A novel oscillating buoy wave energy harvester based on a spatial double X-shaped mechanism for self-powered sensors in sea-crossing bridges

With the sharp increase in the number of sea-crossing bridges, various sensors have been widely used in bridge monitoring systems in order to ensure safety and prevent accidents during the use of sea-crossing bridges. In this paper, an oscillating buoy wave energy harvester (WEH) based on a spatial double X-shaped mechanism is proposed for self-powered sensors in sea-crossing bridges. Fixed to the side of pillars in sea-crossing bridges, the proposed WEH can convert wave energy with high energy density into electricity. The system consists of four modules: wave energy capture module, transmission module, generator module, and energy storage module. The wave energy capture module collects wave energy through a cylindrical buoy. The transmission module converts the up and down motion of the buoy into a unidirectional rotational motion of the generator input shaft in the generator module to produce electricity. The super-capacitors in the energy storage module store this electrical energy, which is applied to the self-powered sensors. A max efficiency of 57% and an average efficiency of 46.17% can be obtained through MTS bench tests. In field tests, the system's voltage can reach approximately 3 V, given wave excitation of 1.2 Hz frequency and 15 nun amplitude, which indicates that the proposed WEH is feasible and practical for generating energy used for self-powered sensors in sea-crossing bridges.