Abstract: As the core of the automotive engine control system, the ECU (Electronic Control Unit) requires independent intellectual property research. Based on domestic realities and an analysis of existing systems, and employing advanced global technologies and integrated design concepts, this paper presents a design scheme for an intelligent electronic controller for automotive engines based on the CAN bus, including the system hardware control structure and software control algorithm. This serves as a foundational work for further designing the overall control system. Keywords: Engine; Electronic Control Unit; CAN bus; Intelligent Electronic Controller 1 Introduction Currently, although the engines of mid-to-high-end cars produced in China generally adopt electronic fuel injection technology, and the country has basically achieved supporting R&D and production capabilities for the components of the electronic injection system, it lacks independent intellectual property rights for electronic fuel injection engines, relying entirely on imported electronic fuel injection engine production lines or systems. In particular, the ECU (Electronic Control Unit), a core component, is controlled by foreign companies. The fuel injection and ignition MAP, control algorithms, and programs within the ECU are completely confidential. Furthermore, the import sources are diverse, and the varieties and specifications are varied. Some companies lack selection and evaluation, resulting in inconsistent levels of imported technology and product quality, and many lack sufficient matching experiments. This research project is an ECU that integrates people, vehicles, and the environment into a comprehensive system, coordinating various factors to optimize the control performance of the vehicle. Therefore, it has high economic and social benefits, and will promote the application of industrial control networks and embedded control systems in the automotive industry, making the car more intelligent and user-friendly. 2 Research Content The main control objects of this project are fuel injection and ignition devices. It also has some related auxiliary control functions. The main functions include: (1) Intelligent Injection Control (IIC), which mainly includes the control of fuel injection quantity, injection timing, fuel supply interruption, and fuel pump. Due to the adoption of intelligent design, the shortcomings of fixed control algorithms are solved, which can effectively save fuel and help improve the overall performance. (2) Intake control, which mainly includes the control of power valve and swirl valve, which can effectively improve and increase the output torque and power of the engine. (3) Boost control, the ECU controls the pressure relief solenoid valve according to the intake pressure signal detected by the intake pressure sensor, so as to control the exhaust passage switching valve, change the direction of the exhaust passage, and thus control the exhaust gas turbocharger to enter the working or stopped state. (4) Electronic Spark Ignite (ESI): The control of the ignition device mainly includes ignition advance angle control, energizing time (closing angle) and constant current control, knock control, etc. (5) Idle Speed ​​Control (ISC): Under different idle operating conditions such as car operation, air conditioning compressor operation, transmission gear engagement, and increased generator load, the ECU controls the idle speed control valve to ensure that the engine operates at the optimal idle speed. (6) Emission Control: The main control items include exhaust gas recirculation control (EGR), oxygen sensor and three-way catalytic converter open-loop and closed-loop control, secondary air injection control, activated carbon canister solenoid valve control, etc. (7) Warnings and Alerts: The ECU controls various alerts and warning devices to display the working status of the control system. If the control system malfunctions, a warning signal is issued. (8) Sensor Fault Prediction Reference System (Failure Protection): When the main ECU detects a sensor or circuit fault, it will use the preset value provided by the main ECU to keep the engine running, but the performance will be reduced. (9) Main ECU Failure Backup Redundancy System: When the main ECU fails, the backup redundancy system will automatically activate, forcing the engine into a forced running state so that the driver can take it for repair. 3. Composition of the Electronic Fuel Injection System In addition to the power supply, charging device, ignition device, and starting device found in most carburetor engines, the electronic fuel injection system also includes an electronic fuel injection control device, an idle speed control device, an electronic control unit (ECU), and various signal acquisition devices (sensors). Figure 3-1 shows the composition of an electronic fuel injection system. [align=center] Fig. 3-1 The basic composition of electronic injection system 1. Fuel tank; 2. Electronic fuel pump; 3. Fuel filter; 4. ECU; 5. Fuel injection valve; 6. Fuel control valve and fuel pressure regulator; 7. Intake manifold; 8. Cold start valve; 9. Throttle position sensor; 10. Air sensor; 11. Oxygen concentration sensor; 12. Thermal timer switch; 13. Coolant temperature sensor; 14. Ignition distributor; 15. Idle speed actuator; 16. Battery; 17. Ignition and start switch[/align] The electronic injection system shown in Fig. 3-1 can be divided into three parts: actuators, signal acquisition devices, and signal processing and control devices. The relationship between them is shown in Fig. 3-2. [align=center] Fig. 3-2 The relationship for parts of electronic injection system[/align] The actuators include the injectors, ignition coils and spark plugs, and idle speed actuator. The collected signals include: throttle opening, intake manifold pressure, engine speed, knock signal, engine coolant temperature, exhaust oxygen concentration, and intake air temperature. The ECU, as a signal processing and control device, processes these signals, converts them into identifiable values, and then calculates and processes them to obtain the control signals for the output actuators. The control accuracy of the ECU requires not only real-time and accurate collected signals but also precise actuator movement. Using algorithms in the ECU control program can not only achieve higher control accuracy but also compensate for errors caused by non-real-time signal acquisition and low actuator movement precision. 4. ECU: Through the analysis of the electronic fuel injection system, we can clearly see the important role of the ECU as the control core. Due to the time-varying and nonlinear nature of the controlled object, engine control systems using ECUs have evolved towards centralized control systems: in terms of control structure, the ECU is the core, communicating with I/O devices via a CAN bus; in terms of control algorithms, a combination of fuzzy control theory, PID regulation, and BP neural networks is used to construct steady-state control MAP and idle speed control models. Figure 4-1 shows the control structure of the electronic fuel injection system. [align=center] Figure 4-1 shows the control structure of the electronic injection system.[/align] The ECU's CPU uses a DSP chip with floating-point arithmetic capabilities, while the various detection signals and drive control circuits can use independent microcontrollers with A/D and switch conversion capabilities or CAN bus interfaces. Once the structure is determined, the ECU's control capability lies in the development of the control program. Due to the complexity of control states and strategies, the following explanation uses ESI as an example. The core control issue of ESI is the control of the ignition advance angle. The control strategies are completely different under different operating conditions: when the engine is in the starting condition, due to the large and rapid fluctuations in starting speed, it is impossible to determine the ignition advance angle based on the MAP diagram; when the engine is in the transient condition, since it is an open-loop control, the ignition advance angle can be directly calculated using interpolation; when the engine is in the steady-state condition, it is necessary to determine whether there is knocking and adopt closed-loop control accordingly, that is, to progressively adjust the previous MAP diagram value to obtain the optimal ignition advance angle. Figure 4-2 is the flowchart of the ignition advance angle control program. [align=center] Fig.4-2 the control procedure flow chart of ignition angle[/align] 5 Conclusion This paper proposes a design scheme for an intelligent electronic controller for automotive engines based on CAN bus, based on the analysis and summary of existing systems and the latest research results of related domestic and foreign studies. Further simulation bench experiments of various parameters are required, and finally, intelligent MAP and control programs for various working conditions are given. References [1] Liu Jianhui et al. Intelligent electronic controller for automotive engines based on CAN bus. Project Research Report, 2003 [2] Yang Xianhui. Fieldbus technology and its application [M]. Beijing: Tsinghua University Press, 1999 [3] Chen Hua. Research on single-point fuel injection electronic control system for engines [D]. Chengdu: Sichuan University, 2001