Three different methods for indirect tire pressure monitoring were developed and tested experimentally. Indirectly measuring systems estimate the tire pressure using sensor signals of the wheel or the suspension which may be already available for other vehicle dynamic control systems and are influenced by the tire pressure. The simplest one uses a comparison of the wheel speeds. However, only relative changes of inflated tires can be detected. The spectral analysis of the wheel speed oscillation and vertical wheel acceleration allows possibly to localize the deflated tire. Vertical wheel acceleration was more sensitive to indicate the deflated tire. An overall strategy for the fusion and the evaluation of the different methods is presently developed. This can be achieved with fuzzy logic. The changes of different residuals can be combined such that an increasing number of deflected residuals increase the probability of detecting a tire deflation. To incorporate redundancy at least one residual for wheel speed comparison and the spectral analysis of at least one signal preferably the vertical tire acceleration should be used. The accuracy of the spectral analysis can be improved if the difference of the natural frequency from a reference value calibrated at the correct tire pressure is used. Additionally the absolute natural frequency should be observed to be able to detect a loss of tire pressure in all tires simultanously. The influence of a reduction in tire pressure on the spectrum of further signals from the suspension system like the vertical body acceleration and deflection of vehicle suspension system is investigated. Results as well as the application of further spectral analysis methods will be presented. Furthermore, all methods have to be tested with all combination of tires, suspensions and under longer running times and environmental influences.
Indirect tire pressure monitoring by using wheel speed and acceleration signals
2008
17 Seiten, 22 Bilder, 1 Tabelle, 20 Quellen
Conference paper
Storage medium
English
Indirect tire pressure monitoring by using wheel speed and acceleration signals
Automotive engineering | 2008
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