RU2397440C1 - Device for measuring angular displacements - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: device has two transformer angle sensors. The output of each sensor is connected to series-connected differential amplifier, storage sampling device, analogue-to-digital converter and register. The outputs of the registers are connected to inputs of an adder. The output of the adder is connected to a data register. Outputs of the control unit are connected to second inputs of the storage sampling devices, analogue-to-digital converters, registers, adder and data register.

EFFECT: higher measurement accuracy owing to reduced errors caused by offset of the rotation axis of conversion of the device for measuring angular displacements, less requirements for accuracy of actuation and rigidity of mechanical assemblies.

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Description

The invention relates to measuring equipment and can be used to measure the angular displacements of various objects, namely, to convert a limited angle of rotation of the shaft into a code, when it is impractical to use complex, full-speed and expensive sensors (gear reducers, high-speed drives, etc.).

A known displacement transducer (V.G.Domrachev, V.R.Matveevsky, Yu.S. Smirnov, Circuit design of digital displacement transducers, M., Energoatomizdat, 1987, p. 58), containing a U-shaped magnetic circuit, the output windings of which are connected to comparison elements CC1.CC2.CC3, the outputs of which are connected to the encoder Ш, containing elements HE1, HE2, HE3 and I1, I2, I3, at the outputs of which a positional displacement code is generated.

The disadvantage of this Converter is the low accuracy of the conversion, due to the large discreteness of measurement.

Closest to the proposed is a device for measuring angular displacements according to RU 2313764 C1, 12/27/2007. IPC: G01B 7/30, containing a sinusoid shaper, a transformer angle sensor, a differential amplifier, a sampling-storage device, an analog-to-digital converter, a data register, a control and synchronization unit, and a generator.

This device is selected as a prototype.

The disadvantage of this device is the error due to the radial displacement of the axis of rotation of the sensing element of the transformer angle sensor.

The present invention is to improve the accuracy of the conversion of the device for measuring angular displacements by reducing the error caused by the radial displacement of the axis of rotation of the sensor element of the transformer angle sensor. The error is reduced by installing a second transformer angle sensor and a compensation circuit.

To achieve this goal, a device for measuring angular displacements, containing a generator, the output of which is connected to the input of the control and synchronization unit, the first output of which is connected to the input of the sine wave shaper, the output of which is connected to the input of the first transformer angle sensor, the first and second outputs of which are connected respectively with the first and second inputs of the first differential amplifier, the output of which is connected to the first input of the first sampling-storage device, the output of which is connected to the first the first input of the first analog-to-digital converter, the second transformer angle sensor, the second differential amplifier, the second sampling-storage device, the second analog-to-digital converter, adder, the first and second registers, the first inputs of which are connected to the outputs of the first and second analog-to-digital converters, are introduced respectively, and the output of the first register is connected to the first input of the adder, the output of the second register is connected to the second input of the adder, the output of which is connected to the first input of the data register, second whose input is connected to the seventh output of the control and synchronization unit, the second output of which is connected to the second input of the first sample-storage device, the third output is connected to the second input of the first data register, the fourth output is connected to the second input of the first analog-to-digital converter, the fifth output is connected with the second input of the second register, the sixth output is connected to the third input of the adder, the eighth output is connected to the second input of the second analog-to-digital converter, the ninth output is connected to the second input m of the second sampling-storage device, the output of which is connected to the first input of the second analog-to-digital converter, and the input is connected to the output of the second differential amplifier, the first and second inputs of which are connected respectively to the first and second output of the second transformer angle sensor, the input of which is connected to the output shaper of a sinusoid.

The essence of the invention is illustrated by drawings, in which Fig. 1 shows a block diagram of a device for measuring angular displacements, Fig. 2 - diagrams of voltages of a device for measuring angular displacements, and Fig. 3 - first and second transformer angle sensors.

The device for measuring angular displacements contains a sinusoid driver 1, a first angle transformer 2, a second angle transformer 3, differential amplifiers 4 and 7, sample-storage devices 5 and 8, analog-to-digital converters 6 and 9, registers 10 and 11, an adder 12, a data register 13, a generator 14, and a control and synchronization unit 15.

The device operates as follows.

Figure 1 shows that at the inputs of the first transformer angle sensor 2 and the second transformer angle sensor 3, a sinusoidal voltage is supplied from the output of the sine wave former 1. Transformer angle sensors operate on the principle of opening the electromagnetic field. Each sensor consists of a magnetic core with a gap in which the sensing element moves - a copper coil with high electrical conductivity. The movement of the sensing element causes a change in the magnitude of the eddy currents induced in it. In this case, the inductive coupling between the primary winding located on the central core and the output windings changes. If the coil is in the zero position, as shown, the voltage at the output of the sensor, equal to the voltage difference at the output windings, will be zero, because output windings are turned on and the voltage at the output windings will be equal in amplitude and opposite in phase. When the sensor starts to rotate, the voltage at the output of the transformer angle sensor 2 and the transformer angle sensor 3 changes in proportion to α - the rotation angle of the coil.

The polarity of the output voltage is determined by the direction of the deviation of the coil from the zero position.

The output sinusoidal voltage of the transformer angle sensor 2 and the transformer angle sensor 3 are fed to the inputs of the differential amplifiers 4 and 7, respectively. Amplified to the required magnitude of the voltage from the outputs of the differential amplifiers 4 and 7 go to the inputs of the sampling and storage devices 5 and 8, respectively.

Using the control and synchronization unit 15 in the sample-storage device 5 and 8, the values of the output voltages of the first transformer sensor 2 of the angle Utdu1 and the second transformer sensor 3 of the angle Utdu2 respectively are stored. The voltages Uvx1 and Uvx2 from the outputs of the sample-storage devices 5 and 8 are supplied to the inputs of analog-to-digital converters 6 and 9, respectively, where they are converted into digital codes Ntdu1 = f (α) and Ntdu2 = f (α), which are a function of α - angle turning a turn.

A situation may arise when the force F, directed along the radius in a certain direction, starts to act on the rotation axis of the sensor. Suppose that the direction of the force F coincides with the Y axis. The axis of rotation together with the sensor element, in the presence of axial play or deformation, can shift along the Y axis. As can be seen from Fig. 3, the sensor element is shifted further from the zero angle for the upper transformer sensor 2 provisions, i.e. in the direction of increasing the modulus of the angle, and for the lower transformer sensor 3 the angle is closer to the zero position, i.e. in the direction of decreasing the modulus of the angle. Together with the axis offset, the voltage at the output of the transformer angle sensors will also change. With a symmetrical arrangement of transformer angle sensors, the displacement of the axis of rotation, and with it the sensing element, shown in figure 3, with respect to each of the transformer angle sensors will be equal in magnitude and opposite in sign. As a result of the displacement of the axis, Ucm - changes in the output voltages Utdu1 and Utdu2 will also be equal in magnitude and opposite in sign.

The output voltages of the sampling and storage devices Uvx1 = Unom + Ucm and Uavh2 = Unom-Usm are input to analog-to-digital converters 6 and 9, where they are converted into digital codes N1 = Nnom + Ncm and N2 = Nnom - Ncm, proportional to the angle of rotation α. The number N1 is recorded in the first register 10, and the number N2 is written in the second register 11. From the outputs of the registers 10 and 11, the digital codes N1 and N2 are fed to the inputs of the adder 12. In the adder 12 they are added and the resulting amount is written into the data register 13. By discarding the least significant bit at the output of the data register 13, this amount is divided into two. At the output of the device, the number Nout appears, proportional to the measured angle of rotation α. Then the registers are reset and in the next measurement cycle the next numerical value of Nout is calculated. As a result of these calculations, the compensation of the measurement error caused by the displacement of the axis of rotation occurs, because the numbers Ncm are included in N1 and N2 with different signs and after addition in the adder 12 are mutually destroyed:

,

,

where Nout - the number at the output of the device, proportional to the angle of rotation α;

N1 is the number corresponding to the measured voltage at the output of the first angle transformer 2;

N2 is the number corresponding to the measured voltage at the output of the second angle transformer 3;

Nnom is the number corresponding to the measured angle of rotation without error caused by the displacement of the axis of rotation;

Ncm is the number corresponding to the bias voltage.

Thus, using the proposed device, containing an additional transformer angle sensor 3 and a compensation circuit, the error in measuring the angle of rotation of the shaft caused by the displacement in a certain direction of the axis of rotation is reduced. It is necessary to first deploy transformer angle sensors relative to the axis of rotation so that the error compensation is the most maximum.

The processes of forming a sinusoid, sample-storage and analog-to-digital conversion, writing to registers and summing are synchronized by the frequency of the generator 14 using the control unit and synchronization 15.

Reducing the measurement error by introducing an additional transformer angle sensor 3 and the compensation scheme made it possible to significantly increase the accuracy of measuring the angle, reduce the requirements for precision and rigidity of mechanical components, reducing the cost of the device.

Of the patent information materials known to the applicant, no signs were found that are similar to the totality of the features of the claimed object.

This device has been tested on a prototype. The test results indicate the achievement of the task. ISS OJSC intends to use this technical solution on standard products.

Claims (1)

A device for measuring angular displacements, comprising a generator, the output of which is connected to the input of the control and synchronization unit, the first output of which is connected to the input of the sine wave shaper, the output of which is connected to the input of the first transformer angle sensor, the first and second outputs of which are connected to the first and second inputs, respectively the first differential amplifier, the output of which is connected to the first input of the first sampling-storage device, the output of which is connected to the first input of the first analog-to-digital converter, characterized in that a second transformer angle sensor, a second differential amplifier, a second storage sampling device, a second analog-to-digital converter, an adder, first and second registers, the first inputs of which are connected to the outputs of the first and second analog-to-digital converters, respectively, are introduced into it and the output of the first register is connected to the first input of the adder, the output of the second register is connected to the second input of the adder, the output of which is connected to the first input of the data register, the second input to the second output is connected to the second input of the first data register, the fourth output is connected to the second input of the first analog-to-digital converter, the fifth output is connected to the second the second register input, the sixth output is connected to the third input of the adder, the eighth output is connected to the second input of the second analog-to-digital converter, the ninth output is connected to the second input of the second sample-storage device, the output of which is connected to the first input of the second analog-to-digital converter, and the first input is connected to the output of the second differential amplifier, the first and second inputs of which are connected respectively to the first and second output of the second transformer angle sensor, the input of which is connected to the output of the shaper sine waves.

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