Gravity and Magnet-Induced Bi-Stability for Broadband Rotational Energy Harvesting

This study investigates a dual mode mechanism for broadband rotational energy harvesting involving a cantilever beam with a magnetic tip mass and a freely moving repulsive magnet to achieve nonlinear bi-stability. At low rotational velocities, gravitational force on the free moving magnet results in a cyclic oscillation linked to the rotation of the wheel, which in turn perturbates the cantilever oscillation via magnetic coupling. At high rotational speeds, centripetal force and magnetically induced bi-stability opens up the possibility for broadband amplitude based response to harvest ambient noise excitations. Analytical and numerical analyses confirm the system's effectiveness across varying rotational speeds, while experiments validating the theoretical hypothesis.