Energy Harvesting From Lifejackets: Modelling, Design and Analysis

Abstract

"If there is something we can do to save lives through technology, there is no reason not to do it."

This thesis presents the development and experimental validation of an energy harvesting system integrated into an IoT lifejacket to assist the sustainable power source for the IoT modules, such as real-time location tracking, health monitoring, and emergency communication. The research aims to address the challenge of limited energy storage in IoT lifejackets by capturing kinetic energy from the wearer’s body movements during a drowning event.

In the energy harvesting system developed, a brushed DC motor is attached to the lifejacket’s waist strap, with a telescopic linkage connecting it to the thigh strap. The kinetic energy from the vertical rotation of the thigh movements during the active stage of drowning, known as the "ladder climbing" motion, is captured by the motor and converted into electrical power.

The research involves modelling, simulation, and experimental testing to evaluate the system’s performance. The results show that the energy harvester can generate a maximum power output of 754 mW and an average power output of 450 mW, which is sufficient to meet the power requirements of basic IoT sensors (210.6915 mW). With an overall power generation efficiency of 89.7%, the power output is adequate for supporting essential IoT functionalities in water safety applications.

The study identifies several limitations, including power losses in the telescopic linkage affecting the wearer’s movements. Recommendations for future research include optimizing the motor type and refining the mechanical linkage. Additionally, incorporating a mechanical rectifier and flywheel system could help maintain consistent rotational speed, eliminating the "dead zone" observed during experimental testing.

Overall, the research successfully demonstrates the feasibility of integrating an energy harvesting system into a lifejacket to provide a reliable and sustainable power source for IoT lifejackets, making them more effective for search and rescue operations and improving overall water safety. This innovative solution also has the potential to be applied to other types of wearable devices.