Disturbance rejection and performance enhancement of perturbed tri-stable energy harvesters by adaptive finite-time disturbance observer

基于自适应有限时间扰动观测器的摄动三稳态俘能器抗干扰及性能提高研究

Tristable energy harvesters(TEHs)have been proposed to achieve broad frequency bandwidth and superior low-frequency energy harvesting performance.However,due to the coexistence of three potential wells and the sensitivity to system conditions and external disturbances,the desired high-amplitude inter-well oscillation in the TEHs may be replaced by the chaotic or intra-well oscillations with inferior energy output.Specifically,the chaos has an unpredictable trajectory and may cause system damages,lessen the structural durability as well as require a more complicated circuit for power management.Therefore,in this paper,we firstly propose an adaptive finite-time disturbance observer(AFTDO)for performance enhancement of TEHs by detecting the external disturbances that induce the chaos,and reject them for the recovery of the desired inter-well motion.The proposed AFTDO eliminates the need to know in advance the upper bounds of imposed perturbations in conventional observers by means of the proposed adaptive protocols,leading to the higher efficacy of estimation.The mathematical model of the piezoelectric TEH system and the AFTDO is provided.To demonstrate the effectiveness of the AFTDO,a series of numerical simulations have been performed.Results show that for both cases with sinusoidal and impulsive disturbances,the AFTDO can successfully track the trajectories of the disturbance signals with the adaptive gain,and reject the disturbance to enable the TEH to sustain the periodic inter-well oscillation with effective energy harvesting performance.

三稳态俘能器被提出用于实现宽频带及优越的低频俘能性能.但是,由于三稳态俘能器具有三个共存的势阱和对系统状态及外界扰动的敏感性,其可能无法产生理想的高振幅阱间振荡运动,取而代之的是降低俘能性能的混沌或阱内振荡运动.特别地,混沌运动会产生无法预测的运动轨迹,可能导致俘能系统损坏并降低结构持久性,且这种运动形态要求俘能器具有更复杂的能量管理电路.因此,本文首次提出自适应有限时间扰动观测器(AFTDO),通过检测并抵制导致混沌运动的外界扰动,以恢复阱间运动从而增强三稳态俘能器的俘能性能.与传统的观测器不同,本文所提出的AFTDO通过自适应协议克服需提前获得扰动上边界信息才可进行观测的要求,从而提高观测器的效能.本论文提出压电三稳态俘能器系统及AFTDO的数学模型,通过一系列的数值仿真证明AFTDO的有效性.结果表明在简谐及脉冲形式的外界扰动下,AFTDO均可成功追踪干扰信号的轨迹且实现自适应增益,并成功抵制外界扰动使得三稳态俘能器维持周期性阱间振荡运动,获得有效俘能性能.