate the feasibility of the control technique in lower level control applications of the hydraulically-actuated robotic excavator.