Development Of Portable Automobile Engine Crankshaft And Camshaft Signal Source

The topic discussed in this paper is from the cooperation project between JILIN UNIVERSITY and FAW R&D Center. For the requirements of FAW R&D Center, a portable signal source is developed to simulate crankshaft position sensor signal and camshaft position sensor signal of automobile engine. This signal source can help the engineers debug and test both hardware and software of various engine ECUs. In the modern automobile engine electronic control system, ECU is thekey part of the whole system. Using the circuit from the ordinary to the large scale integrated circuits and other devices, ECU can judge, calculate and process the information from the engine sensors according to the programs and data in the memory and then control fuel injectors, ignition controller and many other actors. In the engine sensor signals for ECU, crankshaft position sensor signal and camshaft position sensor signal is the necessary two.Generally, automobile working conditions are bad and changing, so in the product development process of the engine ECU, the engineers must do hardware and software debugging to ensure the engine ECU work well in a variety of weather, mechanical and electrical properties environments. After the initial development, the engine ECU should be tested in the environments too. Load box is used for traditional debugging and test, it can provide the sensor signals for ECU. Ordinary load box is very heavy because it is supposed to provide all of sensor signals, loads and interfaces, so it is not easy to move and be used for debugging and fast diagnosis in work-site. Besides, traditional simulation of the crankshaft position sensor signal and camshaft position sensor signal use motor-driven disc with holes, it is easy to make but not widely used because the type of signal is fixed.The crankshaft position sensor signal and camshaft position sensor signal are the most important signals in the automobile engine electronic control system. Using only the two signals, many engine ECUs can work and control fuel injectors, ignition controller and other actors. Therefore, the two signals can be used to construct a minimum platform for automobile environment simulation and a complete signal simulation system if associate with other sensor signals. So a portable signal simulation system what can provide multi-mode crankshaft position sensor signal and camshaft position sensor signal is very significant in debugging and test of hardware and software of engine ECU.In this paper, development of the system based the system design requirements, a lot of relevant information and adequate preparatory work. Its main duties include the following aspects: System framework design; System portability design; Circuit design for signal output; Circuit design for display and adjustment; Circuit design for power supply management; Hardware drivers design; Main control program design; Debugging and test of the whole system.In the system development process, the waveform, level type and load capacity is studied and analyzed. After that, the system framework is designed, the software and hardware is divided and low-power program is determined according to the portability requirement of the system. Then the functional circuits of the hardware and architecture of the software is designed.In the hardware design process of the system, the following hardware design principles are prepared after considering power, cost, size and real-time performance: Select low-power and highly integrated processor; Select low-power peripheral devices; Dynamic power management; Consider the stability of the system; Combine the software design, then select the processor and design the cell circuits according to these principles. In the software design process of the system, the following software design principles are prepared after considering the same factors: Dynamic system clock; Interrupt mode; Intermittent module operation; Reduce the processor's computation; Consider the stability of the system; Consider the transplantation, then design the program modules according to these principles.After a lot of tests and debugging works, the initial development work is accomplished and a sample of"Portable Automobile Engine Crankshaft and Camshaft Signal Source"is provided for FAW R&D Center. After test, All of technology targets are proved to be qualified."Portable Automobile Engine Crankshaft and Camshaft Signal Source"is controlled by low-power processor, it can provide crankshaft position sensor signal and camshaft position sensor signal in a variety of modes. The user can select the mode and adjust the speed of the signals by the buttons and the knob on the panel. The mode, the speed and many other status information of the system can be displayed by the LCD on the panel."Portable Automobile Engine Crankshaft and Camshaft Signal Source"is an intelligent instrument for automobile electronics development. It will facilitate the debugging, test and fast diagnosis works of the hardware and software system of ECU for its portable feature, friendly HCI and excellent stability.