Abstract
In recent years, there has been an increasing demand for portable power sources as people are required to carry more equipment for occupational, military, or recreational purposes. The energy harvesting backpack that moves relative to the human body, could capture kinetic energy from human walking and convert vertical oscillation into the rotational motion of the generators to generate electricity. In our previous work, a light-weight tube-like energy harvester (TL harvester) and a traditional frequency-tuneable backpack-based energy harvester (FT harvester) were proposed. In this paper, we discuss the power generation performance of the two types of energy harvesters and the energy performance of human loaded walking, while carrying energy harvesting backpacks, based on two different spring-mass-damper models. Testing revealed that the electrical power in the experiments showed similar trends to the simulation results, but the calculated electrical power and the net metabolic power were higher than that of the experiments. Moreover, the total cost of harvesting (TCOH), defined as additional metabolic power in watt required to generate 1 W of electrical power, could be negative, which indicated that there is a chance to generate 6.11 W of electricity without increasing the metabolic cost while carrying energy harvesting backpacks.
Highlights
Walking in the fields while carrying heavy loads is a common task for soldiers and hikers.Generally, heavier loads often induce more metabolic cost [1,2], higher ground reaction forces [3,4], and greater muscle strain in shoulders [5,6]
It has been reported that the suspended-load backpack, which moves relative to the human body, could capture kinetic energy from human walking and running and convert vertical oscillation into the rotational motion of the generators to generate
There was a reduction of 50.81 ± 33.78 W and 70.51 ± 25.47 W with the TL harvester based backpack condition (TLB) condition compared with the FT harvester based backpack condition (FTB)
Summary
Walking in the fields while carrying heavy loads is a common task for soldiers and hikers.Generally, heavier loads often induce more metabolic cost [1,2], higher ground reaction forces [3,4], and greater muscle strain in shoulders [5,6]. The electronic devices are generally powered by rechargeable batteries, which increase the load applied to the human body and could accelerate fatigue and increase the risk of injury. To address this problem, energy harvesting techniques that convert human kinetic energy to electrical energy have received increasing attention [7,8,9,10,11,12]. Considering that people are often carrying loads in a backpack, making alternations to a normal backpack structure and installing energy harvesters in the backpack provide an opportunity to generate electrical power from the loads. It has been reported that the suspended-load backpack, which moves relative to the human body, could capture kinetic energy from human walking and running and convert vertical oscillation into the rotational motion of the generators to generate
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