Arm Motion Dynamics to Excite a Mobile Energy Harvesting Autowinder

Author(s):  
Abby George ◽  
David Moline ◽  
John Wagner

Abstract A mobile energy harvester device based on the inertial automatic winding mechanism found in watches is explored. Through normal human motion during walking and running, the arm travels a spatial path that can potentially be used for energy harvesting. The conceptual harvester consists of a rotary pendulum coupled to a small generator through a step-up gear train. The generator’s electrical output may be stored and utilized as a power source for portable electronic devices that require a smaller amount of power for operation. In this paper, the equations of motion governing the human arm motion dynamics and harvester pendulum excitation are fully derived. Two cases of human walking and running are considered to analyze the system response. A series of representative simulation studies have been conducted for representative arm motion to determine the potential energy. The energy available for harvesting was greater in the case of the human subject running at 2.06 mJ, while when walking it offered an output of 0.42 mJ for a 5 second time period. The two numerical results serve as a basis for building a mobile energy harvester for future research into a renewable device that can be used by humans to augment battery life for portable electronic devices.

Author(s):  
Edwar Romero ◽  
Gerardo Carbajal ◽  
Robert Warrington ◽  
Michael Neuman

This study presents a quantitative analysis of experimental data for extracting energy from human body motion and its possibility of powering portable electronic devices, such as consumer electronics or biomedical monitoring sensors. Since portable electronic devices are typically limited by the size and lifespan of batteries, energy harvesting shows potential as alternative for extending battery life. The acceleration was collected experimentally from 10 subjects while walking and running at different velocities on a treadmill. The acceleration results were studied and a figure of merit consisting of the acceleration-squared-to-frequency was found to determine, in addition to the quality factor, as the important factors for optimal energy harvesting. It was determined that from average walking an energy harvester can produce a power output density greater than 1mW/cm3.


2014 ◽  
Vol 590 ◽  
pp. 48-52
Author(s):  
Jie Hong Li ◽  
Ming Jing Cai ◽  
Long Han Xie

This paper presented a magnetic pendulum to scavenge the human kinetic energy from arm motion and convert the kinetic energy to electrical energy for portable electronic devices. The harvester mainly consisted of a stator, a rotor and a control circuit. The stator was set of electric coils while the rotor is an eccentric mass made of permanent magnet. A torsion spring was also added onto the rotor such that the motions in both horizontal and vertical directions can be effectively harvested. The energy harvester could be worn on human arm. When the arm was in motion, the device would then generate power. The paper presented a detailed kinematical analysis and power conversion analysis. As a typical case, the device was 40 mm in diameter and 50 g in weight, the simulation showed that when worn on wrist, it could generate about 30 mW during normal walking.


Author(s):  
Edwar Romero ◽  
Michael R. Neuman ◽  
Robert O. Warrington

Energy harvesting from environmental sources such as motion, light, and temperature changes, has been demonstrated with commercially viable products (such as human-powered flashlights, solar-powered calculators, and thermal-powered wristwatches). Vibration or motion is an attractive environmental energy source due to its abundance and availability. A new electromagnetic energy harvester presented here is found to be capable for scavenging energy from human motion. The electrical power output of an inertial energy scavenger is proportional to the acceleration-squared-to-frequency (ASTF) and the quality (Q) factor. Human motion is associated with large ASTF values and low Q factors while machine vibrations are usually related with the opposite. Thus, passive energy harvesting from human activities could generate as much power as the one available from machine harvesters. The limit for such inertial generator is estimated to be on the order of 1mW/cm3. This paper reviews the energy harvesting limits, the energy generation from human activities, and the development of a new oscillating electromagnetic generator. This energy harvester is built with a permanent magnet (PM) ring with multiple poles and a gear-shaped planar coil. The PM ring has attached an eccentric proof mass for converting external movement into oscillations or rotations, these oscillations induce an electrical potential on the planar coil. As much as 3.45μW of power have been generated with a prototype at a frequency of 2.7Hz on a laboratory shaker and 2.35μW had been obtained when positioned laterally on the hip while walking.


Author(s):  
M. Amin Karami ◽  
Daniel J. Inman

The analytical modeling and experimental investigation of a nonlinear electromagnetic rotational energy harvester, which can harvest power from rotary and translational excitations, are presented. Some application of energy harvesting such as energy harvesting for tire pressure sensing require an energy harvester which is efficient in generating power from rotational ambient vibrations. The majority of literature on vibration energy harvesting assumes that the ambient excitations are along a single axis. The vibrations from human motion or rotary machines have two components of translational motion as well as a strong rotary motion. The energy harvesting device studied in this paper is a pendulum like device. The base excitations result in rotations of a pendulum. The pendulum is connected to a direct current micro generator. The rotational vibrations of the pendulum generates electricity through the DC generator. Since the energy harvester is responsive to both translational and rotational base excitations, it is called Hybrid Rotary-Translational (HRT) generator. In this paper a small size HRT harvester is introduced and modeled. The model is used to investigate the relation between the frequency and the amplitude of base vibrations on the vibrations and power generation characteristics of the HRT system. For each frequency and amplitude of vibrations the coexistence of multiple solutions and their basin of attractions are investigated. Three types of ambient excitations are studied: rotational, translational along the direction of gravity, and translational normal to the direction of the gravity.


2021 ◽  
Author(s):  
Christopher Beach ◽  
Alex Casson

Energy harvesting from human motion can reduce reliance on battery recharging in wearable devices and lead to improved adherence. However, to date, studies estimating energy harvesting potential have largely focused on small scale, healthy, population groups in laboratory settings rather than free-living environments with population level participant numbers. Here, we present the largest scale investigation into energy harvesting potential by utilising the activity data collected in the UK Biobank from over 67,000 participants. This paper presents detailed stratification into how the day of the week and participant age affect harvesting potential, as well as how the presence of conditions (such as diabetes, which we investigate here), may affect the expected energy harvester output. We process accelerometery data using a kinetic energy harvester model to investigate power output at a high temporal resolution. Our results identify key differences between the times of day when the power is available and an inverse relationship between power output and participant age. We also identify that the presence of diabetes substantially reduces energy harvesting output, by over 21%. The results presented highlight a key challenge in wearable energy harvesting: that wearable devices aim to monitor health and wellness, and energy harvesting aims to make devices more energy autonomous, but the presence of medical conditions may lead to substantially lower energy harvesting potential. The findings indicate how it is challenging to meet the required power budget to monitor diseases when energy autonomy is a goal.


2018 ◽  
Vol 211 ◽  
pp. 05004
Author(s):  
Jan Smilek ◽  
Zdenek Hadas

This paper deals with the experimental performance evaluation of the prototype of a novel inertial energy harvester based on Tusi couple mechanism. The harvester was developed as an autonomous power source for environments with very low frequency and magnitude of mechanical vibrations available. The experiments were conducted using human body during different activities as a source of mechanical excitation, with the prospect of using the harvester for powering up future wearable electronic devices. Four different locations on a single measurement specimen were picked for the harvester placement - back of the head, belt, wrist and ankle. Measurements in each location comprised of walking on a straight and level path at natural speed, walking up and down the stairs, jumping, running, and location-specific activities that were expected to provide significant output power. The measured average output power of the device with dimensions 50x50x20 mm on empirically selected 2 kΩ electrical load reached up to 6.5 mW, obtained with the device attached to the ankle while shaking the leg.


2014 ◽  
Vol 81 (6) ◽  
Author(s):  
Z. Wu ◽  
R. L. Harne ◽  
K. W. Wang

In this research we study the dynamics of a coupled linear oscillator-bistable energy harvester system. The method of harmonic balance and perturbation analysis are used to predict the existence and stability of the bistable device interwell vibration. The influences of important parameters on tailoring the coupled system response are investigated to determine strategies for improved energy harvesting performance. We demonstrate analytically that for excitation frequencies in a bandwidth less than the natural frequency of the uncoupled linear oscillator having net mass that is the combination of the bistable and linear bodies, the bistable harvester dynamics may be substantially intensified as compared to a single (individual) bistable harvester. In addition, the linear-bistable coupled system may introduce a stable out-of-phase dynamic around the natural frequency of the uncoupled linear oscillator, enhancing the performance of the harvester by providing a second interwell response not possible when using a single bistable harvester. Key analytical findings are confirmed through numerical simulations and experiments, validating the predicted trends and demonstrating the advantages of the coupled system for energy harvesting.


2021 ◽  
Author(s):  
Christopher Beach ◽  
Alex Casson

Energy harvesting from human motion can reduce reliance on battery recharging in wearable devices and lead to improved adherence. However, to date, studies estimating energy harvesting potential have largely focused on small scale, healthy, population groups in laboratory settings rather than free-living environments with population level participant numbers. Here, we present the largest scale investigation into energy harvesting potential by utilising the activity data collected in the UK Biobank from over 67,000 participants. This paper presents detailed stratification into how the day of the week and participant age affect harvesting potential, as well as how the presence of conditions (such as diabetes, which we investigate here), may affect the expected energy harvester output. We process accelerometery data using a kinetic energy harvester model to investigate power output at a high temporal resolution. Our results identify key differences between the times of day when the power is available and an inverse relationship between power output and participant age. We also identify that the presence of diabetes substantially reduces energy harvesting output, by over 21%. The results presented highlight a key challenge in wearable energy harvesting: that wearable devices aim to monitor health and wellness, and energy harvesting aims to make devices more energy autonomous, but the presence of medical conditions may lead to substantially lower energy harvesting potential. The findings indicate how it is challenging to meet the required power budget to monitor diseases when energy autonomy is a goal.


2020 ◽  
Vol 64 (1-4) ◽  
pp. 201-210
Author(s):  
Yoshikazu Tanaka ◽  
Satoru Odake ◽  
Jun Miyake ◽  
Hidemi Mutsuda ◽  
Atanas A. Popov ◽  
...  

Energy harvesting methods that use functional materials have attracted interest because they can take advantage of an abundant but underutilized energy source. Most vibration energy harvester designs operate most effectively around their resonant frequency. However, in practice, the frequency band for ambient vibrational energy is typically broad. The development of technologies for broadband energy harvesting is therefore desirable. The authors previously proposed an energy harvester, called a flexible piezoelectric device (FPED), that consists of a piezoelectric film (polyvinylidene difluoride) and a soft material, such as silicon rubber or polyethylene terephthalate. The authors also proposed a system based on FPEDs for broadband energy harvesting. The system consisted of cantilevered FPEDs, with each FPED connected via a spring. Simply supported FPEDs also have potential for broadband energy harvesting, and here, a theoretical evaluation method is proposed for such a system. Experiments are conducted to validate the derived model.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pashupati R. Adhikari ◽  
Nishat T. Tasneem ◽  
Russell C. Reid ◽  
Ifana Mahbub

AbstractIncreasing demand for self-powered wearable sensors has spurred an urgent need to develop energy harvesting systems that can reliably and sufficiently power these devices. Within the last decade, reverse electrowetting-on-dielectric (REWOD)-based mechanical motion energy harvesting has been developed, where an electrolyte is modulated (repeatedly squeezed) between two dissimilar electrodes under an externally applied mechanical force to generate an AC current. In this work, we explored various combinations of electrolyte concentrations, dielectrics, and dielectric thicknesses to generate maximum output power employing REWOD energy harvester. With the objective of implementing a fully self-powered wearable sensor, a “zero applied-bias-voltage” approach was adopted. Three different concentrations of sodium chloride aqueous solutions (NaCl-0.1 M, NaCl-0.5 M, and NaCl-1.0 M) were used as electrolytes. Likewise, electrodes were fabricated with three different dielectric thicknesses (100 nm, 150 nm, and 200 nm) of Al2O3 and SiO2 with an additional layer of CYTOP for surface hydrophobicity. The REWOD energy harvester and its electrode–electrolyte layers were modeled using lumped components that include a resistor, a capacitor, and a current source representing the harvester. Without using any external bias voltage, AC current generation with a power density of 53.3 nW/cm2 was demonstrated at an external excitation frequency of 3 Hz with an optimal external load. The experimental results were analytically verified using the derived theoretical model. Superior performance of the harvester in terms of the figure-of-merit comparing previously reported works is demonstrated. The novelty of this work lies in the combination of an analytical modeling method and experimental validation that together can be used to increase the REWOD harvested power extensively without requiring any external bias voltage.


Sign in / Sign up

Export Citation Format

Share Document