Browsing by Author "Leanage, H. B."

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Harvesting energy from human-body movements for ultra-low power appliances
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Gunarathna, T. G. L.; Rupasingha, U. S. D. B. M.; Gunasekara, H. S.; Thennakoon, S. E. R. T. M. M. I.; Senanayake, S. V.; Leanage, H. B.; Kumarage, W. G. C.; Ranaweera, A. L. A. K.
Energy harvesting from human body movements presents a promising approach to sustainably power wearable devices and sensor nodes. This study explores the potential of capturing energy from footsteps using piezoelectric technology. A critical aspect of this technology involves designing an efficient interface between the piezoelectric elements and the electrical load to maximize energy conversion. The irregular and low-frequency nature of human footsteps poses a significant challenge, resulting in low energy extraction. Moreover, achieving a self-powered circuit adds another layer of complexity. To address these challenges, a novel Parallel-Synchronous Switching Harvesting on Inductor (P-SSHI) circuit is proposed. This circuit increases the energy extraction efficiency of piezoelectric elements. Since the output of a piezoelectric element is in the form of alternating current (AC), a MOSFET-based full-bridge rectifier circuit is proposed to convert AC to direct current (DC). As proof of concept, a shoe insole integrated with multiple piezoelectric elements connected in parallel was developed, and the energy conversion circuit was rigorously validated. The system was tested at a frequency of 1 Hz, which corresponds to the typical walking frequency, using a person weighing 60 kg. Under these conditions, the proposed system achieved an average power output of 550 µW per step with a 10 kΩ resistive load and a 10 µF storage capacitor. The effectiveness of the system was further validated by demonstrating its ability to charge a 1 mF capacitor to 2.1 V in 18 steps and a 10 µF capacitor to 7.0 V in a single step. Notably, the circuit is self-powered and capable of initiating operation without the assistance of an external battery, highlighting its potential for autonomous use. The circuit was prototyped using simple discrete components, emphasizing its practicality and feasibility for real-world applications. The proposed MOSFET-based rectifier circuit offers a significant advantage in converting AC to DC with minimal voltage drop, compared to conventional diode full-bridge rectifiers. Furthermore, the system's capability to charge a Li-ion battery (3.7 V, 300 mAh) was demonstrated, showcasing the potential of the wearable piezoelectric energy harvesting system to provide a sustainable power supply for wearable wireless sensors. Future studies will focus on optimizing energy harvesting under different walking conditions, integrating energy storage devices, and enhancing durability. The proposed technology also shows promise for applications in diverse fields such as healthcare, fitness monitoring, and environmental sensing, where reliable, self-sustaining wearable power solutions are in high demand.
Innovative fence monitoring system to mitigate human-elephant conflict
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Bodaragama, B. T. P.; Athawuda, A. H. C.; Gunawardhana, M. A. W. S. N. T.; Senanayake, S. V.; Leanage, H. B.; Gunawardana, K. D. B. H.; Seneviratne, J. A.
Human-elephant conflict (HEC) poses a significant threat to communities and wildlife, prompting the development of an innovative standalone device to enhance electric fence monitoring and mitigate associated risks. This research introduces a system that determines breakage location by measuring fence capacitance, inductance, and resistance, and uses a mathematical model to map changes of these parameters to change of the fence length. This approach enables remote detection of both open and short circuit breakdowns without relying on expensive, failure-prone active nodes along the entire fence. The device can identify the distance to the breached location along the length of the fence approximately and immediately. It will send this alert via SMS to designated contacts using a GSM module, providing real-time monitoring and rapid response capabilities. This key feature ensures timely alerts and quick responses to potential breaches, enhancing the fence's effectiveness in preventing elephants from entering villages and reducing HEC incidents. The standalone nature of the solution simplifies installation and maintenance, eliminating the need for additional wiring or complex infrastructure, thereby significantly reducing overall costs associated with fence monitoring while increasing reliability and efficiency. Furthermore, the device functions accurately by minimizing the effects of weather changes, ensuring consistent performance in various environmental conditions. This innovative breakage detection system represents a significant advancement in fence monitoring technology for wildlife conservation, addressing many shortcomings of traditional solutions by offering a cost-effective, efficient, and reliable method for mitigating human-elephant conflict. The research underscores the potential of integrating advanced technology with traditional conservation methods to create more sustainable and effective strategies for managing human-wildlife conflicts, ultimately improving the effectiveness of electric fences in deterring elephants and reducing the incidence of fatalities and crop damage. Testing on a 150m fence demonstrated promising results, with the system achieving nearly 80% accuracy in detecting and locating both open circuit and short circuit breakages, as verified through manual simulations and observations recorded in the device's test results.