Magnetic induction linear displacement absolute value encoder, data processing method therefor, and device thereof

Abstract

Disclosed in the present invention are a magnetic induction linear displacement absolute value encoder, a data processing method therefor, and a device thereof. The encoder comprises a magnetic induction reading head, a rack mechanism, and a magnetic mechanism; the rack mechanism comprises a main rack and a vernier rack, and the number of teeth of the vernier rack is less than the number of teeth of the main rack by 1; the magnetic mechanism is located directly above the magnetic induction reading head and is configured to provide induction magnetic lines of force for cutting the rack mechanism when the magnetic induction reading head displaces; the magnetic induction reading head is located directly above the rack mechanism, and a gap is provided between the magnetic induction reading head and the rack mechanism; the magnetic induction reading head is capable of moving in the axial direction of the rack mechanism along with a measured object, and generating a sine-cosine orthogonal differential signal on the basis of the induction magnetic lines of force for cutting the rack mechanism, so as to obtain an absolute displacement of the measured object. According to the present invention, the magnetic induction reading head is arranged between the magnetic mechanism having a strong magnetic induction intensity and a rack mechanism having double racks, so that the magnetic induction linear displacement absolute value encoder has a strong anti-interference capability and can be applied to a strong magnetic interference environment.

Description

Magnetic induction linear displacement absolute value encoder and data processing method and device thereof Technical Field

[0001] The present invention relates to the field of displacement measurement, and in particular to a magnetic induction linear displacement absolute value encoder and a data processing method and device thereof. Background Art

[0002] Traditional encoders can be divided into incremental encoders and absolute encoders based on their measurement functions. Incremental encoders can also be called incremental encoders.

[0003] Incremental encoders provide information about the current position relative to the previous position and do not store the current absolute position. If the electromechanical device loses power and the mechanical position shifts due to external forces, causing a position shift, the incremental encoder will be unable to determine whether the current position signal is the same as the position signal recorded before the power outage. Therefore, the encoder must be adjusted to return to zero.

[0004] Each position of an absolute encoder corresponds to a specific digital code, so its indication is only related to the starting and ending positions of the measurement, and is not related to the intermediate measurement process. When the electromechanical equipment is powered off and then restored, the absolute encoder can instantly read the current shaft rotation angle or absolute position.

[0005] The existing magnetic induction encoder is a sensor used to detect angle, position, speed and acceleration. It is a device that compiles and converts the angular displacement or linear displacement of mechanical rotation into an electrical signal that can be used for communication, transmission and storage. It is a precision measuring device that closely combines mechanics and electronics and is widely used in many fields such as motors, automobiles, wind power, and robotics.

[0006] Magnetic induction encoders are based on magnetic sensor technology, which is widely used in modern industry and electronics. They sense magnetic field strength and distribution to measure physical parameters such as current, position, and direction. In the prior art, many different types of sensors are used to measure magnetic fields and other parameters, such as magnetic sensors that use Hall elements, anisotropic magnetoresistance (AMR) elements, giant magnetoresistance (GMR) elements, and tunnel magnetoresistance (TMR) elements as their sensing elements. Compared to other magnetic sensing elements, tunnel magnetoresistance elements offer advantages such as low power consumption, high resolution, a wide dynamic range, excellent temperature stability, and extremely high sensitivity. Absolute encoders offer the advantage of instant readout. Combined with magnetic induction encoders using tunnel magnetoresistance elements, they offer the same advantages for linear displacement measurement: low power consumption, high resolution, a wide dynamic range, excellent temperature stability, extremely high sensitivity, and instant readout.

[0007] A magnetic scale is a component of a magnetic induction absolute encoder commonly used in industrial automation machinery for linear displacement measurement. It primarily consists of a scale and a magnetic head. The North (North) and South (South) poles on the scale—SN and NS—generate an electromagnetic field with varying orientations. As the magnetic head moves along the scale, it senses changes in the electromagnetic field and converts them into analog input signals or digital output signals. While magnetic scales offer high measurement accuracy, due to their thinness, the magnetic field they generate is relatively weak, making them ineffective in strong magnetic environments.

[0008] Summary of the Invention

[0009] The purpose of the present invention is to solve the technical problem that the existing magnetic induction absolute encoder cannot be used in a strong magnetic interference environment, and to propose a magnetic induction linear displacement absolute encoder and a data processing method and device.

[0010] The technical problem of the present invention is solved by the following technical solutions:

[0011] A magnetic induction linear displacement absolute value encoder, comprising: a magnetic induction read head, a rack mechanism, and a magnetic mechanism;

[0012] The rack mechanism includes a main rack and a vernier rack, and the number of teeth of the vernier rack is one less than the number of teeth of the main rack;

[0013] The magnetic mechanism is located directly above the magnetic induction read head and is used to provide induction magnetic lines of force that cut the rack mechanism when the magnetic induction read head is displaced;

[0014] The magnetic induction read head is located directly above the rack mechanism, with a gap between the magnetic induction read head and the rack mechanism. The magnetic induction read head can move along the axial direction of the rack mechanism with the object to be measured, and generate a sine-cosine orthogonal differential signal according to the induced magnetic lines of force cut by the rack mechanism, thereby obtaining the absolute displacement of the object to be measured.

[0015] In some embodiments, a high magnetic permeability sheet is provided between the magnetic mechanism and the magnetic induction read head.

[0016] In some embodiments, an external magnetic shielding mechanism is further included, which is located outside the rack mechanism and is made of a material with high magnetic permeability.

[0017] In some embodiments, the gap between the magnetic induction read head and the rack mechanism is 0.1 mm to 0.3 mm.

[0018] In some embodiments, the magnetic induction read head includes a magnetic induction chip, a circuit board, and a shell. The circuit board is encapsulated in the shell, and the magnetic induction chip is located at the center of the back side of the circuit board.

[0019] In some embodiments, the housing is made of plastic or other plastic material.

[0020] In some embodiments, the magnetic mechanism uses magnetic steel or rare earth permanent magnets.

[0021] The present invention also proposes a data processing method based on the above-mentioned magnetic induction linear displacement absolute value encoder, comprising the following steps:

[0022] S1: The magnetic induction read head generates a sine-cosine orthogonal differential signal according to the induced magnetic lines cut by the rack mechanism; and performs real-time correction and compensation for the DC offset error, amplitude error, and orthogonal phase error of the sine-cosine orthogonal differential signal;

[0023] S2: Generate high-line displacement relative position values ​​relative to the power-on moment based on the corrected and compensated sine and cosine quadrature differential signals;

[0024] S3: Analyze the phase and phase difference of the sine and cosine orthogonal differential signals according to the cursor solution principle, and calculate the absolute position of the current linear displacement through the high-line displacement relative position value.

[0025] The present invention also provides a device comprising the above-mentioned magnetic induction linear displacement absolute value encoder.

[0026] The beneficial effects of the present invention compared with the prior art include:

[0027] The magnetic induction linear displacement absolute value encoder provided by the present invention sets a magnetic induction read head between a magnetic mechanism with strong magnetic induction strength and a rack mechanism with double racks. Through the design of the main rack and the vernier rack, when the magnetic induction linear displacement absolute value encoder is working, the magnetic induction chip in the magnetic induction read head generates a sine-cosine orthogonal differential signal. The absolute displacement value of the measured object and the current linear displacement absolute position are calculated based on the sine-cosine orthogonal differential signal through the vernier solution principle, thereby enabling the magnetic induction linear displacement absolute value encoder to be applied in a strong magnetic interference environment.

[0028] In some embodiments, the following benefits are also achieved:

[0029] By arranging a high magnetic permeability sheet between the magnetic mechanism and the magnetic induction chip, the uniformity of the back magnetic field generated by the magnetic mechanism is ensured, thereby improving the measurement accuracy of the magnetic induction linear displacement absolute encoder.

[0030] Furthermore, an external magnetic shielding mechanism made of a high magnetic permeability material is provided on the outside of the rack mechanism to further shield the interference of the external magnetic field on the magnetic induction linear displacement absolute value encoder.

[0031] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a cross-sectional view of a magnetic induction linear displacement absolute encoder according to an embodiment of the present invention.

[0033] FIG2 is a top view of the magnetic induction linear displacement absolute value encoder according to an embodiment of the present invention.

[0034] FIG3 is an exploded view of the magnetic induction linear displacement absolute encoder according to an embodiment of the present invention.

[0035] FIG4 is a right side view of the magnetic induction linear displacement absolute value encoder according to an embodiment of the present invention.

[0036] FIG5 is a top view of the external magnetic shielding mechanism assembled with the magnetic induction linear displacement absolute value encoder according to an embodiment of the present invention.

[0037] FIG6 is a perspective view of a magnetic induction read head of a magnetic induction linear displacement absolute encoder according to an embodiment of the present invention.

[0038] FIG7 is a schematic diagram of the BISS protocol frame format according to an embodiment of the present invention.

[0039] The reference numerals are as follows:

[0040] 1-Plastic top cover, 2-Mounting screws, 3-Vernier rack, 4-Main rack, 5-Plastic bottom shell, 6-Magnetic induction chip, 7-Circuit board, 8-High magnetic permeability sheet, 9-Magnetic steel, 10-Epoxy resin glue, 11-Transmission line, 12 External magnetic shielding mechanism. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to the accompanying drawings and in combination with preferred embodiments. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0042] It should be noted that the directional terms such as left, right, up, down, top, and bottom in this embodiment are merely relative concepts, or are based on the normal use status of the product, and should not be considered as restrictive.

[0043] In order to solve the technical problem in the prior art that magnetic scales cannot be used in environments with strong magnetic interference, an embodiment of the present invention provides a magnetic induction displacement absolute value encoder suitable for environments with strong magnetic interference, which includes: a magnetic induction read head, a rack mechanism, and a magnetic mechanism; the rack mechanism includes a main rack and a vernier rack, and the number of teeth of the vernier rack is one less than the number of teeth of the main rack; the magnetic mechanism is located directly above the magnetic induction read head, and is used to provide a permanent magnetic working magnetic field that changes the magnetic induction of the entire encoder, thereby providing induced magnetic lines of force that cut the rack mechanism when the magnetic induction read head is displaced; the magnetic induction read head is located directly above the rack mechanism, and there is a gap between the magnetic induction read head and the rack mechanism. The magnetic induction read head can move along the axial direction of the rack mechanism with the object to be measured, and generate a sine-cosine orthogonal differential signal according to the magnetic resistance change of the concave-convex structure on the rack mechanism, specifically, the sine-cosine orthogonal differential signal is generated according to the concave-convex structure on the rack mechanism cutting the induced magnetic lines of force, thereby obtaining the absolute displacement of the object to be measured and the absolute position of the current linear displacement. Specifically, the magnetic induction read head is located between the magnetic mechanism and the rack mechanism. The magnetic induction read head and the magnetic mechanism are mounted together and can move relative to each other along the axial direction of the rack mechanism. The concave and convex structures on each rack mechanism are composed of teeth of equal size and spacing. Because the main rack has one more tooth than the vernier rack, but the two have the same total length, the spacing between the teeth on the main rack is smaller than that on the vernier rack.

[0044] In some embodiments, a high magnetic permeability sheet is provided between the magnetic mechanism and the magnetic induction read head. Specifically, the gap between the magnetic induction read head and the rack mechanism is 0.1 mm to 0.3 mm, and the magnetic mechanism uses magnetic steel or high-performance rare earth permanent magnets.

[0045] In other embodiments, the magnetic induction linear displacement absolute encoder further includes an external magnetic shielding mechanism located outside the rack mechanism, the external magnetic shielding mechanism being made of a material with high magnetic permeability. Specifically, the external magnetic shielding mechanism is closely positioned on both sides of the rack mechanism and includes two external magnetic shielding units of the same size as the rack mechanism, the external magnetic shielding units being disposed outside the rack mechanism.

[0046] Specifically, the magnetic induction reader includes a magnetic induction chip, a circuit board, and a housing. The circuit board is encapsulated in the housing, and the magnetic induction chip is located in the center of the back of the circuit board. Specifically, the housing is made of plastic or other plastic material.

[0047] The embodiment of the present invention further proposes a data processing method based on the above-mentioned magnetic induction linear displacement absolute value encoder, which includes the following steps:

[0048] S1: This magnetic induction absolute displacement encoder uses the working principle of rack-induced magnetic lines of force to perform non-contact scanning on double racks with a tooth number difference of 1. The magnetic induction read head cuts the induced magnetic lines of force according to the rack mechanism, generating a corresponding number of high-reliability sine and cosine orthogonal differential signals, and performs real-time correction and compensation for the DC offset error, amplitude error, and orthogonal phase error of the sine and cosine signals, achieving high-precision interpolation and subdivision of the sine and cosine signals.

[0049] S2: Generate high-line displacement relative position values ​​relative to the power-on moment for the two tracks of the double rack (i.e., the corrected and compensated sine-cosine quadrature differential signals) inside the magnetic induction linear displacement absolute encoder. 。

[0050] S3: Analyze the phase and phase difference between the two trajectories (i.e., sine and cosine orthogonal differential signals) according to the cursor solution principle. Because the phase and phase difference within a stroke are fixed and regular, the magnetic induction linear displacement absolute encoder can calculate the current linear displacement absolute position and absolute displacement through the relative position value of the high-line displacement line.

[0051] The specific operation is as follows: When the magnetic induction read head moves, the changes in the magnetic resistance of the concave and convex structures on the rack mechanism cause the main chip to generate sine and cosine quadrature differential signals. The main chip calculates the absolute value of the current displacement by performing an inverse tangent operation and a vernier solver algorithm on the original sine and cosine quadrature differential signals.

[0052] An embodiment of the present invention further provides a device including the above-mentioned magnetic induction linear displacement absolute value encoder.

[0053] Example:

[0054] The magnetic induction linear displacement absolute value encoder proposed in the embodiment of the present invention has a strong magnetic force mechanism, which is arranged just above the magnetic induction read head. The encoder uses a rack mechanism to sense the magnetic lines of force in the magnetic field of the magnetic mechanism, and calculates the absolute displacement of the measured object and the absolute position of the current linear displacement through the principle of vernier solution, so that the magnetic induction linear displacement absolute value encoder can operate in a magnetic interference environment with a magnetic induction strength less than that of the magnetic mechanism. 。

[0055] This embodiment of the magnetic induction linear displacement absolute encoder includes a rack mechanism for measurement and a magnetic induction read head. The magnetic induction read head is located directly above the rack mechanism and moves along the axial direction of the rack mechanism along with the object being measured. The gap between the magnetic induction read head and the measurement rack mechanism is 0.1mm to 0.3mm.

[0056] The rack mechanism used for measurement is a dual-track rack, the number of teeth of its main rack 4 is Z, and the number of teeth of the vernier rack 3 is Z-1, that is, the number of teeth of the main rack 4 differs from the number of teeth of the vernier rack 3 by 1. The number of teeth of the main rack 4 is preferably 32 (i.e., Z=32), and the number of teeth of the vernier rack 3 is 31 (i.e., Z-1=31).

[0057] The magnetic induction reader includes a magnetic induction chip 6, a circuit board 7 and a shell. The magnetic induction chip 6 and the circuit board 7 are encapsulated in the shell by epoxy resin glue 10. The shell in this embodiment is made of plastic material. The circuit part of the magnetic induction reader (i.e., the circuit board 7) is encapsulated in the plastic shell. The plastic shell includes a plastic upper cover 1 and a plastic bottom shell 5. The plastic upper cover 1 and the plastic bottom shell 5 are fixedly connected by mounting screws 2. As shown in Figure 6, the magnetic induction chip 6 is located in the center of the circuit board 7. On the back of the circuit board 7, a magnetic mechanism is installed directly above the magnetic induction chip 6. The magnetic mechanism of this embodiment is a magnet 9. In this embodiment, the magnet 9 is encapsulated in the shell by epoxy resin glue 10. When the magnetic induction head moves along the axial direction of the rack mechanism with the object to be measured, the sine and cosine orthogonal differential signals generated by the magnetic induction chip 6 are internally conditioned and filtered, and the absolute displacement and the current linear displacement absolute position are calculated by the vernier solution principle. The sine and cosine orthogonal differential signals of the encoder are output through the transmission line 11. In this embodiment, the magnetic induction chip is a highly integrated single chip. Specific signal conditioning, vernier solution algorithm, output protocol and other functions are integrated inside the chip, and a single chip can realize all the functions of the sensor; the transmission line 11 in this embodiment is a 6-core shielded twisted pair cable, which is specifically output by the transmission line 11 through a serial communication protocol interface such as BISS (a full-duplex synchronous serial bus communication protocol) and SSI (synchronous serial interface).

[0058] The BISS protocol frame format in this embodiment is shown in Figure 7, where the dotted wavy lines represent multiple repetitions, and the dotted box is a detailed description of "Data 26 Bits," which includes one reserved bit, 19 data bits, and six zero-padded bits. The character explanations are shown in Table 1, where CK represents the clock signal; D represents the data signal; Ack represents the request bit; Start represents the start bit; CDS represents the flag bit, typically 0; Data represents the data bit; Error represents the error bit; Warn represents the warning bit; and CRC represents the check bit. MSB stands for Most Significant Bit.

[0059] Table 1

[0060] In this embodiment, a high-permeability sheet 8 is inserted between the magnet 9 and the magnetic induction chip 6 of the magnetic induction read head to ensure the uniformity of the magnetic field of the magnetic mechanism. In this embodiment, the high-permeability sheet 8 is encapsulated in the housing with epoxy resin glue 10. The operating principle of the high-permeability sheet 8 is as follows: the magnetic lines of force are always perpendicular to the surface of the ferromagnetic material. The magnetic lines of force form a closed NS curve at the edge of the ferromagnetic material, and are equivalent to a parallel magnetic field within a certain distance of the parallel plane in the middle. The placement of the high-permeability sheet is equivalent to increasing the pole emission surface, increasing the area of ​​the uniform parallel magnetic field, and improving the magnetic field uniformity within a certain sensing area. This improved magnetic field uniformity is conducive to improving measurement accuracy.

[0061] As shown in FIG5 , in this embodiment, an external magnetic shielding mechanism 12 made of high magnetic permeability material is used to provide external magnetic shielding for the rack mechanism and the magnetic induction read head. Specifically, an external magnetic shielding mechanism 12 of similar size to the rack mechanism is placed on each side of the rack mechanism. More specifically, the external magnetic shielding mechanism 12 is mounted closely to both sides of the rack mechanism. The external magnetic shielding mechanism 12 is made of high magnetic permeability material, such as slope film alloy, silicon steel sheet, or easy-to-turn iron, to shield against external magnetic interference. The working principle is as follows: According to electromagnetic field theory, the purpose of static magnetic shielding is to prevent external static magnetic fields and magnetic fields of low-frequency currents from entering a certain area that needs protection. In this case, a magnetic medium must be used as the outer shell. A shell made of high electrical conductivity or high magnetic permeability material is an effective electromagnetic shielding device. Increasing the electrical conductivity or magnetic permeability of the shell material and increasing the thickness of the shell wall can improve the electromagnetic shielding effect. The shielding mechanism is as follows: It primarily relies on the low magnetic resistance of highly permeable materials to shunt magnetic flux, significantly weakening the magnetic field within the shield. The primary shielding mechanism is absorption of interfering electromagnetic waves. This effectively addresses the problem of current magnetic scale displacement encoders being unable to operate in strong magnetic environments.

[0062] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. Those skilled in the art will recognize that several equivalent substitutions or obvious variations can be made without departing from the scope of the present invention, and that any equivalent performance or application should be considered to fall within the scope of protection of the present invention.

Claims

1. A magnetic induction linear displacement absolute encoder, characterized in that: include: Magnetic induction reading head, rack mechanism, magnetic mechanism; The rack mechanism comprises a main rack and a vernier rack, and the number of teeth of the vernier rack is one less than the number of teeth of the main rack; The magnetic mechanism is located directly above the magnetic induction reading head and is used to provide induction magnetic lines of force that cut the rack mechanism when the magnetic induction reading head is displaced; The magnetic induction reading head is located directly above the rack mechanism, and there is a gap between the magnetic induction reading head and the rack mechanism. The magnetic induction reading head can move along the axial direction of the rack mechanism with the object to be measured, and generate a sine-cosine orthogonal differential signal according to the rack mechanism cutting the induced magnetic lines of force, thereby obtaining the absolute displacement of the object to be measured.

2. The magnetic induction linear displacement absolute encoder according to claim 1, characterized in that: A high magnetic permeability sheet is arranged between the magnetic mechanism and the magnetic induction read head.

3. The magnetic induction linear displacement absolute encoder according to claim 1, characterized in that: It also includes an external magnetic shielding mechanism located outside the rack mechanism, and the external magnetic shielding mechanism is made of a material with high magnetic permeability.

4. The magnetic induction linear displacement absolute encoder according to claim 1, characterized in that: The gap between the magnetic induction read head and the rack mechanism is 0.1 mm to 0.3 mm.

5. The magnetic induction linear displacement absolute encoder according to claim 1, characterized in that: The magnetic induction reading head comprises a magnetic induction chip, a circuit board and a shell. The circuit board is packaged in the shell, and the magnetic induction chip is located at the center of the back side of the circuit board.

6. The magnetic induction linear displacement absolute encoder according to claim 5, characterized in that: The shell is made of plastic or plastic material.

7. The magnetic induction linear displacement absolute encoder according to claim 1, characterized in that: The magnetic mechanism adopts magnetic steel or rare earth permanent magnet.

8. A data processing method based on the magnetic induction linear displacement absolute encoder according to any one of claims 1 to 7, characterized in that: The steps include: S1: The magnetic induction read head generates a sine-cosine orthogonal differential signal according to the rack mechanism cutting the induced magnetic field lines; and performs real-time correction and compensation for the DC offset error, amplitude error and orthogonal phase error of the sine-cosine orthogonal differential signal; S2: Generate the corresponding sine and cosine quadrature differential signals according to the corrected and compensated sine and cosine quadrature differential signals. The relative position value of the high-line displacement at the electrical moment; S3: Analyze the phase and phase difference of the sine-cosine orthogonal differential signal according to the cursor solution principle, and calculate the absolute position of the current linear displacement through the relative position value of the high-line displacement.

9. A device, characterized in that: It comprises the magnetic induction linear displacement absolute encoder as claimed in any one of claims 1 to 7.

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