Vehicle Wheel Monitoring and Diagnosis Based on the Vibration Signals of an On-Rotor Sensor

Wheel bearings and tyres are vital components of various vehicles. Their conditions are one of critical factors influencing fuel efficiency, vehicle handling, ride comfort and safe operations, which are more significantly concerned by modern autonomous vehicles. This study introduces a novel On-Rotor Sensing (ORS) method to collect acceleration responses on wheel hub to obtain more accurate and comprehensive information for on-line monitoring wheel conditions. The method is exemplified by a field experiment when a on road car is equipped with an ORS triaxial MEMS accelerometer and ran with different tyre pressures at different speeds. The high signal to noise data from the ORS allows instantaneous wheel rotation speed to be easily calculated for online wheel lockage monitoring and wheel order tracking analysis. Based on tyre resonance responses in the frequency bands from 70 to 200 Hz, the radial and lateral vibrations give a comprehensive detection of changes in tyre pressures using either changes in spectral amplitudes or spectral centroids. However, the lateral amplitudes along can produce sufficiently good detection in the speed ranges tested. Wheel order tracking analysis can be implemented with the instantaneous speed information, making it possible to observe bearing ball pass frequency outer race (BPFO) to assess bearing health conditions. In addition, the amplitudes of wheel harmonics are more accurate, allowing better monitoring and assessing wheel eccentricity and imbalances.