On-board estimation of dynamic tyre forces from optically measured tyre carcass deflections

Active safety systems would benefit from accurate information on tyre forces. A special sensor module has been developed for research purposes to study real-time tyre force estimation from tyre carcass displacements. The forces can be measured in vertical, lateral and longitudinal directions. The sensor measures tyre carcass movement with respect to the rim and transmits the data wirelessly to the chassis. The raw data is analysed and tyre force information is available on a CAN-bus. The sensor is calibrated in a tyre test rig and proving ground measurement results are presented. The lateral and longitudinal force estimates are accurate when compared with the vehicle accelerations, but the vertical force is difficult to estimate during heavy braking manoeuvres.