Modeling And Experimental Research Of Tire Pressure Monitoring System Based On Unitire Model

The tires are important part of the vehicles. They support the whole vehicle’s weight,pass driving force and moment of the vehicle and have an effect on the driving security,comfort and Fuel economy of vehicles. When a vehicle’s tire pressure is abnormal, whichwill speed up the tire wear, cut down the tires’ life and even result in tire blowout. Underthis condition, driving cars hide danger. Therefore, it is important to monitor tire pressureanytime. At present, there are two kinds of tire pressure monitoring systems on sell whichare direct and indirect.Basing on the Unitire model,this paper builds braking force simulation model inMATLAB’s Simulink module based on Unitire model. According to the method of rollingradius of the indirect tire pressure monitoring system, a data acquisition system isdesigned and made, which contains a central processing module, a voltage regulatormodule, a wheel speed signal processing module, a CAN communication module and aserial port communication module. The MCU program is compiled in the software calledCodeWarrior6.3. The program can collect and process wheel speed signal, acquire GPS’sdata through CAN bus, and send data to computer by serial port for simulation. Whendoing car braking test on the road to collect data, left front and left rear wheels’ pressureare set in6grades.The braking test starts when car speed is stable at40km/h and begin tocollect data at the same time to calculate longitudinal force in the Unitire model.The test result shows that, when car is braking and front tires’ pressure is not equal,lower pressure wheel’s speed signals increase, rolling radius decreases and braking forcedecreases. When car is braking and rear tires’ pressure is not equal, wheel’s speed signals,rolling radius and braking force change not much.So front tires in different pressure willcause different braking forces. It will result in braking deviation. In conclusion, it willhave an effect on vehicle’s braking security when tire pressure in abnormal condition.