DESIGN AND ANALYSIS OF A MECHANICAL DEVICE TO HARVEST ENERGY FROM HUMAN FOOTSTEP MOTION

摘要

Portable electronics is usually powered by battery, which is not sustainable not only to longtime outdoor use but also to our living environment. There is rich kinetic energy in human body during walking, so it is ideal to harvest the kinetic energy from human footstep motion as power source for portable electronic devices, In this paper, a novel mechanism based on dual-oscillating mode is designed to harvest such kinetic energy. The harvester contains two oscillating sub-mechanisms: one is spring-mass oscillator to receive the vibration from footstep motion, and the other is cantilever beam with tip mass for amplifying the vibration. The energy conversion sub-mechanism is based on the electromagnetic induction, where the coils fixed at the tip end of the cantilever beam serves as the slider and permanent magnets form the changing magnetic field. Analysis shows that the harvester, with total mass 70g, can produce about 100mW of electricity at the walking speed of 2 steps per second.