A seesaw-inspired bistable energy harvester with adjustable potential wells for self-powered internet of train monitoring

Energy harvesting provides a potential solution to power distributed sensors for train condition monitoring in a self-sustained manner, but the broadband and random nature of the available vibration energy makes effective energy harvesting very challenging. In this paper, a novel seesaw-inspired bistable energy harvester is developed to facilitate self-powered monitoring of trains and the realization of the Internet of Trains. The seesaw-inspired nonlinear harvester is realized for the first time using the attractive magnetic forces between a moving magnet and two fixed magnets to implement the gravitational force effect in seesaws and the restoring spring forces from limit springs to realize the supporting effect of legs to prevent seesaws from being hitting on the floor. A theoretical model is established to describe the dynamics of the whole systems, and the dynamics of the bistable energy harvester are numerically studied for different structural parameters to explore is potential well adjustability and its impact on energy harvesting performance. Through the numerical analysis, it is identified that different fixed magnet positions and spring lengths correspond to different harvesters’ potential well distribution, operational frequency ranges, and changing the coil positions also affects the output power. The results of the theoretical model are validated by a developed prototype and experimental results. The bistable energy harvester performs well over a wide frequency range of 18–38 Hz. An output power of 7.4 mW was obtained at 38 Hz with a 600 Ω load resistor. Finally, this energy harvester is used to fully power a wireless sensor node with a micro-controller, a Bluetooth module and an accelerometer, showing its capability in realizing self-powered condition monitoring of trains.