Adaptive vibration-rotation integrated modulator for harvesting low-frequency energy toward self-powered vehicle intrusion alarming system

Abstract

The pedestrian walkway area is prone to incidents of motor vehicle intrusion, posing a threat to pedestrian safety. Roadbed vibration energy can contribute to self-powered vehicle intrusion alarming (VIA) systems for improving pedestrian safety, but its efficient exploitation is highly difficult due to the adverse low-frequency and intermittent features. This paper introduces an adaptive vibration-rotation integrated modulator (VRIM) that can transform low-frequency vibrations directly to unidirectional and high-speed rotation to increase output power and extend output duration. Enabled by a simple-structured friction-driving mechanism and an innovative magnetic rotation rectifier, the VRIM can output 642 rpm high-speed rotation as actuated by 0.2 Hz low-frequency vibration. Based on the VRIM, a triboelectric-electromagnetic hybrid nanogenerator (VRIM-TEHG) is designed for implementing both energy harvesting and self-driven sensing of different vibration sources. It is demonstrated that, under 1 Hz low-frequency vibration, the VRIM-TEHG can deliver an electrical power of 71 mW and achieve a high output frequency of 160 Hz. After the vibration vanishes, the high-frequency electric outputs can still sustain for 148 s, indicating that the VRIM-TEHG can provide continuous electric outputs even if the vibration frequency is well below 0.01 Hz. A passive VIA system is further constructed with the VRIM-TEHG and its feasibility is verified through outdoor tests, which highlights the promising application of the VRIM-TEHG in harnessing ambient low-frequency vibration energy and achieving self-sufficient smart systems for transportation.