Switching dynamic modeling and driving stability analysis of three-wheeled narrow tilting vehicle

Traffic congestion is one of the main problems modern cities face, exacerbated by widespread use of normal four-wheeled transportation. A promising solution to this challenge is to develop narrow electric vehicles and apply them in daily transportation. These kinds of narrow vehicles need less parking and lane space and cause no air pollution. In this study, we developed a new conceptual narrow tilting vehicle (NTV) that has one front wheel and two rear wheels. All the three wheels can tilt to improve the stability of NTV during turning. To fully describe the dynamic behaviors, a new switching dynamic model of NTV was derived. This model considers several NTV states including normal running, temporary running with one rear wheel not on the ground, and totally falling down. Based on this model, a simulation platform is established, which is useful for testing different control methods and for investigating dangerous driving situations. A new active tilt controller is proposed based on a tilt dynamic model linearized around an equilibrium on which the lateral acceleration is zero. The controller is easily realized from the point of view of engineering and the closed-loop system stability was also investigated. The driving stability problem of NTV was discussed using peak-to-peak analysis method. Stability condition of input steering angle and angular velocity was obtained, which may be a useful tool for designing the steer-by-wire controller in the future. All the proposed model, control method, and stability conditions were verified through simulations and experiments.