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A Combined Softening and Hardening Mechanism for Low Frequency Human Motion Energy Harvesting Application  [PDF]
Khalis Suhaimi,Roszaidi Ramlan,Azma Putra
Advances in Acoustics and Vibration , 2014, DOI: 10.1155/2014/217032
Abstract: This paper concerns the mechanism for harvesting energy from human body motion. The vibration signal from human body motion during walking and jogging was first measured using 3-axes vibration recorder placed at various places on the human body. The measured signal was then processed using Fourier series to investigate its frequency content. A mechanism was proposed to harvest the energy from the low frequency-low amplitude human motion. This mechanism consists of the combined nonlinear hardening and softening mechanism which was aimed at widening the bandwidth as well as amplifying the low human motion frequency. This was realized by using a translation-to-rotary mechanism which converts the translation motion of the human motion into the rotational motion. The nonlinearity in the system was realized by introducing a winding spring stiffness and the magnetic stiffness. Quasi-static and dynamic measurement were conducted to investigate the performance of the mechanism. The results show that, with the right degree of nonlinearity, the two modes can be combined together to produce a wide flat response. For the frequency amplification, the mechanism manages to increase the frequency by around 8 times in terms of rotational speed. 1. Introduction The significant reduction in power consumption to operate mobile gadgets and wireless sensors has induced vast research interest in harvesting energy from ambient sources. Scavenging energy from ambient vibration is one of the examples. Most vibration based scavenging device is traditionally configured as a linear resonant generator that consists of a single degree of freedom (SDOF) mass-spring-damper system. This particular generator is particularly useful for high frequency applications as well as when the ambient frequency does not vary with time. The optimum power of the linear resonant generator can only be obtained when the natural frequency of the device matches the excitation frequency. A Slight mismatch between these two frequencies may lead to a large reduction in the power harvested [1]. Researchers have introduced tuning techniques into the generator so that the natural frequency of the device can be changed according to the input frequency. Eichhorn et al. [2] used a prestress mechanism that can passively be adjusted by rotating a screw to alter the device natural frequency. An active tuning method proposed by Zhu et al. [3] utilized a microcontroller that can adjust the separation of interacting magnets to alter its natural frequency. However, active tuning may induce complex tuning scheme and
Energy Harvesting Strategy Using Piezoelectric Element Driven by Vibration Method  [PDF]
Dong-Gun Kim, So-Nam Yun, Young-Bog Ham, Jung-Ho Park
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.22014
Abstract: This study demonstrates a method for harvesting the electrical power by the piezoelectric actuator from vibration energy. This paper presents the energy harvesting technique using the piezoelectric element of a bimorph type driven by a geared motor and a vibrator. The geared motor is a type of PWM controlled device that is a combination of an oval shape cam with five gears and a speed controller. When using the geared motor, the piezoelectric element is size of 36L×13W×0.6H. The output voltage characteristics of the piezoelectric element were investigated in terms of the displacement and vibration. When using the vibrator, the electric power harvesting is based on piezoelectric effect and piezoelectric vibrator consists of a magnetic type oscillator, a cantilever, a bimorph actuator and controllers. Low frequency operating technique using piezoelectric vibrator is very important because normal vibration sources in the environment such as building, human body, windmill and ship have low frequency characteristics. We can know from this study results that there are many energy sources such as vibration, wind power and wave power. Also, these can be used to the energy harvesting system using smart device like piezoelectric element.
Biomechanical energy harvesting from human motion: theory, state of the art, design guidelines, and future directions
Raziel Riemer, Amir Shapiro
Journal of NeuroEngineering and Rehabilitation , 2011, DOI: 10.1186/1743-0003-8-22
Abstract: We evaluated major motions performed during walking and identified the amount of work the body expends and the portion of recoverable energy. During walking, there are phases of the motion at the joints where muscles act as brakes and energy is lost to the surroundings. During those phases of motion, the required braking force or torque can be replaced by an electrical generator, allowing energy to be harvested at the cost of only minimal additional effort. The amount of energy that can be harvested was estimated experimentally and from literature data. Recommendations for future directions are made on the basis of our results in combination with a review of state-of-the-art biomechanical energy harvesting devices and energy conversion methods.For a device that uses center of mass motion, the maximum amount of energy that can be harvested is approximately 1 W per kilogram of device weight. For a person weighing 80 kg and walking at approximately 4 km/h, the power generation from the heel strike is approximately 2 W. For a joint-mounted device based on generative braking, the joints generating the most power are the knees (34 W) and the ankles (20 W).Our theoretical calculations align well with current device performance data. Our results suggest that the most energy can be harvested from the lower limb joints, but to do so efficiently, an innovative and light-weight mechanical design is needed. We also compared the option of carrying batteries to the metabolic cost of harvesting the energy, and examined the advantages of methods for conversion of mechanical energy into electrical energy.With the increasing use of portable electronics, such as mobile phones, global positioning systems (GPS), and laptop computers, in our daily lives, the need for mobile electrical power sources is increasing. The power demand for the operation of these devices is typically met by batteries. However, the need to recharge batteries (or eventually to replace them) constitutes a significa
Resonance-induced enhancement of the energy harvesting performance of piezoelectric flags  [PDF]
Yifan Xia,Sebastien Michelin,Olivier Doare
Physics , 2015,
Abstract: The spontaneous flapping of a flag can be used to produce electrical energy from a fluid flow when coupled to a generator. In this paper, the energy harvesting performance of a flag covered by a single pair of PVDF piezoelectric electrodes is studied both experimentally and numerically. The electrodes are connected to a resistive-inductive circuit that forms a resonant circuit with the piezoelectric's intrinsic capacitance. Compared with purely resistive circuits, the resonance between the circuit and the flag's flapping motion leads to a significant increase in the harvested energy. Our experimental study also validates our fluid-solid-electric nonlinear numerical model.
Multi-Direction Piezoelectric Energy Harvesting Techniques  [PDF]
Chunhua Sun, Guangqing Shang
Journal of Power and Energy Engineering (JPEE) , 2019, DOI: 10.4236/jpee.2019.79003
Abstract: With the development of portable and self-powering electronic devices, micro-electromechanical system (MEMS) and wireless sensor networks, research on piezoelectric energy harvesting techniques has been paid more and more attention. To enhance the ambient adaptability and improve the generating efficiency, the multi-directional piezoelectric energy harvesting techniques turns to be a research hotspot. The current status of the multi-directional piezoelectric energy harvesting techniques was firstly reviewed. The characteristics of existed multi-directional piezoelectric harvester were then analyzed. An improved structure of multi-directional piezoelectric harvester was finally proposed. The multi-directional piezoelectric energy harvester has a good prospect in miniaturization, more sensitive to vibration directions and better energy efficiency.
Piezoelectric coupling in energy-harvesting fluttering flexible plates : linear stability analysis and conversion efficiency  [PDF]
Olivier Doare,Sebastien Michelin
Physics , 2011, DOI: 10.1016/j.jfluidstructs.2011.04.008
Abstract: This paper investigates the energy harvested from the flutter of a plate in an axial flow by making use of piezoelectric materials. The equations for fully-coupled linear dynamics of the fluid-solid and electrical systems are derived. The continuous limit is then considered, when the characteristic length of the plate's deformations is large compared to the piezoelectric patches' length. The linear stability analysis of the coupled system is addressed from both a local and global point of view. Piezoelectric energy harvesting adds rigidity and damping on the motion of the flexible plate, and destabilization by dissipation is observed for negative energy waves propagating in the medium. This result is confirmed in the global analysis of fluttering modes of a finite-length plate. It is finally observed that waves or modes destabilized by piezoelectric coupling maximize the energy conversion efficiency.
Piezoelectric Energy Harvesting Devices: An Alternative Energy Source for Wireless Sensors  [PDF]
Action Nechibvute,Albert Chawanda,Pearson Luhanga
Smart Materials Research , 2012, DOI: 10.1155/2012/853481
Abstract: The recent advances in ultralow power device integration, communication electronics, and microelectromechanical systems (MEMS) technology have fuelled the emerging technology of wireless sensor networks (WSNs). The spatial distributed nature of WSNs often requires that batteries power the individual sensor nodes. One of the major limitations on performance and lifetime of WSNs is the limited capacity of these finite power sources, which must be manually replaced when they are depleted. Moreover, the embedded nature of some of the sensors and hazardous sensing environment make battery replacement very difficult and costly. The process of harnessing and converting ambient energy sources into usable electrical energy is called energy harvesting. Energy harvesting raises the possibility of self-powered systems which are ubiquitous and truly autonomous, and without human intervention for energy replenishment. Among the ambient energy sources such as solar energy, heat, and wind, mechanical vibrations are an attractive ambient source mainly because they are widely available and are ideal for the use of piezoelectric materials, which have the ability to convert mechanical strain energy into electrical energy. This paper presents a concise review of piezoelectric microgenerators and nanogenerators as a renewable energy resource to power wireless sensors. 1. Introduction The advances in low power electronics, and wireless sensor networks (WSNs) in particular, have driven numerous researches in the field of energy harvesting in the past decade [1–3]. A wireless sensor node consists of low power microcontroller unit, radio frequency transceiver and microelectromechanical- (MEMS-) based sensor. The task of each node is to collect and transmit data to the outside world via a radio link. Thousands of spatially distributed wireless sensors can be developed which can be embedded virtually anywhere in civil structures, bridges, or in the human body. WSN technology has gained increasing importance in industrial automation [4, 5], structural health monitoring [6], healthcare [7], agriculture [8], and civil and military applications [9–11]. Traditionally, batteries are used as the electrical energy power sources to power wireless sensors and embedded electronics. However, batteries have a limited life span and they are expensive to maintain and hence they are not a long-term viable source of energy for WSNs and embedded systems. In fact, the limited capacity of batteries is one of the main factors constraining the performance and limiting the lifespan of a typical WSN [2,
Research Status and Development Direction of Piezoelectric Wind Energy Harvesting Technology  [PDF]
Hongbing Wang, Chunhua Sun
Journal of Power and Energy Engineering (JPEE) , 2019, DOI: 10.4236/jpee.2019.73001
Abstract: In recent years, with the rapid development of large-scale distributed wireless sensor systems and micro-power devices, the disadvantages of traditional chemical battery power supply mode are becoming more and more obvious. Piezoelectric energy collector has attracted wide attention because of its simple structure, no heating, no electromagnetic interference, environmental protection and easy miniaturization. Wind energy is a reproducible resource. Wind energy harvester based on piezoelectric intelligent material can be named piezoelectric wind energy harvesting which converts wind energy into electric power and will have great application prospect. To promote the development of piezoelectric wind energy harvesting technology, research statuses on piezoelectric wind energy harvesting technology are reviewed. The existing problem and development direction about piezoelectric wind energy harvester in the future are discussed. The study will be helpful for researchers engaged in piezoelectric wind energy harvesting.
Energy harvesting efficiency of piezoelectric flags in axial flows  [PDF]
Sebastien Michelin,Olivier Doare
Physics , 2012, DOI: 10.1017/jfm.2012.494
Abstract: Self-sustained oscillations resulting from fluid-solid instabilities, such as the flutter of a flexible flag in axial flow, can be used to harvest energy if one is able to convert the solid energy into electricity. Here, this is achieved using piezoelectric patches attached to the surface of the flag that convert the solid deformation into an electric current powering purely resistive output circuits. Nonlinear numerical simulations in the slender-body limit, based on an explicit description of the coupling between the fluid-solid and electric systems, are used to determine the harvesting efficiency of the system, namely the fraction of the flow kinetic energy flux effectively used to power the output circuit, and its evolution with the system's parameters. The role of the tuning between the characteristic frequencies of the fluid-solid and electric systems is emphasized, as well as the critical impact of the piezoelectric coupling intensity. High fluid loading, classically associated with destabilization by damping, leads to greater energy harvesting, but with a weaker robustness to flow velocity fluctuations due to the sensitivity of the flapping mode selection. This suggests that a control of this mode selection by a careful design of the output circuit could provide some opportunities of improvement for the efficiency and robustness of the energy harvesting process.
Influence and optimization of the electrodes position in a piezoelectric energy harvesting flag  [PDF]
Miguel Pi?eirua,Olivier Doaré,Sébastien Michelin
Physics , 2015, DOI: 10.1016/j.jsv.2015.01.010
Abstract: Fluttering piezoelectric plates may harvest energy from a fluid flow by converting the plate's mechanical deformation into electric energy in an output circuit. This work focuses on the influence of the arrangement of the piezoelectric electrodes along the plate's surface on the energy harvesting efficiency of the system, using a combination of experiments and numerical simulations. A weakly non-linear model of a plate in axial flow, equipped with a discrete number of piezoelectric patches is derived and confronted to experimental results. Numerical simulations are then used to optimize the position and dimensions of the piezoelectric electrodes. These optimal configurations can be understood physically in the limit of small and large electromechanical coupling.
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