Research On Control Of Three-axis Six Degrees Of Freedom Vibration Test System

Based on multiple-input-multiple-output(MIMO) linear system theory, this paper discusses the control method of three-axis six degrees of freedom vibration test system. The system is driven by eight excitation units, so it creates a vibration environment which consists of three line vibration environments along orthogonal axes and three angular vibration environments around orthogonal axes. Three line vibrations and three angular vibrations contribute to the complex three-axis six degrees of freedom vibration environment. The specific work of this paper is as follows:(1) Based on the basic theory of multi input and multi output vibration control, the measurement method of the response and the general equation of the six degrees of freedom coordinate transformation of the three axis six degrees of freedom vibration environment test are studied. Three control methods are summarized, and the basic process of the control of the three-axis six degrees of freedom is established.(2) The three-axis six degrees of freedom vibration test system with rigid table is studied and the dynamic equation of the system is established. Then in the MATLAB, the process of the control is simulated by using the control method of the three-axis six degrees of freedom. It turns out that the six degrees of freedom responses of the specified points match the desired objectives. It is proved that the control method for rigid table is right.(3) Based on the simplified model, this paper discusses that how to find the correlation between different degrees of freedom and how to set up the coherence coefficient between different degrees of freedom through the process of control. This paper also discusses, in the case of measurement noise, that how to place the sensors so that the effect of noise on the test is minimized.(4) The three-axis six degrees of freedom vibration test system with elastic table is studied and the dynamic model of the system is established by combining the finite element method. The control method of three-axis six degrees of freedom vibration test system with elastic table is studied, and a multi point control method is proposed. Theoretical derivation and simulation results show that, when the coordinates of each measurement point meet certain conditions, it can achieve more effective control of the table and improve the control effect.(5) The control software is programmed by NI LabVIEW language, and the test is carried out on a small three-axis electric shaking table by using the NI PXI hardware system. Experiments are carried out on a large single axial vibration table, and the effectiveness of the multi point control method for elastic table is proved.