【作者】 姚建均；

【导师】 韩俊伟； 吴振顺；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2007， 博士

【摘要】 振动台是工程研究的一种重要实验设备,它广泛应用于航天、汽车、建筑等许多重要工业领域。振动试验是把试件固定在试验平台上,通过模拟该试件受载时的情况,来研究载荷对试件的影响、试件的可靠性分析或减振系统的性能分析。随着对产品,尤其是航空航天产品可靠性要求的提高,作为可靠性试验关键设备的振动试验系统的性能要求也越来越高。对于电液伺服振动试验系统来说,如何克服电液伺服系统的不确定性,满足振动试验的特殊要求成为了研究的一个重要课题。本文首先对国内外相关研究进行了系统总结和深入分析,对论文的研究意义和主要研究内容作了介绍;介绍了电液伺服振动台的工作原理,以及硬件和软件实现。为使系统稳定和拓展系统加速度频宽,基于极点配置理论,设计了三状态控制器,并进行正弦振动试验。由于电液伺服振动台的非线性特性,当作正弦振动试验时,系统加速度响应中存在幅值衰减、相位滞后和高次谐波,使得加速度信号严重失真。试验表明谐波的频率通常是试验信号频率的整数倍。为消除加速度响应对于输入信号的相位滞后和幅值衰减,设计了幅相控制网络。它是当加速度响应信号对输入信号有相位滞后和幅值衰减时,利用LMS算法对网络的权值进行调整,经加权后的输入信号作用于振动台系统,消除基频响应信号的相位滞后和幅值衰减,并为谐波抑制提供条件。针对加速度响应信号中的高次谐波,提出了基于自适应陷波器技术的自适应谐波抑制(AHC)策略。其参考信号频率为要抑制的谐波频率,自适应滤波器的输出是一个谐波复制信号,与基本输入相加,以抑制输出中的谐波,使总谐波失真度(THD)大大降低。滤波器的权值通过LMS算法在线调整。设计了基于常规LMS算法和基于归一化LMS算法的自适应谐波抑制策略,并对两种谐波抑制算法进行了比较。从比较中可以看出,基于归一化LMS算法的谐波抑制具有更好的谐波抑制效果和更快的权值收敛性。幅相控制和谐波抑制策略并不需要对控制对象进行辨识,具有结构简单,计算量少的特点,能保证控制系统的实时性。更多还原

【Abstract】 Shaking table system is a very important experimental apparatus in engineering research. It is widely applied to many main industrial fields including aerospace, automobile, architecture, etc. When performed a vibration test, specimen is mounted to the test table and simulative load force is applied to the specimen. Researchers analyze the influence on load brings, the reliability of the specimen, or the damping system’s performance. With the reliability requirement of industrial products, especially for aerospace vehicles, becoming higher and higher, the simulative vibration test system, as the vital apparatus of reliability test, is placed more emphases on its performance. For electro-hydraulic simulative vibration test system, how to get over the uncertainty of the system, meeting the special requirement of the shaking test, becomes a main subject.The thesis firstly gives an overview of related researches both at home and abroad, as well as a statement of thesis objectives, and of the general structure and research contribution of this thesis. The work principle of the electro-hydraulic servo shaking table, and its hardware and software configuration, are described. Three variables controller is developed based on pole placement theory to improve system stability and extend its bandwidth. Sinusoidal tests are also done.Due to the nonlinearity characteristics present in the electro-hydraulic servo shaking table, phase delay, amplitude attenuation and spurious harmonics appear in the system acceleration response when corresponding to a simple sinusoidal signal, which causes harmonic distortion of the acceleration signal. Experiment demonstrates that the harmonics’frequencies are always integer multiples of the fundamental frequency.To eliminate the phase delay and amplitude attenuation of acceleration response, amplitude-phase control (APC) network is developed. The task is accomplished by adjusting the weights using LMS algorithm when there exits phase delay and amplitude attenuation between the input and its corresponding acceleration response. The reference input is weighted in such a way that it makes the system output track the input efficiently. The weighted input signal is added to the control system such that the output phase delay and amplitude attenuation are all cancelled. The above concept is used as a basis for the development of APC algorithm.The method for harmonic cancellation based on adaptive notch filter technology is developed. The task is accomplished by generating reference signals with frequency that should be eliminated from the output. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is cancelled leaving the desired acceleration signal alone, and the total harmonic distortion (THD) is greatly reduced. The weights of filter are adjusted on-line by using LMS adaptive filtering algorithm. The above course is used as a basis for the development of adaptive harmonic cancellation (AHC) algorithm. AHC algorithms, both based on traditional LMS algorithm and based on normalized LMS algorithm, are all developed and are compared with each other. From the comparison results, it is seen clearly that the AHC algorithm, based on normalized LMS algorithm, has better harmonic elimination efficiency and faster weight convergence.Both the APC and the AHC need not to estimate the system model. The advantages of the proposed control schemes are that it has simple structure, low computation burden and high real-time performance.更多还原