The frequency response characteristics of the hydraulic shaking table show the same as that of a two degree of freedom (DOF) resonance system due to the structural flexibility of the hydraulic shaking table. The hydraulic shaking system induces an anti-resonant peak during the working frequency band, which substantially reduces band width of the shaking table. The frequency response influence factor like mass, stiffness, and damping of the reaction wall are studied in this paper. The feed-forward control strategy is proposed in shaking system, which eliminates the effect of zero points at the anti-resonant peak and poles nearly the imaginary axis, broadens the bandwidth, and improves the control precision of the system. The notch filter is used to reduce the magnitude of resonant peak at the nature frequency of servo valve. The experimental results show that the proposed algorithm properly compensates the effect of structural flexibility and improves the bandwidth of the shaking system. INDEX TERMS Hydraulic shaking table, structural flexibility, resonance system, feed-forward control, notch filter.

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High-frequency and long-running hydraulic servo system sinusoidal tests are developed for automobile engine flywheels in this article. The frequency characteristic of the hydraulic system is revealed by the classical control method and the double inertia loop. The feedforward controller is introduced so as to compare it with the adaptive control. The modified amplitude-phase adaptive control (MAPAC) method is proposed to cope with the uncertainties in the hydraulic system to increase the precision of sinusoidal experiments without knowing the structure and parameters of the system. The amplitude error, phase delay, and the center position error of the sinusoidal signal are identified in the time domain, and the iterative equations are established for these three parameters. The simulation and experimental results show that higher tracking accuracy can be achieved with the sinusoidal signal than the feedforward controller by using the MAPAC controller.

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