Design, development, and evaluation of a self-powered GPS tracking system for vehicle security

We describe the design, development, and evaluation of a self-powered tracking system for vehicle security. 3 piezoelectric generators (PG) in cantilever beam configuration were tuned to the dominant frequency of a test vehicle. Voltage doublers were used to rectify the piezoelectric outputs and to isolate the PGs. The harvester designed is not a perturb-and-observe type but directly uses the rectified piezoelectric signals to track the maximum power point. With 30% deviation from the nominal vibration magnitude and 1Hz deviation from the nominal frequency, the harvester is able to maintain its operation within 6% of the MPP. The harvester is able to operate with up to 70.86% efficiency and output 19.8mW of power while consuming a maximum of 200uW. A 2-tank energy storage unit composed of a supercapacitor and an 860 mAh Li-Ion battery stores harvested energy and ensures continuous operation of the harvester. The stored energy is used to power the harvester circuitry, control unit, GPS and GSM modules. The tracking unit was tested by attaching it to the rear axle of the test vehicle. The operation and performance of the overall system were evaluated using the actual vibration profiles of the test vehicle.