This paper presents a vibration-based electromagnetic energy harvester whose resonance frequency can be adjusted to match that of the excitation.Frequency adjustment is attained by controlling a rotatable arm, with tuning masses, at the tip of a cantilever-type energy harvester, thereby changing the effective mass moment of inertia of the system.The rotatable arm is mounted on a servomotor that is autonomously controlled through a microcontroller and a photo sensor to keep the crank sleeve device at resonance for maximum power generation.A mathematical model is developed to predict the system Washers response for different design parameters and to estimate the generated power.
The system is investigated analytically by a distributed-parameter model to study the natural frequency variation and dynamic response.The analytical model is verified experimentally where the frequency is tuned from 8 to 10.25 Hz.A parametric study is performed to study the effect of each parameter on the system behavior.