Magnetic encoder
By adopting dual-code structure and signal processing technology in magnetic encoders, the problem that existing magnetic encoders cannot accurately locate under interference is solved, and high-precision absolute position positioning and anti-interference ability are achieved.
Patent Information
- Application Number
- CN202421097807.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-17
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2034-05-17
AI Technical Summary
Existing magnetic encoders cannot achieve accurate positioning under interference such as vibration or jitter, and they also strictly require installation and use environment.
It adopts a dual-code channel structure, including incremental code channels and pseudo-random binary sequence code channels, and sets multiple encoding areas on each code channel, and uses the first magnetic sensor to realize the area positioning, and the second magnetic sensor to realize the positioning within the area. Average is performed by signal processing circuits or half-bridge circuits to offset the effects of mechanical structure changes.
It realizes absolute positioning in an interference environment, avoids errors and loss of codes, and improves measurement accuracy and anti-interference ability.
Smart Images
Figure CN222279771U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of magnetic sensing, in particular to a magnetic encoder. Background Art
[0002] An encoder is a measuring device used to determine the position of two relatively movable bodies (such as a magnetic field generator (code channel) and a magnetic sensor) in a linear direction or a rotational direction. It is currently widely used in the fields of civil instruments and industrial control as a displacement or angle measuring device. Encoders can be divided into incremental encoders and absolute encoders according to their functions, and can be divided into optical encoders, magnetic encoders, etc. according to the type of sensor.
[0003] The absolute code track of existing magnetic encoders such as vernier encoders is designed with M-sequence code or Gray code. Vernier encoders have high requirements for installation accuracy and are relatively weak in resisting interference such as vibration and jitter during use. When there are interferences such as vibration and jitter, there are cases of wrong codes and missing codes, and accurate positioning cannot be achieved. Therefore, when using them, they have very strict requirements for installation and use environment. Utility Model Content
[0004] In view of this, the embodiment of the utility model provides a magnetic encoder, which can achieve anti-interference, so as to solve the technical problem that the magnetic sensor in the prior art cannot achieve accurate positioning due to interference.
[0005] The technical solution provided by the embodiment of the utility model is as follows:
[0006] A first aspect of an embodiment of the utility model provides a magnetic encoder, which includes: a magnetic field generator and a magnetic sensor, wherein the magnetic field generator includes an incremental code track and a pseudo-random binary sequence code track, and the magnetic sensor includes a first magnetic sensor and a second magnetic sensor, wherein the first magnetic sensor is arranged above the pseudo-random binary sequence code track, and the second magnetic sensor is arranged above the incremental code track, and the incremental code track and the pseudo-random binary sequence code track include multiple encoding areas, the first magnetic sensor is used to sense the magnetic field generated by the pseudo-random binary sequence code track for regional positioning, and the second magnetic sensor is used to sense the magnetic field generated by the incremental code track for position positioning within the area.
[0007] The magnetic encoder provided in this embodiment forms a dual code channel structure by setting an incremental code channel and a pseudo-random binary sequence code channel, and divides multiple coding areas in each code channel, and respectively sets a first magnetic sensor and a second magnetic sensor above the two code channels, wherein the first magnetic sensor can realize regional positioning, and the second magnetic sensor can realize position positioning within the region. Thus, the magnetic encoder can realize absolute position positioning through the cooperation of the dual code channels and the corresponding magnetic sensors, avoiding the problem of being unable to realize accurate positioning due to interference in the related art.
[0008] In an optional implementation, the incremental code track includes a plurality of first magnetic poles and second magnetic poles that are alternately arranged, and adjacent first magnetic poles and second magnetic poles form a pole pair, and a pole pair corresponds to one encoding region.
[0009] In this embodiment, an incremental code track is formed by a plurality of first magnetic poles and second magnetic poles arranged alternately, so that the magnetic field generated by the incremental code track can be a periodic magnetic field, which facilitates position positioning in each area.
[0010] In an optional implementation, the pseudo-random binary sequence code channel includes a plurality of first magnetic poles and second magnetic poles arranged in a pseudo-random binary sequence, and the distance or angle between two adjacent magnetic poles corresponds to the length or angle of the region.
[0011] In an optional embodiment, the first magnetic sensor includes at least one group of magnetic sensor modules, each group of magnetic sensor modules includes a plurality of first magnetic sensor units, and the plurality of first magnetic sensor units are arranged at equal intervals or at equal angles, the interval being the distance between two adjacent coding regions on a pseudo-random binary sequence code channel, and the angle being the angle between two adjacent coding regions on a pseudo-random binary sequence code channel.
[0012] In this embodiment, a pseudo-random binary sequence code channel is formed by first magnetic poles and second magnetic poles arranged in a pseudo-random binary sequence, and multiple first magnetic sensor units are provided in the magnetic sensor module. The magnetic sensor module in the first magnetic sensor can measure the codes of multiple coding areas, thereby realizing the positioning of the coding area.
[0013] In an optional implementation, when the magnetic sensor module includes n first magnetic sensor units, the region positioning is performed based on the n-bit binary code information obtained according to the output of the magnetic sensor module, the n-bit binary code information is unique and non-repetitive n-bit binary code information, and the number of the first magnetic sensor units and the number of coding regions satisfy the following relationship:
[0014] 2 n ≥N
[0015] Where N represents the number of coding regions.
[0016] In this embodiment, the n-bit binary code information output by the first magnetic sensor is set to be unique and non-repetitive n-bit binary code information, while ensuring that 2 n ≥N, the first magnetic sensor can accurately locate the encoding area.
[0017] In an optional implementation, the first magnetic sensor includes two groups of magnetic sensor modules, and the two groups of sensor modules are spaced apart by mp+1 / 2*p, where m is an integer greater than or equal to 0, and p represents a period of the encoding region.
[0018] In this embodiment, two groups of magnetic sensor modules are set in the first magnetic sensor for decoding, which can achieve blind spot detection and further avoid the problem of inaccurate positioning due to interference.
[0019] In an optional implementation, the second magnetic sensor includes a plurality of second magnetic sensor units, and the distance between the i-th second magnetic sensor unit and the first second magnetic sensor unit satisfies the following relationship:
[0020] k(i-1)*p+Δ
[0021] Wherein, k represents an integer, Δ represents the manufacturing tolerance, and p represents the period of the encoding area.
[0022] In this embodiment, by configuring the second magnetic sensor to include a plurality of second magnetic sensor units and making the spacing between the magnetic sensor units satisfy a corresponding relationship, the second magnetic sensors can be roughly evenly distributed above the incremental code track, thereby facilitating sensing of magnetic fields at different positions.
[0023] In an optional embodiment, the second magnetic sensor unit includes a half-bridge circuit or a full-bridge circuit, the full-bridge circuit includes four bridge arm resistors, the first bridge arm resistor and the second bridge arm resistor among the four bridge arm resistors constitute a first half-bridge circuit, the third bridge arm resistor and the fourth bridge arm resistor among the four bridge arm resistors constitute a second half-bridge circuit, and the first bridge arm resistor, the third bridge arm resistor, the second bridge arm resistor, and the fourth bridge arm resistor are arranged in sequence at intervals of one quarter of the coding area period in the direction of relative movement.
[0024] In an optional embodiment, the magnetic encoder further includes a signal processing circuit, which receives an average value of the output voltages of multiple first half-bridge circuits of multiple second magnetic sensor units and an average value of the output voltages of multiple second half-bridge circuits of multiple second magnetic sensor units to perform position positioning within the area; or, the magnetic encoder further includes a signal processing unit, which receives the output voltages of multiple first half-bridge circuits of multiple second magnetic sensor units and the output voltages of multiple second half-bridge circuits of multiple second magnetic sensor units to perform analysis to achieve position positioning within the area.
[0025] In this embodiment, by using a half-bridge circuit or a full-bridge circuit to form the second magnetic sensor unit, the outputs of two half-bridge circuits in a plurality of second magnetic sensor units are averaged, which can offset or reduce the influence of the change in the mechanical structure of the magnetic disk / magnetic ring / magnetic scale on the measurement accuracy. This solves the problem that the relative position of the magnetic disk / magnetic ring / magnetic scale and the sensor is offset due to the change in the mechanical structure, which affects the measurement accuracy of the magnetic sensor.
[0026] In an optional embodiment, the signal processing circuit includes an operational amplifier circuit and a signal processing module, the first input end of the operational amplifier circuit is the average value of the output voltages of multiple first half-bridge circuits of multiple second magnetic sensor units, the second input end of the operational amplifier circuit is the average value of the output voltages of multiple second half-bridge circuits, and the signal processing module receives the output value of the output end of the operational amplifier circuit to perform position positioning within the area. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0028] Figure 1 This is a structural block diagram of a magnetic encoder in an embodiment of the utility model;
[0029] Figures 2 to 4 is a structural schematic diagram of a magnetic encoder using a magnetic ring structure according to an embodiment of the utility model;
[0030] Figure 5 It is a curve diagram of the magnetic field components in a certain direction generated by two code channels in the embodiment of the utility model;
[0031] Figure 6 A top view of a magnetic encoder in an embodiment of the utility model;
[0032] Figure 7 This is a structural block diagram of a magnetic encoder in another embodiment of the present invention;
[0033] Figure 8 A top view of a magnetic encoder in another embodiment of the present invention;
[0034] Fig. 9 It is a structural block diagram of a magnetic encoder in the related art;
[0035] Fig.10 is a cross-sectional view of a magnetic encoder in the related art;
[0036] Fig.11 A schematic diagram of a case in which the arrangement center of the sensor deviates from the center of the disk in the related art;
[0037] Fig.12 This is a schematic diagram of the structure of the full-bridge circuit in the second magnetic sensor unit in an embodiment of the utility model;
[0038] Fig.13 This is a schematic diagram of the output waveform of the second magnetic sensor unit in the embodiment of the utility model;
[0039] Fig.14 Schematic diagram of the output signal processing of the second magnetic sensor unit in the embodiment of the utility model. DETAILED DESCRIPTION
[0040] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0041] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0042] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.
[0043] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0044] The utility model provides a magnetic encoder, such as Figure 1 As shown, the magnetic encoder includes: a magnetic field generator and a magnetic sensor, the magnetic field generator includes an incremental code track 12 and a pseudo-random binary sequence (PRBS) code track 11, the magnetic sensor includes a first magnetic sensor and a second magnetic sensor, the first magnetic sensor is arranged above the pseudo-random binary sequence code track, and the second magnetic sensor is arranged above the incremental code track 12, the incremental code track 12 and the pseudo-random binary sequence code track include multiple encoding areas, the first magnetic sensor is used to sense the magnetic field generated by the pseudo-random binary sequence code track for regional positioning, and the second magnetic sensor is used to sense the magnetic field generated by the incremental code track 12 for position positioning within the area.
[0045] Specifically, the code track in the magnetic field generator can be in the shape of a disk, a magnetic ring, or a magnetic scale. When it is in the shape of a disk or a magnetic ring, the magnetic encoder also includes a base 30 (or a mounting base), the base 30 is fixed on the motor shaft, and the disk or the magnetic ring is fixed on the base 30. In this embodiment, when a disk shape is adopted, the incremental code track 12 can be fixed on the periphery of the base 30, and the pseudo-random binary sequence code track can be fixed on the inner periphery of the base 30. The two code tracks can be spaced a certain distance apart, or they can be set close to each other. That is, the incremental code track 12 and the pseudo-random binary sequence code track form a structure as shown in FIG. Figure 1 In other embodiments, when the double ring structure is in the form of a disk, the incremental code track 12 can be fixed on the inner periphery of the base 30, and the pseudo-random binary sequence code track can be fixed on the outer periphery of the base 30. Figures 2 to 4As shown, when a magnetic ring shape is adopted, a circular mounting seat can be used, and two code tracks are distributed in sequence along the axial direction of the mounting seat and are respectively sleeved on its outer circumference. The two code tracks can be spaced a certain distance along the axial direction of the mounting seat, or can be arranged closely. The outer circumferences of the two code tracks are respectively provided with a first magnetic sensor and a second magnetic sensor. It should be noted that when a code disk or a magnetic scale shape is adopted, the magnetic sensor is arranged above the code track, which means above the code track in the vertical direction; when a magnetic ring shape is adopted, the magnetic sensor is arranged above the code track, which means above the code track in the horizontal direction.
[0046] In this embodiment, a plurality of coding regions are divided in the incremental code channel 12, and the PRBS code channel 11 is divided into regions based on the region division of the incremental code channel 12, thereby facilitating regional positioning. When positioning, the magnetic field signal sensed by the magnetic sensor can be analyzed and determined, for example, the sensed magnetic field signal can be converted into an electrical signal, and then the electrical signal can be processed and implemented. The specific processing method can be implemented with reference to the relevant technology, which will not be described in detail here.
[0047] The magnetic encoder provided in this embodiment forms a dual-code channel structure by setting an incremental code channel 12 and a PRBS code channel 11, and divides multiple coding areas in each code channel, and respectively sets a first magnetic sensor and a second magnetic sensor above the two code channels, wherein the first magnetic sensor can realize regional positioning, and the second magnetic sensor can realize position positioning within the region. Therefore, the magnetic encoder can realize absolute position positioning through the cooperation of the dual code channels and the corresponding magnetic sensors, avoiding the problem of being unable to achieve accurate positioning due to interference in the related art.
[0048] In an optional embodiment, the incremental code track 12 includes a plurality of first magnetic poles and second magnetic poles arranged alternately, and adjacent first magnetic poles and second magnetic poles constitute a pole pair, and one pole pair corresponds to one region. Among them, the first magnetic pole and the second magnetic pole can be respectively an N magnetic pole (hereinafter referred to as N pole) and an S magnetic pole (hereinafter referred to as S pole), and the two magnetic poles have the same size and are arranged alternately along the relative movement direction. It should be understood that the relative movement direction here refers to the movement direction between the magnetic field generator and the magnetic sensor. When the incremental code track 12 includes N N poles and N S poles, an adjacent N pole and an S pole constitute a pole pair, and finally form N pole pairs, and the N pole pairs correspond to N regions on the incremental code track 12, or the N pole pairs divide the incremental code track 12 into N regions, and each region can also be called a coding region.
[0049] Specifically, the incremental code track 12 can be a disk structure, a magnetic ring structure or a magnetic scale structure. When the magnetic scale structure is adopted, the relative movement direction is along the length direction of the magnetic scale, and the distance between the N pole and the S pole center is λ (called "incremental code track 12 magnetic pole center distance"). Figure 5As shown in the figure, the curve period of the component of the magnetic field generated in a certain direction is 2λ, and its period corresponds to the length of each encoding area. When a disk structure is used, the relative movement direction is along the circumference of the disk, as shown in the figure. Figure 6 As shown in the figure, the angle between the center of the N pole and the S pole and the line connecting the center of the disk is θ (called the "incremental code track 12 magnetic pole center angle"). Figure 5 As shown, the curve period of the component of the magnetic field generated in a certain direction is 2θ, corresponding to the angle of each encoding area. When a magnetic ring structure is used, the relative movement direction is along the circumference of the magnetic ring, and the angle between the center of the N pole and the S pole and the line connecting the center of the magnetic ring is also θ.
[0050] In an optional embodiment, the PRBS code channel 11 includes a plurality of first magnetic poles and second magnetic poles arranged in a pseudo-random binary sequence, and the distance or angle between two adjacent magnetic poles corresponds to the length or angle of the region. It should be noted that the incremental code channel 12 is divided into N regions by N pairs of poles in the incremental code channel 12, and the PRBS code channel 11 performs binary encoding on its own code channel with reference to the division of the incremental code channel 12. The PRBS code channel 11 is encoded as a coding sequence composed of N binary numbers, and the area covered by each binary number (the length or angle of the coding area) is called the coding area. The PRBS code channel 11 has a total of N coding areas, which correspond one-to-one to the areas of the incremental code channel 12. In the coding sequence composed of the binary number arrangement, the N pole can correspond to the binary number "1", and the S pole can correspond to the binary number "0". The first magnetic pole and the second magnetic pole are arranged according to the pseudo-random binary sequence obtained according to the encoding result. Among them, the first magnetic pole after arrangement is the N magnetic pole (hereinafter referred to as the N pole), and the second magnetic pole after arrangement is the S magnetic pole (hereinafter referred to as the S pole). As Figure 5 As shown, according to the arrangement of the magnetic poles in the PRBS code track 11, the curve of the component of the magnetic field generated by the PRBS code track 11 in a certain direction is not a fixed periodic waveform.
[0051] Similarly, the PRBS code track 11 can also be a magnetic scale structure, a magnetic ring structure or a disk structure. When the magnetic scale structure is adopted, the relative movement direction is along the length direction of the magnetic scale, and the center distance between two adjacent magnetic poles (referring to two adjacent coding areas) of the PRBS code track 11 is 2λ (referred to as "the center distance between the coding areas of the PRBS code track 11"). The length of each coding area of the PRBS code track 11 in the relative movement direction is also 2λ, that is, the length of each coding area. Figure 6As shown, when a disk structure is adopted, the relative movement direction is along the circumference of the disk, and the angle between the center of two adjacent magnetic poles (referring to two adjacent coding areas) of the PRBS code track 11 and the line connecting the center of the disk is 2θ (called "the center angle of the coding area of the PRBS code track 11"), which is the angle corresponding to each coding area. When a magnetic ring structure is adopted, the relative movement direction is along the circumference of the magnetic ring, and the angle between the center of two adjacent magnetic poles (referring to two adjacent coding areas) of the PRBS code track 11 and the line connecting the center of the magnetic ring is 2θ (called "the center angle of the coding area of the PRBS code track 11"). Among them, the length ("the center spacing of the coding area of the PRBS code track 11") or angle ("the center angle of the coding area of the PRBS code track 11") corresponding to each coding area in the direction of relative movement can also be understood as the period p of the coding area.
[0052] From this, it can be concluded that the "PRBS code channel 11 coding area center spacing" is twice the "incremental code channel 12 magnetic pole center spacing", and the "PRBS code channel 11 coding area center angle" is twice the "incremental code channel 12 magnetic pole center angle".
[0053] It should be noted that the direction can be defined as follows: for the magnetic scale, the extension direction of the magnetic field generator (code track) is identified as the X direction, the direction perpendicular to the X direction in the horizontal plane is identified as the Y direction, and the direction perpendicular to the XY plane is identified as the Z direction. For the magnetic disk, the circumferential direction is defined as the X direction, the radial direction is defined as the Y direction, and the direction perpendicular to the XY plane is identified as the Z direction.
[0054] In an optional embodiment, the first magnetic sensor includes at least one group of magnetic sensor modules 20, each group of magnetic sensor modules 20 includes a plurality of first magnetic sensor units 21, and the plurality of first magnetic sensor units 21 are arranged at equal intervals or angles, the interval being the distance between two adjacent coding regions on the pseudo-random binary sequence code track (i.e., "the center spacing of the coding regions of the PRBS code track 11"), and the angle being the angle between two adjacent coding regions on the pseudo-random binary sequence code track (i.e., "the center angle of the coding regions of the PRBS code track 11"); further explained as follows: when the PRBS code track 11 is a magnetic scale structure, the interval between two adjacent first magnetic sensor units 21 in each group of magnetic sensor modules 20 along the relative moving direction is equal to the center spacing of the coding regions of the PRBS code track 11; when the PRBS code track 11 is a disk (or magnetic ring) structure, the angle between two adjacent first magnetic sensor units 21 in each group of magnetic sensor modules 20 and the center line of the disk (or magnetic ring) is equal to the center angle of the coding regions of the PRBS code track 11. Wherein, Figure 1 and Figure 6As shown, when the first magnetic sensor includes a group of magnetic sensor modules 20, during the rotation of the code channel, if at a certain moment, one or more first magnetic sensor units 21 in a group of magnetic sensor modules 20 are located above the junction of the N pole and the S pole of the PRBS code channel 11, there is a situation where the magnetic field component in the sensing direction of the first magnetic sensor unit 21 is zero, so that the first magnetic sensor unit 21 here cannot sense the magnetic field and the magnetic encoder cannot be positioned. Therefore, there is a detection blind area when using a group of magnetic sensor modules 20.
[0055] Therefore, preferably, Figure 7 and Figure 8 As shown, the first magnetic sensor includes two groups of magnetic sensor modules 20, and the two groups of sensor modules are arranged at an interval of (2m+1)λ (or an interval of (2m+1)θ, that is, an interval of mp+1 / 2*p), where m is an integer greater than or equal to 0. According to the two groups of magnetic sensor modules 20, when the code channel rotates, at a certain moment, if one or more first magnetic sensor units 21 in one group of magnetic sensor modules 20 are located above the junction of the N pole and the S pole of the PRBS code channel 11, then one or more first magnetic sensor units 21 in the other group of magnetic sensor modules 20 are located above the N pole or the S pole, so that positioning can be achieved, that is, setting two groups of magnetic sensor modules 20 can achieve detection without blind spots. In this embodiment, two groups of magnetic sensor modules 20 are arranged in the first magnetic sensor for decoding, which further avoids the problem of inaccurate positioning due to interference.
[0056] Specifically, a plurality of (e.g., n) first magnetic sensor units 21 arranged above the PRBS code channel 11 are arranged at equal intervals or angles along the relative movement direction. Each first magnetic sensor unit 21 is used to sense the magnetic field at the current position, and convert the sensed magnetic field signal into an electrical signal and then perform corresponding processing to obtain the coding information "0" or "1" of the coding area of the corresponding PRBS code channel 11, thereby obtaining a set of n-bit binary code information, thereby confirming the specific coding area in the N coding areas and realizing the coding area positioning. It should be noted that the relative movement direction here is the movement direction between the magnetic field generator and the magnetic sensor.
[0057] When the magnetic sensor module 20 includes n first magnetic sensor units 21, n-bit binary code information can be obtained according to the output of the magnetic sensor module 20 to perform regional positioning, and the n-bit binary code information is unique and non-repeating n-bit binary code information, and the number of the first magnetic sensor units 21 and the number of coding areas satisfy the following relationship:
[0058] 2 n ≥N
[0059] Where N represents the number of coding regions.
[0060] Specifically, the number of N coding areas of the incremental code channel 12 is encoded with 0 and 1 to obtain a sequence composed of N binary numbers (such as: 0110110011100010100101000...), the number of first magnetic sensor units 21 is n, at a certain moment, each first magnetic sensor unit 21 decodes the code (0 or 1) corresponding to the current coding area, and n first magnetic sensor units 21 can decode n consecutive coding areas to obtain a set of binary codes (such as: 10011). In order to achieve positioning, n consecutive binary sequences are selected from the sequence composed of N binary numbers. These n binary sequences must be unique, and repeated n binary sequences cannot appear. Therefore, it is necessary to make 2 n ≥ N, in actual production, other factors should be considered, such as avoiding the occurrence of consecutive 1 (or 0) coding areas as much as possible, usually making 2 n >N.
[0061] In this embodiment, n first magnetic sensor units 21 are set in the magnetic sensor module 20, so that the codes of n consecutive coding areas can be decoded at the same time, so that it can be obtained which coding area is currently located, that is, the positioning of the coding area is achieved. The incremental code track 12 includes a plurality of first magnetic poles and second magnetic poles arranged alternately, and the adjacent first magnetic poles and second magnetic poles constitute a pair of poles, and a pair of poles corresponds to a coding area, that is, for the incremental code track 12, each coding area is set the same, and the magnetic field generated by the incremental code track 12 is a fixed periodic magnetic field. The second magnetic sensor is used to measure the magnetic field generated by the incremental code track 12, so that the specific position in the coding area can be obtained, that is, the position positioning in the area is achieved.
[0062] Therefore, in this embodiment, the first magnetic sensor is used to confirm which coding area it belongs to, and the second magnetic sensor is used to confirm which point (specific position in the area) belongs to the current coding area.
[0063] In the related art, the code track (magnetic scale / disk / magnetic ring) of the encoder cannot remain absolutely straight or flat due to: (1) its own process or application; (2) installation errors or operating errors, resulting in the plane where the code track (magnetic scale / disk / magnetic ring) and the plane where the sensor is located cannot remain absolutely parallel or the code track (magnetic scale / disk / magnetic ring) deviates from the expected position (that is, the distance between the code track (magnetic scale / disk / magnetic ring) and the sensor may be offset from the expected position). The above reasons will affect the measurement accuracy of the encoder, resulting in inaccurate or even erroneous measurement results.
[0064] Taking the encoder using a disk as an example, its structure is as follows Fig. 9As shown, the magnetic disk 43 is fixed on the mounting seat, the mounting seat is fixed on the motor shaft 41, the magnetic disk 43 is provided with a code track 42 along the circumference, and a magnetic sensor 44 is installed above the code track 42 to form the main structure of the magnetic sensor.
[0065] If the disk surface is uneven, or the disk is likely to move, tilt, or warp in the height direction (Z) during installation or operation, the height (ΔG) between the disk and the magnetic sensor 44 will change, causing the measurement accuracy of the magnetic sensor to change. For example, if the disk is tilted at a certain angle, ΔG will not be maintained at the same height after the disk rotates. For example, if the disk is fixed by screws or other means, that is, there is at least one fixed mounting position, this will make the disk warp, such as the part between the two fixed mounting positions tilting upward, etc., and ΔG will not be maintained at the same height after the disk rotates. The structure of the magnetic encoder in the height direction is as follows: Fig.10 shown.
[0066] For example, during installation or operation, the magnetic disk 43 may move in the radial direction (R), so that the center of the magnetic sensor 44 deviates from the center of the magnetic disk. The specific deviation is as follows: Fig.11 When the disk vibrates in the radial direction, the position of the magnetic sensor relative to the disk moves from the dotted line position to the solid line position, causing the period sensed by the magnetic sensor to change, thereby causing the measurement accuracy of the magnetic sensor to change.
[0067] In order to solve the problem that the relative position of the code track (disk / magnetic ring / magnetic scale) and the sensor is offset due to the change in the mechanical structure of the code track (disk / magnetic ring / magnetic scale) (radial / axial jitter / sway, tilt, warping), so that the measurement accuracy of the magnetic sensor is affected. In this embodiment, multiple second magnetic sensor units 22 are provided in the second magnetic sensor, and the output signals of the multiple second magnetic sensor units 22 are averaged to offset or reduce the problem of measurement accuracy being affected.
[0068] In an optional embodiment, if Figure 1 As shown, the second magnetic sensor includes a plurality of second magnetic sensor units 22, the number of the second magnetic sensor units 22 may be q, and the spacing between the i-th second magnetic sensor unit 22 and the first second magnetic sensor unit 22 satisfies the following relationship:
[0069] k(i-1)*p+Δ
[0070] In the formula, k represents an integer, Δ represents the manufacturing tolerance, and p represents the period of the region, that is, p represents the length ("the center spacing of the PRBS code channel 11 coding regions") or angle ("the center angle of the PRBS code channel 11 coding regions") corresponding to each coding region in the direction of relative movement. In the ideal case, the spacing is an integer multiple of the period, that is, Δ = 0; but in the actual manufacturing process, Δ ≠ 0, which is an allowed manufacturing tolerance Δ, which has little effect on the measurement result. If Δ is set appropriately, harmonic compensation can also be achieved.
[0071] According to the relationship satisfied by the above spacing, when q (the number of second magnetic sensor units 22) is divisible by N (the number of encoding areas), k = N / q, and the q second magnetic sensor units 22 are evenly distributed above the incremental code track 12; when q is not evenly divisible by N, k can be: N / q rounded down or N / q rounded up; that is, the q second magnetic sensor units 22 are distributed above the incremental code track 12 in a roughly uniform manner.
[0072] Specifically, when N=64 and q=8, the eight second magnetic sensor units 22 are evenly distributed above the disk incremental code track 12 , and the interval between two adjacent second magnetic sensor units 22 is 45 degrees.
[0073] When N=127 and q=8, the eight second magnetic sensor units 22 are roughly evenly distributed above the disk incremental code track 12, and k can be 15 or 16, and the interval between two adjacent second magnetic sensor units 22 is p*15, or p*16.
[0074] In an optional embodiment, the second magnetic sensor unit 22 includes a half-bridge circuit or a full-bridge circuit. The full-bridge circuit includes four bridge arm resistors. Fig.12 As shown, the first bridge arm resistor and the second bridge arm resistor of the four bridge arm resistors constitute a first half-bridge circuit, and the third bridge arm resistor and the fourth bridge arm resistor of the four bridge arm resistors constitute a second half-bridge circuit. Specifically, the four bridge arm resistors can all be magnetic resistors, that is, the first magnetic resistor R1, the second magnetic resistor R2, the third magnetic resistor R3, and the fourth magnetic resistor R4; as shown Fig.13 As shown, the first magnetic resistor R1, the third magnetic resistor R3, the second magnetic resistor R2, and the fourth magnetic resistor R4 are arranged at intervals of λ / 2 (or θ / 2) in the direction of relative movement. Fig.12 As shown, the first magnetic resistor R1 and the second magnetic resistor R2 form a first half-bridge circuit, and the third magnetic resistor R3 and the fourth magnetic resistor R4 form a second half-bridge circuit. Fig.13As shown, an output waveform with a phase shift of λ / 2 (a quarter cycle, i.e., a quarter cycle of the coding region period) can be obtained from the first half-bridge circuit and the second half-bridge circuit. After processing and calculating the output V1 of the first half-bridge circuit and the output V2 of the second half-bridge circuit, a specific position in a coding region confirmed by the first magnetic sensor can be obtained. When the second magnetic sensor unit 22 adopts a half-bridge circuit, the half-bridge circuit can be set using the first half-bridge circuit or the second half-bridge circuit in the full-bridge circuit. If the first half-bridge circuit configuration is adopted, V2 is the reference voltage.
[0075] In an optional embodiment, the magnetic encoder further includes a signal processing circuit, and the signal processing circuit receives the output voltages of the multiple first half-bridge circuits of the multiple second magnetic sensor units 22 and the output voltages of the multiple second half-bridge circuits of the multiple second magnetic sensor units 22 to perform position positioning within the region. The signal processing circuit includes an operational amplifier circuit and a signal processing module, the first input end of the operational amplifier circuit is the average value of the output voltages of the multiple first half-bridge circuits of the multiple second magnetic sensor units 22, the second input end of the operational amplifier circuit is the average value of the output voltages of the multiple second half-bridge circuits, and the signal processing module receives the output value of the output end of the operational amplifier circuit to perform position positioning within the region.
[0076] Specifically, Fig.14 As shown, when the second magnetic sensor includes q second magnetic sensor units 22, the outputs V11, V12, ... V1q of all the first half-bridge circuits of the q second magnetic sensor units 22 and the outputs V21, V22, ... V2q of all the second half-bridge circuits are averaged, that is, V11, V12, ... V1q are averaged to obtain the average value V1, and V21, V22, ... V2q are averaged to obtain the average value V2. The two average values V1 and V2 are respectively input to the two input ends of the operational amplifier in the signal processing circuit, and then the specific position in a certain coding area confirmed by the first magnetic sensor can be obtained after V1 and V2 are processed and calculated by the signal processing module. Among them, the specific processing process of the signal processing module can be implemented with reference to the relevant technology, which will not be repeated here. Since the q second magnetic sensor units 22 are roughly evenly distributed above the incremental code track 12, by averaging the outputs of the two half-bridge circuits in the q second magnetic sensor units 22, the influence of the change in the mechanical structure of the disk or magnetic ruler on the measurement accuracy can be offset or reduced.
[0077] In addition, in other embodiments, the magnetic encoder also includes a signal processing unit. When the second magnetic sensor includes q second magnetic sensor units 22, the outputs V11, V12, ... V1q of all first half-bridge circuits of the q second magnetic sensor units 22 and the outputs V21, V22, ... V2q of all second half-bridge circuits can be input into the signal processing unit, and the signal processing unit analyzes them respectively to obtain the specific position within a certain coding area confirmed by the first magnetic sensor.
[0078] Although the exemplary embodiments and their advantages have been described in detail, those skilled in the art may make various changes, substitutions and modifications to these embodiments without departing from the spirit of the utility model and the scope of protection defined by the appended claims, and such modifications and variations all fall within the scope defined by the appended claims. For other examples, those of ordinary skill in the art should readily understand that the order of the process steps may be changed while maintaining the scope of protection of the utility model.
[0079] In addition, the scope of application of the present invention is not limited to the processes, mechanisms, manufactures, material compositions, means, methods and steps of the specific embodiments described in the specification. From the disclosure of the present invention, it will be easily understood by those skilled in the art that the processes, mechanisms, manufactures, material compositions, means, methods or steps that currently exist or will be developed in the future, which perform substantially the same functions as the corresponding embodiments described in the present invention or obtain substantially the same results, can be applied according to the present invention. Therefore, the claims attached to the present invention are intended to include these processes, mechanisms, manufactures, material compositions, means, methods or steps within their scope of protection.
Claims
1. A magnetic encoder, characterized in that: The magnetic encoder includes: a magnetic field generator and a magnetic sensor, the magnetic field generator includes an incremental code track and a pseudo-random binary sequence code track, the magnetic sensor includes a first magnetic sensor and a second magnetic sensor, the first magnetic sensor is arranged above the pseudo-random binary sequence code track, and the second magnetic sensor is arranged above the incremental code track, the incremental code track and the pseudo-random binary sequence code track include multiple encoding areas, the first magnetic sensor is used to sense the magnetic field generated by the pseudo-random binary sequence code track for regional positioning, and the second magnetic sensor is used to sense the magnetic field generated by the incremental code track for position positioning within the area.
2. The magnetic encoder according to claim 1, characterized in that The incremental code track includes a plurality of first magnetic poles and second magnetic poles arranged alternately, and adjacent first magnetic poles and second magnetic poles form a pole pair, and a pole pair corresponds to a coding area.
3. The magnetic encoder according to claim 1, characterized in that: The pseudo-random binary sequence code channel includes a plurality of first magnetic poles and second magnetic poles arranged according to a pseudo-random binary sequence, and the distance or angle between two adjacent magnetic poles corresponds to the length or angle of the coding area.
4. The magnetic encoder according to claim 3, characterized in that: The first magnetic sensor includes at least one group of magnetic sensor modules, each group of magnetic sensor modules includes a plurality of first magnetic sensor units, and the plurality of first magnetic sensor units are arranged at equal intervals or at equal angles, the interval being the distance between two adjacent coding areas on a pseudo-random binary sequence code channel, and the angle being the angle between two adjacent coding areas on a pseudo-random binary sequence code channel.
5. The magnetic encoder according to claim 4, characterized in that: When the magnetic sensor module includes n first magnetic sensor units, n-bit binary code information is obtained according to the output of the magnetic sensor module to perform regional positioning, and the n-bit binary code information is unique and non-repetitive n-bit binary code information, and the number of the first magnetic sensor units and the number of coding areas satisfy the following relationship: 2 n ≥N Where N represents the number of coding regions.
6. The magnetic encoder according to claim 4, characterized in that: The first magnetic sensor includes two groups of magnetic sensor modules, and the interval between the two groups of sensor modules is mp+1 / 2*p, wherein m is an integer greater than or equal to 0, and p represents the period of the encoding area.
7. The magnetic encoder according to claim 1, characterized in that: The second magnetic sensor includes a plurality of second magnetic sensor units, and the distance between the i-th second magnetic sensor unit and the first second magnetic sensor unit satisfies the following relationship: k(i-1)*p+Δ Wherein, k represents an integer, Δ represents the manufacturing tolerance, and p represents the period of the encoding area.
8. The magnetic encoder according to claim 7, characterized in that: The second magnetic sensor unit includes a half-bridge circuit or a full-bridge circuit, and the full-bridge circuit includes four bridge arm resistors. The first bridge arm resistor and the second bridge arm resistor of the four bridge arm resistors constitute a first half-bridge circuit, and the third bridge arm resistor and the fourth bridge arm resistor of the four bridge arm resistors constitute a second half-bridge circuit. The first bridge arm resistor, the third bridge arm resistor, the second bridge arm resistor, and the fourth bridge arm resistor are arranged in sequence at intervals of one quarter of the encoding area period in the direction of relative movement.
9. The magnetic encoder according to claim 8, characterized in that: The magnetic encoder further comprises a signal processing circuit, wherein the signal processing circuit receives an average value of output voltages of a plurality of first half-bridge circuits of a plurality of second magnetic sensor units and an average value of output voltages of a plurality of second half-bridge circuits of a plurality of second magnetic sensor units to perform position positioning within the region; Alternatively, the magnetic encoder further comprises a signal processing unit, which receives output voltages of a plurality of first half-bridge circuits of a plurality of second magnetic sensor units and output voltages of a plurality of second half-bridge circuits of a plurality of second magnetic sensor units for analysis to achieve position positioning within the region.
10. The magnetic encoder according to claim 9, characterized in that: The signal processing circuit includes an operational amplifier circuit and a signal processing module. The first input end of the operational amplifier circuit is the average value of the output voltages of multiple first half-bridge circuits of multiple second magnetic sensor units, the second input end of the operational amplifier circuit is the average value of the output voltages of multiple second half-bridge circuits, and the signal processing module receives the output value of the output end of the operational amplifier circuit to perform position positioning within the area.