On-line determination of tyre deformation, a novel sensor principle

An ultrasonic tyre sensor is proposed which determines the wheel load and the vertical deflection of the tyre. The sensor is mounted on the base of the wheel rim inside the tyre and measures continuously the distance to the opposite inner wall of the tyre providing a highly significant information about the status of the tyre. Additional information, e.g. tyre temperature or tyre-road contact parameters can be extracted from a more detailed evaluation of the sensor signal. To demonstrate the feasibility of this novel approach, measurements were performed at different tyre pressures and wheel loads with a small 400 kHz ultrasonic distance sensor on a tyre testbed. The results for the vertical deflection and spring stiffness are in good agreement with those obtained with traditional off-line methods. This proves that the ultrasonic tyre sensor principle can be used for continuously measuring the vertical tyre deflection during cruising