Research Of Vehicle Chassis Integrated Control Based On Multi-model Intelligent Hierarchical Control

With the rapid development of the advanced technologies of modern control theories, multi-sensor information fusion, large scale integrated circuit, and the human constant pursuit of performance, vehicle chassis integrated control system has been become an important field in the vehicle dynamic control. Its control target is to increase the vehicle riding comfort, active safety and handling stability.The potential performance of the vehicle subsystems are attained and the vehicle chassis global integrated control is realized by the vehicle subsystems active coordination control.Combined with the project of NSFC (No.50475064) and the Natural Science Foundation Project of ChongQing (CSTC,2006BA6017), and based on the domestic and abroad research, this thesis is attempting to investigate the coordination control mechanism of vehicle chassis multi-model system including the subsystems of the Electric Power Steering, Anti-lock Braking System and Semi-active Suspension. The control strategy of vehicle active chassis intelligent hierarchical control (VACIHC) is proposed. According to the features of complex chassis system and the advantages of multi-agent system (MAS) theory in solving distributed complicated problems, the MAS theory is introduced into the active chassis control systems and the MAS coordination control strategy for vehicle chassis hierarchical control is presented. The research on how to avoid the conflicts and disturbances between the vehicle chassis subsystems, and achieving the coordination control for the vehicle lateral, longitudinal and vertical motion is discussed. It will establish the theoretical foundation for the vehicle active chassis control research and development.The main work of this dissertation including the following aspects:Regarding the double-axle light-duty vehicle as the research object and based on the method of modularization and the intelligent control theories of robust and fuzzy control, the EPS, SAS and ABS in the chassis multi-model intelligent hierarchical control are simulated. It will establish the foundation for the vehicle chassis multi-model coordination control.According to the problem that some key state variables in the vehicle stability control process are too difficult to measure directly, the state optimization estimation algorithm based on multi-sensors linear combination and strong tracking filter theory is proposed. Then the vehicle nonlinear states estimation model is established and the vehicle key states estimation are simulated and analyzed with the strong tracking filter theory. It is a real-time, accurate and low-cost soft-sensor way for vehicle advance control.According to the vehicle current state information and ideal reference model and based on the theory of intelligent hierarchical control, the vehicle chassis multi-model intelligent hierarchical control system is established. The organization level controller is designed with the sliding mode control and received the target general control forces. And then, combination with the vehicle real state and the anticipation safety stability state by estimated, the coordination control rules of vehicle chassis subsystems are decided. With the coordinated control of the subsystems, the vehicle chassis synthesis control performance is improved.Combination with the personalized, intelligent and distributed characteristics of the chassis subsystems and the advantage of MAS in solving distributed complicated problem, the MAS is introduced in the chassis coordinated control and the strategy of chassis correspond control with MAS is founded. Through communication, interaction and coordination between the various subsystems agent, the vehicle chassis control object of the organization-level is planned automatically and the general forces of coordination-level is allocated dynamically, and the resources, shared data and knowledge were utilized possibly. The MAS control method is aimed to exploring the intelligent control strategy with high initiative and self-adaptive for vehicle chassis.In the end, the coordination control strategy between the vehicle chassis subsystems of ABS and EPS in this thesis is studied by the hardware-in-the-loop test.