agricultural vehicles

path tracking

sliding mode

unmanned surface

tracking errors

disturbance rejection

wheeled mobile

Mechanical Systems and Signal Processing

• The heading control of 6WID/4WIS UGV with variable wheelbase is studied. • An improved model free adaptive control algorithm is used to track the desired heading. • The torque distribution strategy is proposed and validated by simulation results. The six-wheel independent drive and four-wheel independent steering unmanned ground vehicle (6WID/4WIS UGV) with variable wheelbase has unique advantages in environmental adaptability and maneuverability. However, due to its strong nonlinearity and uncertainty, it has the great challenges in control. Based on model free adaptive control (MFAC) method and particle swarm optimization (PSO) algorithm, the heading tracking problem of 6WID/4WIS UGV under the influence of uncertainties is studied in this paper. First, to improve the convergence characteristics, the improved MFAC scheme is proposed, which can effectively overcome the influence of time delay and wheelbase. Then, based on the desired steering angle and yaw moment obtained by MFAC method and the single-track model of 6WID/4WIS UGV, the torque of six electric wheels is distributed by PSO algorithm to achieve the coordinated control of driving, braking and steering. Finally, the feasibility and effectiveness of the proposed control strategy are verified by simulation results.

Heading tracking of 6WID/4WIS unmanned ground vehicles with variable wheelbase based on model free adaptive control