The Design Research Of CAN-bus For The IntelligentAir Conditioner Control System In The Vehicle

Automotive air conditioning temperature control system is a system that does not needhuman intervention,can regulate the temperature to the range which makes people feelcomfortable. With the opening of the car market since China access to the WTO, Chinabecome the world’s second largest car trading market. Since the fierce competition of themarket,the user experience has become the initially consideration of the automobilemanufacturers, so the automotive air conditoner plays an important part in it. The traditionalvehicle air conditioning system adopts the way of manual control, turns out the control effectnot ideal.Besides,the driver adjust the temperature manually during the driving process wouldraise the risk of the car accident. In addition, in the traditional measurement system, the maincontroller directly connected to the sensor,could only set one or two sampling node becausethe limitation of the communication line, so the system can not reflect the temperature of thecar exactly.At the same time, for the limitation of the sampling node which limits the numberof the air outlets, the passenger cabin can hardly regulates the temperature and humidityaccording to different area.All these make the amenity and energy efficiency drop.Trying to solve these problems, this design uses the distributed system instead of thetraditional centralised system to conduct the temperature control, by comparison to severalcommon fieldbus type, it picks the CAN fieldbus which has strong anti-interference abilityand quick arbitrate time, support multi master mode,as the communication protocol of thesystem.As the system using a main point with multiple CAN child node of master-slavestructure, the whole control system turn out to be efficient and reasonable. The whole designof the system follows the design principles for the embedded instrument.The master nodeselection is based on ARM920samsung S3C2440chip of nucleus with LINUX operatingsystem,and the child node use the TI company’s16high performance microprocessorMSP430, child node based on CAN bus received the master node sends informationaccomplish specific work, because use the master node and child node structure, combinedwith the characteristics of CAN bus, make the whole system expands and maintains easily.After the simulation test, the system is under good control.This paper also researches the temperature outside the car, sunlight, water temperature ofthe car engine, air conditioning outlet speed and so on,to know how these factors influencethe temperature of the car.It proposes a kind of fuzzy control rules to make the insidetemperarture of the car reaches to a constant range automatically, at the same time, build the ARM+LINUX embedded control system platform.In the end, this system performs good inthe real-time and reliability during the simulation.