Efficient energy harvesting from human motion by tristable piezoelectric cantilever

Tristable energy harvester is applied to harvesting energy from human motion in order to overcome the narrowband issues of linear resonant piezoelectric energy harvester. Based on the characteristics of human motion, time-varying potential energy function of tristable oscillator with respect to the swing angle is established to derive the theoretical model for harvesting energy from the swing motion during human walking and running. Detailed restoring forces of the tristable energy harvester under different swing angles are measured and the corresponding potential energy functions are obtained. Experimental results under various motion speeds show that the tristable energy harvester exhibits better performance than the linear one for harvesting vibration energy from the swing motion during human walking or running.