JPWO2016068302A1 - Encoder device, drive device, stage device, robot device, and multi-rotation information calculation method - Google Patents

Abstract

An encoder apparatus capable of obtaining multi-rotation information with a simple configuration is provided. An encoder device (EC) includes a first encoder (1) that detects a rotational position of a first shaft (AX1), and a second shaft that rotates at a constant speed ratio with respect to the first shaft (AX1). The second encoder (2) for detecting the rotational position of (AX2), the arithmetic processing based on the rotational position detected by the first encoder (1) and the rotational position detected by the second encoder (2), and the calculation result And a detector (4) for detecting multi-rotation information of the first axis (AX1).

Description

  The present invention relates to an encoder device, a drive device, a stage device, a robot device, and a multi-rotation information calculation method.

  An encoder device that detects multi-rotation information including information on the number of rotations is mounted on various devices such as a robot device. For example, the robot apparatus may require multi-rotation information for starting control, and the multi-rotation type encoder apparatus is required to hold the multi-rotation information when the robot apparatus is stopped.

  In general, an encoder device includes a storage unit that holds multi-rotation information and a battery that supplies power to the storage unit in a state where power supply from the outside is cut off. Such an encoder device requires replacement of the battery, and may increase the frequency of maintenance. Therefore, an encoder device that does not require a battery has also been proposed (see, for example, Patent Document 1 and Patent Document 2 below).

  The encoder device of Patent Document 1 calculates multi-rotation information based on a combination of the tooth number of the main driving gear and the tooth number of the driven gear. The encoder device of Patent Document 2 includes a first code disk, a second code disk, and a third code disk. For example, the second code disk rotates 1/64 of the first code disk, and the third code disk rotates 1/64 of the second code disk. This encoder device obtains position information by counting the codes of the second code disk and the third code disk when the first code disk exceeds one rotation.

Japanese Patent Laid-Open No. 10-47996 JP 2013-164316 A

  The encoder apparatus as described above is desired to obtain multi-rotation information with a simple (simple) configuration.

  According to the first aspect of the present invention, the first encoder that detects the rotational position of the first shaft, and the second encoder that detects the rotational position of the second shaft that rotates at a constant gear ratio with respect to the first shaft. And a detection unit that performs calculation processing based on the rotation position detected by the first encoder and the rotation position detected by the second encoder, and detects multi-rotation information of the first axis based on the calculation result. Is provided.

  According to the second aspect of the present invention, the encoder device according to the first aspect, the power supply unit that supplies power to the first shaft or the second shaft, and the number of rotations detected by the detection unit of the encoder device are used. Thus, a driving device is provided that includes a control unit that controls the power supply unit.

  According to a third aspect of the present invention, there is provided a stage apparatus including a moving object and a driving apparatus according to the second aspect that moves the moving object.

  According to a fourth aspect of the present invention, there is provided a robot apparatus including the driving device according to the second aspect, and a first arm and a second arm that are relatively moved by the driving device.

  According to the fifth aspect of the present invention, the step of detecting the rotational position of the first shaft by the first encoder, and the rotational position of the second shaft rotating at a constant speed ratio with respect to the first shaft are determined by the second encoder. And a step of performing calculation processing based on the rotational position detected by the first encoder and the rotational position detected by the second encoder, and detecting multi-rotation information of the first axis based on the calculation result. A multi-rotation information calculation method is provided.

It is a figure which shows the encoder apparatus which concerns on this embodiment. It is a figure for demonstrating the calculation process of the multi-rotation information which concerns on this embodiment. It is a figure for demonstrating the calculation process of the multi-rotation information in case of N = 2. It is a flowchart which shows operation | movement of the encoder apparatus which concerns on this embodiment. It is a figure which shows the encoder apparatus of a modification. It is a figure which shows the encoder apparatus which concerns on this embodiment. It is a figure for demonstrating the calculation process and correction process which concern on this embodiment. It is a figure which shows the drive device which concerns on this embodiment. It is a figure which shows the stage apparatus which concerns on this embodiment. It is a figure which shows the robot apparatus which concerns on this embodiment.

[First Embodiment]
Embodiments will be described. FIG. 1A is a diagram illustrating an encoder device EC according to the present embodiment, and FIG. 1B is a block diagram illustrating a functional configuration of the encoder device EC. The encoder device EC includes a first encoder 1, a second encoder 2, a transmission unit 3, a detection unit 4, and a casing 5.

  The casing 5 accommodates each part of the encoder device EC. The casing 5 includes a box-shaped main body 10, a lid 11 that closes the opening of the main body 10, and a partition wall 12 and a partition wall 13 that are attached to the inner wall of the main body 10. The lid portion 11 is, for example, a plate-like member, and has an opening 11a through which the first axis AX1 is inserted. The first axis AX1 is, for example, an output shaft (eg, main driving shaft) of an electric motor. The first axis AX1 may be an axis that is connected to the output shaft of the electric motor and rotates together with the output shaft. The partition wall 12 is, for example, a plate-like member, and is provided substantially parallel to the lid 11 at a position away from the bottom of the main body 10. The partition wall 13 is, for example, a plate-like member, and is provided between the partition wall 12 and the lid 11 so as to be substantially parallel to the lid 11. The partition wall 13 has an opening 13a through which the first axis AX1 is inserted.

  The 1st encoder 1 is arrange | positioned between the partition part 12 and the partition part 13, for example. The first encoder 1 detects a rotational position (angular position) within one rotation of the first axis AX1. In the following description, the rotational position of the first axis AX1 is represented by reference sign θ1 (deg). θ1 takes a value between 0 ° and less than 360 °. For example, when the first axis AX1 rotates 365 °, θ1 becomes 5 °. The first encoder 1 is, for example, a reflective optical encoder. The first encoder 1 may be a transmissive optical encoder, or may be a magnetic encoder.

  The first encoder 1 includes a scale Sa and an encoder head 15. The scale Sa is provided on the disc 16 fixed to the first axis AX1. The scale Sa includes an incremental scale and an absolute scale. The encoder head 15 is provided, for example, at a position facing the partition wall 12 and the scale Sa. The encoder head 15 includes, for example, a light emitting element that irradiates light to the scale Sa, and a light receiving element that detects light emitted from the light emitting element and passing through the scale Sa. When the encoder is a magnetic encoder, the encoder head includes, for example, a magnet (magnetic field generation unit) and a magnetic detection element.

  The encoder head 15 detects the rotational position of the first axis AX1 based on a signal indicating the detection result of the light receiving element. For example, the encoder head 15 detects the rotational position of the first resolution using the result of detecting the light from the absolute scale. Further, the encoder head 15 detects the rotational position of the second resolution higher than the first resolution by performing an interpolation operation on the rotational position of the first resolution using the result of detecting the light from the incremental scale. . The encoder head 15 supplies rotation information including the detected rotation position of the first axis AX1 to the detection unit 4.

  The first axis AX1 is connected to the second axis AX2 via the transmission unit 3. For example, the second axis AX2 is disposed substantially parallel to the first axis AX1. The transmission unit 3 includes a plurality of gears (gear 17a, gear 17b, gear 17c, and gear 17d) disposed between the partition wall 12 and the partition wall 13. The transmission unit 3 may include two or more types of gears, timing belts, timing pulleys, chains, and sprockets.

  The gear 17a is fixed to the first shaft AX1, and the number of teeth is M1. The gear 17b is meshed with the gear 17a, and the number of teeth is M2. The gear 17b is fixed to the third axis AX3. The third axis AX3 is supported by the partition wall 12 and the partition wall 13 via the bearing 18. The gear 17c is fixed to the third axis AX3, and the number of teeth is M3. The gear 17d is meshed with the gear 17c, and the number of teeth is M4. The gear 17d is fixed to the second axis AX2.

The transmission gear ratio Gr of the transmission unit 3 is the number of rotations of the second axis AX2 with respect to the number of rotations of the first axis AX1. The gear ratio Gr is set to Gr = 1 + 1 / N or Gr = 1−1 / N using a real number N of 2 or more. The gear ratio Gr is expressed by the following equation (1) using, for example, the number of teeth of the gears 17a to 17d.
Gr = M1 / M2 × M3 / M4 (1)

  For example, when M1 = 45, M2 = 32, M3 = 57, and M4 = 80, Gr = 513/512. In this case, the transmission unit 3 is an accelerator in which the second axis AX2 is faster than the first axis AX1, and is set to Gr = 1 + 1 / N (for example, N = 512). The transmission unit 3 may be a speed reducer in which the second axis AX2 is slower than the first axis AX1, and in this case, Gr = 1−1 / N.

  Note that the number of rotations (gear ratio) of the third axis AX3 with respect to the number of rotations of the first axis AX1 is M1 / M2. For example, when M1 = 45 and M2 = 32, the gear ratio of the third axis AX3 is larger than 1, and the gear 17a and the gear 17b are acceleration units in which the second axis AX2 side is faster than the first axis AX1 side. Configure. Further, the number of rotations (gear ratio) of the second axis AX2 with respect to the number of rotations of the third axis AX3 is M3 / M4. For example, when M3 = 57 and M4 = 80, the speed change ratio of the third axis AX3 is smaller than 1, and the gear 17c and the gear 17d are the speed reduction unit in which the speed of the second axis AX2 is lower than the first axis AX1. Configure.

  The second encoder 2 is disposed between the partition wall 12 and the partition wall 13, for example. The second encoder 2 detects a rotational position (angular position) within one rotation of the second axis AX2. In the following description, the rotational position of the second axis AX2 is represented by the symbol θ2. The second encoder 2 is, for example, a reflective optical encoder. The second encoder 2 may be a transmissive encoder or a magnetic encoder.

  The second encoder 2 has the same configuration as the first encoder 1, for example, and includes a scale Sb and an encoder head 20. The scale Sb is provided on the disc 21 fixed to the second axis AX2. For example, the scale Sb is arranged on the same plane as the scale Sa of the first encoder 1. For example, the encoder head 20 is provided on the partition wall 12 at a position facing the scale Sb. The encoder head 20 irradiates the scale Sb with light, detects the light passing through the scale Sb, and detects the rotational position of the second axis AX2. The light emitting element of the encoder head 20 may be shared with the light emitting element of the encoder head 15. The encoder head 20 supplies rotation information including the detected rotation position of the second axis AX2 to the detection unit 4. When the encoder is a magnetic encoder, the encoder head includes, for example, a magnet (magnetic field generation unit) and a magnetic detection element.

  The detection unit 4 is a controller of the encoder device EC, for example. For example, it is disposed between the bottom of the casing 5 and the partition wall 12. The detection unit 4 calculates a difference value (hereinafter referred to as Δθ) between the rotational position detected by the first encoder 1 and the rotational position detected by the second encoder 2. The rotational position difference value Δθ is expressed by, for example, Δθ = θ1−θ2. The detection unit 4 detects multi-rotation information including the number of rotations of the first axis AX1 based on the calculation result (Δθ). The number of rotations is information represented by an integer such as one rotation and two rotations.

  The multi-rotation information includes, for example, a data string in which the number of rotations of the encoder is represented by a first number of bits and a data string in which a rotation position (for example, an angular position and a rotation angle) is represented by a second number of bits. The multi-rotation information is a data string in which a value obtained by multiplying the number of rotations by a rotation angle of one rotation and a rotation position (hereinafter referred to as a multi-rotation conversion rotation position) is represented by a predetermined number of bits. May be included. The rotation position in terms of multiple rotations is a rotation position that takes into account the number of rotations. The number of rotations of the first axis AX1 may be represented by a rotation position in terms of multiple rotations. For example, when the number of rotations is 1 rotation and the rotation position is 180 °, the rotation position in terms of multiple rotations is 540 °. Further, when the rotation position in terms of multi-rotation is 540 °, the number of rotations is 1.5.

  The detection unit 4 may detect multi-rotation information in which the number of rotations and the rotation position are represented by different data strings, or may detect multi-rotation information represented by a multi-rotation conversion rotation position. Good. The rotation angle of one rotation is 360 ° in a dimensional unit and 2π (rad) in a dimensionless unit. The detection unit 4 may handle an angle of a dimensional unit, or may handle an angle of a dimensionless unit.

  As illustrated in FIG. 1B, the detection unit 4 includes a calculation unit 25, a storage unit 26, and a control unit 27. The arithmetic unit 25 is an arithmetic circuit including, for example, an adder, a difference unit, a multiplier, a divider, and the like. The computing unit 25 calculates the difference value Δθ of the rotational position based on the detection results of the first encoder 1 and the second encoder 2. The computing unit 25 compares the calculated rotational position difference value Δθ with predetermined comparison information to detect multi-rotation information of the first axis AX1. The comparison information includes information indicating the number of rotations of the first axis AX1 with respect to the rotation position difference value. The comparison information is, for example, information indicating the relationship between the rotational position difference value calculated from the gear ratio and the multi-rotation converted rotational position.

  The storage unit 26 stores comparison information, and the calculation unit 25 uses the comparison information stored in the storage unit 26 to calculate the number of rotations of the first axis AX1. The storage unit 26 is, for example, a non-volatile memory such as a flash memory or a ROM (Read Only Memory), and does not consume power for holding comparison information.

  The control unit 27 controls each unit of the encoder device EC. For example, the control unit 27 controls the first encoder 1 and the second encoder 2 to cause the first encoder 1 and the second encoder 2 to perform detection operations almost simultaneously. The control unit 27 also controls the calculation unit 25 to cause the calculation unit 25 to calculate multi-rotation information of the first axis AX1 based on the detection result of the first encoder 1 and the detection result of the second encoder 2. The control unit 27 outputs the calculation result of the calculation unit 25 to, for example, a motor control unit that controls the electric motor connected to the first axis AX1.

  Next, multi-rotation information calculation processing by the calculation unit 25 will be described. FIG. 2A to FIG. 2C are diagrams for explaining multi-rotation information calculation processing. In each drawing of FIG. 2, the vertical axis represents the rotational position θ1 of the first axis AX1, the rotational position θ2 of the second axis AX2, and the difference values (eg, Δθ, θ3, θ4). In each drawing of FIG. 2, the horizontal axis represents the rotational position θ (°) in terms of multiple rotations of the first axis AX1. For example, when the reference position on the scale Sa is rotated by 450 °, the rotational position θ changes by 450 ° (one rotation and 90 °). When the reference position on the scale Sa is rotated by 450 °, the rotation position θ1 in one rotation is reset to 90 ° when the reference position on the scale Sa is rotated by 360 °.

Here, the case where the gear ratio Gr is represented by (1-1 / N) will be described. It is assumed that N = 10, but the value of N can be set to an arbitrary real number of 2 or more. Δθ in FIG. 2A is expressed by the following equation (2) when Δθ> 0, and is expressed by the following equation (3) when Δθ <0.
Δθ = θ × (1−Gr) (2)
Δθ = θ × (1-Gr) −360 (3)

When formula (2) is transformed, the following formula (4) is obtained, and when formula (3) is transformed, formula (5) is obtained.
θ = Δθ / (1-Gr) (4)
θ = (Δθ + 360) / (1-Gr) (5)

  For example, the calculation unit 25 subtracts the rotational position θ2 of the second axis AX2 detected by the second encoder 2 from the rotational position θ1 of the first axis AX1 detected by the first encoder 1 to calculate the difference value Δθ. In addition, the calculation unit 25 determines whether Δθ is positive or negative. When Δθ is positive, the arithmetic unit 25 divides Δθ by (1−Gr), for example, according to the above equation (4), and calculates the rotation position θ (multi-rotation information of the first axis AX1) in multi-rotation. calculate.

  For example, when θ1 detected by the first encoder 1 is 240 ° and θ2 detected by the second encoder 2 is 180 °, Δθ is 60 ° (> 0). In the case of Gr = 9/10, the value of (1-Gr) is 1/10, and θ calculated by the equation (4) is 600 °. In this case, it can be seen that the first axis AX1 rotates by one rotation and 240 °.

  Further, when Δθ is negative, for example, according to the above equation (5), the value obtained by adding 360 to Δθ is divided by (1−Gr) to calculate the rotation position θ in terms of multiple rotations. . For example, when θ1 detected by the first encoder 1 is 10 ° and θ2 detected by the second encoder 2 is 333 °, Δθ is −323 ° (<0). When Δθ + 360 is 37 and Gr = 9/10, θ calculated by Equation (4) is 370 °. In this case, it can be seen that the first axis AX1 rotates by one rotation and 10 °. Thus, in the present embodiment, the number of rotations can be calculated with a simple algorithm using Equation (4) or the like.

  In the present embodiment, the ratio between the number of rotations of the first axis AX1 and the number of rotations of the second axis AX2 is represented by N: N−1, for example. In this case, the encoder device EC can calculate the number of rotations up to N rotations about the first axis AX1. For example, when N = 10, multi-rotation information up to 10 rotations can be calculated for the first axis AX1.

  When the first axis AX1 rotates N from an arbitrary position, the difference between the angular position of the first axis AX1 and the angular position of the second axis AX2 is the same as before the rotation. For example, when N = 10 and the first axis AX1 rotates 3600 ° (10 rotations) from an arbitrary position, the difference between the angular position of the first axis AX1 and the rotational angular position of the second axis AX2 is For example, it is 0 ° as in the case of 0 rotation. In this case, the state rotated by 0 ° and the state rotated by 3600 ° can be distinguished by taking into account that the rotation has occurred. When the 0-degree rotation state and the N-rotation state are not distinguished, the encoder device EC may calculate rotation number information that distinguishes the number of rotations less than N rotations for the first axis AX1.

  For the purpose of detecting multi-rotation information, N is preferably greater than 1 and N is preferably a real number of 2 or more. If N is greater than 1, whether the number of rotations of the first axis AX1 is less than one rotation from the difference Δθ in rotation position between θ1 detected by the first encoder 1 and θ2 detected by the second encoder 2 It becomes possible to tell whether it is more than rotation.

  FIG. 3 is a diagram for explaining multi-rotation information calculation processing when N = 2. In FIG. 3A, the ratio between the number of rotations of the first axis AX1 and the number of rotations of the second axis AX2 is represented by N: N−1. In FIG. 3B, the number of rotations of the first axis AX1. And the number of rotations of the second axis AX2 is represented by N: N + 1. In the case of N = 2, in both FIGS. 3A and 3B, the difference between the rotational positions and the rotational position converted in multiple rotations are within the range where the rotational position converted in multiple rotations is less than 720 °. There is a one-to-one correspondence. Therefore, the multi-rotation information is uniquely determined for the calculated rotational position difference.

  When N is 2 or more, information on the number of rotations of the multi-rotation encoder rotated two or more times is obtained from the difference Δθ in the rotational position between θ1 detected by the first encoder 1 and θ2 detected by the second encoder 2. be able to. The ratio between the number of rotations of the first axis AX1 and the number of rotations of the second axis AX2 may be set to N-1: N. Also in this case, the encoder device EC can calculate the number of rotations information up to N rotations about the first axis AX1. For the second axis AX2, it is possible to calculate the number of rotations up to N-1 rotations.

  The ratio between the number of rotations of the first axis AX1 and the number of rotations of the second axis AX2 may be set to N: N + 1. In this case, the encoder device EC can calculate the number of rotations up to N rotations about the first axis AX1. For the second axis AX2, it is possible to calculate the number of rotations up to N + 1 rotations. For example, when N = 10, multi-rotation information up to 10 rotations can be calculated. Further, the ratio between the number of rotations of the first axis AX1 and the number of rotations of the second axis AX2 may be set to N + 1: N. In this case, the encoder device EC can calculate the number of rotations up to N + 1 rotations.

  In the encoder device EC, the number of rotations that can be detected increases as N is set larger. The reduction ratio between the first axis AX1 and the second axis AX2 approaches 1 as N increases. For example, the speed ratio (reduction ratio) of a general reduction gear is set such that the number of rotations on the output side with respect to the input side is smaller than 1/100. In the encoder device EC of the present embodiment, the reduction ratio (the number of rotations on the low speed side with respect to the number of rotations on the high speed side) between the number of rotations of the first axis AX1 and the number of rotations of the second axis AX2 is, for example, 1 It is set within the range of / 100 or more and less than 1, and is set within the range of 1/10 or more and less than 1, 9/10 or more and less than 1, 99/100 or more and less than 1, and 999/1000 or more and less than 1. Good.

  Note that the value of (1-Gr) is a proportional coefficient determined in advance by the gear ratio, and is stored in the storage unit 26. For example, the calculation unit 25 reads the value of (1-Gr) from the storage unit 26 and uses this value to calculate the rotation position θ in terms of multiple rotations. The storage unit 26 may store a value of 1 / (1-Gr) as comparison information, and the calculation unit 25 multiplies Δθ by a value of 1 / (1-Gr) to calculate the multi-rotation conversion. The rotational position θ may be calculated.

  The calculation unit 25 divides the calculated rotation position θ in multi-rotation by 360, and calculates the integer part as the number of rotations. The calculation unit 25 combines the calculated number of rotations with the rotation position θ1 detected by the first encoder 1, and outputs the combination result as multi-rotation information of the first axis AX1. Note that the calculation unit 25 may output the rotation position θ converted to multiple rotations or a value obtained by rounding the rotation position θ converted to multiple rotations by rounding or the like as the multiple rotation information of the first axis AX1. Further, the calculation unit 25 collates the calculated rotational position difference value Δθ with information (the above-described comparison information) determined in advance as information indicating the number of rotations of the first axis AX1 with respect to the rotational position difference value. The number of rotations of the first axis AX1 may be output as multi-rotation information. The calculation unit 25 collates the calculated rotational position difference value Δθ with information (previously described comparison information) as information indicating the number of rotations of the first axis AX1 with respect to the rotational position difference value, and is output. The number of rotations of the first axis AX1 and the rotational position θ1 detected by the first encoder 1 may be combined and the combination result may be output as multi-rotation information of the first axis AX1.

  The encoder device EC according to the present embodiment as described above calculates the difference Δθ between the rotational position detected by the first encoder 1 and the rotational position detected by the second encoder 2, and the first axis AX1 is calculated from the calculation result. Detect the number of rotations. Therefore, the encoder device EC can detect the number of rotations if there are at least two sensors (for example, the first encoder 1 and the second encoder 2), and can simplify the device configuration.

  Next, a method for detecting multi-rotation information will be described based on the operation of the encoder device EC as described above. FIG. 4 is a flowchart showing the operation of the encoder device EC. The first axis AX1 is an axis connected to an electric motor or the like, and stops rotating when a device (for example, a robot) on which the electric motor is mounted is stopped. The first axis AX1 starts to rotate by the electric motor, for example, when the apparatus on which the electric motor is mounted is started. The encoder device EC is supplied with power from an external device (for example, a power source of the robot) when the first axis AX1 starts to rotate.

  For example, when power supply from the outside is started (step S1), the control unit 27 of the encoder device EC controls the first encoder 1 to cause the first encoder 1 to detect the rotational position of the first axis AX1 ( Step S2). The control unit 27 controls the second encoder 2 in synchronization with the first encoder 1, and causes the second encoder 2 to detect the rotational position of the second axis AX2 almost simultaneously with the first encoder 1 (step S3). In addition, the calculation unit 25 of the encoder device EC calculates a difference value between the rotational position detected by the first encoder 1 and the rotational position detected by the second encoder 2 (step S4). Further, the calculation unit 25 reads the comparison information from the storage unit 26, and calculates the multi-rotation information of the first axis AX1 using the difference value calculated in step S4 and the comparison information read from the storage unit 26 (step S4). S5). The encoder device EC outputs the multi-rotation information of the first axis AX1 calculated by the calculation unit 25 to, for example, the control unit of the electric motor (step S6). For example, the control unit of the electric motor controls the rotation of the electric motor using the multi-rotation information of the first axis AX1 output from the encoder device EC.

  By the way, it is desired that the encoder device can obtain multi-rotation information with a simple (simple) configuration. For example, in the encoder device that associates the detected tooth number with the number of rotations, when the number of teeth of the main gear is A and the number of teeth of the driven gear is B, the combination is (A × B) and detected. The configuration for associating the tooth number with the number of rotations can be complex. Further, in an encoder apparatus including a first code disk, a second code disk, and a third code disk, for example, the second code disk rotates 1/64 of the first code disk, and the third code disk is the second code disk. If the position information is obtained by counting the codes of the second code disk and the third code disk when the first code disk exceeds one rotation, the device increases as the number of code disks increases. The configuration becomes complicated.

  The encoder device EC according to the present embodiment as described above performs arithmetic processing based on the rotational position detected by the first encoder 1 and the rotational position detected by the second encoder 2, and the first axis AX1 based on the arithmetic result. Multi-rotation information including information on the number of rotations is detected. For example, the encoder device EC calculates (calculation processing) a difference between the rotational position detected by the first encoder 1 and the rotational position detected by the second encoder 2, and based on the calculation result (calculation result), the first axis Multi-rotation information including information on the number of rotations of AX1 is detected. Therefore, the encoder device EC can obtain multi-rotation information with a simple configuration. Since multi-rotation information can be obtained by combining a small number of gears, there are few moving parts, and failure due to wear or breakage is unlikely to occur.

  In general, the transmission unit 3 that performs a shift using only gears has a transmission ratio represented by an integer ratio. For example, when a belt such as a flat belt or a V-belt is used as the transmission unit 3, the pulley can have a free diameter, and the transmission ratio can be set to a real number other than the integer ratio. In addition, the first shaft is connected to the second shaft through the transmission unit. At this time, for example, the gear connected to the first shaft is used for deceleration, and the gear connected to the second shaft is used. By using it for acceleration, even if the number of gears is small, it is possible to detect the number of multi-rotations such as several hundreds of revolutions and thousands of revolutions.

  Next, a modified example will be described. FIGS. 5A and 5B are diagrams showing an encoder device EC according to a modification.

  The encoder device EC of the first modified example shown in FIG. 5A has a step between the scale Sa of the first encoder 1 and the scale Sb of the second encoder 2. The disk 16 provided with the scale Sa is arranged so as to overlap the disk 21 provided with the scale Sb. Thus, the scale Sa and the scale Sb do not have to be arranged on the same plane. In this case, the first axis AX1 and the second axis AX2 can be brought close to each other, and the encoder device EC can be saved in the direction orthogonal to the first axis AX1. In this case, when a timing belt and a timing pulley, or a chain and a sprocket are used for the transmission unit 3, the degree of freedom in arrangement of the first axis AX1 and the second axis AX2 can be increased.

  In the encoder device EC of the first modified example shown in FIG. 5B, the first axis AX1 and the second axis AX2 are arranged non-parallel. The transmission unit 3 includes, for example, at least one of a face gear, a bevel gear, a screw gear, and a worm gear, and transmits the rotation of the first axis AX1 to the second axis AX2. Thus, the first axis AX1 and the second axis AX2 may be nonparallel.

[Second Embodiment]
Next, a second embodiment will be described. In the present embodiment, the same components as those in the above-described embodiment are appropriately denoted by the same reference numerals, and the description thereof is omitted or simplified. FIG. 6 is a diagram showing an encoder device EC according to the present embodiment.

  In the encoder device EC according to the first embodiment, the closer the gear ratio is to 1, the higher the upper limit of the number of rotations that can be identified. On the other hand, the closer the gear ratio is to 1, the smaller the difference in rotational position between the first axis AX1 and the second axis AX2, and depending on the detection error of the sensor that detects the rotational position (for example, the first), multiple rotations There is a possibility that the error included in the information becomes large. As shown in FIG. 6, the encoder device EC according to the present embodiment includes a correction unit 51, and the correction unit 51 corrects an error in the rotation information. The correction unit 51 is provided in the detection unit 4, for example, but may be provided in addition to the detection unit 4.

  The correction unit 51 estimates the rotation information obtained from the other detection result based on the detection result of one of the detection result of the first encoder 1 and the detection result of the second encoder 2, and based on the estimation result, The rotation information obtained from the other detection result is corrected. For example, the correction unit 51 uses the rotational position of the first axis AX1 detected by the first encoder 1, the rotational position of the second axis AX2 detected by the second encoder 2, and the speed ratio Gr. Estimate the rotational position.

  FIG. 7 is a diagram for explaining calculation processing and correction processing according to the present embodiment. In FIG. 7A, the horizontal axis is a rotational position that takes into account the number of rotations of the first axis AX1 (eg, the main rotational axis), and the vertical axis is a rotational position that is less than one revolution. Reference sign Q1 is the rotational position of the first axis AX1 detected by the first encoder 1, and reference sign Q2 is the rotational position of the second axis AX2 detected by the second encoder 2. Moreover, the symbol Q3 in FIG. 7A is the difference between the rotational position Q1 and the rotational position Q2.

  Like the rotational position Q1 and the rotational position Q2 in FIG. 7, the detection result of the encoder can have various errors. Here, it is assumed that the errors other than the periodic error are minute and can be ignored. When the error included in the detection result of the encoder is only a periodic error, a count corresponding to 360 °, which indicates that the rotation position of each axis, for example, the origin position, makes a round and returns to the origin position again, An accurate value not included is obtained.

  Further, since the gear ratio (Gr) between the first axis AX1 and the second axis AX2 is known, the rotational position of the second axis AX2 is predicted (estimated) from the detected value of the rotational position of the first axis AX1. Can do. In FIG. 7B, the rotational position of the second axis AX2 estimated from the rotational position Q1 of the first axis AX1 detected by the first encoder 1 is indicated by a symbol Q4. Before the rotational position Q1 reaches 360 °, the rotational position Q4 is calculated by multiplying the rotational position Q1 by the gear ratio. When the rotational position Q1 exceeds 360 °, the rotational position Q4 is obtained by multiplying the added value obtained by adding 360 ° to the rotational position Q1 and the speed ratio.

  In the present embodiment, when the rotation information obtained from one of the detection results of the first encoder 1 and the detection result of the second encoder satisfies a predetermined condition, the correction unit 51 obtains from the other detection result. The rotation information to be corrected is compared with the estimation result. The predetermined condition is, for example, a condition in which one rotation axis (eg, first axis AX1) is at a predetermined reference position (eg, origin, rotation position 0 °). For example, when the first encoder 1 detects that the first axis AX1 is at the rotational position 0 °, the detection result does not include a periodic error, or the periodic error included in the detection result is ignored. It is a level that can be done. Therefore, when the rotation position of the second axis AX2 is estimated using the detection value when the first encoder 1 detects that the first axis AX1 is at the reference position, the estimation result includes a periodic error. The periodic error included in the estimation result is negligible. By comparing this estimation result (estimated value) with the detection result of the rotational position of the other rotation axis (eg, second axis AX2) at the time of detection of the detection result used for estimation, the point (rotation) The error included in the detection result of the second encoder 2 at the position) can be calculated.

  Further, when the transmission ratio is represented by n: n−1, when the first axis AX is continuously rotated in one direction, the angular difference from the second axis AX2 increases by 1 / n rotation every rotation. Therefore, by rotating the first axis AX1 n times, an accurate estimated value can be obtained at each point obtained by equally dividing one rotation of the second axis AX2 by n, and the rotation of the second axis AX2 at each point. An error in the detected position value can be obtained. By calculating a correction value from the detected value error at each point and writing it in the storage unit 26, for example, the periodic error included in the detection result of the second encoder 2 can be corrected.

  Similarly, regarding the periodic error included in the detection result of the first encoder 1, the rotational position of the first axis AX1 is estimated from the detection result of the second encoder 2 detecting the rotational position of the second axis AX2. It is also possible to correct it. For example, the correction unit 51 estimates rotation information obtained from the detection result of the second encoder 2 based on the detection result of the first encoder 1, and obtains from the detection result of the second encoder 2 based on the estimation result. A first correction process for correcting the rotation information to be performed is performed. Further, the correction unit 51 estimates the rotation information obtained from the detection result of the first encoder 1 based on the detection result of the second encoder 2, and obtains from the detection result of the first encoder 1 based on the estimation result. A second correction process for correcting the rotation information to be performed is performed. For example, the correction unit 51 alternately performs a first correction process and a second correction process.

  For example, the correction unit 51 calculates the correction amount as described above, and generates correction information in which the calculated correction amount and the rotation position are associated with each other. For example, the correction unit 51 stores the correction information in the storage unit 26 and corrects the rotation information according to the correction information stored in the storage unit 25. The timing at which the correction unit 51 calculates the correction amount is arbitrarily set. For example, the timing at which the correction unit 51 calculates the correction amount may be the time when the encoder device EC is activated, the time when the predetermined time elapses, or the time when the rotating shaft rotates by the predetermined number of rotations. But you can. Further, the correction information may include discrete data such as table data, or may include a coefficient of a mathematical formula indicating the relationship between the correction amount and the rotation position.

  The correction unit 51 does not have to calculate the correction amount. For example, the correction unit 51 employs the rotation information of the second axis AX2 estimated based on the rotation information of the first axis AX1 detected by the first encoder 1. Thus, the rotation information of the second axis AX2 may be corrected. For example, the correction unit 51 corrects the rotation information of the second axis AX2 by replacing the estimated rotation information of the second axis AX2 with the rotation information of the second axis AX1 based on the detection result of the second encoder 2. Also good.

  The correction unit 51 may correct at least one of the rotation information of the first axis AX1 and the rotation information of the second axis AX2, and corrects the rotation information of the first axis AX1 or the rotation information of the second axis AX2. It does not have to be.

[Driver]
Next, the drive device will be described. FIG. 6 is a diagram illustrating an example of the driving device MTR. In the following description, components that are the same as or equivalent to those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified. The drive device MTR is a motor device including an electric motor. The drive device MTR includes a first axis AX1, a main body (drive unit) BD that rotationally drives the first axis AX1, and an encoder device EC that detects rotation information of the first axis AX1.

  The rotation shaft SF (eg, the first shaft) has a load side end portion SFa and an anti-load side end portion SFb. The load side end portion SFa is connected to another power transmission mechanism such as a speed reducer. The scale S is fixed to the non-load side end portion SFb through a fixing portion. Along with fixing the scale S, an encoder device EC is attached. The encoder device EC is an encoder device according to the above-described embodiment, modification, or combination thereof.

  In the driving device MTR, the motor control unit MC shown in FIG. 1 or the like controls the main body BD using the detection result of the encoder device EC. Since the drive device MTR has no or low need for battery replacement of the encoder device EC, the maintenance cost can be reduced. The drive device MTR is not limited to a motor device, and may be another drive device having a shaft portion that rotates using hydraulic pressure or pneumatic pressure.

[Stage device]
Next, the stage apparatus will be described. FIG. 7 is a diagram showing a stage apparatus STG. This stage device STG has a configuration in which a rotary table (moving object) TB is attached to the load side end portion SFa of the rotation shaft SF (first shaft) of the drive device MTR shown in FIG. In the following description, components that are the same as or equivalent to those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.

  When the stage device STG drives the drive device MTR to rotate the first axis AX1, this rotation is transmitted to the rotary table TB. At that time, the encoder device EC detects the angular position and the like of the first axis AX1. Therefore, the angular position of the rotary table TB can be detected by using the output from the encoder device EC. A reduction gear or the like may be disposed between the load side end SFa of the drive device MTR and the rotary table TB.

  As described above, the stage apparatus STG has no or low need for battery replacement of the encoder apparatus EC, so that the maintenance cost can be reduced. The stage apparatus STG can be applied to a rotary table provided in a machine tool such as a lathe.

[Robot equipment]
Next, the robot apparatus will be described. FIG. 8 is a perspective view showing the robot apparatus RBT. FIG. 8 schematically shows a part (joint part) of the robot apparatus RBT. In the following description, components that are the same as or equivalent to those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified. The robot apparatus RBT includes a first arm AR1, a second arm AR2, and a joint portion JT. The first arm AR1 is connected to the second arm AR2 via the joint portion JT.

  The first arm AR1 includes an arm portion 101, a bearing 101a, and a bearing 101b. The second arm AR2 has an arm portion 102 and a connection portion 102a. The connecting portion 102a is disposed between the bearing 101a and the bearing 101b in the joint portion JT. The connection part 102a is provided integrally with the rotation shaft SF. The rotation shaft SF is inserted into both the bearing 101a and the bearing 101b in the joint portion JT. The end of the rotating shaft SF on the side inserted into the bearing 101b passes through the bearing 101b and is connected to the speed reducer RG.

  The reducer RG is connected to the drive device MTR, and reduces the rotation of the drive device MTR to, for example, 1/100 and transmits it to the rotary shaft SF. Although not shown in FIG. 8, the load side end portion SFa of the rotation shaft SF of the drive device MTR is connected to the speed reducer RG. In addition, the scale S of the encoder device EC is attached to the non-load-side end portion SFb of the first shaft AX1 of the drive device MTR.

  When the robot apparatus RBT drives the drive apparatus MTR to rotate the first axis AX1, this rotation is transmitted to the rotation axis SF via the reduction gear RG. Due to the rotation of the rotation shaft SF, the connecting portion 102a rotates integrally, whereby the second arm AR2 rotates relative to the first arm AR1. At that time, the encoder device EC detects the angular position and the like of the first axis AX1. Therefore, the angular position of the second arm AR2 can be detected by using the output from the encoder device EC.

  As described above, the robot apparatus RBT has no or low need to replace the battery of the encoder apparatus EC, so that the maintenance cost can be reduced. The robot apparatus RBT is not limited to the above configuration, and the drive apparatus MTR can be applied to various robot apparatuses having joints.

  According to the above-described embodiment, it is possible to provide an encoder device, a drive device, a stage device, a robot device, and a multi-rotation information calculation method that can obtain multi-rotation information with a simple configuration.

  The technical scope of the present invention is not limited to the above-described embodiment or modification. For example, one or more of the requirements described in the above embodiments or modifications may be omitted. In addition, the requirements described in the above embodiments or modifications can be combined as appropriate.

DESCRIPTION OF SYMBOLS 1 ... 1st encoder, 2 ... 2nd encoder, 3 ... Transmission part, 4 ... Detection part,
EC ... encoder device, AR1 ... first arm, AR2 ... second arm, AX1 ... first axis, AX2 ... second axis, MTR ... drive device, RBT ... Robot device, STG ... Stage device

  According to the first aspect of the present invention, the first encoder that detects the rotational position of the first shaft, and the second encoder that detects the rotational position of the second shaft that rotates at a constant gear ratio with respect to the first shaft. And a detection unit that performs calculation processing based on the rotation position detected by the first encoder and the rotation position detected by the second encoder, and detects multi-rotation information of the first axis based on the calculation result. Is provided. According to the sixth aspect of the present invention, the first encoder that detects the rotational position of the first shaft connected to the drive device, and the second shaft that rotates at a predetermined speed ratio with respect to the first shaft. A second encoder that detects a rotational position; a third axis that is connected to each of the first and second axes and rotates at a second speed ratio with respect to the first axis; and a rotational position that is detected by the first encoder; An encoder device is provided that includes a detection unit that performs calculation processing based on the rotational position detected by the second encoder and detects multi-rotation information of the first axis based on the calculation result.

  According to the second aspect of the present invention, the encoder device according to the first or sixth aspect, the power supply unit that supplies power to the first shaft or the second shaft, and the detection unit of the encoder device detect A drive unit is provided that includes a control unit that controls the power supply unit using the number of rotations.

Claims (19)

A first encoder for detecting a rotational position of the first shaft;
A second encoder that detects a rotational position of a second shaft that rotates at a constant gear ratio with respect to the first shaft;
An encoder comprising: a calculation unit that performs calculation processing based on the rotation position detected by the first encoder and the rotation position detected by the second encoder, and detects multi-rotation information of the first axis based on the calculation result apparatus.   The encoder apparatus according to claim 1, wherein the calculation process includes calculating a difference between a rotational position detected by the first encoder and a rotational position detected by the second encoder.   The transmission ratio of the second shaft to the first shaft is expressed by (1 + 1 / N) or (1-1 / N) using a real number N of 2 or more. The encoder device according to one item.   The said detection part collates the said calculation result with the comparison information which shows the number of rotations of the said 1st axis | shaft with respect to the difference of the rotation position of the said 1st axis | shaft and the said 2nd axis | shaft, and detects the said multiple rotation information. The encoder device according to any one of claims 1 to 3.   The detection unit calculates θ3 = θ1−θ2 + 360 ° when the value obtained by subtracting the rotation position θ2 of the second axis from the rotation position θ1 of the first axis is negative, and compares the calculated θ3 with the comparison The encoder apparatus according to claim 4, wherein the multi-rotation information is detected by collating with information.   6. The encoder device according to claim 5, wherein the detection unit calculates an integer part of a product of a proportional coefficient of the number of rotations of the first axis with respect to the angle θ <b> 3 and the angle θ <b> 3 as the number of rotations of the first axis. . A storage unit for storing the comparison information;
The encoder device according to any one of claims 4 to 6, wherein the detection unit detects the number of rotations of the first shaft using the comparison information stored in the storage unit.   The said detection part calculates the said comparison information using the said gear ratio, and detects the number of rotations of the said 1st axis | shaft using the calculation result. Encoder device.   The encoder according to any one of claims 1 to 8, wherein the detection unit detects the number of rotations of the first shaft based on electric power supplied when the first shaft starts to rotate. apparatus.   The detection unit is configured to detect the first encoder when at least one of the first encoder detects a predetermined rotational position of the first shaft and the second encoder detects a predetermined rotational position of the second shaft. The encoder device according to any one of claims 1 to 9, wherein the number of rotations of one axis is detected. A transmission unit that connects the first shaft and the second shaft at the transmission ratio;
The speed change part includes an acceleration part in which the second axis side is high speed with respect to the first axis side, and a speed reduction part in which the second axis side is low speed with respect to the first axis side. The encoder device according to any one of claims 1 to 10.   The arithmetic processing obtains the number of rotations of the first axis based on the rotational position detected by the first encoder and the rotational position detected by the second encoder, and calculates the number of rotations of the first axis and the first The encoder device according to any one of claims 1 to 11, wherein the rotation position detected by the encoder is combined and the combined result is output as multi-rotation information of the first axis.   Based on the detection result of one of the detection result of the first encoder and the detection result of the second encoder, the rotation information obtained from the other detection result is estimated, and based on the estimation result, the other detection result The encoder device according to any one of claims 1 to 12, further comprising: a correction unit that performs a first correction process for correcting rotation information obtained from the information.   The correction unit corrects rotation information obtained from the other detection result by comparing with the estimation result when rotation information obtained from the one detection result satisfies a predetermined condition. Encoder device.   The correction unit estimates rotation information obtained from the one detection result based on the first correction process and the other detection result, and is obtained from the one detection result based on the estimation result. The encoder device according to claim 12 or 14, wherein a second correction process for correcting rotation information is alternately performed. The encoder device according to any one of claims 1 to 15,
A power supply for supplying power to the first shaft or the second shaft;
And a control unit that controls the power supply unit using the number of rotations detected by the detection unit of the encoder device. A moving object;
A stage device comprising: the driving device according to claim 16, wherein the moving object is moved. A drive device according to claim 16;
A robot apparatus comprising: a first arm and a second arm that are relatively moved by the driving device. Detecting the rotational position of the first shaft by the first encoder;
Detecting a rotational position of a second shaft rotating at a constant gear ratio with respect to the first shaft by a second encoder;
Calculation processing is performed based on the rotation position detected by the first encoder and the rotation position detected by the second encoder, and multi-rotation information including information on the number of rotations of the first axis is detected based on the calculation result. Process,
A multi-rotation information calculation method.

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