Research On Vehicle Height And Leveling Control Of ECAS For Bus Based On AMESim

As a kind of advanced vehicle suspension system, electronically controlled air suspension system has been widely used in urban public transport, tour bus, heavy duty vehicle and advanced passenger car with its excellent performance advantages. Compared with the traditional mechanical vehicle suspension system, one of the outstanding advantages of the main features for ECAS is that the air spring can be effectively adjusted by charging or discharging, and realize that the body height adjustable in real time. On this basis, further combining with adjustable damping shock absorber, ECAS can effectively ensure the vehicle comprehensive performance in the situation that the load and road condition is complex and changeable, so as to effectively improve the vehicle handling stability, fuel economy and ride comfort.With the development of ECAS research, the design of ECAS vehicle height adjustment control system, which is one of the core technologies, has gradually become a research focus in the field. This article is focus on the undesirable phenomenon of over-charge, over-discharge and oscillation in the target value and the roll angle and pitch angle are too large(vehicle attitude instability) during vehicle height adjustment process of ECAS bus and research on the body height adjustment and posture for ECAS bus based on AMESim and sliding mode control technology. An ECAS vehicle height adjustment system model is established in order to accurately grasp the complex dynamic characteristics of ECAS in the process of vehicle height adjustment and the vehicle height adjustment and attitude sliding mode controller for ECAS bus is designed, then the combined simulation and real vehicle road test for the system control performance are realized. The main research work of this paper is summarized as follows:Firstly, a mathematical model of the ECAS vehicle height adjustment system was created to define the control variables of the vehicle height adjustment and attitude control process after having a total understanding and detailed analysis of the working principles for ECAS vehicle height adjustment system and combining with the gas dynamics, thermodynamics and vehicle system dynamics theories. At the same time, the physical model of ECAS vehicle height adjustment system is established based on AMESim in order to facilitate the follow-up effective verification of the control performance for the system.Secondly, in order to effectively solve all the undesirable phenomena occurring in the vehicle height adjustment process of ECAS and ensure the control precision and the stability of the vehicle posture, the ECAS vehicle height adjustment and leveling controller is designed by using the sliding mode control algorithm, and realize the effective control of the air quality flow in or out of the air spring during the vehicle height adjustment and leveling control of ECAS.Thirdly, the ECAS vehicle height adjustment and leveling controller and the vehicle height adjustment system are connected by the effective tools supplied by AMESim and realize the union simulation in AMESim. The simulation results prove that the designed controller can effectively solve the problems appeared in the process of height adjustment and the control effect response quickly in high precision and satisfy the control performance.Lastly,in order to verify the efficiency and reliability of the ECAS vehicle height adjustment and leveling control system, the rapid control prototype is developed and the real vehicle test for ECAS control system is completed. The real vehicle test results show that the control performance for designed ECAS vehicle height and leveling controller is good. What’s more, the accuracy of the ECAS vehicle height adjustment and the vehicle attitude control performance are effectively improved.