Direct Adaptive Robust Control for Pump Driven Steering System of Heavy-duty Multi-axle Vehicles

Heavy-duty multi-axle vehicles, with their high load capacity and good road adaptability, play a key role in the transport of heavy equipment, construction projects, and infrastructure development. Precise control of the steering system is crucial of the operation of these vehicles. However, traditional control methods are difficult to meet the high-precision requirements due to the trapezoidal structure of the steering system, mechanical coupling with other mechanical structures, the high-order nonlinearity of hydraulic drive, and uncertain disturbances during driving. To address these issues, this paper proposes a backstepping-based direct adaptive robust control (DARC) method. Firstly, considering the nonlinearity of the dynamics, a feedforward compensation method is proposed based on the steering dynamic model. Next, in response to the time-varying parameters in the control process, a parameter adaptation method is introduced to track the parameter changes in real-time and improve control accuracy. Meanwhile, robust feedback control is employed to addressing model errors and disturbances to enhance overall control capability. Finally, a comparison with DARC and three classic control methods shows that the proposed method exhibits better control performance in both steady-state and transient conditions, significantly improving the steering control accuracy of heavy-duty vehicles.