Harvesting ultra-low frequency random vibration, such as human motion or turbine tower oscillations, has always been a challenge, but could enable many potential self-powered sensing applications. In this paper, a methodology to effectively harness this type of energy is proposed using rotary-translational motion and bi-stability. A sphere rolling magnet is designed to oscillate in a tube with two tethering magnets underneath the rolling path, providing two stable positions for the oscillating magnet. The generated magnetic restoring forces are of periodic form with regard to the sphere magnet location, providing unique nonlinear dynamics and allowing the harvester to operate effectively at ultra-low frequencies (< 1 Hz). Two sets of coils are mounted above the rolling path, and the change of magnetic flux within the coils accomplishes the energy conversion. A theoretical model, including the magnetic forces, the electromagnetic conversion and the occurring bi-stability, is established to understand the electromechanical dynamics and guide the harvester design. End linear springs are designed to maintain the periodic double-well oscillation when the excitation magnitude is high. Parametric studies considering different design factors and operation conditions are conducted to analyze the nonlinear electromechanical dynamics. The harvester illustrates its capabilities in effectively harnessing ultra-low frequency motions over a wide range of low excitation magnitudes.

收集超低频随机振动（例如人体运动或涡轮机塔架振动）一直是一个挑战，但可能会实现许多潜在的自供电传感应用。在本文中，提出了一种利用旋转和平移运动和双稳定性有效利用这种能量的方法。球形滚动磁体设计为在管中振荡，在滚动路径下方有两个系留磁体，从而为振荡磁体提供两个稳定的位置。产生的磁恢复力相对于球形磁铁位置呈周期性，提供独特的非线性动力学，并使收割机能够在超低频率（<1 Hz）下有效运行。两组线圈安装在轧制路径上方，线圈内的磁通量变化完成了能量转换。建立了包括磁力，电磁转换和发生的双稳态在内的理论模型，以了解机电动力学并指导收割机的设计。端部线性弹簧设计用于在激发强度高时保持周期性的双阱振荡。进行了考虑不同设计因素和运行条件的参数研究，以分析非线性机电动力学。收割机展示了其在广泛的低激励幅度范围内有效利用超低频运动的能力。旨在了解机电动力学并指导收割机设计。端部线性弹簧设计用于在激发强度高时保持周期性的双阱振荡。进行了考虑不同设计因素和运行条件的参数研究，以分析非线性机电动力学。收割机展示了其在广泛的低激励幅度范围内有效利用超低频运动的能力。旨在了解机电动力学并指导收割机设计。端部线性弹簧设计用于在激发强度高时保持周期性的双阱振荡。进行了考虑不同设计因素和运行条件的参数研究，以分析非线性机电动力学。收割机展示了其在广泛的低激励幅度范围内有效利用超低频运动的能力。