Design and experimental validation of a novel dual half-cycle string-based mechanical motion rectifier for vertical oscillatory systems

This work presents the design, modeling, and experimental validation of a novel dual-string mechanical motion rectifier for vibration energy harvesting. The proposed system converts bidirectional oscillatory motion into continuous unidirectional rotary motion using a dual one-way bearing mechanism, enabling full-cycle energy conversion in contrast to conventional half-cycle rectifier designs. A coupled electromechanical model is developed to capture the interaction between the mechanical and electrical subsystems, and its predictions are validated through dedicated experiments. The experimental results show strong agreement with the theoretical model across the tested operating conditions. The fabricated prototype demonstrates stable dynamic behavior and achieves a maximum average power of 4.56 mW under a 100 Ω load with an overall efficiency of 45% to 51% within the linear operating regime. Both numerical and experimental findings confirm the effectiveness of the proposed rectification approach and establish a foundation for further development of lightweight and efficient mechanical power take-off systems for vibration-based energy harvesting.