Electromagnetic shake table using absolute position feedback to realize active positive rigidity resilient support

Abstract

An electromagnetic shake table using absolute position feedback to realize active positive rigidity resilient support belongs to the vibration metering technical field; the active positive rigidity resilient support method employs an absolute type linear raster ruler as a feedback displacement sensor, and outputs a Lorentz force in a constant proportion with the relative displacement of the absolute zero point position, thus enabling an electromagnetic shake table moving-coil to have the linearity rigidity resilient support in large stroke motions; the electromagnetic shake table moving-coil is connected in series with multistage power resistors so as to increase the load impedance, thus allowing a power amplifier to have a high signal to noise ratio while outputting a milliampere level ultralow frequency current; the electromagnetic shake table can combine the large stroke with the linear resilient support and the high signal to noise ratio, thus providing a large stroke high performance electromagnetic shake table control technology scheme for the ultralow frequency vibration calibration.

Description

technical field [0001] The invention belongs to the technical field of vibration measurement, and mainly relates to an electromagnetic vibrating table that realizes active positive stiffness elastic support based on absolute position feedback. Background technique [0002] The electromagnetic vibrating table that generates standard vibration signals is the key equipment for high-precision vibration calibration and an important part of the national vibration measurement technology system. In recent years, aerospace, building bridges, earthquake prevention and disaster reduction and other fields have raised the need for low-frequency / ultra-low-frequency vibration calibration. In order to improve the signal-to-noise ratio of the standard vibration signal and ensure the calibration accuracy of low-frequency / ultra-low-frequency vibration, the electromagnetic vibrating table is required to have as large a stroke as possible under the premise of ensuring thrust and accuracy, such a...

AI Technical Summary

Problems solved by technology

The following problems in this technical solution make the system adjustment complicated: 1) The position sensor is an incremental linear grating scale, and a zero position sensor needs to be installed, and the current position cannot be confirmed after the power is turned off. ; With cumulative error, it is necessary to accurately correct the error of each grating pitch to reduce the cumulative error when measuring a large stroke; 2) The feedback control system has differentiators, adjustable phase shifters, multiple adjustable amplifiers, etc., and the adjustment is complicated; 3) The resistance value of the moving coil of the electromagnetic vibrating table is generally small, about 1 ohm. When the vibrating table works in the ultra-low frequency band, the peak value of the current loaded on the moving coil is only a few mA, and the input signal of the corresponding signal generator is very small. Poor current signal-to-noise ratio

[0005] In summary, due to factors such as the nonlinear stiffness of the elastic support and the poor signal-to-noise ratio of the output current of the power amplifier, the waveform distortion of the large-stroke electromagnetic vibrating table is relatively large when it works in the ultra-low frequency band, and it is difficult to meet the high-precision calibration of ultra-low frequency vibration.

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