Control Strategy Of Electro-hydraulic Shaking Table Array

The shaking table array is always used for the simulation of actual vibrations to evaluate the reliability of the large structure or specimens.Compared with single shaking table,shaking table array needs a more effective controller which can not only decouple the internal force but also reduce the influence of the non-linear and time-varying characteristics of system.The servo control and waveform replication control of the two degree-of-freedom(DOF)shaking table array are studied in detail in this paper.The main contents are as follows.Control error analysis,redundant force controller and stiffness control are presented in servo control.Kinematic analysis of 6-DOF shaking table is used for error analysis of the traditional matrix control method.Tests of the target execute time of the algorithms showed that the control method combining matrix synthesis and kinematic analysis is more suitable for real-time control system than the other algorithms.The redundant force controller of the shaking table array is developed based on the dynamic analysis of the system.The active stiffness and passive stiffness are modelled in detail and used for stiffness control of the system.Waveform replication control is presented based on servo control of the shaking table array and used to improve the control precision of the test.Frequency response matrix(FRM)of the shaking table array system is assumed to be time invariant in conventional control method.However,FRM is time-varying during the test.The assumption leads to the instability of the control system.Waveform replication control method based on optimization theory is proposed to correct the FRM in this paper.The driving spectrum iteration compensation model is built by using the optimization theory of multiple complex functions.The methods of Broyden and DFP are used to estimate the generalized impedance matrix iteration model.The optimal control methods are used to update the generalized impedance matrix in real time based on the system characteristics and ensure the stability of the control system.Experimental results are used to demonstrate the effectiveness of the presented control methods.Four control methods,including non-iteration,traditional iteration,Broyden iteration and DFP iteration,are used in waveform replication control tests.The results show that the waveform replication control strategy based on Broyden iteration and DFP iteration can effectively improve the accuracy of waveform replication and ensure the stability of the system.