Angle detection device

Abstract

To provide a high-resolution angle detection device based on a principle of a double-row magnetic encoder that has a high degree of freedom in design, can be miniaturized and made light, and can reduce manufacturing costs.SOLUTION: An angle detection device 4 includes: an encoder part 6 having magnetic tracks in which N and S poles are lined up alternately; and a magnetic sensor part 7 facing the magnetic tracks via a gap. In the magnetic tracks, a main track 2 having a magnetic pole width of P and a sub-track 3 having a magnetic pole width of Pn / (n-1) are provided adjacently and in parallel mutually along a longitudinal direction of a sheet-like encoder magnetic body 1 when a reference magnetic width and a reference magnetic pole logarithm are set to P and n, respectively. In the encoder part 6, the sheet-like encoder magnetic body 1 is fixed by winding around an outer peripheral part or an inner peripheral part of a rotor 5 with a length of a reference length of L=2Pn or smaller. The angle detection device 4 includes a correction calculation part 10 for correcting an absolute angle of the rotor by multiplying an absolute angle calculated by an operation part 9 of the magnetic sensor part 7 by a correction coefficient corresponding to the diameter of the encoder part 6.SELECTED DRAWING: Figure 4A

Description

Technical Field

[0001] The present invention relates to an angle detection device for detecting the rotation angle of a rotating shaft or the like, and particularly to an angle detection device for detecting an angle in the range of 360° or less with high resolution in order to position a robot joint or the like at a target position.

Background Art

[0002] Various magnetic encoder devices for detecting the rotation angle have been proposed. The magnetic encoder device disclosed in Patent Document 1 forms a cylindrical base portion from sintered metal, and performs sizing that presses the outer peripheral surface, inner peripheral surface, and both end surfaces of this base portion. Further, the base portion is inserted into a mold, and a resin material mainly composed of a thermoplastic resin and magnetic powder is injection-molded into the cavity. Then, a plurality of magnetic poles arranged in the circumferential direction are provided in the molded portion, and two magnetic encoder tracks having different numbers of magnetic pole pairs are formed by multipolar magnetization.

[0003] The magnetic encoder manufactured in this way is fixed to a rotating body, and a magnetic sensor is provided in proximity to and facing the magnetic encoder track. The magnetic sensor includes two detection elements and an arithmetic unit that face each of the two magnetic encoder tracks, and calculates the absolute angle of the rotating body with high resolution based on the phase difference of the magnetic signals detected by the two detection elements, and outputs it as a sensor output.

[0004] The magnetic encoder disclosed in Patent Document 2 includes a magnetic recording rotating body having a tape-shaped magnetic scale member in which N poles and S poles are alternately magnetized at equal pitches attached to the outer peripheral surface, and magnetic information detection means arranged in proximity to the magnetic recording rotating body. The magnetic information detection means includes two magnetic information detection elements arranged at intervals along the rotation direction of the magnetic recording rotating body. The magnetic information formed on the magnetic scale member is detected by the two magnetic information detection elements, and signals of phase A, phase B, and phase Z are generated from the detection outputs. Thereby, a highly accurate, highly reliable, and highly versatile magnetic encoder can be realized at a relatively low cost.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the disclosed technology of Patent Document 1, after integrally molding a plastic magnet on a press-worked sintered core metal, magnetization is performed so that the number of magnetized poles determined per rotation is obtained. In order to realize a high-resolution angle detection device using a multi-track magnetic encoder while satisfying constraints such as the available space and cost, it is necessary to use a mass-produced product in which the necessary functions of the magnetic sensor are packaged in one package.

[0007] For this reason, main specifications such as the pole width and the number of pole pairs are determined in advance, and it is impossible to respond to individual specifications. For example, when specifications such as the pole width and the number of pole pairs are determined, the diameter of the encoder part is determined by these specifications, so it cannot be manufactured with an arbitrary diameter, and the degree of freedom in design is limited. In addition, since each molded finished product is magnetized individually one by one, it is difficult to improve productivity. Furthermore, it is difficult to configure the molded product integrally with the rotating body, and since it is necessary to attach the magnetized product as a separate part, the rotating body becomes larger and the mass of the rotating body increases, which is also a problem. In addition, in order to manufacture a magnetic encoder device, it is necessary to manufacture a core metal mold and an injection molding mold for the plastic magnet, and there is a problem that the manufacturing cost becomes high.

[0008] The tape-shaped magnetic scale used in the disclosed technology of Patent Document 2 is lightweight and does not require a molding die or the like, so it can address the above problems. However, regarding the improvement of the resolution, nothing is shown. Further, although both ends of the magnetic scale member attached partially around the circumference can be detected by the Z-phase signal, the A-phase or B-phase signal is not output in the state where the ends of the magnetic scale member are detected. For this reason, for example, when using the angle detection signal for control of a rotating device or the like, there is a problem that a normal control method cannot be used.

[0009] An object of the present invention is to solve the above problems, and to provide a high-resolution angle detection device based on the principle of a multi-track magnetic encoder that has a high degree of design freedom, can be miniaturized and lightened, and can reduce the manufacturing cost.

Means for Solving the Problems

[0010] The angle detection devices 4, 4A, 4B of the present invention are angle detection devices including encoder parts 6, 6A, 6B having magnetic tracks in which N poles and S poles are alternately arranged, and a magnetic sensor part 7 facing the magnetic tracks with a gap δ therebetween, When the magnetic tracks have a reference magnetic pole width P and a reference number of magnetic pole pairs n, a main track 2 having a magnetic pole width of P and a sub-track 3 having a magnetic pole width of Pn / (n - 1) are provided adjacent to each other and parallel to each other along the longitudinal direction of the sheet-shaped magnetic body 1 for the encoder. The encoder parts 6, 6A, 6B are such that the sheet-shaped magnetic body 1 for the encoder is wound around and fixed to the outer peripheral part or the inner peripheral part of the rotating bodies 5, 5A, 5B with a length of a reference length L = 2Pn or less, The magnetic sensor part 7 includes two magnetic detection elements 8 that output magnetic signals facing the main track 2 and the sub-track 3 respectively, and an arithmetic unit 9 that calculates the absolute angle of the rotating bodies 5, 5A, 5B based on the magnetic signals of these magnetic detection elements 8, A correction calculation unit 10 is provided that corrects the absolute angle of the rotating bodies 5, 5A, 5B by multiplying the calculated absolute angle by a correction coefficient corresponding to the diameter of the encoder parts 6, 6A, 6B.

[0011] According to this configuration, the sheet-shaped encoder magnetic body 1 is wound around and fixed to the outer peripheral portion or the inner peripheral portion of the rotors 5, 5A, and 5B and used as the encoder units 6, 6A, and 6B of the angle detection devices 4, 4A, and 4B. Therefore, even if the diameter of the encoder unit changes, there is no need to manufacture a mold, and encoder units 6, 6A, and 6B with an arbitrary diameter can be easily manufactured. The calculation unit 9 can calculate the absolute angle of the rotors 5, 5A, and 5B with high resolution based on the magnetic signals of the two magnetic detection elements 8. The correction calculation unit 10 multiplies the calculated absolute angle by a correction coefficient corresponding to the diameter of the encoder units 6, 6A, and 6B, so that even when the diameter of the encoder unit is not L / π, the absolute angle of the rotors 5, 5A, and 5B having a circumferential length L can be accurately detected with high resolution. Further, if the existing rotating parts 11A, 11B, and 11C are used as the rotors, there is no need to add an encoder of a separate member, and the structure of the angle detection device can be simplified and made smaller and lighter.

[0012] When the encoder magnetic body 1 of the reference length L is cut to an arbitrary length and the diameter of the encoder units 6, 6A, and 6B wound around the outer peripheral portion or the inner peripheral portion of the rotors 5, 5A, and 5B is S, the correction calculation unit 10 may use L / (πS), which is obtained by dividing the reference length L by the value obtained by multiplying the diameter S by the pi π, as the correction coefficient. When the diameter of the encoder units 6, 6A, and 6B is a diameter S that is not equal to L / π, the sensor output output from the magnetic sensor unit 7 is different from the actual angle, but an accurate angle can be obtained by multiplying the sensor output by L / (πS) as the correction coefficient.

[0013] The encoder units 6, 6A, and 6B are provided, in which the encoder magnetic body 1, in which the lengths L1 of the main track 2 and the sub-track 3 are less than or equal to the reference length L, is wound around and fixed to the outer peripheral portion or the inner peripheral portion of the rotors 5, 5A, and 5B having a circumferential length longer than the length L1. A limit angle storage unit 12 that stores limit angles corresponding to the outputs of the magnetic sensor unit 7 at both ends of the magnetic track, and a detection range determination unit 13 that determines whether the absolute angle output from the magnetic sensor unit 7 is within the range of the limit angle and outputs an identification signal indicating whether the limit angle has been exceeded may be provided.

[0014] According to this configuration, when an identification signal indicating that the limit angle has been exceeded is output, if the rotation is stopped, a normal sensor signal indicating the absolute angle is output, so that an operation to avoid a detection impossible region can be performed by a normal control method.

[0015] The rotating bodies 5, 5A, and 5B may be rotating parts 11A, 11B, and 11C of a robot joint. When detecting the absolute angle of a robot joint, the required angle detection range is often less than 360°. In that case, if the joint of the magnetic body 1 for the encoder is arranged at a position where angle detection is not required, the influence of the joint can be avoided and an angle detection device can be established. Further, if the existing rotating parts 11A, 11B, and 11C of the robot joint are used as the rotating body and the magnetic body 1 for the encoder is directly wound and fixed to the rotating parts 11A, 11B, and 11C, there is no need to attach an encoder of a separate member, and the robot joint can be made smaller and lighter.

Effects of the Invention

[0016] The angle detection device of the present invention is an angle detection device including an encoder unit having a magnetic track in which N poles and S poles are arranged alternately, and a magnetic sensor unit facing the magnetic track with a gap therebetween. When the magnetic track has a reference magnetic pole width P and a reference number of magnetic pole pairs n, along the longitudinal direction of the sheet-shaped magnetic material for the encoder, a main track having a magnetic pole width of P and a sub-track having a magnetic pole width of Pn / (n - 1) are provided adjacent to each other and parallel to each other. The encoder unit has the sheet-shaped magnetic material for the encoder wound around and fixed to the outer peripheral portion or the inner peripheral portion of the rotating body with a length of a reference length L = 2Pn or less. The magnetic sensor unit includes two magnetic detection elements that output magnetic signals facing the main track and the sub-track respectively, and a calculation unit that calculates the absolute angle of the rotating body based on the magnetic signals of these magnetic detection elements, and includes a correction calculation unit that corrects the absolute angle of the rotating body by multiplying the calculated absolute angle by a correction coefficient corresponding to the diameter of the encoder unit. Therefore, it is possible to obtain a high-resolution angle detection device based on the principle of a multi-row magnetic encoder, which has a high degree of design freedom, can be miniaturized and lightened, and can reduce manufacturing costs.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiment for Carrying Out the Invention

[0018] [First Embodiment] The angle detection device according to the embodiment of the present invention will be described with reference to FIGS. 1 to 5. As shown in FIGS. 1 and 3, the angle detection device 4 includes an encoder section 6 having a magnetic track and a magnetic sensor section 7 facing the magnetic track with a gap δ therebetween. As shown in FIG. 2, the encoder section 6 has a magnetic track in which N poles and S poles are arranged alternately. When the magnetic track has a reference magnetic pole width P and a reference number of magnetic pole pairs n, a main track 2 having a magnetic pole width (circumferential width) of P and a sub-track 3 having a magnetic pole width of Pn / (n - 1) are provided adjacent to each other and parallel to each other along the longitudinal direction of the sheet-shaped encoder magnetic body 1. As shown in FIG. 1, in the encoder section 6, the sheet-shaped encoder magnetic body 1 is wound around and fixed to the cylindrical outer peripheral portion 5a of the rotating body 5 with a length equal to or less than the reference length L.

[0019] The encoder magnetic body 1 shown in FIG. 2 is produced, for example, by vulcanizing a rubber material mixed with magnetic powder into a sheet shape, cutting it to a required length, and then magnetizing the N poles and S poles alternately in the longitudinal direction with a predetermined magnetic pole width determined by the reference magnetic pole width P and the reference number of magnetic pole pairs n to form a magnetic track having the main track 2 and the sub-track 3. Alternatively, a sheet that has been magnetized to completion with a length suitable for conditions such as production equipment or availability of materials may be cut to the required length according to the application. Also, L = 2Pn is used as the reference length.

[0020] For example, when the reference magnetic pole width P is 2 mm and the reference number of magnetic pole pairs n is 32 pole pairs, the magnetization width (magnetization pitch) p 2 (=P) of the main track 2 is 2 mm, and the magnetization width p of the sub-track 33 (=Pn / (n - 1)) is 2.0645 mm. When detecting the absolute angle of 360° with the standard accuracy of the magnetic sensor, the number of magnetization pole pairs (number of pole pairs) n of the main track 2 2 (=n) is 32 pole pairs (64 poles in total for N poles and S poles), and the number of magnetization pole pairs n of the sub - track 3 3 (=n - 1) is 31 pole pairs (62 poles in total for N poles and S poles). The length of the magnetic track at this time is the reference length L, and L = 2Pn = 128 mm.

[0021] Here, the main track 2 of the magnetic body 1 for the encoder has a magnetization width of 2 mm and 32 pole pairs, and the sub - track 3 has a magnetization width of 2.0645 mm and 31 pole pairs. However, the pole specifications of the magnetic body for the encoder can be appropriately selected according to the magnetic sensor to be used.

[0022] The angle detection device 4 shown in FIG. 1 includes an encoder unit 6 in which a magnetic body 1 for an encoder is adhered or fixed to the outer peripheral portion 5a of a rotating body 5 with double - sided tape or the like, and a magnetic sensor unit 7. A hole 5b is formed at the center of the rotating body 5, and a rotating shaft (not shown) is inserted into the hole 5b so as not to be relatively rotatable with respect to the rotating body 5. Note that the rotating shaft may be provided integrally with the rotating body 5. The term "integrally" means that the rotating shaft and the rotating body 5 are not formed by combining a plurality of elements, but are formed as a part or the whole of a single object from a single material, for example, by forging, machining, etc.

[0023] As shown in FIG. 4(A), the magnetic sensor unit 7 includes two magnetic detection elements 8 that output magnetic signals facing the main track 2 and the sub - track 3 from the outside in the radial direction of the rotating body 5, respectively, and an arithmetic unit 9 that calculates the absolute angle of the rotating body 5 with high resolution based on the phase difference of the magnetic signals detected by these magnetic detection elements 8 and outputs it as a sensor output.

[0024] As shown in FIG. 2, when an encoder magnetic body 1 having a length L with a magnetic track of a reference length L provided over the entire length is wound one turn around the outer peripheral portion 5a of a rotating body 5 as shown in FIG. 1 to fabricate an encoder portion 6 having a diameter of L / π, as shown in FIGS. 4(A) and 5, the arithmetic unit 9 utilizes the fact that the phase difference (FIG. 5(C)) between the signal obtained from the main track 2 (FIG. 5(A)) and the signal obtained from the sub-track 3 (FIG. 5(B)) becomes one pole pair per rotation, and can detect the absolute angle with standard accuracy.

[0025] In addition, when the encoder magnetic body 1 provided with the magnetic track of the reference length L shown in FIG. 2 is cut so that the length of the magnetic track becomes shorter than the reference length L and wound around the rotating body 5 shown in FIG. 1, even if there is a gap (circumferential gap) at the joint T between one end and the other end in the longitudinal direction of the encoder portion 6, if the diameter of the encoder portion 6 is L / π, the absolute angle can be detected with the standard accuracy of the magnetic sensor within the range where the encoder magnetic body 1 is fixed.

[0026] FIG. 5(A) is a waveform of a detection signal corresponding to the main track 2, and FIG. 5(B) is a waveform of a detection signal corresponding to the sub-track 3. FIG. 5(C) shows a waveform of an output signal of the phase difference obtained by the arithmetic unit 9 (FIG. 4A) based on the detection signals of FIGS. 5(A) and (B). The arithmetic unit 9 (FIG. 4A) performs a process of converting the obtained phase difference into an absolute angle according to preset calculation parameters. The calculation parameters are stored, for example, in a storage means Mr such as a non-volatile memory provided in the magnetic sensor unit 7 shown in FIG. 4(A). In addition to the calculation parameters, information necessary for the operation of the device, such as the reference magnetic pole width P of the magnetic track, the reference magnetic pole pair number n, the magnetization pole pair numbers of each of the tracks 2 and 3, and the signal output method, is stored in the storage means Mr in a rewritable manner.

[0027] This angle detection device 4 includes a correction calculation unit 10 at a subsequent stage of the arithmetic unit 9. The correction calculation unit 10 corrects the absolute angle of the rotating body 5 by multiplying the absolute angle output from the arithmetic unit 9 by a correction coefficient corresponding to the diameter of the encoder portion 6. When the magnetic body 1 for the encoder with the reference length L is cut to an arbitrary length and the diameter of the encoder unit 6 wound around the outer peripheral portion 5a (FIG. 1) of the rotating body 5 is S, the correction calculation unit 10 uses the value L / (πS) obtained by dividing the reference length L by the value obtained by multiplying the diameter S by the pi (π) as the correction coefficient.

[0028] When the diameter of the encoder unit 6 is not equal to L / π, the sensor output output from the magnetic sensor is different from the actual angle, but an accurate angle can be obtained by multiplying the sensor output by the correction coefficient. When the diameter of the encoder unit 6 is set as S as described above, the absolute angle output from the calculation unit 9 may be multiplied by the correction coefficient L / (πS). The correction calculation unit 10 includes a storage function for storing the correction coefficient and a calculation function, and executes correction calculation according to the calculation function using the stored correction coefficient. In this example, the correction calculation unit 10 is provided at the subsequent stage of the calculation unit 9 in the magnetic sensor unit 7, but the correction calculation unit 10 may be provided in the calculation unit 9. Further, as shown in FIG. 4(B), the correction calculation unit 10 may be provided as a dedicated circuit in the vicinity of the magnetic sensor unit 7, and although not shown, the correction calculation unit may be included in a higher-level control unit.

[0029] <Function and effect> According to the angle detection device 4 described above, the sheet-shaped magnetic body 1 for the encoder shown in FIG. 1 is wound around and fixed to the outer peripheral portion 5a of the rotating body 5 and used as the encoder unit 6 of the angle detection device 4. Therefore, even if the diameter of the encoder unit 6 changes, there is no need to manufacture a mold, and an encoder unit 6 with an arbitrary diameter can be easily manufactured. The calculation unit 9 can calculate the absolute angle of the rotating body 5 with high resolution based on the magnetic signals of the two magnetic detection elements 8. The correction calculation unit 10 can accurately detect the absolute angle of the rotating body 5 with high resolution even when the diameter of the encoder unit 6 is not L / π by multiplying the calculated absolute angle by a correction coefficient corresponding to the diameter of the encoder unit 6. Further, if an existing rotating part is used as the rotating body 5, there is no need to add an encoder of a separate member, and the structure of the angle detection device 4 can be simplified and made smaller and lighter.

[0030] <Regarding other embodiments> In the following description, parts corresponding to matters already described in each embodiment are denoted by the same reference numerals, and redundant descriptions are omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those in the form described previously unless otherwise specified. The same configuration exhibits the same operational effects. Not only combinations of parts specifically described in each embodiment, but also partial combinations of the embodiments are possible as long as there is no problem with the combination.

[0031] [Second Embodiment] FIG. 6 is a diagram showing a configuration example of an angle detection device 4A when the diameter of the encoder section is different from L / π. FIG. 7 is a block diagram of a correction calculation section 10 of the angle detection device. When the diameter of the encoder section in which the encoder magnetic body of the reference length L is wound around the rotating body is different from L / π, the sensor output output from the magnetic sensor section is different from the actual angle. In that case, if a correction calculation section 10 is provided in the angle detection device 4A and the sensor output is multiplied by a correction coefficient, an accurate absolute angle can be obtained.

[0032] FIG. 6 shows an angle detection device 4A in which an encoder magnetic body 1 of length L provided with a magnetic track of reference length L over its entire length is cut in half to length L / 2 and wound around the outer peripheral portion 5Aa of a rotating body 5A in one circumferential direction to form an encoder section 6A capable of detecting an absolute angle of 360° with a diameter of L / (2π). Since the outer peripheral length of the encoder section 6A is half of the reference length L, the detection output of the absolute angle output from the magnetic sensor section 7 is half of the actual angle. Therefore, if the correction calculation section 10 shown in FIG. 7 is provided and the sensor output is multiplied by a correction coefficient of "2", the actual absolute angle can be obtained.

[0033] [Third Embodiment] FIG. 8 shows an angle detection device 4B in which the encoder magnetic body 1 is wound around a part of the outer peripheral portion 5Ba of a rotating body 5B and there is a large gap between one longitudinal end and the other end of the encoder section 6B. Even when the diameter S of the encoder section 6B is not L / π (S≠L / π), the actual absolute angle can be detected by performing correction calculation of the sensor output by the correction calculation section 10 of FIG. 7 described above.

[0034] For example, when detecting the absolute angle of a robot joint or the like, the required angle detection range is often less than one rotation (360°), and there may be joints or gaps in the magnetic body for the encoder. In that case, if the joint or gap in the magnetic body for the encoder is arranged at a position where angle detection is not required, the absolute angle can be detected while avoiding the influence of the joint or gap. The robot joint shown in FIG. 10 is required to be small and lightweight. However, after cutting the magnetic body 1 for the encoder (FIG. 2) to the required length, the rotating parts 11A, 11B, 11C such as the annular parts of the existing robot joint are used as the rotating body, and the magnetic body 1 for the encoder is directly wound around the outer peripheral parts of the respective rotating parts 11A, 11B, 11C to form the angle detection device 4B. In this way, there is no need to attach an encoder as a separate member, and the robot joint can be miniaturized and lightened.

[0035] As in the example of FIG. 8, when the magnetic track is shorter than the outer peripheral part 5Ba of the rotating body 5B, in order to avoid a situation where the magnetic track does not exist at the position facing the magnetic sensor part 7 and the current position of the rotating body 5B cannot be detected, it is necessary to detect both ends of the magnetic track. Since the angle detection device 4B of the present embodiment can detect the absolute angle just by turning on the power supply, as shown in FIG. 9, it is provided with a limit angle storage part 12 that stores the angles (limit angles) output from the magnetic sensor part at both ends of the magnetic track. Further, a detection range determination part 13 is provided that compares the content of the limit angle storage part 12 with the sensor output to determine whether the magnetic sensor part is within the range of the limit angle and outputs an identification signal.

[0036] That is, the angle detection device 4B in FIG. 8 includes an encoder unit 6B in which an encoder magnetic body 1 with the lengths L1 of the main track and the sub-track being less than or equal to the reference length L is wound and fixed to the outer peripheral portion 5Ba of a rotating body 5B having a circumference longer than the length L1. In this case, the angle detection device 4B includes a limit angle storage unit 12 in FIG. 9 that stores the limit angles corresponding to the outputs of the magnetic sensor units 7 at both ends of the magnetic track, and a detection range determination unit 13 that determines whether the absolute angle output from the magnetic sensor unit 7 is within the range of the limit angles and outputs an identification signal indicating whether the limit angle has been exceeded.

[0037] According to this configuration, if rotation is stopped when an identification signal indicating that the limit angle has been exceeded is output, since a normal sensor signal indicating the absolute angle is being output, an operation to avoid the undetectable region can be performed using a normal control method. Also, in the limit angle storage unit 12, if the limit angle is set with a margin of 1 to several magnetic pole pairs from both ends of the magnetic track, the reliability of the operation can be increased.

[0038] A sheet-shaped encoder magnetic body may be wound and fixed to the inner peripheral portion of a cylindrical rotating body. Each angle detection device can be used not only for robot joints but also, for example, for wheel bearings, steering devices, precision positioning devices, machine tools, industrial machines, etc. As described above, the embodiments for implementing the present invention based on the embodiments have been described. However, the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Description of Reference Numerals

[0039] 1... Encoder magnetic body, 2... Main track, 3... Sub-track, 4, 4A, 4B... Angle detection device, 5, 5A, 5B... Rotating body, 6, 6A, 6B... Encoder unit, 7... Magnetic sensor unit, 8... Magnetic detection element, 9... Arithmetic unit, 10... Correction calculation unit, 11A, 11B, 11C... Rotating parts, 12... Limit angle storage unit, 13... Detection range determination unit

Claims

1. An angle detection device comprising an encoder unit having magnetic tracks in which N poles and S poles are arranged alternately, and a magnetic sensor unit facing the magnetic tracks with a gap therebetween, wherein when the magnetic tracks have a reference magnetic pole width P and a reference number of magnetic pole pairs n, a main track having a magnetic pole width of P and a sub-track having a magnetic pole width of Pn / (n - 1) are provided adjacent to each other and parallel to each other along the longitudinal direction of a sheet-shaped magnetic body for an encoder, and the encoder unit has the sheet-shaped magnetic body for an encoder wound and fixed around the outer peripheral portion or the inner peripheral portion of a rotating body with a length of a reference length L = 2Pn or less, the magnetic sensor unit includes two magnetic detection elements that output magnetic signals facing the main track and the sub-track respectively, and an arithmetic unit that calculates the absolute angle of the rotating body based on the magnetic signals of these magnetic detection elements, An angle detection device comprising a correction calculation unit that corrects the absolute angle of the rotating body by multiplying the calculated absolute angle by a correction coefficient corresponding to the diameter of the encoder unit.

2. The angle detection device according to claim 1, wherein when the magnetic body for an encoder having the reference length L is cut to an arbitrary length and the diameter of the encoder unit wound around the outer peripheral portion or the inner peripheral portion of the rotating body is S, the correction calculation unit uses, as the correction coefficient, a value L / (πS) obtained by dividing the reference length L by a value obtained by multiplying the diameter S by the circumference ratio π.

3. The angle detection device according to claim 1 or claim 2, comprising the encoder unit in which the magnetic body for an encoder having a length L1 of the main track and the sub-track equal to or less than the reference length L is wound and fixed around the outer peripheral portion or the inner peripheral portion of the rotating body having a circumference longer than the length L1, a limit angle storage unit that stores limit angles corresponding to the outputs of the magnetic sensor unit at both ends of the magnetic track, and a detection range determination unit that determines whether or not the absolute angle output from the magnetic sensor unit is within the range of the limit angle and outputs an identification signal indicating whether or not the limit angle has been exceeded.

4. The angle detection device according to any one of claims 1 to 3, wherein the rotating body is a rotating component of a robot joint.

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