Comfort, safety and diversity have become the development trend of automobile industry.
Body control module is the core of body function requirements. In this paper, the overall scheme of body control based on CAN/LIN bus is designed, which is mainly CAN bus and assisted by LIN bus.
The hardware of the front body controller is designed, and the software design of the front body controller is completed on the basis of the hardware design.
In order to provide reference and reference for the development of automotive electronic technology in China. In today’s society, automobile is one of the most important means of transportation in economic development and life. With the development of computer technology and automobile technology, thermostatic element electronic control technology has been widely used in modern automobile industry to improve vehicle safety, economy and comfort. It has become the development trend and important symbol of modern automobile industry. Many parts of automobile body benefit from electronic control system, including ignition control, rule diagnosis, steering, braking, lamp, wiper, door lock and so on. According to the application of automotive electronic technology in different control systems, it can be divided into engine control system, body control system, chassis control system, communication and information/entertainment system. In order to shorten the gap with foreign automotive electronic control technology and continuously improve its competitiveness, it is imperative to develop automotive electronic control system. The body control system adopts distributed control system and CAN / LIN bus hybrid network. The system structure is shown in Figure 1. In the past, the body control system was the core to coordinate the control of all parts of the body.
In the whole system, the front body controller acts as the gateway of high and low CAN and LIN bus to realize the communication and signal sharing of different networks. The high-speed CAN network transmits the chassis control system signal to other necessary control components and displays it on the dashboard in real time. The signal of the light-controlled switch is sent to the BCM of the back end through the LIN network to control the left and right light groups of the rear. Two LIN buses are used to collect signals of combination switch and car lamp switch. The second way is used to control anti-jamming windows, window lifting and so on. In addition to signal processing and network management, the front-body control module also controls the front and rear lights, the front and rear lights, anti-clip windows, speakers, intelligent wipers and other functions.
The rear body control module mainly controls the rear part of the vehicle, such as left and right lamp group, rear lamp, car door lock, window heating and other functions. The front body controller collects a large number of switching signals and outputs many control signals, as well as serves as the gateway of CAN network and LIN network.
This requires the selection of microprocessors with high performance and reliability to achieve high-speed and reliable data processing. The mc9s12xs256 microcontroller designed and manufactured by Freescale Semiconductor Company is applied to automobile.
It integrates MSCAN module, serial communication interface and supports CAN bus and LIN bus protocol.
The front body controller consists of two CAN buses and two LIN buses. The UJA1078 SBC power chip integrated with one CAN bus is used in the low-speed CAN bus, and the TJA1042 transceiver is used in the high-speed CAN bus. TJA1020 transceiver is used in both LIN buses. There are also 21 channels of switching signal acquisition, 7 bits of A/D signal acquisition, 11 channels of lighting driving signal output, 4 wipers, speaker output. Figure 2 is the block diagram of the former BCM module system.
According to the real-time requirement of the whole body part, the communication rate of high-speed CAN network is 500 kb/s, that of low-speed CAN network is 250 kb/s, and that of two LIN buses is 19.
2 kb/s. The whole vehicle body part of the network load is low, the communication rate can fully meet the requirements of real-time and reliability. The software design of automobile controller includes system initialization, system application, CAN/LIN protocol conversion and system fault programming. The program flow chart of the front body BCM control module is shown in Figure 3. Although the domestic automobile manufacturing technology and innovation ability are constantly improving, at present, the manufacturing technology and innovation ability of domestic independent brand automobile manufacturers are low. The body control module based on CAN/LIN bus is designed, which is mainly composed of CAN bus and assisted by LIN bus.
Reasonable network structure and hardware design are adopted to meet the requirements of complex body control system, which has good economy and makes the design simple.