Reseaching And Designing Of Tire Pressure Monitoring System

The vehicle safety .has been paid attention to modern time.Statistic shows that the tire failure is a chief factor to induce the traffic accidents(especially on the super highway).It is desiderated to find a solution to avoid the tire failure.Tire Pressure Monitoring System(TPMS)is developed to solve the problem. The system can measure the pressured and temperature of tires real-time, and when either of the tire parameters is exceptional, it alarms to the driver to avoid traffic accident by corresponding operation.The TPMS adopts the idea of module-designed. The tire module which can achieve the signals catching and processing launched by RF is comprised of temperature and pressure measured unit,MCU,Rf. The CPU which can achieve signals recieving, ,processing and showing contains RF,MCU,information controlling and showing unit.In the whole the system is made of one receiver module and four tire modules,between which data is transferred by wireless radio frequency.The tire module has the function of the sampling signal and the transmission, and receiver module has the function of receive of wireless signal, process and alarm.In the whole the system is made of one receiver module and four tire modules.Each one module which is fixed in a tire has the function of measureing pressure and temprature and then transfer the data by wireless radio frequency.The receiver module in one hand has the function of receive of wireless signal,in the other hand control the four tire modules and alarm the innormal data.For the main design purpose of tire module is to reduce the power consumption and minish volume and weight, we adopt the sensor SP12 made in Infineon technologies AG which can control the tire module working by acceleration sensor. When the speed is slow ,the tire module is in the dormancy state in which the system is not working.If the speed can reach the given level,the system can begin to work.So it can reduce the power consumption and make the battery working longer.we use serial asynchronous communication in software and the data is output to the emitter circuit.The baud rate is 4800bps.The radio system measures the tire pressure and temprature each 8 second and compare this two data.If the two data are similar, it can show that the pressure and temprature in the tire isn't changed.If not,the recerver module receive and process the data, then warn the driver by sound and light.THe ARAT862-3 chip is adopted in the tire module which can reduce the power comsuption and space. The principle of the tire module is that: the signal which comes from the pressure sensor and temprature sensor is converced by A/D in the MCU after amplified by amplify circuit.IF the data transmission is needed,the signal is coded and then transmitted by radio.The receiver system contain receiving demodulation circuit,data processing,display and alarming circuit.The signal is received and filered by demodulation circuit and then processed by MCU.IF the pressure and temprature data are abnormal,the system can warn the driver to check the tire.Through the software program, it can give the mix and minimum warning value.The LCD is used in the desplay system.When the given tire pressure and temprature is desplayed,the indicator light is light which can make the driver see the situation easily.Aiming at the characteristic of bad environment and serious disturbance,many kind of software and hardware technology are applied to improve systematic anti-interference ability,which comprehensively improve systematic dependability and practicability.The system improve on the traditional TPMS.It can make the battery working longer. It has the merit of little volume, little power comsuption,signal transmissing distortionless,high reliability and simple circuit.