Pendulum-based embedded energy harvester for rotating systems

Rotating systems accumulate a substantial quantity of kinetic energy while in operation, however, it is arduous to extract that energy when the transduction mechanism is embedded in the rotating body. In this paper, it is proposed that the use of a pendulum system attached to an electromagnetic generator, can be an efficient solution to extract the kinetic energy from rotating systems. Three pendulum systems are experimentally tested: simple pendulum, double pendulum and Rott's pendulum. The harvester can be used for rotating elements such as car's wheel, where tire pressure monitoring systems (TPMS) can benefit from such harvester. An experimental set up is developed to emulate a commercial car's wheel rotating at constant and variable speeds. The three pendulums are tested first under various constant rotation speeds. It is experimentally observed that the systems undergoes three different dynamic regimes depending on the rotation speed. An analytical model is also developed for the three proposed pendulums in order to compare the experimental results with the one obtained numerically. For constant rotation speed, the double pendulum showed the best performance, with a peak power of 9.5 mW at 89 rpm. For a variable speed of the disk, using different initial positions of the disk for each pendulum, the RMS values of the generated power showed that the double pendulum gives better performance for a majority of the tested initial conditions.