The Research Of Fault Diagnostics For A Column-assist Type Electric Power Steering System (C-EPS)

As a new automobile power steering technology and configuration, Electric Power Steering (EPS) Systems have many advantages over traditional hydraulic power steering systems in engine efficiency, space efficiency, safety, and environmental compatibility. In developed countries such as America and Japan, through more than twenty years research in EPS, they have applied this technology to several kinds of car. Though this technology is development late in our country, EPS has become a hotspot in automobile fields, many academics and automobile research centers focus on it and beat fruit. Nowadays, EPS technology has the trend of put into production, as a most important safety system in a car, researching on the fault diagnostics of EPS has become the focus.The thesis is based on the most important project of Zhejing province in 2004, Focus on the research of fault diagnostics for Column-assist Type EPS (C-EPS).The Principal contents studied in this thesis are as follows:1. Research on the failure mode and ascertain the failure code of the C-EPS. In order to ascertain the failure mode, Author have analyzed the consist parts of the system and told of the work principle of C-EPS. In terms of the Failure Mode and Effects Analysis theory, author have ascertained the potential failure mode and coded for the failure mode.2. Adopted the artificial neural networks (ANN) to the On-line Fault Diagnosis of the C-EPS. As an important safety system of a car, it is necessary for us to detect the fault of the pivotal parts of the C-EPS real-timely. As for the C-EPS, the Torque-Position sensor (TPS) and the Electronic Control Unit (ECU) are the key parts, so, we decide to use the real-time fault diagnosis to these two parts.3. In order to acquire the training data of the ANN model, we have designed the performance test system for C-EPS. The test-bed can totally simulate a car that the C-EPS can work normally on it. Data acquisition and processing is the basic performance of the test-bed. The design for the test-bed including hardware design and software programming.4. Have built three fault diagnosis models for Torque signal. Position signal and ECU with ANN, Using the training data acquired from performance test-bed to train these three models.5. We can use the performance test-bed to set several faults such as the TPS isn't calibrated, electrical source malfunction and so on. Then we can acquire the accordingly data and use the data to test the validity of ANN models, the result proved the validity of the fault diagnosis strategy.