Research On Key Technologies Of Running Stability Control For Bus

The main indicators of vehicle running stability consist of handling stability and roll stability which belong to the content of vehicle active safety. Due to some characteristics such as high center of gravity, large weight and special function of buses, the running stability control of buses is especially important. At present, during the development of these kinds of running stability control systems of buses, the handling stability or the roll stability is focused independently by most designers, while the dynamics coupling among correlative actuators is not considered integrally. As a result, it is hard to accomplish the integrated control of these two stabilities. The research of this paper focuses on key technologies of the running stability control for the handling stability or roll stability, new methods for slip prevention and rollover prevention control of buses, as well as the coordinated integrated control problems related to these two stabilities. The main contents of this study are as follows:(1) Four degrees of freedom of chassis dynamics model, some actuators dynamics model related to tire model, suspension, brake, etc. are established for running stability control problems of buses.(2) Aiming at the slip prevention, the mathematical model of Differential braking Yaw-moment Control (DYC) for buses is established by applying the performance of differential braking; using sliding mode control, DYC for buses is designed to guarantee handling stability. DYC is divided into the higher-level controller and the lower-level controller:the higher-level controller generates the desired yaw moment in terms of control indicators, while the lower-level controller outputs the braking pressure for each tire corresponding to the desired yaw moment.(3) Aiming at the rollover prevention, the control strategy, mathematical model and rollover prediction model for Counter-rollover Damping Control (CDC) for buses are established by applying the performance of semi-active suspension; using sliding mode control, CDC for buses is designed to guarantee roll stability. CDC is also divided into the high-level controller and the lower-level controller:the high-level controller generates the desired roll moment, while the lower-level controller outputs the driving current for each damper corresponding to the desired roll moment.(4) Aiming at the running stability for buses, the dynamics coupling of differential braking and semi-active suspension are analyzed, and the running stability control system is divided into the coordination layer and the regulation layer using hierarchical integrated control structure. The coordination controller (Coordinator) is designed to optimize the performance of regulation controllers.(5) The communication network of running stability control of buses is designed by applying bus-type topological structure.Targeting a type of bus, the simulating test platform for running stability control system of buses is established with MATLAB/Simulink; the performances of upper three different control modes are analyzed through standard maneuvers of bus driving. According to the result, the integrated control mode is more effective to improve the control performance. Research achievements in this paper could be used as the theoretical foundation and technological basis for developing running stability control system of buses, while the active safety for buses could also be enhanced by means of further test research.