Sensing of multiple unrelated tire parameters using electrically open circuit sensors having no electrical connections

All sensors or sensor systems previously used for tire measurements have one common feature - the sensors are part of electrically closed circuits and electrical connections are used to form the closed circuits. In this paper, we present a new tire safety monitoring system using a recently developed method for designing, powering and interrogating sensors developed at NASA. In lieu of sensors being a collection of components assembled using electrical connections, the sensors are patterns of electrically conductive material that can store electric fields and magnetic fields without electrical connections. They are powered using oscillating magnetic fields and respond with their own magnetic fields whose signatures give information about the measured parameters. Because no electrical connections are used to power, communicate with the sensor or to make the sensor, there is no point on the sensor that if damaged, renders the sensor non-functional. Many damage events simply shift the sensor´s frequency range. Survivability of the sensor allows it to continue measurement while damaged. The physical quantities to be measured are correlated to the sensor´s magnetic field response amplitude, frequency and bandwidth. The proposed method measures wheel speed, rotation angle, direction, acceleration, temperature, damage and wear of tread element by using two or more sensors. In this study, two sensors are used. One of the sensors is coated with temperature sensitive dielectric material. The two sensors working cooperatively are able to measure the seven parameters. The results and multifunctional measurement strategies are presented.