Modeling and Simulation of Wireless Passive Sensors Based on Surface Acoustic Wave Delay Lines
ABSTRACT The coupling-of-mode (COM) model of the interdigital transducer (IDT) is modeled by deriving and solving the COM equations which considered the voltage and resistance of the IDT finger electrodes. In addition, zero input and zero state solutions are added as the solution of the COM matrix equations. According to the IDT model and the reflectance of the reflector, the surface acoustic wave (SAW) delay line is modeled, and the wireless passive sensor based on SAW delay lines is modeled and simulated. The COM model of the wireless passive sensor can simulate the delay phase variation with the pressure well, and it can be used as an effective tool for designing and analyzing the sensors based on SAW delay lines.
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ABSTRACT: 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.Intelligent Control and Automation, 2004. WCICA 2004. Fifth World Congress on; 07/2004
Conference Proceeding: Intelligent tires based on wireless passive surface acoustic wave sensors[show abstract] [hide abstract]
ABSTRACT: The structure and principle of an intelligent tire based on wireless passive surface acoustic wave (SAW) sensors are described. The SAW sensor is made by two identical delay lines on both sides of the substrate symmetrically. In each delay line, there were two reflectors with difference distance from interdigital transducer (IDT). The sensor was hermetically sealed in an all-quartz-package (APQ) technology and embedded in the tire. It can measure the tire pressure and temperature parameters automatically. According to the measurement result, the sensor systems can estimate the tire state intelligently and present the driver an alarm when the pressure or temperature was abnormal. The theory of measuring pressure and temperature is discussed and analysis for measures with pressures from 150 kPa to 300 kPa and temperatures from 25°C to 95°C is conducted. The results of measurement agree with the theory well.Intelligent Transportation Systems, 2004. Proceedings. The 7th International IEEE Conference on; 11/2004