Angle measurement circuit and angle sensor

Abstract

The utility model relates to angle measurement technical field, concretely provides a kind of angle measurement circuit, comprising: magnetic induction module, signal adjustment module, signal conversion and processing module;The magnetic induction module includes two pairs of AMR Wheatstone bridge placed 45 ° with each other, to make the resistance change of AMR material and external magnetic field rotation angle linear relationship;One end of the signal adjustment module is connected with the magnetic induction module, and the signal adjustment module is used to adjust and handle the signal generated by the magnetic induction module;One end of the signal conversion and processing module is connected with the other end of the signal adjustment module, and the other end of the signal conversion and processing module is used to output the rotation angle of target device.The utility model provides technical scheme, can effectively amplify the resistance difference brought by magnetic field angle change, and then improve the resolution of original electric signal.This makes that circuit can capture tiny angle change, so that the precision of angle measurement can be improved to some extent.

Description

Technical Field

[0001] This invention relates to the field of angle measurement technology, and in particular to an angle measurement circuit and an angle sensor. Background Technology

[0002] With the rapid development of industrial automation and intelligent manufacturing, angle measurement technology is increasingly widely used in industrial control, robotics, aerospace, and other fields. As a key component for measuring rotation angles, the performance of angle sensors directly affects the accuracy and reliability of the system. Currently, common angle sensors on the market include potentiometer-type, photoelectric-type, and magnetic types. Among them, non-contact angle sensors based on magnetic principles are gradually becoming a research hotspot in the field of angle measurement due to their advantages such as no mechanical wear, long lifespan, and strong resistance to contamination.

[0003] However, traditional angle sensors based on the Hall effect principle have weak resistance to magnetic field interference, and stray magnetic fields from the outside can easily lead to a decrease in measurement accuracy. Utility Model Content

[0004] The present invention provides an angle measurement circuit and an angle sensor, which at least solves the problem of low measurement accuracy of traditional angle sensors.

[0005] In a first aspect, this utility model provides an angle measurement circuit, including: a magnetic induction module, a signal adjustment module, and a signal conversion and processing module;

[0006] The magnetic induction module includes two pairs of AMR Wheatstone bridges placed at 45° to each other, so that the resistance change of the AMR material is linearly related to the rotation angle of the external magnetic field.

[0007] One end of the signal adjustment module is connected to the magnetic induction module, and the signal adjustment module is used to harmonize the signal generated by the magnetic induction module;

[0008] One end of the signal conversion and processing module is connected to the other end of the signal adjustment module, and the other end of the signal conversion and processing module is used to output the rotation angle of the target device.

[0009] In an optional embodiment, aluminum strips are deposited on both pairs of Wheatstone bridges.

[0010] In an optional embodiment, the signal conversion and processing module includes: an analog-to-digital conversion unit and a digital signal processing unit;

[0011] The analog-to-digital conversion unit is used to convert the target signal, which has been harmonicized and processed by the signal adjustment module, into a digital signal.

[0012] The digital signal processing unit is used to perform calculations on the digital signal to obtain the rotation angle of the target device.

[0013] In an optional embodiment, the angle measurement circuit further includes a bias voltage module; the signal conversion and processing module further includes a digital-to-analog converter unit.

[0014] The digital-to-analog converter is connected to the digital signal processing unit; the digital-to-analog converter is used to convert the digital signal processed by the digital signal processing unit into an analog voltage signal.

[0015] The bias voltage module is connected to the digital-to-analog converter unit; the bias voltage module is used to add a bias voltage to the analog voltage signal so that the target voltage signal does not have a zero point; the target voltage signal is the sum of the analog voltage signal and the bias voltage.

[0016] In an optional embodiment, the angle measurement circuit further includes a current output module;

[0017] The current output module is connected to the bias voltage module and is used to convert the target voltage signal into a linear current signal output.

[0018] In an optional embodiment, the angle measurement circuit further includes: a protection circuit;

[0019] The protection circuit is connected to the current output module; the protection circuit is used to protect the angle measurement circuit.

[0020] In an optional embodiment, the signal adjustment module includes: an operational amplifier and resistive-capacitive components;

[0021] The operational amplifier is used to amplify the analog voltage signal output by the magnetic induction module, so that the amplified analog voltage signal is adapted to the sampling amplitude of the signal conversion and processing module.

[0022] The resistor-capacitor components are used to remove high-frequency noise from the amplified analog voltage signal.

[0023] Secondly, embodiments of the present invention provide an angle sensor, the angle sensor including the angle measurement circuit described in the first aspect of this application.

[0024] In an optional embodiment, the angle sensor further includes: a housing, black adhesive, and a cable;

[0025] The inner surface of the housing is fixedly connected to the angle measuring circuit;

[0026] The outer shell forms a cavity; the cavity is filled with black glue;

[0027] The cable is connected to the angle measuring circuit, and the cable is wrapped with vulcanized rubber to shield it from external electromagnetic interference.

[0028] In an optional embodiment, the housing is a metal housing;

[0029] There is a gap between the inner surface of the housing and the angle measuring circuit.

[0030] The angle measurement circuit provided in this invention uses two pairs of AMR Wheatstone bridges placed at 45° to each other as the magnetic induction modules. Since AMR Wheatstone bridges are more sensitive to changes in magnetic field than traditional resistive or inductive sensing elements, and the symmetrical 45° arrangement effectively amplifies the resistance difference caused by changes in magnetic field angle, thereby improving the resolution of the original electrical signal. This allows the circuit to capture minute angle changes, thus improving the accuracy of angle measurement to a certain extent. Attached Figure Description

[0031] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0032] Figure 1 This is a schematic diagram of the angle measurement circuit provided in one embodiment of this application.

[0033] Figure 2 This is a schematic diagram of the structure of an angle sensor provided in one embodiment of this application.

[0034] Explanation of reference numerals in the attached figures:

[0035] 100. Angle measurement circuit; 110. Magnetic induction module; 120. Signal adjustment module; 130. Signal conversion and processing module; 131. Analog-to-digital conversion unit; 132. Digital signal processing unit; 133. Digital-to-analog conversion unit; 140. Bias voltage module; 150. Current output module; 160. Protection circuit;

[0036] 200, Angle sensor; 210, Housing; 220, Cable. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0039] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0040] Traditional Hall effect angle sensors measure the magnetic field component perpendicular to the chip surface, resulting in low accuracy and resolution. They are also sensitive to magnet calibration, temperature drift, and external stray magnetic fields. Furthermore, they are highly demanding in terms of installation location; any misalignment of the magnet during installation will affect the output. High-quality magnets are required, and their strength and uniformity also influence the output. Additionally, traditional Hall effect angle sensors primarily output voltage, making them susceptible to interference. Voltage drop on the signal line and electromagnetic interference during transmission can cause voltage noise that affects the output. Moreover, traditional Hall effect angle sensors often cross zero, making it difficult to determine whether a zero output indicates a detected angle or a sensor malfunction, lacking zero-point fault detection functionality. Finally, if Hall effect angle sensors operate in high-pressure underwater environments, water can easily enter the housing and cable connections, affecting product performance and potentially causing sensor failure.

[0041] Based on this, this application provides an angle measurement circuit. By setting the magnetic induction module as two pairs of AMR Wheatstone bridges placed at 45° to each other, the AMR Wheatstone bridge, compared to traditional resistive or inductive sensing elements, is more sensitive to changes in the magnetic field. Combined with the symmetrical 45° arrangement, it can effectively amplify the resistance difference caused by changes in the magnetic field angle, thereby improving the resolution of the original electrical signal. This allows the circuit to capture minute angle changes, thus improving the accuracy of angle measurement to a certain extent.

[0042] See Figure 1 One embodiment of this application provides an angle measurement circuit 100, which may include a magnetic induction module 110, a signal adjustment module 120, and a signal conversion and processing module 130.

[0043] The magnetic induction module 110 includes two pairs of AMR Wheatstone bridges placed at 45° to each other, so that the resistance change of the AMR material is linearly related to the rotation angle of the external magnetic field.

[0044] One end of the signal adjustment module 120 is connected to the magnetic induction module 110, and the signal adjustment module 120 is used to harmonize the signal generated by the magnetic induction module 110.

[0045] One end of the signal conversion and processing module 130 is connected to the other end of the signal adjustment module 120, and the other end of the signal conversion and processing module 130 is used to output the rotation angle of the target device.

[0046] In this embodiment, two pairs of AMR Wheatstone bridges are placed at 45° to each other. The resistance value of the AMR (anisotropic magnetoresistance) material changes with the rotation angle of the external magnetic field. The arrangement of the two pairs of bridges ensures that the resistance change is linearly related to the rotation angle of the external magnetic field, providing an accurate raw signal basis for angle measurement.

[0047] In this embodiment, the signal adjustment module 120 is used to adjust the voltage signal output by the magnetic induction module 110. On one hand, the voltage signal output by the magnetic induction module 110 can be scaled to make its signal amplitude match the sampling range of the signal conversion and processing module 130. On the other hand, high-frequency noise in the voltage signal output by the magnetic induction module 110 can be filtered.

[0048] In this embodiment, the signal conversion and processing module 130 first converts the adjusted analog signal into a digital signal, and then obtains the rotation angle of the target device based on the linear relationship between voltage and angle.

[0049] This application configures the magnetic induction module 110 as two pairs of AMR Wheatstone bridges placed at 45° to each other. Since AMR Wheatstone bridges are more sensitive to changes in magnetic field than traditional resistive or inductive sensing elements, and the 45° symmetrical arrangement effectively amplifies the resistance difference caused by changes in magnetic field angle, thereby improving the resolution of the original electrical signal. This allows the circuit to capture minute angle changes, thus improving the accuracy of angle measurement to a certain extent.

[0050] Furthermore, the design of placing two pairs of AMR Wheatstone bridges at a 45° angle to each other is a core prerequisite for achieving accurate measurements. AMR materials inherently possess magnetoresistance anisotropy, meaning their resistance changes regularly with the direction of the external magnetic field. This 45° angle arrangement establishes a strict linear relationship between the magnetic field rotation angle and the resistance change, avoiding the nonlinear signal distortion problems caused by improper placement angles in traditional magnetic sensing elements, and providing a high-fidelity original signal for angle measurements.

[0051] Optionally, aluminum strips are deposited on both pairs of Wheatstone bridges.

[0052] In this embodiment, depositing aluminum strips on the Wheatstone bridge can improve the conductivity, structural stability and anti-aging ability of the bridge, and further ensure the reliability of the signal output of the magnetic induction module 110.

[0053] Optionally, the signal conversion and processing module 130 may include an analog-to-digital conversion unit 131 and a digital signal processing unit 132. The analog-to-digital conversion unit 131 and the digital signal processing unit 132 are arranged sequentially. The analog-to-digital conversion unit 131 is used to convert the target signal, which has been harmonicized and processed by the signal adjustment module 120, into a digital signal. The digital signal processing unit 132 is used to perform calculations on the digital signal to obtain the rotation angle of the target device.

[0054] Optionally, the angle measurement circuit 100 may also include a bias voltage module 140. The signal conversion and processing module 130 may also include a digital-to-analog converter unit 133.

[0055] The digital-to-analog converter 133 is connected to the digital signal processing unit 132 and is used to convert the digital signal processed by the digital signal processing unit 132 into an analog voltage signal.

[0056] The bias voltage module 140 is connected to the digital-to-analog converter unit 133. The bias voltage module 140 is used to add a bias voltage to the analog voltage signal so that the target voltage signal does not have a zero point; the target voltage signal is the sum of the analog voltage signal and the bias voltage.

[0057] In this embodiment, the digital-to-analog converter 133 is used to convert the digital signal processed by the digital signal processing unit 132 into an analog voltage signal, in preparation for subsequent signal output.

[0058] In this embodiment, by adding a bias voltage module 140, the probability of the angle sensor 200's output zero-crossing is reduced. Therefore, when the output voltage is detected to be 0, it is determined that the angle measurement circuit 100 is faulty, thereby reducing the probability of incorrect fault diagnosis of the angle measurement circuit 100.

[0059] Optionally, the angle measurement circuit 100 may further include a current output module 150. The current output module 150 is connected to the bias voltage module 140 and is used to convert the target voltage signal into a linear current signal output.

[0060] In this embodiment, the current output module 150 can convert the input target voltage signal into a "linear current signal" and output it, and the change in the current signal maintains a linear correspondence with the original angle change. Voltage signals are easily affected by wire resistance and electromagnetic interference in industrial transmission (such as significant voltage attenuation during long-distance transmission), while current signals (especially 4-20mA standard current signals) have the characteristics of strong anti-interference ability, long transmission distance, and less influence from wire resistance. Therefore, the core function of this module is to convert the angle signal processed by the circuit from "voltage form" to "current form" which is more suitable for industrial scenarios.

[0061] Optionally, the angle measuring circuit 100 may further include a protection circuit 160. The protection circuit 160 is connected to the current output module 150; the protection circuit 160 is used to protect the angle measuring circuit 100.

[0062] In this embodiment, the protection circuit 160 includes a surge protection circuit 160 composed of diodes, TVS diodes, transistors and other devices, a reverse connection protection circuit and an overcurrent protection circuit 160, which reduces the risk of circuit damage due to abnormal operating conditions and improves the service life and operational reliability of the measurement circuit.

[0063] Optionally, the signal adjustment module 120 may include an operational amplifier and resistive-capacitive components. The operational amplifier amplifies the analog voltage signal output by the magnetic induction module 110 so that the amplified analog voltage signal is adapted to the amplitude sampled by the signal conversion and processing module 130. The resistive-capacitive components are used to remove high-frequency noise from the amplified analog voltage signal.

[0064] In this embodiment, the operational amplifier amplifies the analog voltage signal output by the magnetic induction module 110, making the amplitude of the amplified signal compatible with the sampling range of the signal conversion and processing module 130. Resistors and capacitors are used to filter out high-frequency noise in the amplified signal, improving signal purity. It is understood that in other embodiments, the operational amplifier and the resistive-capacitors can be interchanged; that is, noise in the voltage signal output by the magnetic induction module 110 is removed first, and then the denoised voltage signal is amplified.

[0065] See Figure 2 Another embodiment of this application provides an angle sensor 200, which includes the angle measurement circuit 100 described in the above embodiments.

[0066] In this embodiment, the angle sensor 200 includes all the technical features of the angle measurement circuit 100 described above, and can achieve the same technical effect. Therefore, the technical effect of the angle sensor 200 on the angle measurement circuit 100 can be referred to the description in the above embodiment of the angle measurement circuit 100, and will not be repeated here.

[0067] Optionally, the angle sensor 200 may also include: a housing 210, black adhesive, and a cable 220. The inner surface of the housing 210 is fixedly connected to the angle measuring circuit 100. A cavity is formed inside the housing 210, and the cavity is filled with black adhesive. The cable 220 is connected to the angle measuring circuit 100. The cable 220 is wrapped with vulcanized rubber to shield it from external electromagnetic interference.

[0068] In this embodiment, the outer shell 210 provides physical protection for the circuit, the black adhesive enhances the shock resistance and moisture resistance, and the cable 220 realizes signal transmission. The three work together to improve the structural stability and environmental adaptability of the sensor.

[0069] In this embodiment, black adhesive is filled into the cavity of the outer shell 210 to fix, buffer, and seal the circuit, thereby improving the sensor's environmental adaptability.

[0070] In this embodiment, the vulcanized rubber on the outside of the cable 220 serves as electromagnetic shielding, reducing the impact of external electromagnetic interference on signal transmission and ensuring the stability and accuracy of the sensor output signal.

[0071] Optionally, the outer casing 210 is a metal casing 210; there is a gap between the inner surface of the outer casing 210 and the angle measuring circuit 100.

[0072] In this embodiment, the metal casing 210 enhances the sensor's electromagnetic interference resistance and mechanical strength. The gap between the inner surface of the casing 210 and the circuit provides space for heat dissipation, preventing overheating of the circuit from affecting performance. Furthermore, increasing the thickness of the metal casing 210 improves the waterproof performance of the angle sensor 200. Moreover, increasing the thickness of the metal casing 210 does not interfere with the sensitivity of the Wheatstone bridge in the angle measurement circuit 100. That is, the waterproof performance of the angle sensor 200 can be improved while maintaining the sensitivity of the angle measurement circuit 100.

[0073] In this embodiment, to prevent electrical connection between the metal casing 210 and the angle measuring circuit 100, a certain gap needs to exist between them. Then, for example, the angle measuring circuit 100 can be fixed to the inner surface of the metal casing 210 by applying adhesive or double-sided tape, thereby reducing the probability of contact between the metal casing 210 and the angle measuring circuit 100, i.e., reducing the possibility of electrical connection between them.

[0074] In one specific embodiment, the assembly process of the angle sensor 200 may include the following steps:

[0075] Step 1: Solder the programming wires and the shielded cable 220 (to shield external electromagnetic interference) to the back of the circuit board of the angle measuring circuit 100. Apply double-sided tape to the front of the circuit board where there are no components. Fix the circuit board to the bottom of the inner shell 210 with double-sided tape. The double-sided tape also serves as insulation to prevent the components on the board from directly contacting the metal shell 210. Apply 496 glue to the contact part between the side of the board and the inner wall of the shell 210 to further secure it.

[0076] Step 2: Connect the programming box to the programming cable and the computer. Fix the product on the programming machine and set three programming points: control the magnet to rotate to -45°, 0° and 45° respectively, and set VDD to 10%, 50% and 90% VDD respectively; at this time, the output current is 4-20mA linearly output from the sensor from -45° to 45°.

[0077] Step 3: Pour black glue into the stainless steel casing 210 and put on the back cover.

[0078] Step 4: Perform vulcanization treatment on cable 220.

[0079] The following technical effects can be achieved: (1) Two pairs of AMR Wheatstone bridges placed at 45° to each other and deposited with highly conductive aluminum strips, so that the current direction and the magnetization direction form a 45° angle, and the outputs VX and VY are proportional to cosθ and sinθ respectively; (2) The digital signal processing unit calculates the unique angle value of 0-360° through arctangent operation, so that the sensor is not sensitive to small changes; (3) The analog voltage signal with zero-crossing jump is linearly mapped to a 4-20mA continuous current, which effectively suppresses the noise generated by electromagnetic interference and can realize zero-position fault detection; (4) The ultra-thick all-metal stainless steel shell 210 makes the product resistant to 100MPa water pressure; (5) The fully enclosed metal end face shell 210, combined with potting and vulcanization process, achieves IP68 waterproof rating; (6) The cable 220 adds shielding wire inside to improve the product's anti-interference performance.

[0080] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0081] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0082] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An angle measuring circuit, characterized in that, include: Magnetic induction module, signal adjustment module, signal conversion and processing module; The magnetic induction module includes two pairs of AMR Wheatstone bridges placed at 45° to each other, so that the resistance change of the AMR material is linearly related to the rotation angle of the external magnetic field. One end of the signal adjustment module is connected to the magnetic induction module, and the signal adjustment module is used to harmonize the signal generated by the magnetic induction module; One end of the signal conversion and processing module is connected to the other end of the signal adjustment module, and the other end of the signal conversion and processing module is used to output the rotation angle of the target device.

2. The angle measuring circuit according to claim 1, characterized in that, Aluminum strips are deposited on both pairs of Wheatstone bridges.

3. The angle measuring circuit according to claim 1, characterized in that, The signal conversion and processing module includes: an analog-to-digital conversion unit and a digital signal processing unit; The analog-to-digital conversion unit is used to convert the target signal, which has been harmonicized and processed by the signal adjustment module, into a digital signal. The digital signal processing unit is used to perform calculations on the digital signal to obtain the rotation angle of the target device.

4. The angle measuring circuit according to claim 3, characterized in that, The angle measurement circuit also includes a bias voltage module; the signal conversion and processing module also includes a digital-to-analog converter unit. The digital-to-analog converter is connected to the digital signal processing unit; the digital-to-analog converter is used to convert the digital signal processed by the digital signal processing unit into an analog voltage signal. The bias voltage module is connected to the digital-to-analog converter unit; the bias voltage module is used to add a bias voltage to the analog voltage signal so that the target voltage signal does not have a zero point; the target voltage signal is the sum of the analog voltage signal and the bias voltage.

5. The angle measuring circuit according to claim 4, characterized in that, The angle measurement circuit also includes: a current output module; The current output module is connected to the bias voltage module and is used to convert the target voltage signal into a linear current signal output.

6. The angle measuring circuit according to claim 5, characterized in that, The angle measurement circuit also includes: a protection circuit; The protection circuit is connected to the current output module; the protection circuit is used to protect the angle measurement circuit.

7. The angle measuring circuit according to claim 1, characterized in that, The signal adjustment module includes: an operational amplifier and resistive-capacitive components; The operational amplifier is used to amplify the analog voltage signal output by the magnetic induction module, so that the amplified analog voltage signal is adapted to the sampling amplitude of the signal conversion and processing module. The resistor-capacitor components are used to remove high-frequency noise from the amplified analog voltage signal.

8. An angle sensor, characterized in that, Includes the angle measuring circuit as described in any one of claims 1 to 7.

9. The angle sensor according to claim 8, characterized in that, The angle sensor also includes: a housing, black adhesive, and a cable; The inner surface of the housing is fixedly connected to the angle measuring circuit; The outer shell has an internal cavity; the cavity is filled with black glue; The cable is connected to the angle measuring circuit, and the cable is wrapped with vulcanized rubber to shield it from external electromagnetic interference.

10. The angle sensor according to claim 9, characterized in that, The outer casing is a metal casing; There is a gap between the inner surface of the housing and the angle measuring circuit.

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