Abstract
BackgroundMuch research in the field of energy harvesting has sought to develop devices capable of generating electricity during daily activities with minimum user effort. No previous study has considered the metabolic cost of carrying the harvester when determining the energetic effects it has on the user. When considering device carrying costs, no energy harvester to date has demonstrated the ability to generate a substantial amount of electricity (> 5W) while maintaining a user effort at the same level or lower than conventional power generation methods (e.g. hand crank generator).Methodology/Principal FindingsWe developed a lower limb-driven energy harvester that is able to generate approximately 9W of electricity. To quantify the performance of the harvester, we introduced a new performance measure, total cost of harvesting (TCOH), which evaluates a harvester’s overall efficiency in generating electricity including the device carrying cost. The new harvester captured the motion from both lower limbs and operated in the generative braking mode to assist the knee flexor muscles in slowing the lower limbs. From a testing on 10 participants under different walking conditions, the harvester achieved an average TCOH of 6.1, which is comparable to the estimated TCOH for a conventional power generation method of 6.2. When generating 5.2W of electricity, the TCOH of the lower limb-driven energy harvester (4.0) is lower than that of conventional power generation methods.Conclusions/SignificanceThese results demonstrated that the lower limb-driven energy harvester is an energetically effective option for generating electricity during daily activities.
Highlights
Battery capacity has a critical impact on the performance and operation time of portable devices, such as GPS and cell phones
We propose a new measure, total cost of harvesting (TCOH), which is the ratio between the metabolic power increase from normal walking and the amount of electrical power produced
The initial improvement in efficiency was due to the increase in the amount of electricity generated, which made the mechanical power for driving the device components a smaller portion of the total input mechanical power
Summary
Battery capacity has a critical impact on the performance and operation time of portable devices, such as GPS and cell phones. An ideal energy harvester should generate a substantial amount of electricity with a minimal increase in user effort It should operate in concert with the user during daily activities such as walking and jogging, without disturbing his/her natural movement. These requirements inspire studies of biomechanics and energetics of energy harvesting through human experimentation. When considering device carrying costs, no energy harvester to date has demonstrated the ability to generate a substantial amount of electricity (> 5W) while maintaining a user effort at the same level or lower than conventional power generation methods (e.g. hand crank generator)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have