Trajectory Tracking Control of Multi-axle Hybrid Steering Vehicles on Soft Terrain

Abstract Aiming at the problem of large trajectory tracking control errors for multi-axle vehicles on soft terrain, this study comprehensively considers complex wheel-terrain interaction relationships on soft terrain and develops a time-varying parameter-based trajectory tracking control algorithm for soft terrain using MPC (Model Predictive Control). Specifically, it establishes calculation methods for tire longitudinal/lateral forces on soft terrain and fits corresponding force curves. A vehicle dynamics model and trajectory tracking error model adapted to soft terrain conditions are constructed to enhance model accuracy. Considering load transfer during vehicle movement on soft terrain and the correlation between tire lateral forces and wheel loads, time-varying parameter matrices are established to accurately characterize vehicle dynamic characteristics under such conditions. By incorporating time-varying lateral force proportionality coefficients for wheel-terrain interaction, an MPC-based control algorithm is designed. Simulation tests of multi-axle vehicle trajectory tracking demonstrate the effectiveness of the proposed algorithm, showing significant improvement in control accuracy compared with conventional control methods that neglect parameter time-variation characteristics.