Research On Braking And Driving Anti-slip Control System Based On Electromechanical Brake System For Light Vehicle

EMB (Electro-mechanical Brake System), a type of"Brake-by-Wire", represents the direction of"Brake-by-Wire"development. It has been extensively concerned home and abroad and become a hot research topic. Compared with conventional braking systems, EMB has many advantages including: mechanical or hydraulic connections between the brake pedal and the wheel brakes are replaced by electrical signal paths and components, large vacuum booster is eliminated and electronic brake pedal is used instead of conventional brake pedal, these lead to reduction in system weight, simplicity in system configuration and quick system response; ABS, TCS, ESP, ACC can simply be integrated in EMB without additional mechanical or hydraulic components; EMB motor is directly controlled to generate target braking torque with high accuracy,this enables a continuos modulation of the braking torque, and the clamping force is known in real time; powerred by electric energy, no brake fluid, environmentally friendly etc.As a wholly new type of braking system, EMB technology has been actively researched and the research on EMB is of great significance. In this thesis, research on EMB is carried out, including: the design of ABS&TCS control algorithm for EMB, the establishment of EMB off-line simulation platform and HIL (Hardware in the Loop) test platform, off-line simulation test and HIL test of control algorithm.1. ABS&TCS control algorithm design based on EMBOn the basis of documents home and abroad, control objectives of ABS&TCS controller are analyzed and relative control strategies are proposed according to different road conditions; Control algorithm which takes wheel slip rate as the control target is designed, in order to overcome the disadvantages of traditional PID control, a BP neural network algorithm is designed to tune and optimize the PID parameters; based on the designed algorithm, the ABS&TCS controller is built.2. Off-line SimulationAccording to the function of EMB vehicle dynamics simulation platform, the main configuration of the platform is confirmed, and the vehicle dynamics models are developed under Matlab/Simulink environment, including: driver's intentions model, engine model, powertrain model, tire model, suspension model, vehicle model, assistant module, EMB actuator-load-braker model, motor control model etc; based on the developed platform, simulation of EMB three-loop control and designed ABS&TCS control system is carried out under chosen control conditions. The simulation results shows: over-skid of wheels while braking and over-slip of driven wheels can be efficiently controlled by designed ABS&TCS control algorithm, brake performance and traction performance of the vehicle are efficiently improved. Control algorithm can adjust brake pressure in time on jump-μroad, it is of good adaptability. On split-μroad, the control algorithm can assure good handling performance of the vehicle.3. Hardware in the Loop Test PlatformAccording to general scheme of EMB hardware in the loop test platform, every part of the platform is confirmed, including: real-time platform, hardware and software. Then the HIL platform is developed. Electronic brake pedal, one of main parts in EMB system, is designed. The work of electronic brake pedal designment is as following: design of pedal feel emulator which can emulate the pedal feel of conventional brake system, choose of pedal sensor units, manufacture and assembly.4. Hardware in the Loop TestHIL tests are executed based on the EMB HIL test platform. Firstly, EMB characteristics tests which include EMB actuator load characteristics test and three-loop control test are carried out. The EMB actuator load characteristics curve is obtained by fitting the test data of brake pressure and ballsrew displacement, the load characteristics curve is used to EMB modeling. Secondly, HIL test of designed ABS&TCS control system is executed. The test results show that: EMB three-loop control algorithm can efficiently control the EMB actuator to execute brake as desired, and EMB test bench satisfies the design requirements; over-skid of wheels while braking and over-slip of driven wheels can be efficiently controlled by designed ABS&TCS control algorithm, brake performance and traction performance of the vehicle are efficiently improved. Control algorithm can adjust brake pressure in time on jump-μroad, it is of good adaptability. On split-μroad, the control algorithm can assure good handling performance of the vehicle.