High-precision absolute value magnetic grating device and mover position detection method

Abstract

The application relates to a high-precision absolute-value magnetic grating device and a mover position detection method. The high-precision absolute-value magnetic grating device comprises a mover, a base and a Hall chip fixed on the base. A plurality of Hall chips form a Hall array, and the Hall array is arranged in two rows. One row of the Hall array is a large-number magnetic induction Hall array, and the other row of the Hall array is a small-number magnetic induction Hall array. The mover is respectively provided with a large-number magnetic head and a small-number magnetic head corresponding to the large-number magnetic induction Hall array and the small-number magnetic induction Hall array. The sensing device is fixed, and the moving part does not need to be provided with a power line and a signal line, so that the reliability of long-distance position measurement is improved. Through the double-row or even multi-row Hall sensing array arrangement form, the measurement principle similar to that of a vernier caliper is adopted, and a large-number and small-number detection combination mode is adopted, so that long-distance position detection can be realized, and the position detection precision is improved.

Description

Technical Field

[0001] This invention relates to the field of motor position detection technology, and more specifically, to a high-precision absolute magnetic grating ruler device with a double-row Hall array. Background Technology

[0002] Linear motors are increasingly being used in many fields such as rail transportation, machine tools, robots, and industrial automated production lines. Because they reduce intermediate transmission devices, they have the advantages of higher speed, higher acceleration, and higher precision compared to the linear motion of traditional rotary motors with ball screws. Position detection is a key component that determines the performance of linear motors.

[0003] The main types of linear position feedback devices currently available are as follows:

[0004] 1. Grid ruler: High precision, but it has high requirements for the environment and working conditions, and is not suitable for occasions with high vibration.

[0005] 2. Magnetic grating ruler: It has low precision but low environmental requirements and is widely favored in industries such as metallurgy, machinery, petrochemical, transportation, and water conservancy. This technology is widely used in general displacement sensors, level gauges, gate opening instruments, crane stroke detectors, and hydraulic cylinder stroke detectors in harsh industrial environments.

[0006] In currently common products, the signal acquisition (reading head) is installed on the mobile end, which requires the installation of a power supply and signal source. This is not suitable for some long-distance measurement applications, such as logistics transportation lines that typically require long-distance applications of tens or hundreds of meters. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the first objective of this invention is to provide a high-precision absolute magnetic grating ruler device that can meet the requirements of long-distance position detection and has high detection accuracy. The second objective of this invention is to provide a method for detecting the position of a linear motor mover.

[0008] To achieve the first objective mentioned above, the present invention adopts the following technical solution:

[0009] A high-precision absolute magnetic grating ruler device includes a mover, a base, and Hall chips fixed on the base. Multiple Hall chips form a Hall array, which is arranged in two rows. One row of Hall array is a large-number magnetic induction Hall array, and the other row is a small-number magnetic induction Hall array. The mover is respectively provided with a large-number magnetic head and a small-number magnetic head corresponding to the large-number magnetic induction Hall array and the small-number magnetic induction Hall array.

[0010] As a preferred embodiment: the multiple Hall chips in the large-number magnetic induction Hall array and the small-number magnetic induction Hall array are distributed at equal intervals, and the spacing between the multiple Hall chips in the large-number magnetic induction Hall array is greater than the spacing between the multiple Hall chips in the small-number magnetic induction Hall array.

[0011] As a preferred embodiment, both the large-number and small-number magnetic heads use single-pole or multi-pole magnets.

[0012] As a preferred embodiment: the base is a stator fixing bracket, and the stator fixing bracket is also provided with a bus for transmitting the signal of the Hall chip to the controller, and a DA converter is also provided between the Hall chip and the controller.

[0013] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0014] A method for detecting the position of a linear motor mover employs the magnetic grating ruler device described in any of the above-mentioned methods. By magnetizing the magnetic grating in the direction of movement, the large and small magnetic heads on the mover generate a regular sinusoidal magnetic field. When the magnetic grating of the mover passes over the corresponding linear Hall chip, the Hall chip can sense the magnetic field strength signal emitted by the mover. The span and strength of a sinusoidal magnetic field are known. After processing by a DA converter, the signal is sent to the controller via a bus for position decoding. By arranging one or more Hall chip arrays in a regular pattern in the direction of movement of the magnetic head, the real-time absolute position information of the magnetic head at any given time can be obtained.

[0015] As a preferred solution: when the decimal magnetic head passes through two adjacent Hall chips, it will obtain two sinusoidal magnetic fields that are 90 degrees apart. By using the open-loop lookup table method or the closed-loop phase tracking method, the accurate angle value can be obtained. By using the angle value and the length of the known complete sine wave, the accurate position of the direction of travel can be obtained.

[0016] As a preferred option, the open-loop lookup table method obtains the precise angle of the sine by calculating the arctangent value through a lookup table.

[0017] As a preferred embodiment, the closed-loop phase tracking method involves passing the calculated angle cosine value through a feedback channel and performing closed-loop correction with the sine and cosine values ​​measured by Hall effect, so that the calculated value can always track the actual value.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] This invention proposes an absolute magnetic scale device suitable for long-distance linear position detection. Unlike the magnetic or optical scales widely used in industry, the sensing device of this invention is fixed, and the moving parts do not require power or signal lines, thus improving the reliability of long-distance position measurement. Furthermore, by using a double-row or even multi-row Hall effect sensor array arrangement, similar to the measurement principle of a vernier caliper, and employing a combination of large and small number detection, it can achieve both long-distance position detection and improved position detection accuracy. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation thereof.

[0021] Figure 1 This is a schematic diagram of a single Hall magnetic field induction.

[0022] Figure 2 This is a schematic diagram (end face) of the moving and stating positions of the magnetic grating ruler of the present invention;

[0023] Figure 3 This is a side view of the position of the moving and stating elements of the magnetic grating ruler according to the present invention.

[0024] Figure 4 This is a schematic diagram showing the positions of two adjacent Hall chips calculated using the closed-loop phase tracking method of the present invention.

[0025] Figure 5 This is a schematic diagram of the signal conversion between two adjacent Hall chips according to the present invention.

[0026] The attached diagram is labeled as follows: 1. Hall chip; 2. Base; 3. Stator fixing bracket; 31. Large number magnetic induction Hall array; 32. Small number magnetic induction Hall array; 4. Mover; 41. Large number magnetic head; 42. Small number magnetic head. Detailed Implementation

[0027] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0028] 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.

[0029] Furthermore, in the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0031] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0034] like Figure 1 and Figure 5As shown, a high-precision absolute magnetic scale device includes a mover 4, a base 2, and Hall effect chips 1 fixed on the base 2. Multiple Hall effect chips 1 form a Hall effect array, which is arranged in two rows. One row is a large-number magnetic induction Hall effect array 31, and the other row is a small-number magnetic induction Hall effect array 32. The mover 4 is equipped with large-number magnetic heads 41 and small-number magnetic heads 42, respectively, corresponding to the large-number magnetic induction Hall effect array 31 and the small-number magnetic induction Hall effect array 32. Both the large-number magnetic heads 41 and the small-number magnetic heads 42 employ single-pole or multi-pole magnets.

[0035] The multiple Hall chips 1 in the large-number magnetic induction Hall array 31 and the small-number magnetic induction Hall array 32 are all equally spaced, and the spacing between the multiple Hall chips 1 in the large-number magnetic induction Hall array 31 is greater than the spacing between the multiple Hall chips 1 in the small-number magnetic induction Hall array 32.

[0036] The base 1 is a stator fixing bracket 3. The stator fixing bracket 3 is also provided with a bus for transmitting the signal of the Hall chip 1 to the controller. A DA converter is also provided between the Hall chip 1 and the controller.

[0037] A method for detecting the position of a linear motor mover employs the magnetic grating ruler device described in any of the above-mentioned methods. By magnetizing the magnetic grating in the direction of movement, the large-number magnetic head 41 and the small-number magnetic head 42 on the mover generate a regular sinusoidal magnetic field. When the magnetic grating of the mover passes over the corresponding linear Hall chip, the Hall chip can sense the magnetic field strength signal emitted by the mover. The span and strength of a sinusoidal magnetic field are known. After processing by a DA converter, the signal is sent to the controller via a bus for position decoding. By arranging one or more Hall chip arrays in a regular pattern in the direction of movement of the magnetic head, the real-time absolute position information of the magnetic head at any given time can be obtained.

[0038] When the decimal magnetic head 42 passes through two adjacent Hall chips 1, it will obtain two sinusoidal magnetic fields that are 90 degrees apart. By using the open-loop lookup table method or the closed-loop phase tracking method, the accurate angle value can be obtained. By using the angle value and the length of the known complete sine wave, the accurate position of the direction of travel can be obtained.

[0039] The large-number coarse positioning method in this invention can represent a large range, but has low precision. Depending on different product specifications, the smallest counting unit for the large number is determined based on the magnetization span, typically an integer value such as 1mm, 5mm, or 10mm. After obtaining the large-number coarse positioning value, the small-number precise positioning is then determined. Within a large-number Hall interval span, there must be at least one small-number Hall count; the higher the precision, the more small-number Hall counts are included.

[0040] The fractional Hall effect sensor array senses the moving magnetic head through a magnetic field and obtains a set of alternating sine and cosine waves. Then, it obtains the precise position value through an open-loop lookup table method or a closed-loop tracking method. The fractional counting can make up for the lack of precision of the large-number counting, and can usually be accurate to 0.001mm. By combining the fractional and large-number counting, a high-precision position value for the entire travel length can be obtained. The working principle is similar to that of a vernier caliper.

[0041] The open-loop lookup table method calculates the arctangent value to obtain the precise angle of the sine wave. The closed-loop phase tracking method performs closed-loop correction by passing the calculated angle cosine value through a feedback channel and comparing it with the sine and cosine values ​​measured by Hall effect, ensuring that the calculated value always tracks the actual value. Both methods have their advantages and disadvantages. The open-loop method is simpler but slightly less accurate, while the closed-loop method offers higher accuracy but involves more computation. Different subdivision methods should be selected depending on the specific application.

[0042] This invention, based on position decoding using a single Hall chip sensing magnetic grating intensity, arranges a double-row Hall array along the movement direction on a basic module. The first row is a large-number Hall chip sensing array, and the second row is a small-number Hall chip sensing array; these are sequentially numbered, allowing absolute position information to be determined based on the numbering. Correspondingly, the mover at the moving end also has two rows of magnetic gratings, large-number and small-number magnetic gratings, which can be multi-pole or single-pole (the schematic diagram shows three pairs of magnetic gratings). The large-number magnetic grating has a relatively wide magnetic field span and is used only for large-number counting; the small-number magnetic grating has a relatively narrow magnetic field span and relatively high magnetization precision, used for small-number counting. When the mover sequentially passes the Hall sensing chips mounted on a fixed bracket along the movement direction, the corresponding chips in the Hall array record the entire movement process and send the signal in real time to the processor via a bus for large-number and small-number position splicing to form high-precision absolute position information. The measuring device of this invention can also be made into a unit module for easy splicing and expansion, and its length is unlimited.

[0043] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for detecting the position of a linear motor mover, characterized in that: A high-precision absolute magnetic scale device is adopted. The device includes a mover (4), a base (2), and Hall chips (1) fixed on the base (2). Multiple Hall chips (1) form a Hall array. The Hall array is arranged in two rows. One row of Hall array is a large number magnetic induction Hall array (31), and the other row of Hall array is a small number magnetic induction Hall array (32). The mover (4) is respectively provided with a large number magnetic head (41) and a small number magnetic head (42) corresponding to the large number magnetic induction Hall array (31) and the small number magnetic induction Hall array (32). The multiple Hall chips (1) in the large number magnetic induction Hall array (31) and the small number magnetic induction Hall array (32) are distributed at equal intervals, and the spacing between the multiple Hall chips (1) in the large number magnetic induction Hall array (31) is greater than the spacing between the multiple Hall chips (1) in the small number magnetic induction Hall array (32). By magnetizing the magnetic grating in the direction of movement, the large number magnetic head (41) and small number magnetic head (42) on the mover generate a regular sinusoidal magnetic field. When the magnetic grating of the mover passes over the corresponding linear Hall chip, the Hall chip can sense the magnetic field strength signal emitted by the mover. The span and strength of a sinusoidal magnetic field are known. After being processed by the DA converter, it is sent to the controller for position decoding via the bus. By arranging one or more Hall chip arrays in a regular arrangement in the direction of movement of the magnetic head, the real-time absolute position information of the magnetic head at any time can be obtained. When the decimal magnetic head (42) passes through two adjacent Hall chips (1), it will obtain two sinusoidal magnetic fields that are 90 degrees apart. By using the open-loop lookup table method or the closed-loop phase tracking method, the accurate angle value can be obtained. By using the angle value and the known length of the complete sine wave, the accurate position of the direction of travel can be obtained. The open-loop lookup table method obtains the precise angle of the sine by calculating the arctangent value through a lookup table; The closed-loop phase tracking method involves passing the calculated angle cosine value through a feedback channel and performing closed-loop correction with the sine and cosine values ​​measured by Hall effect, so that the calculated value can always track the actual value; The large-number magnetic grating is used only for counting large numbers; the small-number magnetic grating is used for counting small numbers; when the mover passes the Hall sensor chip installed on the fixed bracket in sequence along the direction of movement, the corresponding chip of the Hall array will record the entire movement process and send the signal to the processor in real time via the bus to splice the large and small number positions to form high-precision absolute position information.

2. The method for detecting the position of a linear motor mover according to claim 1, characterized in that: Both the large-number magnetic head (41) and the small-number magnetic head (42) use single-pole or multi-pole magnets.

3. The method for detecting the position of a linear motor mover according to claim 1, characterized in that: The base (2) is a stator fixing bracket (3), and the stator fixing bracket (3) is also provided with a bus for transmitting the signal of the Hall chip (1) to the controller. A DA converter is also provided between the Hall chip (1) and the controller.

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