A single field scanning device for a magnetic grid displacement sensor

Abstract

A single field scanning device for a magnetic grating displacement sensor is composed of M groups of scanning detection units, each group of scanning detection units is composed of N micro-scale Hall elements. The N micro-scale Hall elements (numbered A1, A2,..., A N ) are equally spaced within a magnetic grating displacement sensor grating pitch Lambda, and the signal lines of the micro-scale Hall elements with the same number are connected together. During scanning, the Hall elements for sensing the magnetic field change of the magnetic grating displacement sensor are mixed with each other in space. The final output sensing signal is generated by multiple micro-scale Hall elements with different spatial positions and the same phase relationship. Compared with the four-field scanning mode of the existing magnetic grating displacement sensor, the error homogenization effect is achieved. When the magnetic grating displacement sensor is locally contaminated or individual sensing elements fail, the invention can still output high-quality and high-reliability sensing signals, thereby improving the service precision and reliability of the magnetic grating displacement sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision displacement measurement, and particularly relates to a single-field scanning Hall sensor microarray for a magnetic grating displacement sensor. BACKGROUND

[0002] A large number of precision grating sensors such as grating rulers and magnetic grating displacement sensors are key sensing components for determining the precision of manufacturing equipment. The measurement precision of a grating ruler can reach sub-micron level and is widely used in fields such as numerical control machine tools, electronic manufacturing equipment and semiconductor equipment. However, the grating ruler is sensitive to local pollution, dust and vibration of the grating ruler based on the photoelectric scanning principle, and thus is not suitable for harsh working conditions.

[0003] A magnetic grating ruler, also known as a magnetic grating displacement sensor, measures displacement by sensing magnetic field changes through a magnetic induction coil probe or a Hall element based on the magneto-electric scanning principle. Compared with the grating ruler, the magnetic grating displacement sensor has relatively better anti-shock, corrosion resistance and pollution resistance, and is widely used in harsh environments with low precision requirements, such as the metallurgy, machinery and petrochemical industries.

[0004] The sensing signal quality of the magnetic grating displacement sensor is one of the key problems restricting the improvement of the precision of the magnetic grating displacement sensor. The traditional magnetic grating displacement sensor adopts a traditional four-field scanning reading mode, as shown in FIG. 1, which senses magnetic field changes through four independent sensing elements (magnetic induction coil probes or Hall elements) in space to output four-channel sine and cosine sensing signals S1-S4. The spacing between the sensing element 1 and the sensing elements 2, 3 and 4 is (L+1 / 4)Λ, (L+2 / 4)Λ and (L+3 / 4)Λ respectively, where L is an integer and L≥1. Figure 1 The traditional four-field scanning mode has the following technical defects: 1) Although the pollution resistance of the magnetic grating displacement sensor is better than that of the grating ruler, when the grating ruler is locally polluted, the sensing signal quality, especially the consistency of the four-channel signals, will be severely affected, reducing the service precision of the magnetic grating displacement sensor. 2) When individual magnetic induction coil probes or Hall elements fail, the sensing signals will have large errors or even be missing, causing the sensing system of the magnetic grating displacement sensor to fail. SUMMARY

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present application provides a single-field scanning device and scanning method for a magnetic grating displacement sensor. Compared with the traditional four-field scanning magnetic field detection method (i.e. sensing magnetic field changes through four independent magnetic induction coil probes or Hall elements), when there is local pollution of the magnetic grating displacement sensor or individual sensing element failure, the single-field scanning device and scanning method can still output high-quality and highly reliable sensing signals, thereby significantly improving the service precision and reliability of the magnetic grating displacement sensor.

[0006] In order to achieve the above object, the technical scheme adopted by the present application is:

[0007] A single-field scanning device for a magnetic grating displacement sensor, the scanning device comprising a reading unit and a digital display device, the reading unit and the digital display device being connected through a data line; the reading unit and the magnetic grating displacement sensor are parallel along the X direction, and are aligned along the Y direction and have a gap of 0.3-2 mm along the Z direction. The interior of the reading unit is a single-field scanning Hall microarray, which is composed of M groups of scanning detection units, each group of scanning detection units being composed of N microscale Hall elements, the N microscale Hall elements being distributed at equal intervals within a grating pitch Λ of a magnetic grating displacement sensor, the N microscale Hall elements of each group of scanning detection units being numbered as A1, A2,..., A N , and the microscale Hall elements with the same number are connected together through a signal line.

[0008] Further, the microscale Hall elements are linear Hall elements with a scale of 0.1-0.5 mm.

[0009] Further, M is an integer, and takes a value of 3, 4, 5 or 6.

[0010] Further, N is an integer, and takes a value of 3 or 4.

[0011] A scanning method of a single-field scanning device based on a magnetic grating displacement sensor, the scanning method comprising the following steps:

[0012] S1: placing the reading unit parallel to the magnetic grating displacement sensor, and then scanning the magnetic grating displacement sensor along the X direction, the single-field scanning Hall sensing microarray sensing the periodic magnetic field change, and the microscale Hall element numbered A i outputting a signal, the expression of the signal being:

[0013]

[0014] In formula (1), ε is the signal amplitude, Λ is the grating pitch of the magnetic grating displacement sensor, N is the number of microscale Hall elements contained in each group of scanning detection units, and x is the displacement to be measured.

[0015] S2: the single-field scanning Hall sensing microarray finally outputs N sinusoidal wave electrical signals, the i-th electrical signal S i is the sum of the signals I i outputted by all the microscale Hall elements numbered A i .

[0016]

[0017] In formula (2), i=1, 2, …N. The phase change 2πx / Λ caused by the measured displacement x is reflected as the intensity change of the single-field scanning Hall sensor microarray output signal S i .

[0018] S3: verifying the quality of the signal S i .

[0019] When the signal S i has non-ideal characteristics, displacement measurement errors are introduced. The quality of the signal S i is represented by a Lissajous figure. An ideal Lissajous figure is a circle centered at the origin, i.e., a Lissajous circle. When there are non-ideal signal characteristics, the Lissajous figure deviates from the nominal Lissajous circle. If the Lissajous figure does not deviate from the nominal Lissajous circle, it is proved that there are no non-ideal signal characteristics.

[0020] S4: the measured displacement value x is obtained by performing demodulation algorithm processing such as arctangent subdivision and linearization subdivision on the output signal S i .

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1) The single-field scanning Hall sensor microarray proposed in the present application is essentially a mixing of Hall elements for sensing magnetic field changes in space. The final output sensing signal is generated by multiple microscale Hall elements with different spatial positions and the same phase relationship. Compared with the prior art (i.e., using mutually independent separate sensing elements to detect magnetic field changes), the present application has an error homogenization effect.

[0023] 2) In the existing separate sensing element detection method, when there is local pollution in the magnetic grating displacement sensor, the output signal quality, especially the consistency of multiple signals, is severely affected. In the single-field scanning Hall sensor microarray of the present application, the effect of local pollution in the magnetic grating displacement sensor on the output signal quality and the consistency of multiple signals is extremely limited through the averaging effect of the output signals of multiple microscale Hall elements, thereby ensuring the service precision.

[0024] 3) In the existing separate sensing element detection method, when an individual magnetic induction coil probe or Hall element fails, the sensing system of the magnetic grating displacement sensor fails. In the single-field scanning Hall sensor microarray of the present application, when an individual microscale Hall element fails, the other groups of microscale Hall elements can still accurately output sensing signals, thereby improving the service reliability of the magnetic grating displacement sensor under harsh working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural diagram of a conventional four-field scanning sensing element for a magnetic grating displacement sensor;

[0026] Figure 2 The installation position relationship of the magnetic grid displacement sensor and the reading unit;

[0027] Figure 3 The structure diagram of the single-field scanning Hall microarray for the magnetic grid displacement sensor of the present application;

[0028] Figure 4 The structure diagram of the single-field scanning Hall microarray, wherein: Λ=2mm, M=4, N=4;

[0029] Figure 5 The output signal waveform and the Lissajous figure of the single-field scanning Hall microarray;

[0030] Figure 6 The waveform diagram of the output signal of the traditional four-field scanning mode when the magnetic grid displacement sensor is locally contaminated;

[0031] Figure 7 The waveform diagram of the output signal of the single-field scanning mode when the magnetic grid displacement sensor is locally contaminated.

[0032] The reference numerals in the figure: magnetic grid displacement sensor-1; reading unit-2; digital display unit-3; sensing element-4; single-field scanning Hall microarray-5; micro-scale Hall element-6. DETAILED DESCRIPTION

[0033] The following will make a detailed description of the embodiment examples of the present application, which are implemented on the premise of the technical solution of the present application, and give detailed implementation manners and specific operation processes, but the protection scope of the present application is not limited to the following examples.

[0034] A single-field scanning device for a magnetic grid displacement sensor, as shown in Figures 2-3 The scanning device includes a reading unit 2 and a digital display device 3, which are connected through a data line; the reading unit 2 and the magnetic grid displacement sensor 1 are parallel along the X direction, and are aligned along the Y direction and have a gap of 0.3-2mm along the Z direction. The inside of the reading unit 2 is a single-field scanning Hall microarray 5, which is composed of M groups of scanning detection units, each group of scanning detection units is composed of N micro-scale Hall elements 6, the N micro-scale Hall elements 6 are distributed at equal intervals within a magnetic grid displacement sensor grid distance Λ, and the N micro-scale Hall elements of each group of scanning detection units are numbered as A1, A2,..., A N The micro-scale Hall elements 6 with the same number are connected together through a signal line. When the magnetic grid displacement sensor 1 and the reading unit 2 move relatively along the X direction, the reading unit 2 outputs a positive cosine electrical signal corresponding to the measured displacement, and the measured displacement amount is obtained by demodulating the positive cosine electrical signal.

[0035] Preferably, the microscale Hall element 6 is a linear Hall element with a scale of 0.1-0.5 mm.

[0036] Preferably, M is an integer with a value of 3, 4, 5, or 6.

[0037] Preferably, N is an integer with a value of 3 or 4.

[0038] As shown in Figures 4-7 , a scanning method of a single-field scanning device based on a magnetic grating displacement sensor, the scanning method comprising the following steps:

[0039] S1: placing the reading unit 2 parallel to the magnetic grating displacement sensor 1, and then scanning the magnetic grating displacement sensor 1 along the X direction, the single-field scanning Hall sensing microarray 5 sensing the periodic magnetic field change, and the microscale Hall element numbered A i outputting a signal, the expression of which is:

[0040]

[0041] In formula (1), ε is the signal amplitude, Λ is the grating pitch of the magnetic grating displacement sensor, N is the number of microscale Hall elements contained in each scanning detection unit, and x is the displacement to be measured.

[0042] S2: the single-field scanning Hall sensing microarray 5 finally outputs N-channel sinusoidal wave electrical signals, the i-th channel electrical signal S i is the sum of the signals I i outputted by all microscale Hall elements numbered A i :

[0043]

[0044] In formula (2), i=1, 2,...N. As can be seen from formula (2), the phase change 2πx / Λ caused by the measured displacement x is reflected as the intensity change of the single-field scanning Hall sensing microarray output signal S i .

[0045] When the magnetic grating displacement sensor has local pollution, the influence on the signal quality outputted by the single-field scanning Hall sensing microarray, especially the consistency of the multi-channel signals, is extremely limited, thereby ensuring the service precision of the magnetic grating displacement sensor; when an individual microscale Hall element of the single-field scanning Hall sensing microarray fails, the other groups of microscale Hall elements can still accurately output sensing signals, thereby improving the reliability of the magnetic grating displacement sensor under harsh service conditions.

[0046] S3: verifying the quality of the signal S i :

[0047] When the signal Si The presence of non-ideal characteristics will introduce displacement measurement errors. Signal S i The quality is represented by a Lissajous figure, such as Figure 5 As shown, an ideal Lissajous figure is a circle centered at the origin, i.e., the Lissajous circle. When there are non-ideal signal features, the Lissajous figure will deviate from the nominal Lissajous circle. If the Lissajous figure does not deviate from the nominal Lissajous circle, it proves that there are no non-ideal signal features.

[0048] S4: By controlling the output signal S i Demodulation algorithms such as arctangent subdivision and linear subdivision are used to obtain the measured displacement value x.

[0049] Example 1

[0050] refer to Figure 4 The magnetic grating displacement sensor has a grating pitch Λ = 2mm; the single-field scanning Hall sensor microarray consists of M = 4 scanning detection units, each consisting of N = 4 microscale Hall elements. When the reading unit scans the magnetic grating displacement sensor along the X direction, the single-field scanning Hall sensor microarray outputs 4 channels of sine and cosine electrical signals S. i (x), the phase difference between adjacent signals is π / 2, that is:

[0051]

[0052]

[0053]

[0054]

[0055] In formulas (3)-(6), ε is the amplitude of the output signal of a single microscale Hall element. Differential operations are performed on the four sinusoidal and cosine electrical signals, as follows: Figure 4 As shown, two orthogonal signals S are finally obtained. a (x) and S b (x):

[0056]

[0057]

[0058] It can be seen from formulas (7) and (8) that the signal S a (x) and S b The intensity of (x) varies sinusoidally with the measured displacement x; and for every grid pitch Λ that the measured displacement x moves, the signal S... a (x) and S b (x) varies by one sine or cosine period. Most generally, this is achieved by varying the signal S...a (x) and S b (x) is an arctangent operation to obtain the measured displacement value x:

[0059]

[0060] The premise of high-precision demodulation of the measured displacement value x in formula (9) is that the signal S a (x) and S b (x) are two ideal phase-quadrature (phase difference π / 2) sine signals. Therefore, when the signal S a (x) and S b (x) has non-ideal characteristics, displacement measurement errors will be introduced. The signal S a (x) and S b (x) can be represented by the Lissajous figure, as shown in Figure 5 The ideal Lissajous figure is a circle centered at the origin (the nominal Lissajous circle). When there are non-ideal signal characteristics, the Lissajous figure deviates from the nominal Lissajous circle.

[0061] Figure 6 For the magnetic grid displacement sensor with local pollution, the waveform of the output signal and its Lissajous figure of the traditional four-field scanning mode are shown. The sensor signal quality, especially the consistency of the four signals, is severely affected, so the Lissajous figure deviates significantly from the nominal Lissajous circle. In addition, for the traditional four-field scanning mode, when an individual sensing element fails, the corresponding sensing signal will have a large error or even be missing, causing the magnetic grid displacement sensor sensing system to fail.

[0062] Figure 7 For the magnetic grid displacement sensor with local pollution, the waveform of the output signal and its Lissajous figure of the single-field scanning mode of embodiment 1 are shown. Due to the error homogenization effect of the single-field scanning Hall microarray, the waveform of the four signals and its consistency remain basically unchanged, so the Lissajous figure remains consistent with the nominal Lissajous circle. In addition, for the single-field scanning mode of embodiment 1, when an individual sensing element fails, other groups of micro-scale Hall elements can still accurately output the sensing signal, improving the service reliability of the magnetic grid displacement sensor under harsh working conditions.

[0063] The above only describes the preferred embodiments of the present application. It should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A single field scanning device for a magnetic grid displacement sensor, characterized in that, The scanning device comprises a reading unit (2) and a digital display device (3), which are connected through a data line; the reading unit (2) and the magnetic grid displacement sensor (1) are parallel along the X direction, both are aligned along the Y direction and the gap along the Z direction is 0.3-2 mm; the inside of the reading unit (2) is a single field scanning Hall sensor microarray (5), which is composed of M groups of scanning detection units, each group of scanning detection units is composed of N microscale Hall elements (6), the N microscale Hall elements (6) are equally spaced within a magnetic grid displacement sensor grid pitch Lambda, the numbering of the N microscale Hall elements of each group of scanning detection units is A1, A2,..., A N , and the microscale Hall elements (6) with the same number are connected together through a signal line; The micro-scale Hall element (6) is a linear Hall element with a scale of 0.1-0.5 mm; M is an integer, and is 3, 4, 5 or 6; N is an integer, and is 3 or 4.

2. A scanning method based on the single-field scanning apparatus according to claim 1, characterized by, The scanning method comprises the following steps: S1 : The readout unit (2) is placed parallel to the magnetic grating displacement sensor (1), after which the readout unit (2) is scanned along the X direction over the magnetic grating displacement sensor (1), the single-field scanning Hall sensor microarray (5) senses the periodic magnetic field change, numbered A i The microscale Hall element output signal, the expression of which is: In formula (1), ε is a signal amplitude, Λ is a magnetic grating displacement sensor grating pitch, N is the number of micro-scale Hall elements contained in each group of scanning detection units, and x is a displacement to be measured. S2: the single field scanning Hall sensor microarray (5) finally outputs N-channel sinusoidal wave electrical signals, the i-channel electrical signal S i is the sum of the output signals I i of all the microscale Hall elements numbered A i ​ In formula (2), i = 1, 2, … N; the phase change 2πx / Λ caused by the measured displacement x is reflected as the intensity change of the single-field scanning Hall sensor microarray output signal S i ; S3: verification signal S i Quality: When the signal S i The displacement measurement error is introduced when there is non-ideal characteristics; the quality of the signal S i is represented by the Lissajous figure, and the ideal Lissajous figure is a circle with the center at the origin, i.e. the Lissajous circle. When there is a non-ideal signal characteristic, the Lissajous figure deviates from the nominal Lissajous circle. If the Lissajous figure does not deviate from the nominal Lissajous circle, it is proved that there is no non-ideal signal characteristic; S4: the output signal S i is obtained by performing an arc tangent subdivision, linearization subdivision demodulation algorithm processing, and obtaining the measured displacement value x.

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