SU1679189A1 - Device for measuring object motion - Google Patents

Abstract

This invention relates to a measurement technique. The aim of the invention is to improve the accuracy of measurements by providing automatic elimination of errors associated with violation of the identity of the photodetectors. A device for measuring the movement of an object contains the first and second position-sensitive photodetectors 1, 7 located at a distance d from each other. From the outputs of photodetectors 1, 7, signals are fed to the inputs of bandpass filters 3, 8, which are tuned to the frequency of parasitic pulsations of the light source, and the signal is fed to the input of filter 3 through an adjustable amplifier-attenuator 2, the gain factor of which varies under the action of voltage, attached to the control input. The output signal of the subtractor 6, proportional to the difference of the input signals, is fed to the control input of the amplifier-attenuator 2, equalizing the conversion factors of the photoreceiver 7 and the chain of photodetector 1 - amplifier-attenuator 2, providing the necessary conditions at the input of processing unit 11. 1 il.

Description

The invention relates to a measurement technique and can be used to measure angular and linear movements.

The aim of the invention is to increase -. nor the accuracy of measurements by ensuring the automatic elimination of errors associated with the violation of the identity of the photodetectors.

The drawing shows a block diagram of the device.

A device for measuring object movements contains, in series, a first position-sensitive photodetector 1, a controlled amplifier-attenuator 2, a first band-pass filter 3, a first detector 4, a first low-frequency filter 5 and

analog subtractor 6, the output of which is connected to the control input of amplifier-attenuator 2, are connected in series to a second position-sensitive photodetector 7, some fixed distance from the first photodetector 1 for some fixed distance, the second band-pass filter 8, the second detector 9 and the second filter 10 are low frequency, the output of which is connected to the second input of the analog subtractor 6, the processing unit 11, the first and second inputs of which are connected respectively to the outputs of the amplifier-attenuator 2 and the second photodetector 7.

The device works as follows.

The light flux falls on the photodetectors 1 and 7, located at a distance d

ABOUT

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from each other. From the outputs of photodetectors 1 and 7, an electrical signal is fed to the inputs of bandpass filters (PF) 3 and 8, respectively (PF is tuned to the frequency of parasitic pulsations of the light source), and, to the input of filter 3, the signal is fed through an adjustable amplifier-attenuator 2, the gain of which varies due to the voltage applied to the control input. From the outputs of the bandpass filters 3 and 8, the signal through the detectors 4 and 9, the low-pass filters 5 and 10, respectively, is fed to the inputs of the analog subtractor b, at the output of which a signal is formed that is proportional to the difference of the input signals. The output signal of the subtractor b is fed to the control input of the amplifier-attenuator 2. From the output of the amplifier-attenuator 2 and the photodetector 1, signals are also sent to the signal processing unit of the photodetectors 7.

By using an adjustable amplifier-attenuator 2, included in the feedback loop at the frequency of the parasitic pulsations of the light source, the conversion factors of the photoreceiver 7 and the circuit of the photodetector 1 — the amplifier-attenuator 2 are automatically equalized, resulting in an increase in the accuracy of the device

calibration calibration before each measurement.

Claims (1)

Claims An apparatus for measuring movements of an object, comprising two position-sensitive photodetectors separated by a fixed distance, connected in series by an amplifier / attenuator, whose input is connected to the output of the first photoreceiver, and a processing unit, the second input of which is connected to the output of the second photoreceiver. characterized by the fact that, in order to increase accuracy, it is equipped with series-connected first bandpass filter, first detector and first low-frequency filter, connected by a second bandpass filter, a second detector and a second low-frequency filter, an analog subtractor, the first and second inputs of which are connected respectively to the outputs of the first and second low-frequency filters, the amplifier-attenuator is controllable, its control input is connected to the output of the analog subtractor, the output of the amplifier-attenuator is connected to the input of the first band-pass filter, and the output of the second photodetector is connected to the input of the second band-pass filter.