Modeling and Motion Control of Industrial Tractor-Trailers Vehicles Using Force Compensation

This article presents the dynamic modeling and trajectory tracking control of the industrial tractor-trailers vehicle composed of a full-size car-like tractor and multiple full trailers. To eliminate the high uncertainty of the kinematic and dynamic parameters of the trailers in the model, we propose to install a force sensor to monitor the forces exerted on the tractor in real time. With the force measurements, the tractor can be considered separately and the dynamic model is significantly simplified. The inaccurate parameters and varying configurations of the trailers can all be ignored, whereas their dynamic effects on the tractor are still precisely captured. A Lyapunov-based trajectory tracking controller is proposed to online compensate the forces and drive the tractor onto the desired trajectory. The controller is developed using backstepping techniques and the stability is rigorously proved. The performance is illustrated with practical implementations on a full-scale industrial tractor towing several full trailers. The robustness and accuracy of the controller with force compensation are verified with different trailer settings. Implementation results show that applying the simplified model has generally superior performance than using the whole-vehicle model.