Analysis methodology of compatibility between motion control and mechanical architecture of a newly designed gantry virtual track train and the path-tracking control strategy

This study aimed to propose a gantry virtual track train (G-VTT) architecture and investigate the path-tracking control of it. Based on the decoupling control theory, the concept and judgment criterion of the path-tracking independence of the G-VTT was proposed to provide a method to analyzing the compatibility between motion control and mechanical architecture, and instructing the design of the architecture of the G-VTT that could realize autonomous path-tracking with simple control strategy. The controllability and observability of the path-tracking control system were discussed from the perspective of vehicle kinematics and the decouplibility of each tracking point's lateral motion and the path-tracking independence of the vehicle was proved. The distributed virtual driving (DVD) model based on self-adaptive preview PID algorithm was proposed to achieve independent path-tracking of each axle. This model consists of two parts: forward preview model based on the fractional calculus theory simulating the driver's visual field and the parameter self-tuning PID controller based on variable universe fuzzy control theory (VUF-PID controller). The effectiveness and adaptability of the DVD model were verified by co-simulation test. The results show that the VUF-PID controller has an excellent control performance and could realize the self-tuning of PID parameters effectively and could adapt to the noticeable hysteresis effect with the forward preview model introduced. Moreover, the VUF-PID controller could significantly improve the curve-passing stability of the G-VTT, and exhibits excellent adaptability to the traveling speed, curve radius, and vehicle payload. Even when the train travels under an adverse operating condition with lateral acceleration about 3.2m/s², the maximum tracking error could still be kept below ±0.02 m.