Strain-based piezoelectric energy harvesting for wireless sensor systems in a tire

Vehicle safety can be improved by tire pressure monitoring with a wireless sensor system. Since a battery-powered wireless sensor system for tire pressure information is limited by the life of the battery, energy harvesting technology is applied. In order to develop an energy harvester based on a piezoelectric material for the tires, modeling of tire behavior and the energy harvester, and the validation of the modeling were performed. The structural behavior of a tire was numerically modeled and verified by comparing the simulation results with experimental data. In order to compare the generated voltages between the modeling and the experiment, comparisons of the root-mean-square voltage values for various velocities and loads, the distortion factor using the root-mean-square value of the wave form, and the crest factor for verifying the efficiency of the peak value of the wave form were conducted. The results showed that the differences are on average 10% for the loads between 300 and 700 kgf and velocities between 20 and 60 km/h (430 r/min). For the improvement of the energy harvester’s performance, the thickness of substrate was controlled and the generated voltage was increased. If a sensor for measuring radius is applicable to the tire, the strain on the tire can be collected, and thus the loads applied to the tire can be estimated. With a wireless sensor system for measuring radius driven by energy harvesting, we can be one step closer to the embodiment of an intelligent tire.