Research On Tire Pressure Monitoring Algorithm Based On The Fusion Of Wheel Speed Pulse Number And Frequency Method

Tire pressure monitoring system(TPMS)is an important part of automobile safety system.When the tire pressure is abnormal,the system will send out an alarm to remind the driver in time to ensure driving safety.The indirect tire pressure monitoring system has became one of the mainstream methods for tire pressure monitoring because of its advantages such as low cost and no need of battery,but its reliability has became a difficult problem to be solved urgently.In order to further reduce the false alarm rate of the indirect tire pressure monitoring system,a indirect tire pressure monitoring algorithm based on the fusion of wheel speed pulse number and frequency method is proposed in this paper,the main research contents include the following four aspects:Firstly,Static and dynamic tire tests under different working conditions were carried out by using tire drum test rig.According to the test results,the relationship between tire pressure,load and tire radius under static condition,and the relationship between tire pressure,load and speed and rolling radius under dynamic condition are respectively established.Which provides mathematical basis for indirect tire pressure monitoring.Secondly,tire wear,turning and other factors can affect the wheel speed pulse,the original data of the wheel speed pulse number under abnormal driving is corrected to eliminate the influence of non-tire pressure factors.When the vehicle travels the same distance,the difference of tire pressure can be reflected by comparing the wheel speed pulse number between four tires,so that the mean comparison method of wheel speed pulse number can be used effectively to judge whether there is abnormal tire pressure.Thirdly,for indirect tire pressure monitoring system is the special working condition of the false positives,namely four wheel pressure value consistent,a grey correlation model among vehicle speed,load,tire pressure and wheel speed pulse number is established,the degree of correlation between vehicle speed,load,tire pressure and the number of wheel speed pulses was respectively solved,wheel speed pulse mean comparison method are analyzed the reason of false positives.Finally,when the four wheels are under pressure to the same degree,only the wheel speed pulse mean comparison method has a high false alarm rate,and the frequency method is introduced to optimize this.The gear ring error was identified and corrected by the weighted recursive least square method,and the corrected gear ring signal was homogenized by linear interpolation;Then the spectrum of the uniformly reconstructed wheel speed signal is estimated by using the fast Fourier transform;Finally,the two algorithms of frequency method and wheel speed pulse mean comparison method are fused together effectively.Through the combination of theory and real vehicle test,the accuracy of four-wheel underpressure identification with the same degree is improved by16.7%.