Energy recovery from a pendulum tuned mass damper with two independent harvesting sources

This paper focuses on vibration mitigation and energy harvesting in a coupled oscillator-pendulum system. Generally, the concept of a vibration-based energy harvester is similar to a vibration absorber, it is naturally desired to use the same system for simultaneous vibration reduction and energy recovery. However, a problem of whether or not vibration mitigation and energy recovery is contradictory has arisen, based mainly on the intuition that the former tries to reduce vibration while the latter profits from large vibrations. In the paper, the pendulum construction is modified by the use of two independent electromagnetic harvester systems. The first harvester is based on oscillation of a levitating magnet in a coil. The second device is a DC electrical motor mounted in the pendulum's pivot. An effort is made to obtain comparison of an energy harvesting/vibration mitigation effectiveness of both harvesters. We propose new indicators to find a consistency between vibration suppression and energy recovery, and compliance regions were detected. Finally, we confirm some results by the means of a comparison with an experiment. The study gives an answer about effectiveness of the both harvesters and suggests that the proposed concept can be useful in practice.