Wearable Human Motion and Heat Energy Harvesting System with Power Management

A combined human motion and heat energy harvesting system are under investigation. Main parts of the developed human motion energy harvester are flat, spiral-shaped inductors. Voltage pulses in such flat inductors can be induced during the motion of a permanent magnet along its surface. Due to the flat structure, inductors can be completely integrated into the parts of the clothes, and it is not necessary to allocate extra place for movement of the magnet as in usual electromagnetic harvesters. Prototypes of the clothing with integrated proposed electromagnetic human motion energy harvester are created and tested. Voltage of generated impulses is shown to be high enough to be effectively rectified with commercially available diodes and ready to be stored; however, efficiency depends on properties of controlling circuit. In order to increase the sustainability of the energy source and its stability, an option for combining a motion energy harvester with a human body heat energy harvester is also considered. Thermoelectric generator that harvests electricity from waste heat of human body is presented, and generated voltage and power are compared at different activity levels and ambient temperatures. Power generated with thermoelectric generator located on lower leg reached up to 35 mW with peak voltages reaching 2 V at certain conditions. A possible power management set-up and its efficiency are discussed

Energy Harvesting From Passive Human Motion

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2010Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2010Tümleşik devre tasarım teknolojisinin gelişmesi paralelinde taşınabilir elektronik aletlerin kullanımı oldukça yaygınlaşmıştır. Günümüzde taşınabilir elektronik aletlerden beklenilen en önemli unsur işlevsel olması, uzun operasyon zamanı ve boyutlarının küçük olmasıdır. Fakat enerji depolama teknolojisindeki ilerlemelerin elektronik aletlerde yararlanılan diğer teknolojilere göre yavaş olması beklentileri sınırlamaktadır. Bu açığı operasyon zamanını artırarak biraz kapatabilmek amacıyla son 15 senedir ortaya atılan insan hareketinden enerji kazanım fikri oldukça popülerdir. Bu tezde, insanın yaptığı hareket tiplerinden bazıları incelenerek enerji kazanımı için uygunluğu değerlendirilmiştir. Sonuçta, yürüme hareketinden enerji kazanım fikri benimsenmiştir. Daha sonra yürüme hareketinden enerji kazanımı ile ilgili literatürde yapılan çalışmalar dikey bacak hareketi ve yatay bacak hareketi ile enerji kazanımı altında ikiye ayrılmıştır. Dikey bacak hareketinden piezoelektrik maddesi kullanılarak yapılan enerji kazanımı ile ilgili literatürdeki bazı çalışmalar değinilmiş ve sonuçları değerlendirilmiştir. Yatay bacak hareketinden enerji kazanımı için iki farklı tipte lineer jeneratör tasarımları önerilmiştir. Bu tasarımların kullanılabilirliğini tespit etmek amacıyla bazı deneysel ve teorik çalışmalar yapılmıştır. Özellikle sonlu elemanlar yöntemi ile yapılan analizler tasarlanan jeneratörün hareket parametreleri ve endüktif gerilimi hakkında bilgi sahibi olmamızı sağlamıştır.The usage of portable electronics has been widen in the basis of the development of integrated circuit technology. Today, the most important property expected from portable electronics is their being functional and smaller size and having long operation time. However, being slower of the development of energy storage technology than the other technologies used in portable electronics limits the expectations. The idea of human energy harvesting has been proposed for fifteen years, which aims to fill this gap by increasing the operation time, is very popular. In this thesis, some of the motion types of human do are investigated and then evaluated for feasibility of implementing. As a result, the idea energy harvesting from the motion of walking is adopted. The, the studies of energy harvesting from walking in literature are separated as energy harvesting from vertical and horizontal leg motion. Some of the studies made in literature about energy harvesting making use of piezoelectric materials from vertical leg motion are mentioned and the results are evaluated. It is proposed two types of linear generator designs for energy harvesting from horizontal leg motion. To determine the feasibility of these designs it was made some of the practical and theoretical studies. Especially the analyses made by finite elements method maintained to have an idea about the movement parameters and induced emf of the designed generator.Yüksek LisansM.Sc

Low-profile and wearable energy harvester based on plucked piezoelectric cantilevers

The Pizzicato Energy Harvester (EH) introduced the technique of frequency up-conversion to piezoelectric EHs wearable on the lateral side of the knee-joint. The operation principle is to pluck the piezoelectric bimorphs with plectra so that they produce electrical energy during the ensuing mechanical vibrations. The device presented in this work is, in some ways, an evolution of the earlier Pizzicato: it is a significantly more compact and lighter device; the central hub holds 16 piezoelectric bimorphs shaped as trapezoids, which permits a sleek design and potentially increased energy output for the same bimorph area. Plectra were formed by Photochemical Machining of a 100-μm-thick steel sheet. To avoid the risk of short-circuiting, the plectra were electrically passivated by sputtering a 100 nm layer of ZrO2. Bench tests with the steel plectra showed a very large energy generation. Polyimide plectra were also manufactured with a cutting plotter from a 125μm-thick film. Besides bench tests, a volunteer wore the device while walking on flat ground or climbing stairs, with a measured energy output of approximately 0.8 mJ per step. Whereas most of the tests were performed by the traditional method of discharging the rectified output from the EH onto a resistive load, tests were performed also with a circuit offering a stabilised 3.3 V supply. The circuit produced a stable 0.1 mA supply during running gait with kapton plectra

Performance testing of a low power consumption wireless sensor communication system integrated with an energy harvesting power source

This paper presents the performance testing results of a wireless sensor communication system with low power consumption integrated with a vibration energy harvesting power source. The experiments focus on the system’s capability to perform continuous monitoring and to wirelessly transmit the data acquired from the sensors to a user base station, completely battery-free. Energy harvesting technologies together with system design optimisation for power consumption minimisation ensure the system’s energy autonomous capability demonstrated in this paper by presenting the promising testing results achieved following its integration with Structural Health Monitoring (SHM) and Body Area Network (BAN) applications

Feasibility of wireless horse monitoring using a kinetic energy harvester model

To detect behavioral anomalies (disease/injuries), 24 h monitoring of horses each day is increasingly important. To this end, recent advances in machine learning have used accelerometer data to improve the efficiency of practice sessions and for early detection of health problems. However, current devices are limited in operational lifetime due to the need to manually replace batteries. To remedy this, we investigated the possibilities to power the wireless radio with a vibrational piezoelectric energy harvester at the leg (or in the hoof) of the horse, allowing perpetual monitoring devices. This paper reports the average power that can be delivered to the node by energy harvesting for four different natural gaits of the horse: stand, walking, trot and canter, based on an existing model for a velocity-damped resonant generator (VDRG). To this end, 33 accelerometer datasets were collected over 4.5 h from six horses during different activities. Based on these measurements, a vibrational energy harvester model was calculated that can provide up to 64.04 mu W during the energetic canter gait, taking an energy conversion rate of 60% into account. Most energy is provided during canter in the forward direction of the horse. The downwards direction is less suitable for power harvesting. Additionally, different wireless technologies are considered to realize perpetual wireless data sensing. During horse training sessions, BLE allows continues data transmissions (one packet every 0.04 s during canter), whereas IEEE 802.15.4 and UWB technologies are better suited for continuous horse monitoring during less energetic states due to their lower sleep current

A Combined Softening and Hardening Mechanism for Low Frequency Human Motion Energy Harvesting Application

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 at response. For the frequency amplification, the mechanism manages to increase the frequency by around 8 times in terms of rotational speed

Nonlinear Energy Harvesting Device For Low Frequency Human Motion Application

Energy harvesting from ambient sources had received much attention in the past few years due to worldwide awareness on green technology expands. In vibration based energy harvesting, resonant linear generator are commonly used as the harvesting devices. However, a linear generator induces several limitations. The power harvested by a linear generator is proportional to the cube of excitation frequency and the power is maximum in a narrow bandwidth only. In this research, human motion vibration was selected as an input excitation and its frequency content is investigated. The frequency of human motion was investigated by placing a vibration recorder on a test subject under 5km/h walking and 9 km/h jogging speed.The investigation shows that the human motion vibration is distributed in the low frequency region. Hence, a device that can operate optimally with low frequency input and has the ability to overcome the narrow bandwidth limitation is designed. A device is designed to overcome the limitations of the linear generators. This device has the combination of the tuning, frequency-up conversion, multimodal and non-linear techniques. The aim is to amplify the input frequency to a higher frequency and at the same time, widen the bandwidth of response. The frequency-up mechanism is made by transforming the translation motion into the rotary motion by using gear ratio to amplify the response to a higher rotational speed. Winding springs are used with twistable enclosure cap to alter the device stiffness. The angles of twist of the enclosure cap are ranging from 180 degree to 900 degree. Two oscillating masses are connected to the device. Each mass can be set with different characteristic to widen the bandwidth. The two masses are also configured with non-linear softening and non-linear hardening properties to further widen the bandwidth. The non-linearities of the system are changed by varying the magnets gap. The non-linear restoring force of the system shows the influences of the linear coefficient and non-linear coefficient. The device is then investigated with two sets of experiments. The quasi-static measurement is to investigate the system stiffness and dynamic measurement is to investigate its response across a frequency range. In the dynamic measurement the device is excited with sinusoidal inputs and real human motion inputs. Overall, the results obtained from the experiment show that device is able to produce frequency amplification. The response also shows that with a properly tuned system, both softening and hardening can produce a flat response which is insensitive to excitation frequency as well as at amplified amplitude