Operation Of Wireless Sensor Node Research Articles

Design development and testing of traffic induced wind based artificial tree type hybrid energy harvester for wireless sensor nodes

With the rapid development of the urban system, the structural health monitoring (SHM) of high-rise buildings, flyovers, and bridges have attracted researchers’ attention. Currently, wireless sensor nodes (WSNs) are used for the SHM, however, WSNs use batteries as power sources which have limited shelf life. To attain the self-sustain long-term operation of WSNs, ambient energy from their surrounding can be harvested for their power requirements. In this research, a traffic induced wind based artificial tree type hybrid energy harvester is designed, developed, and tested. The developed prototype is able to harvest traffic induced wind. The prototype consists of multiple piezoelectric leaves and two electromagnetic energy harvesters (EM-EH) - short beam EM-EH and long beam EM-EH. Each EM-EH is composed of a cantilever beam, a permanent magnet, an airfoil, and a planar coil. Test results reveals that at a maximum windspeed of 10 m/s, the prototype can harvest 1.60 μW from a single piezoelectric leaf, 53 μW from a short beam EM-EH and 50 μW from a long beam EM-EH at optimum load. This artificial tree type hybrid energy harvester will help in the deployment of WSNs and in the beautification of the urban system.

Hybrid acoustic, vibration, and wind energy harvester using piezoelectric transduction for self-powered wireless sensor node applications

Energy harvesters are considered to be a promising solution for long lasting operation of wireless sensor nodes, moreover, make these power-sustainable in hazardous, implantable, remote, harsh, embedded, and abandoned environments where frequent battery replacement is a challenge. Existing energy harvesters utilize only one or two ambient energy sources, however, in this paper, we developed a novel piezoelectric-based energy harvester that converts three ambient energies (acoustic, vibration, and wind) simultaneously into electrical energy. The developed harvester comprises a Helmholtz resonator, a unimorph piezoelectric composite plate, and a cambered aerofoil connected with a piezoelectric plate using a base support. Acoustic, vibration, and wind induced deformation in the harvester’s piezoelectric plate and intrun electrical energy is produced based on piezoelectric phenomena. The harvester showed two peaks (at 802 and 1417 Hz frequencies) when subjected to a forward frequency sweep (FFS) which corresponds to its resonant frequencies. Under resonance, in the acoustic and vibrations environment, the harvester produced a maximum power of 210.6 µW, and 1.38 mW on excitation at 130 dB sound pressure level (SPL) and 0.8 g base acceleration, respectively. Furthermore, the harvester produced maximum power of about 285 µW when exposed to 8 m/s wind speed. The developed harvester can be a potential power source for self-powered wireless sensors used for the structural health monitoring of bridges, tall buildings, and railway tracks.

Hybrid vibro-acoustic energy harvesting using electromagnetic transduction for autonomous condition monitoring system

Condition monitoring systems (CMS) play a significant role in enhancing performance and lowering failure losses in any industrial setup. Appropriate wireless sensor nodes (WSNs) used in CMS will permit the user to check the live status of machines, however, these WSNs are facing the periodic replacement and recharging problems of batteries. Energy harvesters, used to scavenge ambient energy, are viable alternatives to batteries for achieving the self-sustained long-term operation of WSNs. Ambient vibration and acoustic energies are abundantly available in the industrial environment. The currently available energy harvesters are utilizing only vibration or acoustic energy, however, research on harvesters using both vibration and acoustic sources is missing. We present a new hybrid vibro-acoustic energy harvester (HVA-EH) using electromagnetic transduction, where the power to the WSNs can be harvested from both vibration and acoustic sources simultaneously. The architecture, working principle, fabrication, and experimentation of the HVA-EH are discussed. The HVA-EH was operated at a low vibration and acoustic frequencies and low acceleration and sound pressure levels (SPL). At matching impedance, the maximum power generated by the HVA-EH under vibration energy at zero SPL is 372 μW at acceleration level of 0.3 g and under acoustic energy at zero acceleration level is 271 μW under SPL of 130 dB. While, under a hybrid environment, the HVA-EH generates maximum power of 153 μW, 361 μW, and 656 μW at vibration levels of 0.1 g, 0.2 g, and 0.3 g respectively, under SPL of 130 dB at 2nd acoustic mode (495 Hz). The results are promising and the ability of harvesting low-frequency sound and vibration simultaneously makes the HVA-EH an energy efficient system. Furthermore, this study demonstrates the possibility of new solutions to the problems of WSNs utilizing both sound and vibration energy resources.

Vibration‐based piezoelectric, electromagnetic, and hybrid energy harvesters for microsystems applications: A contributed review

Wireless sensor nodes (WSNs) and embedded microsystems have recently gained tremendous traction from researchers due to their vast sensing and monitoring applications in various fields including healthcare, academic, finance, environment, military, agriculture, retail, and consumer electronics. An essential requirement for the sustainable operation of WSN is the presence of an uninterrupted power supply; which is currently obtained from electrochemical batteries that suffer from limited life cycles and are associated with serious environmental hazards. An alternative to replacing batteries of WSNs; either the direct replacement or to facilitate battery regular recharging, is by looking into energy harvesting for its sustainable drive. Energy harvesting is a technique by which ambient energy can be converted into useful electricity, particularly for low-power WSNs and consumer electronics. In particular, vibration-based energy harvesting has been a key focus area, due to the abundant availability of vibration-based energy sources that can be easily harvested. In vibration-based energy harvesters (VEHs), different optimization techniques and design considerations are taken in order to broaden the operation frequency range through multi-resonant states, increase multi-degree-of-freedom, provide nonlinear characteristics, and implement the hybrid conversion. This comprehensive review summarizes recent developments in VEHs with a focus on piezoelectric, electromagnetic, and hybrid piezoelectric-electromagnetic energy harvesters. Various vibration and motion-induced energy harvesting prototypes have been reviewed and discussed in detail with respect to device architecture, conversion mechanism, performance parameters, and implementation. Overall sizes of most of the reported piezoelectric energy harvesters are in the millimeter to centimeter scales, with resonant frequencies in the range of 2-13 900 Hz. Maximum energy conversion for electromagnetic energy harvesters can potentially reach up to 778.01 μW/cm3. The power produced by the reported hybrid energy harvesters (HEHs) is in the range of 35.43-4900 μW. Due to the combined piezoelectric-electromagnetic energy conversion in HEHs, these systems are capable of producing the highest power densities.

A Vibration Energy Harvester and Power Management Solution for Battery-Free Operation of Wireless Sensor Nodes.

Electromagnetic Vibration Energy Harvesting (EM-VEH) is an attractive alternative to batteries as a power source for wireless sensor nodes that enable intelligence at the edge of the Internet of Things (IoT). Industrial environments in particular offer an abundance of available kinetic energy, in the form of machinery vibrations that can be converted into electrical power through energy harvesting techniques. These ambient vibrations are generally broadband, and multi-modal harvesting configurations can be exploited to improve the mechanical-to-electrical energy conversion. However, the additional challenge of energy conditioning (AC-to-DC conversion) to make the harvested energy useful brings into question what specific type of performance is to be expected in a real industrial application. This paper reports the operation of two practical IoT sensor nodes, continuously powered by the vibrations of a standard industrial compressor, using a multi-modal EM-VEH device, integrated with customised power management. The results show that the device and the power management circuit provide sufficient energy to receive and transmit data at intervals of less than one minute with an overall efficiency of about 30%. Descriptions of the system, test-bench, and the measured outcomes are presented.

System reliability analysis of piezoelectric vibration energy harvesting considering multiple safety events under physical uncertainty

The most important duty of a piezoelectric vibration energy harvesting (PVEH) device is to reliably generate electric power as an output for sustainable operation of wireless sensor nodes, without experiencing mechanical failure. However, physical uncertainty, such as inherent variability in material properties and manufacturing tolerances, makes it difficult to guarantee satisfactory performance of the required functions of a PVEH device. Reliability analysis has been widely recognized as of great importance to evaluate system performance, while accounting for physical uncertainty. There have been a few prior attempts to delve into reliability analysis for the design of PVEH devices; these prior efforts were limited to calculating the probability of component success. However, PVEH devices need system reliability analysis that examines multiple performance functions, with the aim of calculating the probability of overall system success. The objective of this study is thus to present a systematic methodology for system reliability analysis of multiple safety events of a PVEH device under physical uncertainty. In this research, after deriving the electroelastically-coupled analytical model, the limit state functions of a PVEH device are derived under multiple safety events including: (1) resistance against fatigue failure; and (2) fulfillment of the target output electrical performances. Finally, system reliability analysis is performed by using the complementary intersection method. This study can provide insightful guidelines for designing a PVEH device under physical uncertainty.

Experimental Validation of Energy Harvesting-System Availability Improvement Through Battery Heating

Operation of wireless sensor nodes or battery powered embedded systems in cold and harsh environments requires careful battery selection and management. In this paper, we first provide a general model of an energy harvesting sensor system and the respective energy flows. We then present a maximum power point tracking solar harvesting system according to that model. The system is coupled with rechargeable Li-ion batteries and equipped with a battery heating mechanism. The significant signals of that system are monitored to have a deeper insight into the energy distribution. Real-world experiments demonstrate benefits of battery heating during high irradiation periods at temperatures below safe charging conditions. The presented case study for a cold winter day shows that the additional energy, which can be stored thanks to battery heating would more than double the autonomy of the sensor system.

DEVELOPMENT OF A LOW VOLTAGE AC TO DC CONVERTER FOR MESO AND MICRO ENERGY HARVESTERS

Energy harvesting is widely used for the operation of wireless sensor nodes. Most of the energy harvesters gen- erated voltage levels are sinusoidal or random in nature, moreover, the output voltage levels these produce are in low (in mV range). For sensor operation, in order to convert this low AC voltage levels into relatively high DC voltage DC, a three stage Cockcroft Walton converter is developed. The paper presents fabrication and characteri- zation of a 3 stage Low Voltage Cockcroft-Walton converter in an area of 5.5 x 3.3 cm 2 . The converter was capable of converting a minimum AC voltage amplitude of 10 mV with a transformation factor of 6.5. The variation in the input frequency had almost no effect on the DC output voltage of the converter. Upon integration of the converter to different energy harvesters, the converter successfully rectified the AC or random output voltage signals of the harvesters into corresponding DC voltage.

A Non-volatile Reconfigurable Offloader for Wireless Sensor Nodes

Energy saving is currently one of the most important issues in the development of battery-powered wireless sensor nodes (WSNs). We have developed a non-volatile reconfigurable offioader for flexible and highly efficient processing on WSNs that uses NanoBridges (NBs), which are novel non-volatile and reprogrammable switching elements. Non-volatility is essential for the intermittent operation of WSNs due to the requirement of power-on without loading configuration data. We implemented a data compression algorithm on the offioader that reduces energy consumption during data transmission. Simulation results showed that the energy consumption on the offioader was 1121 of that on an ultra-low power cpu.

A non-volatile reconfigurable offloader for wireless sensor nodes

Energy saving is currently one of the most important issues in the development of battery-powered wireless sensor nodes (WSNs). We have developed a non-volatile reconfigurable offioader for flexible and highly efficient processing on WSNs that uses NanoBridges (NBs), which are novel non-volatile and reprogrammable switching elements. Non-volatility is essential for the intermittent operation of WSNs due to the requirement of power-on without loading configuration data. We implemented a data compression algorithm on the offioader that reduces energy consumption during data transmission. Simulation results showed that the energy consumption on the offioader was 1121 of that on an ultra-low power cpu.

Energy generation for an ad hoc wireless sensor network-based monitoring system using animal head movement

The supply of energy to electronics is an imperative constraining factor to be considered during the design process of mobile ad hoc wireless sensor networks (MANETs). This influence is especially important when the MANET is deployed unattended or the wireless modules within the MANET are not easily accessible. Therefore, exploring novel sources of energy generation rather than operating electronics only on limited power supplies such as batteries is a major challenge. Monitoring free-ranging animal behavior is an application in which the entities (animals) within the MANET are not readily accessible; however, animal movement can be potentially used to generate energy. In this study, the head movements of individual sheep in a flock during grazing were monitored in order to investigate the amount of energy that can be generated by these movements. By applying the Lagrange–d’Alembert Principle to this problem, the equations of motion from each neck-mounted sensor as well as the amount of mechanical energy generated per time instant (each second) during upward and downward head movements were calculated. This resulted in the production of 857 mW and 1660 mW during the downward and upward movements, respectively. Furthermore, the energy consumption of each wireless node within the MANET was estimated to be 117.8 mW per second. Conversion of energy from mechanical to electrical requires miniature electromechanical generators that can currently provide between 25% and 50% conversion efficiency. Even using the worst conversion efficiency (25%), a minimum of 214 ± 25 mW of electrical energy per second could be generated. This amount exceeds the energy consumed by the wireless sensors that can be used to gather parameters describing animal behavior such as neck and head movement. This study suggests that the amount of energy generated by the vertical neck–head movement of sheep during grazing can be converted to useful electrical power adequate to provide power for operation of wireless sensor nodes on a continuous basis within a MANET-based animal behavior monitoring system.