## 5 Conclusions  
Due to the various configurations of VTTs, this paper presented a universal modeling and controller that is adaptable for any VTTs' dynamics control. The proposed control framework covers path-tracking accuracy, hinge forces, and tire sideslip, and one can  
Figure 12: Maximum lateral deviation and width of turning passageway of SRT curve radii, speeds, and payloads: (**a**) maximum lateral deviation under different speeds and curve radii, payload = 50 t; (**b**) width of turning passageway under different speeds and curve radii, payload = 50 t; (**c**) maximum lateral deviation under different payloads and curve radii, speed = 8 m/s; (**d**) width of turning passageway under different payloads and curve radii, speed = 8 m/s. add or delete some of them depending on the vehicle's configuration and needs. We first introduced reconfigurable modeling and extended it to any actuator configurations. Then, a hierarchical controller was designed to cover the problems of multi-input, multi-output, over-actuation, and different actuator configurations. Based on the actual vehicle parameters and the HIL real-time simulation, the application of the proposed control strategy on the SRT was verified through a comparative analysis of different control strategies. The circular curve passing performance, continuous curve adaptability, and robustness of the control strategy under different boundary conditions were further analyzed. The specific research and conclusions are as follows. A multi-body dynamics model of the SRT has been established with the CG generalized forces of each module as the control input. A CG generalized force model was established, which indicates the relationship between the wheel steering angle and torque input and the generated equivalent CG generalized forces. The proposed Boolean matrix makes the model compatible with different actuator configurations in each module. The hinge is equivalent to the dynamics and kinematics constraints of adjacent modules, and the hinge force is expressed by the vehicle state and CG generalized forces. This method can quickly expand and reconstruct the dynamics model for different vehicle numbers and facilitate the implementation of model-based control algorithms. The control strategy based on the improved MPC and hierarchical framework first calculates the CG generalized forces of each module required for path tracking. The CG generalized force redistribution and \"virtual axle\" method are adopted to ensure high tracking accuracy, effectively reduce the width of the turning passageway and the hinge force, and solve the problem of insufficient actuators in the middle module of the SRT. Finally, the control allocation of the first, second, and fourth modules is carried out with different CG generalized force models. It avoids the difficulties in designing end-to-end control strategies and their weak robustness, reducing the computational complexity of each controller layer and facilitating the deployment. Compared with the extended Ackermann steering strategy, the control strategy proposed in this paper reduces tracking error, hinge force, and sweeping lane width by 20.6 to 29%. The vehicle heading error, yaw rate, folding angle, and tire sideslip angle verify the proposed control strategy's excellent circular curve performance, anti-folding stability, vehicle maneuverability, and low tire wear. The adaptability and robustness of the control strategy were also verified by tracking errors under continuous curves and different payloads, speeds, and curve radii. In conclusion, this paper explores the dynamics modeling and path-tracking control for any configurations of VTTs and verifies the effectiveness of the application on the SRT through the HIL real-time simulation platform. It provides theoretical support for comprehensively improving the tracking control ability of the vehicle. The future work of this study will focus on verifying and optimizing the proposed control strategy using a 1:1 model. Conceptualization, Z.W. and Z.L. ; methodology, Z.W.