The Research Of Indirect Tire Pressure Monitor System Based On The Frequency Method

In recent years, with the rapid development of automobile industry, automobilehas been integrated into all aspects of daily life; it has brought great convenience topeople and promoted the development of the world economy. As the vehicle speed ismore and more higher, road condition becomes more and more complex, theoccupants begin to pays more attention to for vehicle safety, a variety of active andpassive safety technology emerge in an endless stream. As the vehicle tire is the onlycomponent to contact with the ground, all sources of automobile road adhesion comesfrom it, it is also the most important link of vehicle handling stability. Once tire faultoccurs, the vehicle driving safety is extremely influenced. In the process ofhigh-speed driving, tire fault is the highest and most difficult to prevent dangeroushidden trouble, all kinds of malignant traffic accidents due to tire are fearsome sight.How to realize the monitoring of the working status of tire and tire failure earlywarning to reduce tire blowout has important significance in the field of automobilesafety. Meanwhile it has become a new focus of attention of the industry.Presently the major manufacturers generally use the tire pressure monitoringsystem (TPMS) to conduct automatic monitoring on tire pressure in the runningprocess of the automobile. In accordance with the principle of monitoring, TPMS ismainly divided into two types; the first kind is the direct tire pressure monitoringsystem. Through the pressure sensor installed in the tire valve and the wireless RFreceiving device in the cab, a wireless transmitter transmits tire information to thereceiving device to realize real-time monitoring of tire temperature and pressure atauto static and moving process, alarm the tire pressure it too high or insufficient andhigh temperature to avoid the blowout accident. The second is the indirect tirepressure monitoring system, traditional indirect tire pressure monitoring system usethe ABS system to compares the tire speed difference to achieve the purpose of tirepressure monitoring. When the tire pressure is reduced, the vehicle quality will makethe tire rotation radius change, because the four tire line speed should be consistent,the tire whose pressure is low rotates faster than other normal tire, the purpose ofpressure tire inspection is completed. This method does not need to add new hardware, what need to do is to adjust the software in ABS or ESP system. At last it can realizethe tire pressure monitoring function.This paper analyzed the advantages and disadvantages of direct tire pressuremonitoring system and the indirect tire pressure monitoring system, the tire pressuremonitoring method based on frequency method is put forwarded, a physical model ofthe tire is constructed, the effect of each parameter in the model is analyzed. Throughanalyzing the structure characteristics of the Hall wheel speed sensor and the workingprinciple, the source of the error of the sensor is found and the error is eliminated byRecursive Least squares algorithm. For the question of the unevenly sampling of thewheel speed sensor, using interpolation method and Toeplitz matrix inversion tocomplete the wheel speed signal reconstruction. At last the wheel speed is carried outthe spectrum analysis and the tire resonance frequency is extracted by the forgettingfactor method of modern spectrum estimation. Because different tire pressure iscorresponded with different resonant frequency, this relation can be used to monitorthe tire pressure.