Harvested power and sensitivity analysis of vibrating shoe-mounted piezoelectric cantilevers

Abstract

This paper presents a preliminary investigation on energy harvesting from human walking via piezoelectric vibrating cantilevers. Heel accelerations during human gait are established by correlating data gathered from the literature with direct experimental measurements. All the observed relevant features are synthesized in a typical (standard) acceleration signal, used in subsequent numerical simulations. The transient electromechanical response and the harvested power of a shoe-mounted bimorph cantilever excited by the standard acceleration signal is computed by numerical simulations and compared with measurements on a real prototype. A sensitivity analysis is finally developed to estimate the mean harvested power for a wide range of scavenger configurations. Acceptability criteria based on imposed geometrical constraints and resistance strength limits (e.g. fatigue limit) are also established. This analysis allows a quick preliminary screening of harvesting performance of different scavenger configurations.

Designing and manufacturing a piezoelectric tile for harvesting energy from footsteps

“…Four piezoelectric modules were matched at 15 kU, yielding output powers of 770-mW RMS and 55-mW peak. This RMS value was 203% higher than Moro's shoe-mounted harvester [22]. This indirect type harvester has many advantages to applying real environment.…”

An In-Shoe Harvester With Motion Magnification for Scavenging Energy From Human Foot Strike

“…In previous studies, the power density of the electromagnetic energy harvester by Niu [19] was 0.286 mW/cm 3 . The power density of the in-shoe piezoelectric energy harvester by Shenk [20], by Kymissis [21] and byMoro [22] were 0.226 mW/cm 3 , 0.035 mW/cm 3 and 0.13 mW/cm 3 , respectively. The proposed energy harvester in this work can provide much greater power density than other existing similar type of energy harvesters during human normal walking.…”

“…Kymissis [21] employed a PVDF stave and a unimorph as parts of the sneaker insole to harvester energy from human walking, which can generate total electrical power of 2.9 mW. Moro [22] also used a PZT cantilever beam to harvest footstep kinetic energy and to provide electrical power of 0.3 mW. However, there is still considerable room for improvement for the power output of energy harvesting from foot strike motion.…”

Footstep energy harvesting using heel strike-induced airflow for human activity sensing

“…Among all energy sources from human motion, footstep motion has the highest potential energy (67 W, estimated in [8]), but the low-motion frequency and the limited vertical deformation of shoes make energy harvesting from footsteps intractable [9]. Different mechanisms have been investigated to address these issues, such as gear trains [10] or frequency up-conversion [11] to increase the excitation frequency, a rotary arm [7] or a trapezoid-shaped slider [12] to generate rotation from the shoe distortion. However, these devices still have the issues of complication, high weight and high costs.…”