Design and Analysis of Ball Screw-Based Inertial Harvester

In this paper, innovative design of an Inertial Ball Screw Harvester (IBSH) has been proposed. In comparison with the conventional devices, the conceived design has incorporated mechanical links to amplify angular acceleration of the ball screw with ratio of 2.11. Furthermore, use of two unidirectional bearings improves efficiency by reducing power loss due to frequent reversing of the nut. Numerical simulations have been performed and the results have been validated with experimentations on a prototype. The simulation results have been used in design of the real size IBSH with electrical loading operating at its resonance frequency. Effect of important design parameters on the efficiency has been evaluated and optimum electrical and mechanical damping have been determined to achieve peak power of 16-25W. It has been revealed that lower mechanical damping and optimum electrical damping improves power output. Significant increase in power output can be ensured by tuning the harvester stiffness according to the excitation frequency.