High-precision absolute position magnetic encoder measuring system

Abstract

The invention discloses a high-precision absolute position magnetic encoder measuring system, and relates to the technical field of encoders, the absolute position magnetic encoder measuring system comprises a magnetic sensor, an encoding disc and a coil power supply; the coding disc comprises two code channels; the two code channels are coaxial and are formed by continuously winding periodic inductance coils into a ring shape; and the coil power supply is a circuit or an element capable of providing a constant power supply. According to the invention, common inductance coil and multi-antipode magnetic ring coding modes are considered, the realization mode is simple and accurate, signals are easy to process, and the anti-interference performance of multi-induction point differential signals is stronger.

Description

Technical Field

[0001] The invention relates to the technical field of encoders, in particular to a high-precision inductive absolute position magnetic encoder measurement system. Background Art

[0002] An encoder is a sensor that converts angular displacement or linear displacement into an electrical signal; At present, in the measurement system of dual-channel multi-pole magnetic ring encoder, the encoder adopts the method of one magnetic pole difference between the inner and outer channels. This method of encoder has very high requirements on the magnetization process, and it is easy to distort the boundary of the magnetized N and S poles, resulting in the phenomenon of inner and outer channels being connected, which will cause a high signal tolerance. The inductive measurement system contains stator, rotor windings and AC excitation power supply. The signals processed are different groups of electrical signals obtained due to electromagnetic induction, and then the absolute position is measured by calculating the electrical angle. However, the configuration of the number of coil poles is extremely complicated, and the subsequent signal processing circuit is also very complex. Summary of the invention

[0003] The object of the present invention is to provide a high-precision absolute position magnetic encoder measurement system to solve the problems raised in the prior art.

[0004] To achieve the above object, the present invention provides the following technical solutions: a high-precision absolute position magnetic encoder measurement system, the absolute position magnetic encoder measurement system comprising a magnetic sensor, an encoding disk and a coil power supply; The encoding disk includes two code tracks; the two code tracks are coaxial and are both composed of periodic inductance coils continuously wound into a ring shape; The coil power supply is a circuit or element that can provide a constant power supply.

[0005] The magnetic sensors are placed above the two code tracks of the encoder disk.

[0006] When the encoding disk layout format is a left and right code channel, the left code channel is composed of m coils of the same shape, and the right code channel is composed of m-1 coils of the same shape. The coil shapes of the left and right code channels are similar, and only the size is slightly different due to the different number of coils in the left and right code channels, and the width is slightly different, where m is a positive integer.

[0007] When the layout format of the encoding disk is two code tracks, left and right, at least two magnetic sensors are selected and placed symmetrically.

[0008] At least two magnetic sensors are selected and placed symmetrically, respectively at two ends of the same diameter of the encoding disk, with their spatial position angles differing by 180 degrees.

[0009] When the encoding disk layout format is an inner and outer code channel, the outer code channel is composed of m coils of the same shape, and the inner code channel is composed of m-1 coils of the same shape. The coil shapes of the inner and outer code channels are similar, but due to the different numbers of coils in the inner and outer code channels and the difference in the inner and outer diameters, the widths are slightly different.

[0010] When the layout format of the encoding disk is two code tracks, inner and outer, at least one magnetic sensor is selected and placed just above the inner and outer code tracks.

[0011] When the layout format of the encoding disk is an inner and outer code channel, the position of the magnetic sensor spans the inner and outer code channels of the encoding disk, including two design schemes: one is to equip two groups of inner and outer sensing point units to respectively receive the magnetic field signals of the inner and outer code channels at the respective positions; the other is to select two magnetic sensors, each magnetic sensor is equipped with a group of sensing units to respectively sense the magnetic field signals of the inner and outer code channels.

[0012] The inductor coil in the encoding disk includes two parts of opposite shapes: one part is an inner package and the other part is an outer package. The inner package and the outer package form a complete periodic coil.

[0013] The magnetic sensor can be selected from a single Hall sensor, an AMR sensor based on magnetoresistance effect, a TMR sensor, and a sensor integrating AMR, TMR, Hall and CMOS circuits.

[0014] The TMR is a magnetic sensitive element using the tunnel magnetoresistance effect; The AMR is a magnetic sensor using anisotropic magnetoresistance effect; The CMOS is a semiconductor technology used to manufacture integrated circuits.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention takes into account both the general inductor coil and the multi-pole magnetic ring encoding method, the implementation method is simple and accurate, the signal is easy to process, and the multi-sensing point differential signal has stronger anti-interference ability; 2. The encoding disk structure of the present invention has only one coil winding, which generates a constant multi-pole magnetic field in alternating directions after passing direct current, solving the magnetization problem of multi-pole magnetic ring technology; the coil winding is thin and light, with low power consumption, and can achieve accurate and reliable measurement under harsh conditions; 3. The present invention proposes a similar multi-pole magnetic ring, which avoids the temperature dependence of the magnetic ring poles and has high stability; there are no complex electrical signals such as eddy currents, data processing is simpler, and it is easier to achieve miniaturization and large-scale automated production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A top view of the relative positions of the components of the embodiment 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; Figure 2 A side view showing the relative positions of the components of the embodiment 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; Figure 3 A top view of the encoder disk of Embodiment 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; Figure 4 This is a schematic diagram of magnetic field distribution after current is applied in Example 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; Figure 5 It is a difference curve between the output angle signal of the inner and outer code channels and the output angle in Example 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; Figure 6 A top view of the relative positions of the magnetic sensor and the encoding disk of Example 2 of the high-precision absolute position magnetic encoder measurement system of the present invention; Figure 7 This is a schematic diagram of magnetic field distribution after current is applied in Example 2 of the high-precision absolute position magnetic encoder measurement system of the present invention; Figure 8 Schematic diagram of the left code channel differential voltage signal in Example 2 of the high-precision absolute position magnetic encoder measurement system of the present invention; Fig. 9 Schematic diagram of the output angles of the left and right code channels and the output angle difference signals in Example 2 of the high-precision absolute position magnetic encoder measurement system of the present invention; In the figure: 1. Magnetic sensor; 2. Encoder disk: 2.1. PCB board of encoder disk; 2.2. Coil of outer code track of encoder disk: 2.2.1. Lead end of outer code track; 2.3. Coil of inner code track of encoder disk: 2.3.1. Lead end of inner code track; 3. PCB board on which magnetic sensor is placed; 4. Magnetic sensor: 4.1. Left code track magnetic sensor; 4.2. Right code track magnetic sensor; 5. Encoder disk: 5.1. PCB board of encoder disk; 5.2. Coil of left code track of encoder disk; 5.3. Coil of right code track of encoder disk. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example: Figure 1-Figure 9 As shown, the present invention provides a technical solution, a high-precision absolute position magnetic encoder measurement system, the absolute position magnetic encoder measurement system includes a magnetic sensor, an encoding disk and a coil power supply; The encoding disk includes two code tracks; the two code tracks are coaxial and are both composed of periodic inductance coils continuously wound into a ring shape; The coil power supply is a circuit or element that can provide a constant power supply.

[0019] The magnetic sensors are placed above the two code tracks of the encoder disk.

[0020] When the encoding disk layout format is a left and right code channel, the left code channel is composed of m coils of the same shape, and the right code channel is composed of m-1 coils of the same shape. The coil shapes of the left and right code channels are similar, and only the size is slightly different due to the different number of coils in the left and right code channels and the width.

[0021] When the layout format of the encoding disk is two code tracks, left and right, at least two magnetic sensors are selected and placed symmetrically.

[0022] At least two magnetic sensors are selected and placed symmetrically, respectively at two ends of the same diameter of the encoding disk, with their spatial position angles differing by 180 degrees.

[0023] When the encoding disk layout format is an inner and outer code channel, the outer code channel is composed of m coils of the same shape, and the inner code channel is composed of m-1 coils of the same shape. The coil shapes of the inner and outer code channels are similar, but due to the different numbers of coils in the inner and outer code channels and the difference in the inner and outer diameters, the widths are slightly different.

[0024] When the layout format of the encoding disk is two code tracks, inner and outer, at least one magnetic sensor is selected and placed just above the inner and outer code tracks.

[0025] When the layout format of the encoding disk is an inner and outer code channel, the position of the magnetic sensor spans the inner and outer code channels of the encoding disk, including two design schemes: one is to equip two groups of inner and outer sensing point units to respectively receive the magnetic field signals of the inner and outer code channels at the respective positions; the other is to select two magnetic sensors, each magnetic sensor is equipped with a group of sensing units to respectively sense the magnetic field signals of the inner and outer code channels.

[0026] The inductor coil in the encoding disk includes two parts of opposite shapes: one part is an inner package and the other part is an outer package. The inner package and the outer package form a complete periodic coil.

[0027] The magnetic sensor can be selected from a single Hall sensor, an AMR sensor based on magnetoresistance effect, a TMR sensor, and a sensor integrating AMR, TMR, Hall and CMOS circuits.

[0028] The TMR is a magnetic sensitive element using the tunnel magnetoresistance effect; The AMR is a magnetic sensor using anisotropic magnetoresistance effect; The CMOS is a semiconductor technology used to manufacture integrated circuits.

[0029] Embodiment 1: like Figure 1 As shown, it is a top view of the relative positions of the components of the embodiment 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; the encoding disk is composed of a periodic inductor coil, or a dense coil winding is realized by PCB technology, and the inductor coil is divided into inner and outer code channels, similar to a pulse wave " "The shape of the " is a periodic coil, including an inner coil (opening toward the center of the circle) and an outer coil (opening away from the center of the circle), and the inner coil and the outer coil form a complete periodic coil; however, the width of the inner and outer track coils is different due to the different inner and outer diameters and the different numbers; for example, in the present embodiment 1, the number of outer track coils is 32, so the width of a single periodic coil is about 3mm, the number of inner track coils is 31, and the width of a single periodic coil is about 2.36mm; The coil can be printed on a PCB board. To ensure a larger signal, the number of winding turns can be increased as much as possible. Multiple turns can be wound in each plane, and then multiple layers of windings are formed on the PCB board, with each layer connected in series with a through hole. When the coil power supply is constant, the more inductance turns there are, the higher the induced magnetic field is. The number of turns can be adjusted according to different sensor magnetic field parameters. For example, the number of turns of the coil used in this embodiment 1 is 64, and the induced magnetic field can be controlled at about 20G-30G. The position of the magnetic sensor in this embodiment 1 spans the inner and outer code channels of the encoding disk, and includes two groups of inner and outer sensing point units, which respectively receive the magnetic field signals of the inner and outer code channels of the orientation; the magnetic sensor is a highly integrated AMR and CMOS circuit, and the CMOS circuit performs various processing on the received signal and finally outputs a voltage corresponding to the magnetic angle, with small error and higher accuracy.

[0030] like Figure 2 As shown, it is a side view of the relative positions of the components of the embodiment 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; the magnetic sensor chip is above the inner and outer code tracks of the encoding disk, and the distance between the magnetic sensor and the encoding disk directly affects the magnitude of the magnetic field received by the magnetic sensor. The magnetic sensor can be pasted on the PCB board and then placed together above the inner and outer code tracks of the encoding disk. In order to reduce the distance between the magnetic sensor and the encoding disk, the magnetic encoder chip can be reversely pasted on the PCB board; the specific placement can be adjusted according to the height of the received magnetic field, and the relative position can also be adjusted within a certain tolerance according to the customer's structural requirements; like Figure 3 , which is a top view of the encoding disk of Embodiment 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; In Example 1, the magnetic sensor is placed in a patch type, and the tolerance can be controlled to be very small; the magnetic sensor chip can also be inserted from the side; for practical applications, the patch type or the insertion type can be selected according to the actual space and orientation design; like Figure 4 As shown, it is a schematic diagram of the magnetic field distribution after current is added to the embodiment 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; an external constant voltage source or a constant current source, or a circuit capable of providing a constant source; as shown in the figure, the inner and outer code channels have their own lead ends respectively, and in actual applications, the inner and outer code channels can also be connected in series and connected to the constant source with the same lead end; When a constant current is applied to the lead end, the shape of the coil determines the direction of the magnetic field of the encoder disk. The coil consists of two parts. According to the right-hand screw theorem, the inner part, due to the direction of the current, determines that the magnetic field at the inner part of the coil is perpendicular to the paper surface and inward. (Of course, when the current is reversed, the magnetic field will change direction accordingly), and the magnetic field at the outer part is perpendicular to the paper surface and outward. Indicates that; under the action of constant current, such a periodic coil forms a constant magnetic field with alternating directions, which is similar to the magnetic field distribution of axial magnetization of a multi-pole magnetic ring; The magnetic sensor in Example 1 of the present invention outputs a magnetic angle difference. The distribution curve in Example 1 is a signal of a rotation of 30 degrees by selecting only part of the data when the encoder disk rotates. The difference is obtained by the difference of the magnetic angles of the inner and outer code channels: the inner and outer code channels have two groups of sensing points, each group has four (receiving Bx1, By1...Bx4, By4). In the process of the encoder disk rotating around the axis, the two groups of sensing points receive the magnetic field signals at their respective positions, and the magnetic field signals are respectively differentiated by two to obtain two differential magnetic field signals, and then a magnetic angle is obtained from the two differential magnetic field signals. The relationship between the magnetic angle difference signals of the inner and outer code channels and the rotation angle of the encoder is obtained by differentiating the two magnetic angles; since the inner and outer code channels differ by only one inductor coil, that is, they actually differ by a constant magnetic field of a pair of magnetic poles, the magnetic angle difference between the inner and outer code channels varies between 0 and 360 degrees, and the magnetic angle difference is unique when the encoder disk rotates to different angles, thereby distinguishing the absolute position of the encoder; In practical applications, the number of sensing points of the inner and outer ring magnetic sensors can be other numbers, and differential processing can be performed. In this embodiment, a multi-channel sensing point unit is used to obtain a differential signal with stronger anti-interference performance.

[0031] The magnetic sensor may also be a Hall sensor or a TMR sensor; two magnetic sensors may also be used to replace one sensor in Example 1, and placed above the inner and outer code channels respectively to sense the magnetic field signals of the inner and outer code channels. In this design, the difference in the magnetic angles of the inner and outer code channels may cause a certain error due to the difference in different magnetic sensors and installation tolerances; like Figure 5 As shown in FIG. 1 , it is a curve showing the difference between the output angle signals of the inner and outer code channels and the output angle in Example 1 of the high-precision absolute position magnetic encoder measurement system of the present invention; it can be seen from the figure that as the mechanical rotation angle of the encoder disk changes, the magnetic angle difference changes substantially linearly, and the exact absolute position of the encoder disk can be directly inferred from the curve.

[0032] Embodiment 2: like Figure 6 As shown, it is a top view of the relative position of the magnetic sensor and the encoding disk of Example 2 of the high-precision absolute position magnetic encoder measurement system of the present invention; the magnetic sensor chip is above the code track of the encoding disk, and the distance between the magnetic sensor and the encoding disk directly affects the magnitude of the magnetic field received by the magnetic sensor. The placement of the magnetic sensor can be changed according to actual conditions; in this Example 2, the magnetic sensor AMR and the CMOS circuit are highly integrated, with small errors and higher precision; In practical applications, the magnetic sensor can also be a Hall or TMR sensor; the magnetic sensor can be placed in a patch style or inserted from the side; for practical applications, it can be selected according to the actual space and orientation design; like Figure 6 As shown, it is a top view of the relative position of the magnetic sensor and the encoding disk of the embodiment 2 of the high-precision absolute position magnetic encoder measurement system of the present invention; the inductance coil of the encoding disk is divided into a left code channel and a right code channel, and the shape of the inductance coil is similar to a pulse wave " ", the left track contains 16 periodic coils, the right track contains 15, the left half circle is consistent with the right half circle in shape, but because the number is different by one, the width is slightly different: in this embodiment 2, the number of coils in the left track is 16, and the width of a single periodic coil is about 3.04mm, the number of coils in the right track is 15, and the width of a single periodic coil is 3.24mm;" " is a periodic coil, which includes an inner coil (opening toward the center of the circle) and an outer coil (opening away from the center of the circle). The inner coil and the outer coil form a complete periodic coil; In practical applications, the shape of the encoding disk may not be the “ "The shape can be an arc shape, but no matter what the specific shape is, it is the same as a shape containing an inner package and an outer package, and the width changes accordingly according to the number of coils in the left code channel and the right code channel; The inductance coils of the left and right code channels are continuous windings, and can share a lead end to apply power; the power supply can be a constant current source or a constant voltage source, or a power supply circuit that can provide a constant source; like Figure 7As shown in FIG. 1 , it is a schematic diagram of the magnetic field distribution after current is applied to the embodiment 2 of the high-precision absolute position magnetic encoder measurement system of the present invention; when a constant current is applied to the coil, according to the right-hand screw theorem, a magnetic field will be generated after the coil is energized. Since the current is constant, the direction of the magnetic field is also constant: since the coil is composed of two parts, the inner part, the magnetic field at the inner part of the coil is perpendicular to the paper surface and inward due to the direction of the current, (Of course, when the current is reversed, the magnetic field will change direction accordingly), and the magnetic field at the outer part is perpendicular to the paper surface and outward. It means that such a periodic coil forms a constant magnetic field with alternating directions under the action of a constant current; In the second embodiment of the present invention, the inductive coil encoder disk rotates around the axis, which is equivalent to the magnetic field with alternating directions rotating around the axis. The magnetic sensor receives the change signal of the magnetic field caused by the rotation of the encoder disk around the axis and outputs it in the form of magnetic angle. like Figure 8 As shown in FIG. 1 , it is a schematic diagram of the left code channel differential voltage signal in Embodiment 2 of the high-precision absolute position magnetic encoder measurement system of the present invention; Fig. 9 As shown in the figure, it is a schematic diagram of the output angles of the left and right code channels and the output angle difference signals in Example 2 of the high-precision absolute position magnetic encoder measurement system of the present invention; the curve in Example 2 is a partial signal intercepted when the encoder disk rotates by 30 degrees, and the magnetic angle is obtained by two differential magnetic field signals of the left code channel or the right code channel respectively: each magnetic sensor has four sensing points, which are receiving points for receiving external magnetic field signals. In the process of the encoder disk rotating around the axis, the four sensing points receive magnetic field signals at their respective positions, and the magnetic field signals are differentiated by two to obtain two differential magnetic field signals, and then a magnetic angle is obtained from the two differential magnetic field signals; the two magnetic angles obtained by the two magnetic sensors are differentiated, and the difference is the magnetic angle difference between the left code channel and the right code channel. When the encoder disk starts to rotate, the right code channel leads the left code channel, and the phase difference becomes larger and larger. After rotating 180 degrees, the right code channel begins to lag behind the left code channel, and the phase difference between the two varies between -360 and 360 degrees. When the encoder disk rotates to different angles, the magnetic angle difference is unique, thereby inferring the absolute position of the encoder.

[0033] As a preference, the number of sensing points of the left code channel and the right code channel magnetic sensors can be other numbers, and both can be subjected to differential processing, so that the differential signal obtained has stronger anti-interference performance; The absolute encoder measurement system proposed in the present invention can realize the detection of absolute position by using only one encoding disk, which is simple and accurate, and has lower cost. Moreover, the magnetic signals of two code channels (left code channel and right code channel) are collected by multiple sensing points respectively, and the anti-interference ability is stronger.

[0034] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. High-precision absolute position magnetic encoder measurement system, characterized by: The absolute position magnetic encoder measurement system includes a magnetic sensor, an encoding disk and a coil power supply; The encoding disk includes two code tracks; the two code tracks are coaxial and are both composed of periodic inductance coils continuously wound into a ring shape; The coil power supply is a circuit or element that can provide a constant power supply.

2. The high-precision absolute position magnetic encoder measurement system according to claim 1, characterized in that: The magnetic sensors are placed above the two code tracks of the encoder disk.

3. The high-precision absolute position magnetic encoder measurement system according to claim 2, characterized in that: When the encoding disk layout format is a left and right code channel, the left code channel is composed of m coils of the same shape, and the right code channel is composed of m-1 coils of the same shape. The coil shapes of the left and right code channels are similar, and only the size is slightly different due to the different number of coils in the left and right code channels and the width.

4. The high-precision absolute position magnetic encoder measurement system according to claim 3, characterized in that: When the layout format of the encoding disk is two code tracks, left and right, at least two magnetic sensors are selected and placed symmetrically.

5. The high-precision absolute position magnetic encoder measurement system according to claim 4, characterized in that: At least two magnetic sensors are selected and placed symmetrically, respectively at two ends of the same diameter of the encoding disk, with their spatial position angles differing by 180 degrees.

6. The high-precision absolute position magnetic encoder measurement system according to claim 2, characterized in that: When the encoding disk layout format is an inner and outer code channel, the outer code channel is composed of m coils of the same shape, and the inner code channel is composed of m-1 coils of the same shape. The coil shapes of the inner and outer code channels are similar, but due to the different numbers of coils in the inner and outer code channels and the difference in the inner and outer diameters, the widths are slightly different.

7. The high-precision absolute position magnetic encoder measurement system according to claim 6, characterized in that: When the layout format of the encoding disk is two code tracks, inner and outer, at least one magnetic sensor is selected and placed just above the inner and outer code tracks.

8. The high-precision absolute position magnetic encoder measurement system according to claim 7, characterized in that: When the layout format of the encoding disk is an inner and outer code channel, the position of the magnetic sensor spans the inner and outer code channels of the encoding disk, including two design schemes: one is to equip two groups of inner and outer sensing point units to respectively receive the magnetic field signals of the inner and outer code channels at the respective positions; the other is to select two magnetic sensors, each magnetic sensor is equipped with a group of sensing units to respectively sense the magnetic field signals of the inner and outer code channels.

9. The high-precision absolute position magnetic encoder measurement system according to any one of claims 1 to 8, characterized in that: The inductor coil in the encoding disk includes two parts of opposite shapes: one part is an inner package and the other part is an outer package. The inner package and the outer package form a complete periodic coil.

10. The high-precision absolute position magnetic encoder measurement system according to claim 9, characterized in that: The magnetic sensor can be selected from a single Hall sensor, an AMR sensor based on magnetoresistance effect, a TMR sensor, and a sensor integrating AMR, TMR, Hall and CMOS circuits.

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