| Tyre Pressure Monitoring System(TPMS)is the third major automotive safety system after the anti-lock braking system and airbag,which is used to monitor the tyre pressure in real time during the driving process,giving an alert in time when the tyres are leaking and in a state of insufficient pressure,which greatly protects the safety and economy of the car driving.With the implementation of national mandatory standards for TPMS in China from 2020,the research and development of TPMS has been promoted.Indirect Tyre Pressure Monitoring System(i TPMS)has the advantages of simple structure,low cost,simple maintenance and strong durability,which has good development prospect and research value.This paper aims to design and develop a tyre pressure monitoring technology that meets the performance requirements of national regulations.Based on the successful ESC technology developed by the subject group,the research on indirect tyre pressure monitoring technology and algorithms is carried out,the main research contents and results are as follows:(1)The tyre rolling radius and resonance frequency monitoring algorithm and tyre pressure monitoring method based on the rigid ring tyre model are proposed.The excitation to which the rolling tyre is subjected is analysed according to the effective road surface model and the tyre’s operating conditions,the vibration characteristics of the tyre are analysed using the rigid ring tyre model,and the basic principles of the two tyre pressure monitoring algorithms based on tyre rolling radius analysis and resonance frequency analysis.Secondly,in the two tyre pressure monitoring methods implementation,the two-wheel comparison method and the autoregressive model method are used respectively.In order to improve the accuracy and stability of the algorithm,a more comprehensive analysis of the factors that may affect the performance of the system is carried out,including the influence of tyre stiffness,algorithm implementation and working conditions from three perspectives.Finally,the architecture of the indirect tyre pressure monitoring algorithm is established.(2)Based on the requirements of the tyre pressure monitoring algorithm,a wheel speed sensor signal processing method is established.The wheel speed signal that meets the requirements for the use of the algorithm is obtained through sensor error identification,wheel speed correction,interpolation and filtering processes and the wheel speed components in different frequency domains are extracted.For the rolling radius analysis method,the pulse data required for one calculation is obtained by means of pulse count accumulation.Wheel angular acceleration is estimated using the Kalman filter method.(3)An identification method for vehicle state parameters and road conditions affecting tyre pressure monitoring and a tyre operating temperature estimation model are proposed.According to whether the vehicle is equipped with acceleration sensors or not,two algorithms for estimating the overall vehicle mass and road slope are established respectively.A front wheel load estimation method based on tyre longitudinal slip stiffness is proposed,and a multialgorithm interaction strategy is used to estimate the front wheel load,and finally a four-wheel load is obtained based on the whole vehicle mass estimation.Two types of road condition identification methods are proposed,one is to estimate the unevenness level of the road surface based on the wheel angular acceleration signal,and the other is to identify the road surface unevenness and snow surface based on the vibration information in the wheel speed signal.In order to estimate the real-time tyre temperature,the existing physical tyre temperature model is improved and simplified,and a generic heat transfer model is established to reduce the complexity of the model and improve the applicability of the temperature model for engineering applications,while ensuring that the model accuracy meets the requirements of use.(4)Engineering application techniques for indirect tyre pressure monitoring algorithms are established.Based on theoretical analysis and experimental research,and based on the estimated state parameters,corresponding compensation algorithms are proposed for the key parameters(pulse comparison value,underpressure threshold value and resonance frequency estimation value)of the two tyre pressure monitoring algorithms,which eliminate the influence of multiple disturbing factors such as load,temperature,road conditions,vibration disturbance and driving conditions,and improve the robustness of the tyre pressure monitoring algorithms.For engineering applications,the execution logic of the tyre pressure monitoring system is designed,including the logic of self-learning,underpressure state monitoring and system fault monitoring functions,and the algorithm fusion strategy is proposed so that the system can identify various complex underpressure situations and improve the tyre pressure identification capability of the algorithm in complex application environments.(5)A matching specification for the vehicle application of the indirect tyre pressure monitoring algorithm was established,and the application of the developed algorithm to vehicle was realised.The developed tyre pressure monitoring algorithm was integrated into the ABS/ESC software,and the matching of the algorithm was completed according to the matching specification.The algorithm and system functions were verified through vehicle tests,the results showed that the developed algorithm can achieve the recognition of various complex underpressure situations,and the performance meets the requirements of national regulations,realising the engineering application of the algorithm. |
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