Performance Analysis of Linear and Rotary Energy Harvesting Shock Absorber Systems

Simultaneous vibration control and energy harvesting from vehicle shock absorbers has received considerable research attention over the last decade. In fact, conventional vehicle suspensions generally dissipate a significant amount of energy induced by road irregularities and vehicle roll and pitch motion. Regenerative suspension systems, in contrast to other configurations (i.e. passive, semi-active or active suspensions), are able to convert the lost kinetic energy into electrical energy. In general, finding the best compromise between suspension performance and high efficiency energy harvesting is the main objective of Energy Harvesting Shock Absorbers (EHSAs). In this work, an EHSA called the Inerter Pendulum Vibration Absorber (IPVA) is considered. It consists of an electromagnetic rotating EHSA with a non-linear pendulum vibration absorber. Furthermore, an optimal H2 multi-objective control law, based on Linear Matrix Inequalities (LMI) formulations is presented and applied to the proposed IPVA in order to appropriately trade-off among road handling, ride comfort and the amount of harvested energy. Simulation tests show that it is possible to harvest a significant amount of energy while maintaining ride comfort requirements, thank to a suitable control law, which is designed by considering a full vehicle suspension system model. Finally, the results obtained are compared with those obtained by taking into account other linear and rotary EHSAs.