Studies On Matching Process And Calibration Technologies Of ABS

Anti-lock braking system (ABS) is an important part of the vehicle chassis control systems, which can improve braking performance and enhance active safety of vehicle. With the development of Chinese automotive industry, the studies on ABS for industrialization are highly significant, the ABS matching process and calibration technologies are key issues.ABS matching process is the guiding framework to carry out the matching work, it is also the basis to standardize matching project and guarantee matching quality. The main tasks and management process of the ABS matching work are summarized and the standard matching process is developed in practice. Using critical path analysis, a fast matching process is developed based on customer demand, which can effectively control the matching period in the application. By analyzing the ABS quality factors, practical quality standards are developed. The relationship between efficiency and stability of braking is researched, a quality control method aiming at adhesion coefficient utilization is proposed with the steering wheel angle correction constraints, which can solve problems in ABS comprehensive performance calibration.ABS hardware matching determines the difficulty of the calibration and affects ABS performance. To improve the efficiency of hardware selection, the theoretical models of the master cylinder, wheel cylinder and key components of hydraulic control unit (HCU) of ABS are established, the flow and pressure characteristics of wheel cylinder and HCU inlet and outlet valves are researched, the hydraulic sensitivity of wheel cylinder and flow resolution of HCU valves are proposed, based on which the theoretical method of the HCU hardware selection is studied and the simulation results fit the actual test well. By analyzing output voltage characteristics of the wheel speed sensor and the ABS wheel speed calculation method, the sensor selection method is proposed based on the lowest wheel speed, which can meet the ABS requirements better.The extended control algorithms are necessary to improve ABS performance. The braking force distribution of front and rear axles under straight-line braking is simulated with different road friction coefficients, and the electronic braking force distribution (EBD) control algorithm using deceleration parameters is proposed. To solve the system noise and vibration problems, the flow characteristics of ABS switching valve under PWM control mode are analyzed, and the valve control mode using high frequency PWM signal is proposed to achieve continuous flow characteristics. To improve ABS performance of steering braking, the characteristics of wheel speed under steering condition are studied. The algorithms of turning identification and parameter correction are proposed based on ABS control information. To enhance the system fault detection, combined with the lowest measurable wheel speed of sensor and wheel running kinetic parameters, the sensor fault detection algorithm based on wheel speed characteristics is proposed. Vehicle road tests verify the effectiveness of these algorithms.ABS software calibration technique can improve the calibration quality and efficiency. To improve ABS robust performance, the influence of the noise factors to ABS control is analyzed, and ABS robust calibration test method is proposed. To assist the calibration work, ABS calibration software is developed based on CAN calibration protocol (CCP) and COM communication interface. The free-type and directed-type calibration interfaces are designed. These are successfully applied in the vehicle ABS calibration.