Novel Energy-Efficient Variable-Speed Pump-Controlled Steering System With Enhanced Barrier Lyapunov Control for Heavy Vehicles

A pump-controlled electrohydraulic servo steering system (PC-EHSSS) is proposed, to accommodate high energy-efficiency steering control of heavy vehicles; whereas, it's prone to steering-angle overshoot under abrupt signals, resulting from systematic low damping, poor dynamic performance, and unknown disturbances. For overshoot inhibition, barrier Lyapunov functions (BLF), were utilized to strictly restrict high-order steering-angle errors within boundaries. Once contravened, the BLF controller would be invalid, especially in complex road conditions with erratic and variable initial steering angles. For faster and better error convergence under any initial angle, the integral sliding mode control-BLF switching strategy was proposed. ISMC quickly constrained state variables to BLF's control domain before BLF took over. Still, based on the backward-iteration approach, BLF triggered “differential explosion” for its virtual control rates iteration when applied in high-order systems. To enhance its engineering applicability, dynamic surface control (DSC) was incorporated, by converting differentiation into algebraic operations. A closed PC-EHSSS experiment platform for heavy vehicles was constructed. The steering-angle overshoot is restrained within 0.73° under a trapezoidal signal, with 31.68% higher steady-state accuracy than DSC, and 28.04% greater energy efficiency than pump-valve-combined-controlled steering at 0.15 Hz, 3T. A low-overshoot, high-precision, and high-efficiency variable-speed PC-EHSSS for heavy vehicles has been developed.