Research On Vehicle Chassis System Based On Layered Coordinated Control

Along with the development of vehicle chassis integrated control, research on it became more urgent. Under this circumstance, research on layered coordinated control among suspension system, electric power steering system and braking system was carried out. Compared with concentrated control and distributed control, advantages of layered coordinated control can be described as follows: complication of controller design is decreased, control stability is improved and it is easier to extend control subsystem. Layered coordinated control supplied a new method for vehicle chassis integrated control.Based on semi-vehicle model, mathematical model was separately established for suspension system, electric power steering system (EPS) and braking system. During the course of model establishment, influences among subsystems were not taken into account. Different control methods were adopted for controllers' design of subsystems, the simulation research was carried out. Took controllers designed for subsystems as bottom controllers, upper coordinated controller was designed based on deeply analyzing the influences among suspension system, electric power steering system and braking system. Upper coordinated controller was a decision-making controller, the function was to make decisions and monitor bottom controllers. Just like a switch, upper coordinated controller only monitored bottom controllers when vehicle ran normally. Sensor signals were transmitted to upper coordinated controller through CAN bus; when exceptional circumstances happened such as emergency brake, main indexes were monitored and the decisions were made by upper coordinated controller. Simulation results show that vehicle synthesis performance is improved adopting layered coordinated control.Deeply experimentation research was carried out. First, hardware in the loop(HIL) experiment of anti-lock braking system(ABS) was carried out, the developing periods of ABS electronic control unit (ECU)was obviously decreased. Second, controllers' development of ABS and EPS were carried out based on ARM7 and protel software platform. At last, based on layered coordinated control strategy, upper coordinated controller was designed in order to coordinate the contradictions between ABS and EPS. The experimentation results show that decision-making of upper coordinated controller is logical and control logic of bottom controllers is correct. Vehicle maneuver performance and lateral stabilization are obviously improved based on decreasing brake performance. A better vehicle synthesis performance can be achieved by using layered coordinated control.