A four-quadrant tracking and positioning sensor based on eddy current differential nonlinear effect

Abstract

The application discloses a four-quadrant tracking and positioning sensor based on eddy current differential nonlinear effect, which comprises an upper and lower parallel detection coil array plate and a target conductor. The application passes the same excitation signal into four plane coils on the detection coil array plate, converts the two-dimensional micro displacement of the detection coil array plate relative to the target conductor array plate into the voltage signals of the four plane coils by using an inductance measurement circuit, processes the four voltage signals by using a microprocessor system, obtains the differential signal related to the displacement, and takes the differential signal as the input signal of an executing mechanism. Due to the sensitivity characteristics of high center and low edge, the application can be specialized in the negative feedback regulation of a plane displacement mechanism, and can also adapt to harsh environments such as oil stains and dust. The application has the advantages of simple structure and good reliability, and is suitable for the negative feedback position regulation scenes of detecting the plane two-dimensional displacement, such as a fast steering mirror, a laser stabilizer, a solar panel attitude calibration and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automatic control calibration, and particularly relates to a four-quadrant tracking positioning sensor based on eddy current differential nonlinear effect. BACKGROUND

[0002] Automatic calibration technology has wide application in the fields of precision optical systems, aerospace platforms, micro-electro-mechanical systems, etc. At present, a widely used method for realizing position calibration is as follows: the pose information of a target to be calibrated is acquired through a single sensor or a sensor group, and then the output signal of the sensor or the sensor group is taken as the input of a control link to realize negative feedback regulation through a specific algorithm. For example, the exposure machine mask position calibration method proposed in patent CN116819907A uses a distance measuring sensor group to detect the mask pose information to realize non-contact correction. Patent CN117198977A discloses a wafer centering method during wafer transmission, in which two reflective sensors are used to scan and record the coordinate information of the wafer, and the center position and radius are calculated, and then the centering operation is completed through a set value. However, the existing position calibration sensor scheme usually involves the combination of multiple sensors, which requires a large amount of subsequent work of error compensation, data fusion and control algorithm design, thereby bringing a burden to software and hardware design. SUMMARY

[0003] The application aims to provide a four-quadrant tracking positioning sensor based on eddy current differential nonlinear effect, which has high sensitivity in the center and low sensitivity at the edges in the measurement range, can well maintain the signal-to-noise ratio in the center region, and suppresses noise. At the same time, the eddy current sensor has good high-frequency characteristics, is not sensitive to dust and oil, and is suitable for fast calibration and adjustment requirements in complex industrial sites.

[0004] In order to achieve the above application purpose, the application adopts the following technical scheme:

[0005] A four-quadrant tracking positioning sensor based on eddy current differential nonlinear effect, comprising a detection coil array plate and a target conductor:

[0006] The detection coil array plate is in the XY plane and comprises four planar coils and a detection coil array plate in which the planar coils are inlaid, and the four planar coils are arranged in a diamond shape.

[0007] The target conductor is in the XY plane.

[0008] The detection coil array plate and the target conductor are arranged in parallel, the symmetrical center of the detection coil array plate and the target conductor coincides at the initial position and serves as the origin O of the Cartesian coordinate system, the geometric centers of the four coils are located on the positive half of the X-axis, the positive half of the Y-axis, the negative half of the X-axis and the negative half of the Y-axis, and the detection coil array plate and the target conductor are relatively translated in the XY plane while the vertical distance remains unchanged.

[0009] For the two-dimensional position tracking positioning problem of planar motion components, a fixed detection coil array plate is provided, then the target conductor is connected with the moving component, and the two are arranged in parallel;

[0010] The four planar coils of the detection coil array plate are respectively connected to the same sinusoidal excitation signal, the inductance values L1, L2, L3 and L4 of the four planar coils are differentiated by a hardware circuit to obtain differential inductance ΔL x , ΔL y , and through an inductance-voltage conversion circuit, two voltage signals U x , U y which are positively correlated with displacement and have a larger correlation coefficient K closer to the center are output through analog signal amplification and band-pass filtering.

[0011] The difference between U x , U y and the initial zero position signal is used as the input signal of the actuator to realize negative feedback regulation of the overall system.

[0012] The planar coils and the target conductor are arranged in a specific size and position, so that the differential inductance ΔL x , ΔL y has a large range and high sensitivity in the center area, specifically: the outer diameter of the planar coil is D, the inner diameter is 0.1D, the shape of the planar coil is circular, the center distance of adjacent planar coils in X and Y directions is 1.8D, the diameter of the target conductor is 2D, and the shape of the target conductor is circular.

[0013] Further technical solutions of the application:

[0014] Preferably, the thickness of the target conductor is 0.02D.

[0015] Preferably, the separation height range between the detection coil array plate and the target conductor is (0, 0.1D).

[0016] Preferably, the displacement range of the detection coil array plate relative to the target conductor in X and Y directions is (-0.5D, 0.5D).

[0017] Preferably, the inductance values L1, L2, L3 and L4 of the four planar coils are differentiated by using an alternating current bridge method, and a voltage signal to be processed is output, specifically:

[0018]

[0019] L1 is the inductance value of the first planar coil;

[0020] L2 is the inductance value of the second planar coil;

[0021] L3 is the inductance value of the third planar coil;

[0022] L4 is the inductance value of the fourth planar coil.

[0023] The calculated U x is a function of the displacement of the probe coil array plate relative to the target conductor array plate in the X-axis direction, U y is a function of the displacement of the probe coil array plate relative to the target conductor array plate in the Y-axis direction.

[0024] Preferably, the material of the planar coil is copper; and the material of the target conductor is aluminum.

[0025] The beneficial effects of the present application are:

[0026] Compared with traditional laser type, grating type planar two-dimensional displacement sensors, the present application uses one sensor to measure X and Y direction displacement simultaneously, has simple structure, small volume, saves cost, avoids installation errors caused by independent installation of sensors in multiple directions such as Abbe error, and has better high frequency characteristics in MHz or above band, and is suitable for fast calibration.

[0027] Compared with traditional capacitive two-dimensional displacement sensors, the present application has the physical characteristics of high central sensitivity and low edge sensitivity, so that the central resolution is high, and small deviations can be quickly detected and corrected. Once the input changes too much and deviates from the center, it enters the edge with low sensitivity, and the system response to changes will be slow. Therefore, it naturally defines the "effective working range" and specializes in the position calibration requirement of "center alignment". In addition, since most random noise (such as detector electronic noise, background light) has small amplitude, and high frequency noise and small amplitude disturbance are more likely to occur in the edge or non-central area. This sensor naturally has a physical filtering effect, greatly improving the anti-noise ability of the system.

[0028] At the same time, compared with traditional laser type, grating type, capacitive type planar two-dimensional displacement sensors, the eddy current sensor is more resistant to oil stains, dust and other harsh environments, and can maintain high reliability in harsh environments.

[0029] In summary, the four-quadrant tracking and positioning sensor based on the eddy current differential nonlinear effect provided by the present application has excellent central resolution and signal-to-noise ratio, and excellent high frequency characteristics. And its structure is simple, reliable, suitable for fast steering mirror, laser stabilizer, solar panel attitude calibration and other negative feedback position adjustment scenes that need to detect planar two-dimensional displacement. BRIEF DESCRIPTION OF DRAWINGS

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 Isometric and side views of the eddy current four-quadrant tracking and positioning sensor provided by the present invention;

[0032] Figure 2 This is a schematic diagram of the sensor detection coil array board structure;

[0033] Figure 3 This is a schematic diagram showing the initial positions of the detection coil array plate and the target conductor.

[0034] Figure 4 A graph showing the relationship between the inductance of a single coil and the relative displacement of the target conductor along the X-axis, and its differential.

[0035] Figure 5 This is a schematic diagram illustrating the differential principle and the results of axis differential adjustment.

[0036] Figure 6 This is a block diagram illustrating the system principle of the present invention;

[0037] Figure 7 For U x (x,y) Full-range function graph;

[0038] Figure 8 For U y (x,y) Full-range function graph;

[0039] Figure 9 This is a schematic diagram of a circuit example according to an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] Example 1: As Figures 1 to 3 The planar two-dimensional micro-displacement sensor based on the four-quadrant eddy current effect shown includes a probe coil array plate 1 and a target conductor 2. The probe coil array plate 1 and the target conductor 2 are placed in parallel with a tiny gap of 0.05D between them.

[0042] As shown in Figure 2 Fig. 1, the detection coil array board 1 comprises four planar coils 11, which are circular in shape. The outer diameter of the planar coil 11 is D, and the inner diameter is 0.1D. The planar coils 11 are made of copper, and the number of turns of the four planar coils 11 are equal and arranged in a diamond shape on the detection coil array board 1. The center-to-center distance of the planar coils 11 in the X direction and the Y direction is 1.8D.

[0043] As shown in Figure 3 Fig. 2, the target conductor 2 is circular in shape, with a diameter of 2D and a thickness of 0.02D.

[0044] In this embodiment, the outer diameter of the planar coil 11 is 20mm, and the inner diameter is 2mm. The diameter of the target conductor 2 is 40mm, and the height of the target conductor 2 from the planar coil 11 is 1mm. The maximum distance that the target conductor 2 can move in a single direction in the XY plane is 10mm, and the total range is 20x20mm. 2 .

[0045] The inductance of the planar coil 11 is negatively related to the relative coverage area between the planar coil 11 and the target conductor 2. When the planar coil 11 and the target conductor 2 have no overlapping area, the inductance approaches the theoretical initial value L0. When the target conductor 2 completely covers the planar coil 11, the inductance reaches the minimum value L min , and remains unchanged when the target conductor 2 completely covers the entire area of the planar coil 11. The inductance L is sensitive to displacement X in the section from the outer tangential movement to the inner tangential movement of the planar coil 11 and the target conductor 2, which is one diameter D. Figure 4 The relative displacement process of a single planar coil 11 and the target conductor 2 in the X axis, the L(x) response curve, and its derivative dL(x) / dx are shown.

[0046] As shown in Figure 5 Fig. 3, by arranging the positions of the planar coils 11 on the detection coil array board 1, L1 and L3, and L2 and L4 can both cover the high sensitivity area of the inductance-displacement response, and are opposite to each other, so that the differential inductance ΔL x , ΔL y has a sensitivity that is twice that of the original response, with the highest sensitivity in the center area and gradually decreasing towards the edges. In this embodiment, the relative coil center distance is 36mm.

[0047] The four planar coils 11 are respectively connected to the same alternating excitation signal, with a frequency of 1MHz.

[0048] When the probe coil array plate 1 is coincided with the symmetry center of the target conductor 2 in the initial position, the coincided center point is taken as the origin O of the Cartesian coordinate system, and the geometric centers of the four coils are located on the positive X-axis, the positive Y-axis, the negative X-axis and the negative Y-axis respectively. In the initial position, the overlapping areas of the four planar coils 11 with the target conductor 2 are equal, so the influence of the target conductor 2 on the four planar coils 11 is consistent, that is, the inductance values of the four planar coils 11 are completely the same. According to the four-quadrant detection method, it can be determined that the probe coil array is in the origin position at this time.

[0049] When the target conductor 2 starts to move in the XY plane, the position of the target conductor 2 relative to the respective opposite planar coils 11 changes differently. For example, when the probe coil array plate 1 moves from the initial position along the X-axis direction, the overlapping areas of the planar coils 11 located on the positive and negative X-axes with the target conductor below change (increase / decrease), thereby causing the inductance values of the two planar coils 11 to decrease (increase); the overlapping areas of the planar coils 11 located on the positive and negative Y-axes with the target conductor change (increase / decrease) in the same way, thereby causing the inductance values of the two planar coils 11 to change in the same way. When the probe coil array plate 1 moves from the initial position along the Y-axis direction, the overlapping areas of the planar coils 11 located on the positive and negative Y-axes with the target conductor below change (increase / decrease), thereby causing the inductance values of the two planar coils 11 to decrease (increase); the overlapping areas of the planar coils 11 located on the positive and negative X-axes with the target conductor change (increase / decrease) in the same way, thereby causing the inductance values of the two planar coils 11 to change in the same way.

[0050] As shown in Figure 6 , the inductance values L1, L2, L3 and L4 of the four planar coils 11 are differentiated by a hardware circuit to obtain differential inductance ΔL x , ΔL y , and through an inductance-voltage conversion circuit, two voltage signals U x , U y with positive correlation with displacement are output through analog signal amplification and band-pass filtering, and the closer to the center, the greater the correlation coefficient K and the voltage signal U x , U y :

[0051] The difference between U x , U y and the initial zero position signal is taken as the input signal of the control execution mechanism to realize a large range, wide range and high resolution, high signal-to-noise ratio positioning tracking sensor.

[0052] The U x (x,y) relationship in the full range is shown in Figure 7 , and U y (x,y) is shown in Figure 8 .

[0053] The embodiment provides a circuit design idea as shown in the figure Figure 9 The current source outputs a 1MHz sine AC signal I(t), which is input into an AC bridge. Two adjacent bridge arms of the AC bridge are connected with an X positive half-axis coil L1 and an X negative half-axis coil L3 respectively, and the other two adjacent bridge arms are connected with a variable resistor R S One node of the bridge output is grounded, and the other node is connected with a positive electrode of a subsequent non-inverting amplification circuit. The voltage signal amplified through the amplification circuit is filtered through a second-order low-pass filter, and a signal U x , U y corresponding to the X and Y positions is output. Those skilled in the art can also use an active bridge design scheme according to different stability, excitation frequency, signal-to-noise ratio and other requirements when designing technical details according to specific engineering requirements.

[0054] The above content is only an example and description of the structure of the application. Those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific embodiments, as long as they do not deviate from the structure of the application or exceed the scope defined by the claims.

Claims

1. A four-quadrant tracking and positioning sensor based on the eddy current differential nonlinear effect, comprising a detection coil array plate (1) and a target conductor (2), characterized in that: the detection coil array plate (1) is in the XY plane and comprises four planar coils (11) and a detection coil array plate (1) inlaid with the planar coils (11), the four planar coils (11) are arranged in a diamond shape; the target conductor (2) is in the XY plane; the detection coil array plate (1) and the target conductor (2) are arranged in parallel, the center of symmetry of the detection coil array plate (1) and the target conductor (2) coincides at the initial position and serves as the origin O of the Cartesian coordinate system, the geometric centers of the four coils are located on the positive half of the X-axis, the positive half of the Y-axis, the negative half of the X-axis, and the negative half of the Y-axis, respectively, the detection coil array plate (1) and the target conductor (2) are relatively translated in the XY plane, and the vertical distance remains unchanged; for the problem of tracking and positioning the two-dimensional position of a planar moving part, the detection coil array plate (1) is fixed, then the target conductor (2) is connected with the moving part and arranged in parallel; the thickness of the target conductor (2) is 0.02D; the lift-off height range between the detection coil array plate (1) and the target conductor (2) is (0, 0.1D); the displacement range of the detection coil array plate (1) relative to the target conductor (2) in the X and Y directions is (-0.5D, 0.5D); the inductance values L1, L2, L3, and L4 of the four planar coils (11) are processed differentially using the AC bridge method, and a voltage signal to be processed is output, specifically: L1 is the inductance value of the first planar coil; L2 is the inductance value of the second planar coil; L3 is the inductance value of the third planar coil; L4 is the inductance value of the fourth planar coil; the material of the planar coil (11) is copper; and the material of the target conductor (2) is aluminum. ​ ​ ​ ​ The four planar coils (11) of the probe coil array plate (1) are respectively connected to the same sinusoidal excitation signal, the inductance values L1, L2, L3, L4 of the four planar coils (11) are differentiated by a hardware circuit to obtain differential inductance ΔL x , ΔL y , and through an inductance-voltage conversion circuit, two voltage signals U x , U y with positive correlation with displacement are output through analog signal amplification and band-pass filtering, and the closer to the center, the greater the correlation coefficient K. U x , U y The difference between the initial zero position signal and the output signal of the sensor is used as the input signal of the control mechanism to realize a large range, wide range, high resolution at the center position, high signal-to-noise ratio, and positioning tracking sensor.

2. A four-quadrant tracking and positioning sensor based on the eddy current differential non-linear effect according to claim 1, characterized in that: The planar coil (11) and the target conductor (2) are arranged in specific sizes and positions, so that the differential inductance ΔL x , ΔL y At the same time, a large range and high sensitivity in the central region are provided, specifically, the outer diameter of the planar coil (11) is D, the inner diameter is 0.1D, the shape of the planar coil (11) is circular, the center distance of adjacent planar coils (11) in the X and Y directions is 1.8D, the diameter of the target conductor (2) is 2D, and the shape of the target conductor (2) is circular.

3. A four-quadrant tracking and positioning sensor based on the eddy current differential non-linear effect according to claim 2, characterized in that: ​ 4. A four-quadrant tracking and positioning sensor based on the differential non-linear effect of eddy currents as claimed in claim 2, characterized in that: ​ 5. A four-quadrant tracking and positioning sensor based on the differential non-linear effect of eddy currents as claimed in claim 2, characterized in that: ​ 6. A four-quadrant tracking and positioning sensor based on the differential non-linear effect of eddy currents as set forth in claim 1, characterized in that: ​ ； ​ ​ ​ ​ 7. A four-quadrant tracking and positioning sensor based on the differential non-linear effect of eddy currents as set forth in claim 1, characterized in that: ​

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