Numerical Simulation of a New Passive Auto-tuning Mechanism and Study on its Tuning Motion

Abstract

The authors devised a test equipment which automatically adjust its natural frequency to the excitation frequency. The equipment consists of a sector-like shaped base, a plate spring and a rotating shaft. The horizontal motion of the plate spring enables the equipment to change its own natural frequency. Under the excitation, the test equipment automatically matches its natural frequency to excitation frequency without any controllers. By applying this automatic tuning to a vibration energy harvester, it is possible to realize a device that can maintain high efficiency in an environment where the excitation frequency changes. However, the mechanism of the motion, how the test equipment automatically tunes its natural frequency into excitation frequency, has not been explained. In this study, we created an analytical model with rattles at the root of the plate spring so as to obtain effective results that is difficult to obtain through experiments. As a result, we found that the plate spring’s motion starts when the root of the plate spring conflicts with rattles, and vertical inertial force affects this motion.