基于加加速度的地震模拟振动台控制技术

摘要

地震模拟振动台试验是工程结构地震反应模拟和抗震性能观测的直接有效的手段,但由于电液伺服地震模拟振动台系统具有复杂的非线性,当伺服阀90°相移频率与系统油柱共振频率比较接近时,伺服阀特性对振动台系统特性有较大影响,严重影响系统的有效频带范围.现有的电液伺服地震模拟振动台系统的有效频带多为0.4~50 Hz,不足以满足大比例缩尺结构抗震试验的需求.为减小现有电液伺服地震模拟振动台系统的伺服阀特性对系统性能的影响和拓宽振动台系统的有效频带,在三参量控制的基础上,将加加速度反馈信号和加加速度前馈信号引入控制环节,形成一种基于加加速度的地震模拟振动台多参量控制算法.对所提出的控制算法的控制效果进行了理论推导和系统仿真分析,揭示了加加速度反馈可降低系统油柱共振频率并减小伺服阀特性对振动台系统性能的影响,而加加速度前馈使得系统的有效频带由三参量控制下的0.35~54 Hz拓宽至0.35~64 Hz,表明所提出的基于加加速度的地震模拟振动台多参量控制算法明显改善了地震模拟振动台的控制性能.%Shaking table test is a direct and effective means of seismic response simulation and seismic performance observation of engineering structures,but because the electro-hydraulic servo shaking table system is complex nonlinear system,the performance of shaking table system is apparently affected by the servo valve when the 90° phase-shift frequency of the servo valve is near to the oil-column resonance frequency of shaking table system,so that the effective frequency band of shaking table system is severely affected.The effective frequency band of existing electro-hydraulic servo shaking table is generally from 0.4 Hz to 50 Hz,which is not enough to satisfy the demand of the seismic test of large re-duced scale structure.In order to decrease the adverse effect of the servo valve of existing electro-hydraulic servo shaking table system on the sys-tem performance,and to broaden the effective frequency band of existing shaking table system,a new control algorithm was proposed by introdu-cing the jerk feedback and jerk feed-forward into the controlling unit on the basis of the three-variable control algorithm.The control effect of the proposed control algorithm was deduced theoretically and analyzed by the system simulation.It was revealed that the oil-column resonance fre-quency was reduced by the jerk feedback so that the influence of servo valve characteristics on the system performance was decreased,and the ef-fective frequency band of shaking table system was widen from 0.35~54 Hz for the three-variable control algorithm to 0.35~64 Hz for the jerk feed-forward control algorithm,and it was proved that the control performance of the shaking table system was obviously improved by the pro-posed control algorithm.