Design considerations on intelligent tires utilizing wireless passive surface acoustic wave sensors

The design level of the intelligent tire utilizing wireless passive surface acoustic wave (SAW) sensors decided its practicability. We have developed a wireless passive SAW sensor with two sides of SAW delay lines. It can measure the tire pressure and temperature at the same time. The basic structure of intelligent tires utilizing this SAW sensor is presented. In the design, deformation sensitivity coefficient, temperature sensitivity coefficient and electromechanical coupling factor of SAW sensor substrate were defined as the factors of choice of the substrate. The sensors were coded by reflectors. In the signal processing, the method of averaging the received pulses in a few periods was used to increase signal-noise-ratio (SNR). In the decision-making of the tire state, we consider the trend of the tire pressure variation and the relation of tire pressure and tire temperature to increase the tire´s intelligent level. All the considerations improved the practicability of this intelligent tire.