Research On Fault Diagnosis Technology Of Vehicle Anti-Lock Braking System

ABS (Anti-lock Braking System, ABS) is an important active safety control technology, which controls the instantaneous breaking valve to regulate the slip of the tire, so that makes that the adhesion coefficient of the wheels with the ground is the best. It is very significant that shortening the braking distance and improving the braking stability by ABS. This paper will study the fault diagnosis technology of ABS to provide a kind of technical and method for fault diagnosis.This study is divided into two aspects. First, combination of hardware in the loop test technology, a fault simulation system of ABS has been established through simulating the sensor failures and actuator failures to provide evaluation environment for evaluating the capability of fault diagnosis and fault handling. Second, a new diagnostic method through the fault reconstruction has been provided for the sensor of ABS.The functional requirements of the system has been provided based on the analysis on the structure and working principle of ABS, and then the structure of the fault simulation system. In order to evaluate the real-time of fault diagnosis and the correctness of fault handling in different states, a fault event control module and fault generation module methods has been provided to set fault in different controlling. This paper presents a fault simulation system which can meet the the test requirements of fault diagnosis performance of ABS, but also provides a reliable test environment for the study of subsequent fault diagnosis technology.Based on the principle of both the electromagnetic and Hall-type wheel speed sensors, signal characteristics are extracted for teeth-missing fault of wheel speed sensor as well as a big gap between the sensor and the gear ring, so that various faults of ABS system can be simulated accurately. Accordingly, a hardware and software design is proposed to simulate the faults of wheel speed sensor, namely, teeth-missing, big gap, open circuit, short circuit. Additionally, fault simulation for the wheel cylinder pressure sensor, pumps, and also solenoid valve circuit can also be disposed. The influence on the fault simulation signal is analyzed, which is made by the phase difference signal in output sinusoidal signal. And then the circuit simulation and experimental results are given. There are there control modes in ABS, namely, Increase, Decrease, and Hold modes, and it may result in different affects on the braking performance when fault occurs in various modes. Consequently, a model-based control mode predictive approach is presented to produce given fault in arbitrary mode, and it provides an effective test environment for the evaluation of failure treatments.For a certain class of fault in ABS sensors which can be described as a kind of additive one, a sliding mode-based reconstruct method is investigated. Then, it is applied to the open circuit fault of the wheel cylinder pressure sensor, by establishing a nonlinear math model of the wheel cylinder. The simulation results show that the fault can be reconstructed.