Pendulum-based hybrid system for multidirectional energy harvesting

This work presents a hybrid multidirectional mechanical energy harvester to enhance the performance of a cantilever-based harvester when subjected to multidirectional excitations. The multidirectional capabilities are achieved by employing a pendulum structure. Hybrid transduction is provided by combining a piezoelectric element and an electromagnetic transducer. A reduced-order model is presented based on the electromechanical Lagrangian formulation, and numerical analyses are performed to characterize the system behavior. A comparison based on energy harvesting performance is established among the novel multidirectional hybrid energy harvester (MHEH), the classical piezoelectric harvester (CPEH), and a multidirectional piezoelectric harvester (MPEH). Results show that the addition of the pendulum alone indeed provides multidirectional capabilities, but the overall performance can be reduced in some scenarios since it works as an energy absorber. This limitation is overcome by the hybridization strategy of the MHEH, by incorporating an electromagnetic transducer into the pendulum support. Overall, a significant improvement is achieved in all scenarios by utilizing the hybrid system.