RU2401461C2 - Frequency angular-displacement sensor and measuring device for it - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in frequency sensor, the disk dielectric base is made rotating and current conductors located on this base are made in the form of segments applied on both sides of the disk. Furthermore, two one-layer flat-topped inductance coils are introduced into the device and connected to frequency-driving circuit of the first and the second high-frequency auto generators. Offered sensor is not critical to contamination with dust, oil, detergents and permits disk axial play within gap of flat-topped coils 5 and 6. Measuring device can be made in the form of "ЧИП" and embedded into sensor structure. Sensor dimensions are practically determined by disk diametre which can be selected within 10-80 mm when total height of structure is within limits of 2-10 mm.

EFFECT: increase in speed and accuracy of angular displacement measurements under conditions of high-intensity noise providing direct digital reading both small and large angular displacements.

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Description

The invention relates to instrumentation and is intended for operational digital measurement of angular displacements under the action of intense electromagnetic interference from actuators of robots and can be used to build portable digital sensors of angular displacements.

A known angle of rotation sensor [1], containing a magnetic circuit, in the form of an open ring, distributed along the magnetic circuit of the primary and secondary windings and a rotor in the form of a short-circuited coil, associated with a controlled object.

The disadvantages of the analogue [1] are:

- low accuracy and noise immunity of measuring the amplitude output signal of the sensor;

- complex design of the sensor and the technology of uniform winding of the windings on the magnetic circuit;

- unsuitability for measuring angular displacements in dynamics.

Closest to the proposed known technical solution is a high-frequency position and speed sensor for changing the position of an object [2], containing a line segment in the form of a housing with a conductive coating, a dielectric base with a conductive conductor in the form of a group of short conductive rods, on the one hand, electrically shorted to each other. The prototype provides an operational measurement of the position of the conductive surface relative to the open ends of the conductive rods by controlling the frequency or amplitude of the RF oscillations at the output of the RF resonator formed by the housing, the dielectric base and the group of rods.

The disadvantages of the prototype [2] when it is used to convert the angle of rotation into frequency are:

- the influence of the gap between the rotating body and the group of rods on the frequency and amplitude of the RF oscillations at the output of the sensor;

- significant influence of destabilizing factors on the measurement result due to the single-channel structure of the sensor;

- low sensitivity of the output frequency to a change in the angular position of a rotating object;

- the absence in the integrated sensor design of a built-in converter of output signals into a direct code of the measured angular displacement

Also known is a measuring information device (3), which provides an operative conversion of the frequency signals of a differential sensor into a direct code of the measured value for any analytical dependence of the frequency signals of the sensor on this value. This analogue allows accurate conversion of small angular displacements into a direct code of the measured quantity, however, when measuring large angular displacements, there is no device for converting them into a direct digital code.

The technical result of the invention is to increase the speed and accuracy of measurement of both small and large angular displacements in conditions of intense interference with the operational conversion of the measured displacements into a direct digital code.

To achieve a technical result:

- in the sensor, the dielectric base is made movable in the form of a disk, and the conductive conductors placed on this base are made in the form of segments deposited on both sides of the disk, in addition, two single-layer U-shaped inductors are introduced into the device and connected to the frequency setting circuit of the first and second high-frequency oscillators;

- a frequency discriminator, a rotation direction sensor, a large displacement code generator with inputs for the initial installation of large displacements and with an input for enabling the initial installation, the digital outputs of which are connected to the high-order bits of the digital indicator in the device, are inserted into the measuring device, and the frequency discriminator is connected by inputs to the outputs of the oscillators of the frequency sensor of angular displacements, the output of the frequency discriminator is connected to the counting input of the For the code of large displacements, and the output of the rotation direction sensor is connected to the input of the direction control of the account of the generator of the code of large displacements

The structure of the proposed sensor is shown in figure 1, figure 2 shows the differential frequency Δf = f ₁ -f _{2 of the} generators 7 and 8 as a function of the angular position of the disk I, figure 3 shows the structure of a digital converter of angular displacements with the proposed frequency sensor of angular displacements . The sensor contains a dielectric disk 1, mounted on an axis 2, and non-magnetic highly conductive sectors 3 are applied to the disk surface, alternating with dielectric sectors 4. Two single-layer U-shaped inductors 5 and 6 interact with disk 1 and are included in the frequency-setting circuits of high-frequency oscillators 7 and 8. Coils 5 and 6 are placed in such a way that their mutual angular position differs by an angle φ _{c of} sectors 3 and 4. Resonance frequencies f ₁ and f _{2 of} generators 7 and 8 can be represented as follows:

where L _C is the intrinsic inductance of coils 5 and 6;

L _∂ is the equivalent inductance of sector 3 interacting with the inductor;

M is the mutual inductance of sector 3 and the coil when the sector is fully inserted into the coil;

With _n - the initial capacity of the LC circuit, which sets the resonant frequency of the oscillators 7 and 8;

ξ ₀ = 8.8541 · 10 ^-12 F / m is the dielectric constant;

S is the area of the conductor of the coil, interacting with the conductive sectors 3;

ξ is the relative dielectric constant of the gas in the gap between the inductor and the sector;

φ _c is the angle of sector 3;

φ _n is the angle of overlap of sector 3 by coil 7 and 8;

in - the gap between the surfaces of the coil and sector 3.

The difference frequency Δf = f ₁ -f _{2 of the} generators 7 and 8 is presented in the form of a graph of Figure 2 as a function of the angular position of the disk I.

Due to the antiphase change in the frequencies f ₁ and f ₂ , a high conversion coefficient of angular displacements into the frequency difference Δf is ensured while compensating the additive bias of these frequencies from destabilizing factors. With raw data

L _C = 10 ^-6 H; M ² / L _∂ = 0.8 L _C ; φ _c = 22.5 °; C _n = 10 ^-11 F; S = 4 · 10 ^-5 M ² ; in = 0.001 m;

ξ ₀ = 8.854 · 10 ^-12 F / m the conversion coefficient is provided in the range (306 ÷ 634) kHz / Grad (see table 1).

With the really provided instability of the frequencies of high-frequency oscillators 7 and 8 not higher than 10 ^{-5, it} is possible to count angular movements with an absolute error of no more than 0.5 × 10 ^-4 angular degrees with a sufficiently short measurement time and high noise immunity. For example, at the required discreteness of the digital reading of the angle of no more than 1/300 degrees, the time t _{and a} single digital measurement of the difference frequency Δf can be limited to 10 ^-3 s. Table 1 shows the main parameters of the sensor as a function of the measured angular displacement.

Table 1 Angular movement Equivalent inductance Equivalent capacity Resonant frequencies Angle to Frequency Conversion Rate hail e1 e2 Se1 Se2 one 2 kHz / deg GN · 10 ^-7 GN · 10 ^-7 F10 ^-11 F10 ^-11 Hz · 10 ⁶ Hz · 10 ⁶ 0,0 10,000 1,666 1,000 1,354 5,0329 10.0594 634 2.5 9,074 2,592 1,039 1,315 5.1824 8,6203 517 5,0 8,148 3,518 1,079 1,275 5,3683 7.5129 382 7.5 7,222 4,444 1,118 1,236 5,6008 6,7902 323 10.0 6,296 5,370 1,157 1,197 5,8957 6,2779 306 12.5 5,370 6,296 1,197 1,157 6,2779 5,8957 323 15.0 4,444 7,222 1,236 1,118 6,7902 5,6008 382 17.5 3,518 8,148 1,275 1,079 7.5128 5,3683 517 20,0 2,592 9,074 1,315 1,039 8,6203 5.1824 634 22.5 1,666 10,000 1,354 1,000 10.0594 5,0329 517 25.0 2,592 9,074 1,315 1,039 8,6203 5.1824 382 27.5 3,518 8,148 1,275 1,079 7.5128 5,3683 333 30,0 4,444 7,222 1,236 1,118 6,7902 5,6008 377

Table 1 confirms the ability to accurately control the angular displacements of the executive bodies of robots at a sufficiently high rate of change of angle.

The structure of the digital Converter angular displacement with the proposed sensor is shown in Fig.3.

The meter includes generators 7 and 8 of the proposed sensor, a frequency-to-digital converter (CCP) of 9 frequencies f ₁ and f ₂ into a code N _{m of} small displacements (made, for example, according to the USSR AS No. 1314360), as well as a frequency discriminator 10 shaper 11 code Nσ large displacements, high order 13 digital indicator 12, the sensor 14 of the direction of rotation, the inputs 15 of the code N ₀ initial setting and input 16 enable initial setting of the counter 11. Before starting work, the sensor disk 1 is set to the initial position, and input 14 of the shaper 11 feeds the signal U _app , while the shaper 11 is installed in the initial state specified by the code N ₀ at its inputs. Code N ₀ can be supplied from the keyboard or from the output of another external digital preset. At the outputs of CCP 9 with a delay in the counting interval t _u, information on the value of small displacements (code N _m ) is updated regardless of the speed and direction of rotation, the value of angular displacements is displayed on indicator 13. In the presence of rotation of the disk I at the moments of equal frequencies f ₁ and f ₂ , the signal U ₀ is formed at the output of element 10, and the former 11 changes its state by one in the direction of increasing (at U _p = I) or decreasing (at U _p = 0).

Small angular displacements can be counted by a combination of frequencies f ₁ and f ₂ , and movements exceeding the angle φ _c should be counted by the number of times the frequency discriminator 10 is triggered, for example, at the moment of equal frequencies f ₁ and f ₂ . The angular size of sectors 3 can be chosen to provide unique combinations of frequencies f ₁ and f ₂ within small movements up to 10 angular degrees, (for example φ _c = 5), while large movements will be counted in increments of 10 angular degrees.

Thus, at the lower digits 12 and senior digits 13 of the digital indicator and at the outputs of the converter of FIG. 3, digital codes N _σ and N _m are issued that carry information about the value of the angular displacement of the disk 1 and axis 2.

The device of FIG. 3 can operate in the counting mode of the value of large displacements specified by the code N ₀ , provided that the signal U _p = 0 subtracts the pulse count U ₀ after writing code N ₀ to the shaper 11. Then, when counting the large displacements specified by the code, the signal U _OT = I takes place at the output RA (zero state) of the shaper 11, which signals the development of code N ₀ . This mode of operation of the device of Figure 3 is necessary in robotics to set certain angular displacements of the actuating elements of robots.

The frequency-digital converter 9 can be implemented on the basis of the known device [3], the driver 11 can be implemented on a reversible counter with a preset code, to the outputs of which a non-volatile memory device is connected, with the help of which the output code of the counter is converted into a code N _{σ of} large displacements .

Compared with the prototype [2], the proposed sensor has the following advantages:

- uncriticality of the sensor to the axial displacement of the dielectric disk 1 relative to the U-shaped coils 5 and 6;

- significantly less influence of temperature, supply voltage and other destabilizing factors on the measurement result due to the same additive frequency offset f ₁ and f ₂ ;

- higher sensitivity and accuracy of the sensor due to the differential change in the frequencies f ₁ and f ₂ from changes in the angle of rotation φ.

Compared with the known measuring device (3), the proposed structure of the measuring device of Fig. 3 provides an operative digital readout of arbitrarily large angular displacements specified by code N ₀ . The closest known industrial option is the commercially available ST-320 goniometer table with a digital readout, in which an optical raster sensor on interference gratings is used as a rotation angle sensor. The use of the basic version in robots is difficult due to the high requirements for the absence of contamination of interference gratings, which is practically impossible due to the unacceptable increase in the dimensions of the sensor and the need to supplement it with dust and moisture protection fittings.

The proposed sensor is not critical to contamination of the disk 1 by dust, oil, detergents, allows axial play of the disk within the clearance of U-shaped coils 5 and 6. The dimensions of the sensor are practically determined by the diameter of the disk I, which can be selected within 10-80 mm with a total height designs ranging from 2 mm to 10 mm.

Other known analogues [4, 5] have disk rotors, on which are printed or printed windings, or electromagnetic screens in the form of curved sectors. Their disadvantage is low sensitivity and noise immunity due to the amplitude method of picking up the output signal. In analogue [5] there is a high-frequency current source supplying the primary winding, and the emf is removed from the secondary printed windings and fed to phase demodulators. A common drawback for analogues [4, 5] is the influence of the gap between the rotor and stator on the measurement result. In the proposed solution, this effect is practically eliminated due to the frequency output and the design of inductors, covering the movable disk on both sides. When identifying signs similar to those known in science and technology, the latter were not found - therefore, the claimed technical solution meets the criterion of "significant differences". The proposed sensor design is technologically advanced, the process of its manufacture and assembly is acceptable for automation. A digital measuring device can be structurally implemented as a CHIP and integrated into the sensor structure, and the digital outputs of codes N _m and N _{b can be} connected to an external processor or to any other digital device.

INFORMATION SOURCES

1. Auth. St. USSR No. 1232937, M. Cl. G01B 7/30.

2. Auth. St. USSR No. 859800, M. Cl. G01B 7/00.

3. Auto USSR No. 1314360, M. Cl. G08C 19/28.

4. Aut. St. USSR No. 442945, M. Cl. G01B 7/30.

5. Aut. St. USSR No. 887921, M. Cl. G01B 7/30.

Claims (3)

1. A frequency sensor of angular displacements containing a dielectric base, a group of conductive elements placed on this base, a high-frequency oscillation oscillator, and an element transmitting angular displacement, characterized in that the base is made in the form of a movable disk with conductive elements deposited on both sides in the form of sectors uniformly spaced around the circumference, two single-layer U-shaped inductors and a second oscillator are inserted into the device, enclosing a movable disk with a gap or high-frequency oscillations, moreover, the movable disk is rigidly connected to the element transmitting angular displacement, and the first and second inductors are displaced one relative to the other along the disk circumference by the width of the conducting sector and are included in the frequency setting circuits of the first and second high-frequency oscillation oscillators, respectively. 2. The frequency sensor of angular displacements according to claim 1, characterized in that the number of conductive sectors on the movable disk is chosen even, and the material of the sectors is selected non-magnetic. 3. A measuring information device for a frequency sensor of angular displacements, comprising a frequency-to-digital converter, the inputs of which are connected to the outputs of high-frequency oscillators of a frequency sensor of angular displacements, and a digital indicator is connected to the outputs of the frequency-to-digital converter, characterized in that a frequency discriminator is inserted into the device, rotation direction sensor, large displacement code generator with inputs of the initial installation of large displacements and with the input of the resolution of the beginning installation, the digital outputs of the large displacement code generator are connected to the high bits of the digital indicator available in the device, the frequency discriminator being connected by the inputs to the outputs of the high-frequency oscillators of the frequency sensor for angular displacements, the frequency discriminator output is connected to the counting input of the large displacement code generator, and the output of the rotation direction sensor connected to the input of the direction control of the account of the shaper code of large displacements.

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