Development Of Fault Simulation And Diagnosis Platform For Analog Circuit

With the increasing improvement on functions of missiles, satellites and other large systems, requirements of reliability for the systems are also increasing. Electronic equipments are the core control units of large systems, so requirements of reliability for them are strict. Analog circuits take a small proportion of electronic circuits, but they are easier to go wrong than digital circuits. So it's more urgent to study fault diagnosis of analog circuit. However, there are two main challenges in fault diagnosis study: lack of fault samples and evaluation of methods. So it's difficult for methods with good theory to be applied widely. To solve this problem, this paper takes analog circuits in the electrical system of a device as diagnosis targets to study the analog circuit fault simulation and diagnosis including fault models of typical components, methods to inject faults and to acquire fault samples. Fault simulation platform and fault sample acquisition platform are developed to acquire fault samples of actual circuits and to evaluate the intelligent fault diagnosis methods based on the research results.Based on analysis of the functional and technical requirements of fault simulation and diagnosis system, the overall design of the system is presented. The system is divided into three parts: fault simulation platform, fault sample acquisition platform and fault diagnosis platform. The fault simulation platform takes the DC power supply circuit and autopilot circuit of the device's electrical system as diagnostic objects to analyze fault modes of typical components, and use relays and FPGA to inject faults. Fault sample acquisition platform takes ARM controller as control unit to control all modules within the platform, and communicate with the host control computer by LAN bus. It can generate test stimulus and acquire fault samples. Fault diagnosis platform controls the whole system implementing equipment testing, fault simulation and fault diagnosis. Support vector machine algorithm is taken as the diagnosis method. The whole system was debugged and conclusions and evaluation were given.Test results in lab show that fault simulation platform can simulate analog circuits in the device's electrical system effectively, every fault simulation module can be injected more than 30 kinds of faults, and provides actual fault samples. Fault diagnosis platform's diagnostic accuracy is than 90% and has a good user interface. The fault simulation and diagnosis system meets the design requirements. In addition, the research results have a certain generalization.