Research And Development Of Tire Burst Early-warning System For Vehicles

1.IntroductionTire must hold right pressure, as important as oil box of the automobile musthave enough oil. If not, the automobile cannot work. According to statistic data, 70percent of traffic accidents attribute to tire burst in the Chinese speedway. Manydrivers don't understand that the tire performance is crucial for driving safety andefficient running. They almost don't check the tire safety and ignore regularmaintenance. Lots of traffic accidents cause great casualties and economic lossesbecause of this matter. Consequently, good tire safety sense is very important forevery driver. However, developing reliable and applied tire safety monitoringproducts is more efficient for the automobile safety. Nowadays, it will makeconsiderable economic and social benefits with the increasing of Chineseautomobiles.While automobile is working, how to monitor real-timely the tire status forpreventing tire burst, is an important study project in the automobile safety. Thesystem in this paper, the tire burst early-warning system, is a new product of activedirect Tire Pressure Measurement System (TPMS). It is an advanced active safetyinstrument applied in the modern automobile.The system application object of this paper is the automobile tire. And itsstudy purpose is to strengthen the security of automobile high-speed running. Thesystem is designed and developed according to the mechanism of tire burst andother factors of influence upon the tire performance. Under the state of automobilerunning, this system can measure every tire status real-timely. When the safe statusof a tire is abnormal, the system host in the cab sends out the sound and lightwarning to the driver, and informs the driver that the tire should be checked afterstopping the automobile immediately. The system can prevent the tire bursteffectively and ensure the automobile traffic safety.2.Main research work in this paper This paper is based on the mechanism of tire burst. By analyzing tire pressureand temperature parameters of influence upon the tire performance, the tire burstearly-warning system is designed and developed according to the technicaldemand for practical application. The central task of system hardcore design includes MC68HC908 seriesmicro-controllers and wireless radio frequency transmitter/receiver mainly.According to system capability achieved practically, the system consists of twoparts: the tire module that is installed inside the automobile tire, and the hostmodule in the cab. On the basis of hardware circuit, the software executes datameasuring, analog signals to digital signals conversion, wireless communicationcontrolling, temperature compensation to tire pressure early-warning threshold,system status monitoring, and so on. As long as the status of a tire or tires havebeen lower or higher than standard tire inflation pressure, tire temperature too high,or air leakage has happened, the system will transmit immediately this informationfrom the tire module inside the tire to the system host in the cab by tireless ratiocommunication. Host sends out a warning to drivers after confirming theearly-warning request by data processing of host micro-controller. Main research work can be divided into the following several parts: (1)Analysis and demonstration of systematic operation principle If tire pressure is too high, the tire longevity will decrease seriously. And it issensitive to sudden impact or collision. The automobile brake performance is bad.If tire pressure is too low, the tire temperature will increase overly. The vehicle iscontrolled badly. Furthermore, too low tire pressure causes tire body fatigue andtire works abnormally. This is the greatest hidden danger of the tire burst. If tiretemperature is too high, the intensity of tire structure layer will fall and everycomponent will be destroyed. The tire loses its load capacity finally. According toworking performance influencing the vehicle running safety and analysis on themechanism of tire burst, monitoring tire pressure and temperature can prevent thetire burst efficiently.Tire pressure will be changed largely with tire temperature changed. So thestandard tire pressure must be adjusted accordingly. A temperature compensationto tire pressure early-warning threshold with different tire temperature is given outin this paper. This can reduce efficiently the missing probability rate and the falseprobability rate of the system. (2)The tire burst early-warning system design The micro-controller MC68HC908RF2 is the core of controlling and dataprocessing unit of the tire module. The integrated sensor MPXY8020A executestire pressure and temperature measuring. The UHF transmitter integrated insidethe micro-controller executes wireless transmittal task. The entire module ispowered by Lithium battery. The micro-controller MC68HC908KX8 is the core of controlling and dataprocessing unit of the host module. The UHF receiver MC33594 executes wirelessreceive task. The host has a liquid crystal module, LCM046. The host adopts LEDand buzzer to achieve sound and light warning. We assess the system performance by three aspects: working environment,working longevity and operation reliability. The system developed in this paperreached the original designing requirement and applied technical feasibility. (3)Developing and debugging of MC68HC908 series micro-controller Nowadays, the develop mode of most MCU still adopts the simulator anddebugger mainly. So cheap available debuggers, enough reference materials andtechnical services are very important for selecting MCU and developingapplication system. Because of the lack of available debuggers and referencematerials, MC68HC908 series micro-controller application is not popular in china. According to the especial systematic architecture of Freescale's MC68HC908series micro-controller, its procedure characteristic and system debugging methodare introduced detailedly. And a Simple and feasible debugging method ofMC68HC908 application system developing is given out in this paper. Referring to lots of domestic developing materials and debugging tools, weadopt the P&E Micro Company's free download ICS08 software kit to achievedeveloping task with the interface circuit of the MC68HC908 monitor mode. This...