JP2012137310A - Encoder device, driving device, and robot device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an encoder device capable of accurately detecting position information.SOLUTION: An encoder device comprises: a first encoder outputting a first signal; a second encoder outputting a second signal; a first position information generating part for generating first location information indicating rotational position information of the first encoder based on the first signal; a second position information generating part for generating second position information indicating rotational position information of the second encoder based on the second signal and a correction table indicating correction values of the rotational position information of the second encoder; a determination part for detecting relative displacement of the second position information to the first position information by using the first position information and the second position information; and a correction table generating part for generating the correction table according to the displacement of the second position information when the relative displacement of the second position information is detected.

Description

  The present invention relates to an encoder device, a drive device, and a robot device.

  Robot devices that perform cooperative work with people, such as industrial robots and service robots, are known. Such a robot apparatus is driven by a drive apparatus including an encoder apparatus, and performs position control and speed control of an output shaft and the like based on position information detected by the encoder apparatus (for example, see Patent Document 1). ).

JP 11-245191 A

  By the way, the external environment in which the above-described robot apparatus operates may operate in an electrical disturbance, and the encoder apparatus detects the position information detected by the electric field / magnetic field disturbance (commonly referred to as “noise”). Deviation (displacement of position information) may occur. Further, the encoder apparatus may be displaced in position information due to factors such as wear due to the use of a speed reducer or a drive unit. When such displacement of the position information occurs, there is a problem that the detection accuracy of the position information detected by the encoder device may decrease.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an encoder device, a drive device, and a robot device that can detect position information with high accuracy when displacement of position information occurs. It is to provide.

  In order to solve the above problem, the present invention is connected to a first encoder that outputs a first signal corresponding to a rotational position of an input shaft rotated by a driving unit, and the input shaft and a power transmission unit. A second encoder that outputs a second signal corresponding to the rotational position of the output shaft, and a first position that generates first position information indicating rotational position information of the first encoder based on the first signal Based on the information generation unit, the second signal and the correction table indicating the correction value of the rotation position information of the second encoder, the second position information indicating the rotation position information of the second encoder is generated. A position determination unit configured to detect a relative displacement of the second position information with respect to the first position information using the second position information generation unit, the first position information, and the second position information; Relative of second position information When detecting the position, an encoder device, characterized in that it comprises a correction table generation unit for generating the correction table according to the displacement of the second position information.

  Moreover, this invention is a drive device provided with said encoder apparatus.

  Moreover, this invention is provided with said drive device, It is a robot apparatus characterized by the above-mentioned.

  According to the present invention, position information can be detected with high accuracy.

It is a block diagram which shows the structure of the drive device by one Embodiment of this invention. It is a block diagram which shows the structure of the encoder apparatus in the drive device of FIG. It is a block diagram which shows the structure of the signal processing circuit in the drive device of FIG. It is a figure explaining the eccentric error of the 2nd encoder in the embodiment. It is an image figure which shows an example of the correction table and eccentric error in the same embodiment. It is an image figure which shows an example of the correction table after reproduction | regeneration by one Embodiment of this invention, and eccentricity error. FIG. 6 is a second block diagram illustrating another example of the configuration of the encoder device in the drive device of FIG. 1. FIG. 6 is a second block diagram showing another example of the configuration of the signal processing circuit in the drive device of FIG. 1. It is a block diagram which shows an example of a robot apparatus provided with the drive device of FIG. It is a 2nd image figure which shows another example of the correction table after reproduction | regeneration by one Embodiment of this invention, and eccentricity error.

Hereinafter, an encoder device and a drive device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a driving apparatus 1 according to an embodiment of the present invention.
In this figure, the drive device 1 includes a gear 2, a first encoder 3, a second encoder 4, a motor 7, an input shaft 10, and an output shaft 11. The drive device 1 includes an encoder device 20, and the encoder device 20 includes a first encoder 3 and a second encoder 4.

  The motor 7 (driving unit) rotates the input shaft 10. The gear 2 (power transmission portion) rotates the output shaft 11 by decelerating at a predetermined gear ratio (for example, 1/100) according to the rotation of the input shaft 10. That is, in the drive device 1, the motor 7 rotates the input shaft 10, and the input shaft 10 rotates, whereby the output shaft 11 rotates through the gear 2.

The first encoder 3 is a one-rotation type absolute encoder, and outputs a first detection signal (first signal) corresponding to the rotational position of the input shaft 10 rotated by the motor 7.
The second encoder 4 is a one-rotation type absolute encoder and outputs a second detection signal (second signal) corresponding to the rotational position of the output shaft 11 connected to the input shaft 10 via the gear 2. To do.
That is, the first encoder 3 has a function of detecting the positional displacement of the input shaft 10 of the motor 7 and is a one-rotation type absolute encoder that can detect where the mechanical angle is 360 degrees. The single-rotation type absolute encoder is an encoder that cannot detect multi-rotation information indicating how many rotations have been made as rotation information. Here, the first encoder 3 is, for example, an absolute encoder having a 13-bit resolution (0 to 8191).

  In the drive device 1, the gear 2 connects the input shaft 10 and the output shaft 11 with a predetermined gear ratio. Therefore, the encoder device 20 uses the first encoder 3 that is a one-turn type absolute encoder and the second encoder 4 that is a one-turn type absolute encoder, and the encoder device 20 as a whole is a multi-turn type absolute. Functions as an encoder.

  Incidentally, the first encoder 3 has a signal processing circuit 6 therein. A second detection signal detected by the second encoder 4 is input to the signal processing circuit 6 via the communication line 12. Then, the signal processing circuit 6 makes one rotation together with the number of rotations of the input shaft 10 based on the first detection signal detected by the first encoder 3 and the second detection signal detected by the second encoder 4. The combined position data (multi-rotation position information) indicating the position displacement within is combined. Further, the signal processing circuit 6 detects a failure or the like based on the first detection signal and the second detection signal, and generates error status information as a result. The signal processing circuit 6 outputs the combined position data and error status information to the controller 8 via the communication line 9.

  As a result, the controller 8 can detect the number of rotations of the input shaft 10 and the position displacement within one rotation based on the combined position data. Further, the controller 8 determines, based on the error status information, for example, an abnormality in the rotation mechanism of the motor 7, an abnormality in the gear 2, a rotation disk 301 or a rotation disk, which will be described later, built in the first encoder 3 or the second encoder 4. It is possible to detect a failure of the encoder device 20 due to an abnormality 401 or the like.

Next, the configuration of the encoder device 20 of the drive device 1 will be described in detail with reference to FIGS. 2 and 3. 2 and 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 2 is a block diagram showing a configuration of the encoder device 20 in the drive device 1 of FIG.
First, the structure of the 1st encoder 3 and the 2nd encoder 4 is demonstrated using FIG.

  The first encoder 3 is a one-rotation type absolute encoder that can detect where the marker that rotates with the rotation of the input shaft is located at a mechanical angle of 360 degrees. The first encoder 3 is, for example, a one-rotation type absolute encoder, and is an optical encoder.

  The first encoder 3 includes a rotating disk 301 having an absolute pattern and an incremental pattern defined by a predetermined M series code. The rotating disk 301 rotates as the input shaft 10 rotates. Light emitted from the light emitting element 302 passes through each pattern of the rotating disk 301 and enters the light receiving sensor 303. The light receiving sensor 303 outputs two types of signals, a signal detected from the absolute pattern and a signal detected from the incremental pattern, to the signal processing circuit 6 as a first detection signal.

One of the two types of signals output from the light receiving sensor 303 and detected from the absolute pattern is a signal processing circuit 6 (described later) as an absolute position detection signal (or M series signal). Is output to the absolute position detection circuit 611).
Further, the other signal of the two types of signals output from the light receiving sensor 303 and detected from the incremental pattern is a signal processing circuit 6 as a first incremental signal (or a two-phase pseudo sine wave). It is output to (first interpolation circuit 612 described later).

The second encoder 4 has a function of detecting a displacement position in rotation of the output shaft 11 connected via the gear 2 from the input shaft 10 of the motor 7, that is, position information. This second encoder outputs a pseudo sine wave having a phase difference of 90 degrees that causes a displacement of 1λ (≈phase angle, 360 degrees) in one magnetic rotation. The second encoder 4 is, for example, a one-rotation type absolute encoder, and is a magnetic encoder. The first encoder 3 is, for example, an absolute encoder with 11-bit resolution (0-2047).
The second encoder 4 includes a rotating disk 401 (disk) having an area that is divided into two parts of an N pole and an S pole on the disk surface. That is, the rotating disk 401 is a disk having a magnetic pole configuration of N poles and S poles. The rotating disk 401 rotates as the output shaft 11 rotates.

  A magnetic sensor device 402 is disposed on the rotating disk 401. The magnetic sensor device 402 includes two magnetic sensors 403 and a magnetic sensor 404 that are arranged on a circumference around which the rotary disk 401 rotates. The two magnetic sensors 403 and 404 are, for example, Hall elements arranged at predetermined positions so that their positions are at an angle of 90 degrees with respect to the rotation center axis of the rotating disk 401. is there.

  The magnetic sensor device 402 outputs a sine wave signal of one pulse per rotation in response to the rotation of the rotating disk 401 having N and S poles as a rotating magnet. Since the magnetic sensor device 402 includes a magnetic sensor 403 and a magnetic sensor 404 having an angle of 90 degrees with each other, the magnetic sensor device 402 has a phase difference of 90 degrees by each magnetic sensor. A two-phase pseudo sine wave (for example, A and B two-phase signals) is output. The two-phase pseudo sine wave output from the magnetic sensor device 402 is output to the signal processing circuit 6 (second interpolation circuit 621 described later) as a second detection signal, that is, a second incremental signal.

Next, the configuration of the signal processing circuit 6 will be described with reference to FIG.
FIG. 3 is a block diagram showing a configuration of the signal processing circuit 6 in the encoder device 20.
In this figure, the signal processing circuit 6 includes a first position data detection circuit 61, a second position data detection circuit 62, a position data synthesis circuit 63, a position data comparison / collation circuit 64, an external communication circuit 65, and a correction table generation. A unit 67 and a storage unit 68 are provided.

The first position data detection circuit 61 (first position information generation unit) is a first position data indicating a position displacement in the rotation of the input shaft 10 based on the first detection signal input from the light receiving sensor 303. (First position information) is detected. That is, the first position data detection circuit 61 generates first position information indicating the rotational position information of the first encoder 3 based on the first detection signal.
The first position data detection circuit 61 includes an absolute position detection circuit 611, a first interpolation circuit 612, a position detection circuit 613, and a conversion table storage unit 614.

The absolute position detection circuit 611 detects absolute position information by converting (decoding) the absolute position detection signal output from the light receiving sensor 303 by the conversion table storage unit 614. That is, the absolute position detection circuit 611 converts the absolute position detection signal into absolute position information by reading out the absolute position information corresponding to the absolute position detection signal output from the light receiving sensor 303 from the conversion table storage unit 614. The absolute position information is detected.
The conversion table storage unit 614 stores in advance an absolute position detection signal (M-sequence signal) and information indicating the absolute position within one rotation of the input shaft and associated with absolute position information having a predetermined resolution. Has been. This absolute position information is information indicating the absolute position in the rotation of the input shaft 10.

The first interpolation circuit 612 interpolates the first incremental signal output from the light receiving sensor 303. That is, the first interpolation circuit 612 electrically subdivides the first incremental signal that is a two-phase pseudo sine wave output from the light receiving sensor 303.
The position detection circuit 613 detects first position data based on the absolute position information detected by the absolute position detection circuit 611 and the first incremental signal interpolated by the first interpolation circuit 612. As an example, the position detection circuit 613 matches the absolute position information detected by the absolute position detection circuit 611 with the incremental signal subdivided by the first interpolation circuit 612 by a predetermined calculation method. Synthesize. Accordingly, the position detection circuit 613 generates first position data that is absolute position information with higher resolution than the absolute position information detected by the absolute position detection circuit 611.

The second position data detection circuit 62 (second position information generation unit), which will be described later, indicates a second detection signal input from the magnetic sensor device 402 and a correction value for rotational position information of the second encoder 4. Based on the correction table 681, second position data (second position information) indicating the position displacement in the rotation of the output shaft 11 is detected. That is, the second position data detection circuit 62 generates second position information indicating the rotational position information of the second encoder 4 based on the second detection signal and the correction table 681.
The second position data detection circuit 62 includes a second interpolation circuit 621.

The second interpolation circuit 621 interpolates the second incremental signal (two-phase pseudo sine wave) output from the magnetic sensor device 402 of the second encoder 4, and the position displacement in the rotation of the output shaft 11. Position data indicating is detected. The second encoder 4 detects a rotational position displacement including a transmission error between the input shaft 10 and the output shaft 11. For this reason, the second interpolation circuit 621 uses the correction table 681 stored in the storage unit 68 to generate second position data obtained by correcting the detected position data.
Here, the transmission error between the input shaft 10 and the output shaft 11 indicates an error inherent in the gear 2 itself. For example, when the center of the rotation system of the gear 2 is deviated from the ideal rotation center of the output shaft 11, an eccentric error component described later appears as a cumulative error. In the present embodiment, the second interpolation circuit 621 corrects the above transmission error mainly due to the eccentricity error using the correction table 681.

  The position data synthesizing circuit 63 synthesizes the first position data detected by the first position data detecting circuit 61 and the second position data detected by the second position data detecting circuit 62 to obtain the input shaft 10. The combined position data indicating the position displacement within one rotation is generated together with the number of rotations. The position data combining circuit 63 combines the first position data detected by the first position data detecting circuit 61 and the second position data detected by the second position data detecting circuit 62. The synthesized position data is synthesized based on predetermined gear ratio information. The position data combining circuit 63 outputs the generated combined position data to the controller 8 through the communication line 9 via the external communication circuit 65.

The position data comparison / collation circuit 64 (determination unit) uses the first position data detected by the first position data detection circuit 61 and the second position data detected by the second position data detection circuit 62. Thus, a shift of the second position data with respect to the first position data (relative displacement of the second position information) is detected. That is, the position data comparison / collation circuit 64 calculates an estimated value (second estimated value) of the second position data based on, for example, the first position data and the gear ratio information. Then, the position data comparison / collation circuit 64 compares and collates the second position data detected by the second position data detection circuit 62 with the calculated estimated value of the second position data. When the position data comparison / collation circuit 64 detects the deviation of the second position data as a result of the comparison and collation, the error status information is sent to the controller 8 through the communication line 9 via the external communication circuit 65. Output.
If the position data comparison / collation circuit 64 determines that the amount of deviation of the second position data is greater than or equal to the first threshold, which is a predetermined threshold, for example, It is determined that it has been detected.

  Further, the position data comparison / collation circuit 64 is based on the second position data and the estimated value of the second position data calculated from the first position data when the shift of the second position data is detected. Thus, the shift amount (displacement amount) of the second position data is calculated. Then, the position data comparison / collation circuit 64 generates a correction table by generating the correction table 681 together with a command for regenerating the correction table 681 (hereinafter referred to as a regeneration command) when detecting a shift of the second position data. To the unit 67. In other words, the position data comparison / collation circuit 64 rotates the input shaft 10 and the output shaft 11 due to some factors such as malfunction due to noise, wear due to use, collision, slip (eg, slip of output shaft or gear) and load. When the relative positional relationship in FIG. 3 is shifted (displaced state), this regeneration command is output to the correction table generating unit 67. For example, the position data comparison / collation circuit 64 determines that “the displacement of the second position data has been detected” when the amount of displacement of the second position data is equal to or greater than a first threshold that is a predetermined threshold. Then, the regeneration command may be output to the correction table generating unit 67.

  The correction table generation unit 67 is based on the amount of deviation of the second position data calculated by the position data comparison / collation circuit 64 in response to the regeneration command output from the position data comparison / collation circuit 64. Is generated. That is, when the position data comparison / collation circuit 64 detects the shift of the second position data, the correction table generation unit 67 regenerates the correction table 681 according to the shift of the second position data. Then, the correction table generation unit 67 stores the regenerated correction table 681 in the storage unit 68. Details of the method for generating the correction table 681 will be described later.

The storage unit 68 is, for example, a nonvolatile memory, and stores a correction table 681 and eccentricity information 682.
The correction table 681 is information indicating the correction value of the rotational position information of the second encoder 4. In the correction table 681, the second position data including the transmission error detected by the second incremental signal (two-phase pseudo sine wave) is associated with the corrected second position data. For example, the correction table 681 is created in advance so as to output the corrected second position data using the second position data including a transmission error in the address information input to the storage unit 68. . Accordingly, the second interpolation circuit 621 can obtain corrected second position data with high accuracy based on the second position data including the transmission error.

  The eccentricity information 682 is information regarding an eccentricity error component that is a main factor of a transmission error between the input shaft 10 and the output shaft 11. The eccentricity information 682 includes, for example, the radius R of the rotating disk 401 (disk) provided in the second encoder 4 and the amount of eccentricity ε between the center of the input shaft 10 and the center of the output shaft 11 measured in advance. is there. The radius R is distance information from the center of the rotating disk 401 having a pattern indicating position information to the pattern.

Here, the eccentric error component and the correction table 681 will be supplementarily described with reference to FIGS.
FIG. 4 is a diagram for explaining an eccentric error of the second encoder 4 in the present embodiment.
In this figure, a point P 1 indicates the center point of the output shaft 11. A circular locus L1 indicates a locus drawn by the center of the rotating disk 401 when the rotating disk 401 (output shaft 11) of the second encoder 4 rotates around the point P1. Here, when the amount of displacement indicating the amount of deviation between the center of the rotating disk 401 and the point P1 is the amount of eccentricity ε, the eccentricity error component θ is expressed by the relational expression (1).

θ = 2 · sin ⁻¹ (ε / R) (1)

  Therefore, based on the radius R of the rotating disk 401 and the amount of eccentricity ε that are the eccentricity information 682, the eccentricity error component θ that is an accumulated error due to the eccentricity can be calculated by using the above equation (1). In this example, the maximum eccentric error amount is (θ / 2).

FIG. 5A shows a relative positional relationship in which the second position data of the second encoder 4 is “0” when the first position data of the first encoder 3 is “0”. is there. That is, FIG. 5A is a diagram illustrating a case where the shift amount of the second position data is “0” (no displacement state without displacement). FIG. 5B is an example of the eccentricity error distribution of the second encoder 4 calculated based on the eccentricity error component θ. In this figure, the horizontal axis indicates the second position data in the second encoder 4, and the vertical axis indicates the eccentricity error amount. That is, the waveform W1 indicates the eccentric error amount corresponding to the second position data. Further, for example, the position information 0 degree (0 °) in FIG. 5B is the position closest to the magnetic sensor 403 or 404 (light receiving sensor in the case of an optical encoder) in the circular locus L1 in FIG. .
FIG. 5C is a diagram showing an example of the correction table 681 calculated based on the eccentric error component θ. In this figure, the horizontal axis shows the second position data before correction in the second encoder 4, and the vertical axis shows the second position data after correction in the second encoder 4. That is, the waveform W3 indicates the correction table 681 calculated based on the eccentric error component θ. The waveform W2 shows an example when there is no eccentric error (example when correction is not performed).

Here, the correction table 681 (waveform W3) shown in FIG. 5C is calculated based on the eccentric error component θ. Further, the eccentric error component θ is calculated using the above equation (1) based on the radius R of the rotating disk 401 and the eccentric amount ε, which are the eccentric information 682. That is, the correction table 681 (waveform W3) can be generated based on the radius R of the rotating disk 401 and the eccentric amount ε.
For example, the second encoder 4 detects 11-bit position data and outputs second position data of 0 to 2047. Therefore, the position data of 0 to 360 degrees on the horizontal axis in FIG. 5C is shown as data of 0 to 2047 in the correction table 681.

Next, the operation of the encoder device 20 in the present embodiment will be described.
First, an operation in which the encoder device 20 detects the combined position data in the output shaft 11 using the first encoder 3 and the second encoder 4 will be described.

  In the encoder device 20, first, the first position data detection circuit 61 detects first position data based on the first detection signal input from the light receiving sensor 303. The absolute position detection circuit 611 in the first position data detection circuit 61 converts the absolute position detection signal output from the light receiving sensor 303 into absolute position information using the conversion table storage unit 614, thereby Detect absolute position information. The first interpolation circuit 612 interpolates the first incremental signal output from the light receiving sensor 303. The position detection circuit 613 detects first position data based on the absolute position information detected by the absolute position detection circuit 611 and the first incremental signal interpolated by the first interpolation circuit 612 ( Composite).

  The second position data detection circuit 62 detects second position data (second position information) based on the second detection signal input from the magnetic sensor device 402 and the correction table 681.

  Next, the position data combining circuit 63 combines the first position data detected by the first position data detection circuit 61 and the second position data detected by the second position data detection circuit 62, Combined position data indicating the position displacement within one rotation is generated along with the number of rotations of the input shaft 10. The position data synthesis circuit 63 synthesizes the first position data detected by the first position data detection circuit 61 and the second position data detected by the second position data detection circuit 62. Composition position data is synthesized based on predetermined gear ratio information. Thereby, the encoder device 20 detects the combined position data on the output shaft 11.

The generated combined position data is output by the position data combining circuit 63 to the controller 8 through the communication line 9 via the external communication circuit 65.
Thus, the controller 8 can detect the generated combined position data, and the controller 8 can perform various controls of the drive device 1 based on the detected combined position data.

  Next, due to some factors such as noise, wear due to use, collision, slip (eg, slip of output shaft or gear) or load, the relative positional relationship in rotation between the input shaft 10 and the output shaft 11 is shifted (position information The operation of the encoder device 20 when the relative displacement occurs will be described. Here, the state before the relative positional relationship in the rotation of the input shaft 10 and the output shaft 11 is shifted is, for example, as shown in FIG. When the position data is “0”, the relative position relationship is such that the second position data of the second encoder 4 is “0”. When the relative positional relationship in the rotation between the input shaft 10 and the output shaft 11 is shifted due to some factor (unexpected factor) as described above, and the relative positional relationship is as shown in FIG. An example will be described. In this case, the description will be made assuming that the eccentricity error distribution before the deviation in the relative positional relationship and the correction table 681 are in the state shown in FIGS. 5B and 5C.

In the encoder device 20, when a deviation occurs in the relative positional relationship in the rotation between the input shaft 10 and the output shaft 11, the position data comparison / collation circuit 64 generates a regeneration command for regenerating the correction table 681. The data is output to the unit 67. That is, the position data comparison / collation circuit 64, for example, based on the first position data, the gear ratio information, the resolution B1 of the first encoder 3 and the resolution B2 of the second encoder, An estimated value (second estimated value) is calculated.
Then, the position data comparison / collation circuit 64 compares and collates the second position data detected by the second position data detection circuit 62 with the calculated estimated value of the second position data. The position data comparison / collation circuit 64 calculates the amount of deviation of the second position data when performing this comparison and collation. For example, when the position data comparison / collation circuit 64 determines that the shift amount of the second position data is equal to or greater than a first threshold (for example, 10 LSB (quantization unit)) that is a predetermined threshold. Is output to the correction table generation unit 67.

The correction table generation unit 67 is based on the amount of deviation of the second position data calculated by the position data comparison / collation circuit 64 in response to the regeneration command output from the position data comparison / collation circuit 64. Is regenerated.
Here, as shown in FIG. 6A, when the first position data of the first encoder 3 is “0”, the second position data of the second encoder 4 is “20”. A case where the relative positional relationship is displaced will be described. That is, the amount of deviation of the second position data is “20”.

In FIG. 6B, the waveform W5 shows the distribution of the eccentricity error when the shift amount of the second position data is “20”. The waveform W4 shows the distribution of the eccentricity error before the second position data shift occurs. In this figure, it is shown that the distribution of the eccentricity error is shifted in the horizontal axis direction with respect to the state without deviation (non-displacement state) in accordance with the amount of deviation of the second position data. Further, for example, when the first position data of the first encoder 3 is used as a reference, the displacement direction of the second position information is compared with the estimated value of the second position data described above and the second position data. Can be calculated.
Therefore, when the correction table generation unit 67 regenerates the correction table 681 based on the shift amount of the second position data calculated by the position data comparison / collation circuit 64, the correction table 681 that has already been generated is displayed. The correction table 681 is regenerated by reading from the storage unit 68 and shifting by the shift amount of the second position data. The correction table generation unit 67 stores the regenerated correction table 681 in the storage unit 68. As a result, a new correction table 681 corresponding to the shift of the second position data is generated, and the encoder device 20 can correct the shift of the second position data.

  FIG. 6C is a diagram illustrating an example of the correction table 681 regenerated by the correction table generation unit 67. In this figure, a waveform W 7 shows the correction table 681 regenerated by the correction table generating unit 67. The regenerated correction table 681 (waveform W7) is a table obtained by shifting the pre-regeneration correction table 681 (waveform W3) shown in FIG. Therefore, in this example, the waveform W7 is a correction table having a waveform W7a portion and a waveform W7b portion. The waveform W6 shows an example when there is no eccentric error (example when correction is not performed).

  As described above, in the encoder device 20 according to the present embodiment, the first position data detection circuit 61 obtains the rotational position information of the first encoder 3 based on the first detection signal input from the light receiving sensor 303. The first position information shown is generated. Further, the second position data detection circuit 62 performs the first detection based on the second detection signal input from the magnetic sensor device 402 and the correction table 681 indicating the correction value of the rotational position information of the second encoder 4. Second position information indicating rotational position information of the second encoder 4 is generated. Then, the position data comparison / collation circuit 64 detects the shift (displacement) of the second position data using the first position data and the second position data, and the correction table generation unit 67 performs the position data comparison. When the shift of the second position data is detected by the verification circuit 64, the correction table 681 is regenerated according to the shift of the second position data. The encoder device 20 has a deviation in the relative positional relationship in the rotation between the input shaft 10 and the output shaft 11 due to some factors such as noise, wear due to use, collision, slippage (eg, slippage of the output shaft and gear) and load. In the case that the correction table 681 is generated, the correction table 681 is regenerated.

  As a result, the encoder device 20 can correct the shift of the second position data. Therefore, due to some factors such as noise, wear due to use, collision, slip (eg, slip of output shaft or gear) or load, the relative positional relationship in rotation between the input shaft 10 and the output shaft 11 (position in the encoder device) Even when information displacement occurs, the displacement of the position information can be corrected. Further, the encoder device 20 according to the present embodiment can detect the position information with high accuracy even when the displacement of the position information as described above occurs.

In the present embodiment, the position data comparison / collation circuit 64 calculates the displacement amount of the second position data based on the second position data and the second estimated value calculated from the first position data. calculate. Then, the correction table generation unit 67 generates a correction table 681 based on the shift amount of the second position data calculated by the position data comparison / collation circuit 64. That is, the correction table generation unit 67 reads the correction table 681 that has already been generated from the storage unit 68 and shifts it by the amount of deviation of the second position data, thereby regenerating the correction table 681.
Accordingly, the correction table generation unit 67 can regenerate and update the correction table 681 in the rotation state of the input shaft 10 and the output shaft 11. Therefore, the encoder device 20 in the present embodiment always (or dynamically) detects the position information with high accuracy when the displacement of the position information as described above occurs in the rotation state of the input shaft 10 and the output shaft 11. can do.

In the present embodiment, the correction table generation unit 67 also determines that the correction table generation unit 67 determines that the shift amount of the second position data is greater than or equal to a predetermined first threshold value by the position data comparison / collation circuit 64. 681 is regenerated.
As a result, an allowable range is provided for the amount of deviation of the second position data, so that the encoder device 20 corrects erroneously when erroneous detection occurs in the first encoder 3 and the second encoder 4 due to noise or the like. It is possible to prevent the table 681 from being regenerated and updated. In addition, the encoder device 20 can prevent unnecessary correction table 681 from being regenerated when the shift of the second position data is within a range that can be handled by the correction table 681 that has already been generated.

In the present embodiment, the correction table generation unit 67 stores the generated correction table 681 in the storage unit 68. The storage unit 20 is a nonvolatile memory (nonvolatile storage unit).
The encoder device 20 according to the present embodiment is based on the second position information of the second encoder 4, the resolution B <b> 1 of the first encoder 3, and the resolution B <b> 2 of the second encoder 4. For example, the number of rotations) is calculated. Therefore, the encoder device 20 does not need to include a backup battery for holding the multi-rotation information of the input shaft 10 in the nonvolatile memory.

In the present embodiment, the first encoder 3 is an absolute encoder that detects absolute position information in the rotation of the input shaft 10.
Thereby, it is possible to accurately detect the first position data indicating the rotational position information of the input shaft 10 and indicating the rotational position information of the first encoder 3.

In the present embodiment, the first encoder 3 is an optical encoder, and the second encoder 4 is a magnetic encoder.
Thereby, since the detection system is duplicated, it is strong against disturbance and the reliability of the encoder device 20 can be improved.

  In the above embodiment, the correction table generation unit 67 reproduces the correction table 681 by a method (first generation method) of shifting the already generated correction table 681 by the shift amount of the second position data. Although the form to be formed has been described, the form in which the correction table 681 is regenerated by the following method may be used. The correction table generation unit 67 regenerates the correction table based on the first position data, the second position data, and the transmission error information indicating the transmission error between the input shaft 10 and the output shaft 11. Form may be sufficient.

  For example, the transmission error information is the radius R and the eccentric amount ε of the rotating disk 401, which is the eccentric information 682, and the correction table generating unit 67 includes the radius R and the eccentric amount ε of the rotating disk 401 and the second position data. Based on the deviation amount, the correction table 681 shown in FIG. 6C is regenerated (generated) by calculation (second generation method). Note that the shift amount of the second position data is calculated from the first position data and the second position data as described above.

  The shift amount of the second position data can be calculated more finely than the resolution of the second encoder 4. Therefore, in this case, the correction table generation unit 67 can generate the correction table 681 that accurately reflects the shift amount of the second position data. In the case of the first generation method in which the correction table 681 that has already been generated is shifted and the correction table 681 is regenerated, the shift is performed in units of 1 LSB (unit of quantization amount). Therefore, the encoder apparatus 20 can correct the correction table 681 with higher accuracy than when the correction table 681 is regenerated with the first generation method when the correction table 681 is regenerated with the second generation method.

  As another embodiment, the transmission error information described above may be information acquired based on the first position data and the second position data detected by rotating the output shaft 11 once. For example, when the position data comparison / collation circuit 64 determines that the amount of deviation of the second position data is equal to or greater than a first threshold that is a predetermined threshold, error status information is sent via the external communication circuit 65. And output to the controller 8 through the communication line 9. For example, the controller 8 rotates the motor 7 slowly (low-speed rotation) and rotates the output shaft 11 once as the correction mode. When the output shaft 11 is rotated once (during rotation), the detected first position data and second position data are converted into a correction table generation unit 67 via, for example, the position data comparison / collation circuit 64. Get. The correction table generation unit 67 calculates the measurement error (transmission error information) of the second encoder 4 as shown in FIG. 6B based on the acquired first position data and second position data. get.

Here, the measurement error of the second encoder 4 is a measurement error corresponding to the total rotational position data (0 to 2047) of the second encoder 4 because it is acquired by rotating the output shaft 11 once. Then, the correction table generation unit 67 regenerates the correction table 681 using the measurement error of the second encoder 4 (third generation method).
As a result, when the displacement of the position information as described above occurs, the transmission error information is reacquired by rotating the output shaft 11 once. Therefore, the correction table generation unit 67 determines the amount of deviation of the second position data. Based on this, it is possible to generate a correction table 681 that can be corrected with higher accuracy than when the correction table 681 is generated by shift or calculation. That is, the third generation method can generate the correction table 681 that can correct the second position information with higher accuracy than the first generation method and the second generation method.

Further, the transmission error information described above is based on the first position data and the second position data detected by rotating the output shaft 11, and the upper limit value and the lower limit value in the measurement error of the second encoder 4. The position data of the corresponding second encoder may be used. In this case, the correction table generation unit 67 regenerates the correction table 681 based on the position data of the second encoder corresponding to the acquired upper limit value and lower limit value. As an example, the correction table generation unit 67 is based on the position data of the second encoder corresponding to the upper limit value and the lower limit value in the measurement error of the second encoder 4, and the radius R and the eccentricity ε of the rotating disk 401. The correction table 681 is calculated (fourth generation method).
As a result, the correction table generation unit 67 shortens the period necessary for generating the correction table 681 as compared to the case where the transmission error information is acquired by rotating the output shaft 11 once (third generation method). can do.

  In the above embodiment, the plurality of generation methods (first to fourth generation methods) in the correction table 681 have been described. However, the plurality of generation methods are switched according to the shift amount of the second position data. May be used. Next, an example of a mode in which a plurality of generation methods in the correction table 681 are switched and used will be described.

  For example, the position data comparison / collation circuit 64 determines that the amount of deviation of the second position data is equal to or greater than a predetermined second threshold value (eg, 5 LSB or greater) smaller than the first threshold value and smaller than the first threshold value. Then, the regeneration command is output to the correction table generation unit 67 using the second threshold value as the shift amount of the second position data. Further, the position data comparison / collation circuit 64 outputs error status information to the controller 8 through the communication line 9 via the external communication circuit 65 when the shift amount of the second position data is equal to or greater than the first threshold value. To do.

The correction table generation unit 67 outputs from the position data comparison / collation circuit 64 when the shift amount of the second position data is smaller than the first threshold and equal to or larger than a predetermined second threshold smaller than the first threshold. The correction table 681 is regenerated by the first generation method or the second generation method based on the shift amount (second threshold value) of the second position data. Further, the correction table generation unit 67 can regenerate the correction table 681 more easily by setting the shift amount of the second position data as the second threshold value.
Further, when the deviation amount of the second position data is equal to or larger than the first threshold value, the controller 8 rotates the motor 7 slowly to rotate the output shaft 11 once, and sets the correction table 681 in the correction table generation unit 67. Regenerate. The correction table generation unit 67 regenerates the correction table 681 by the third generation method or the fourth generation method when the shift amount of the second position data is equal to or larger than the first threshold value.

  In the encoder device 20 according to the present embodiment, the correction table generation unit 67 is a simple generation method when the shift amount of the second position data is small (when the shift amount is between the second threshold value and the first threshold value). The correction table 681 is generated by (the first generation method or the second generation method). In addition, when the shift amount of the second position data is large (when the shift amount is greater than or equal to the first threshold), the correction table generation unit 67 can generate the second position information with high accuracy (third method). The correction table 681 is generated by the generation method or the fourth generation method). As a result, the generation period of the correction table 681 can be shortened when the shift amount of the second position data is small, and the correction table 681 that can be accurately corrected when the shift amount of the second position data is large. Can be generated.

Next, an encoder device and a drive device according to another embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an example of an encoder device that can be applied even when the output shaft 11 of the second encoder 4 rotates two or more times will be described. Note that the encoder device 20a shown in FIG. 7 is applicable even when the output shaft 11 is one rotation or less.
FIG. 7 is a second block diagram illustrating another example of the configuration of the encoder device 20 in the drive device 1 of FIG. In this figure, the same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted. The encoder device 20 a includes a first encoder 3 a and a second encoder 4.
FIG. 8 is a second block diagram showing another example of the configuration of the signal processing circuit 6 in the driving apparatus of FIG. In this figure, the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 7, the first encoder 3a includes a rotating disk 301a having an absolute pattern, an incremental pattern, and a magnetic pattern 305 defined by a predetermined M-sequence code. The rotating disk 301a rotates as the input shaft 10 rotates. Light emitted from the light emitting element 302 passes through each pattern of the rotating disk 301 and enters the light receiving sensor 303.
The light receiving sensor 303 outputs two types of signals, that is, a signal detected from the absolute pattern and a signal detected from the incremental pattern, to the signal processing circuit 6a. Moreover, the magnetic sensor 304 outputs a signal (multi-rotation detection signal) for detecting that the magnetic pattern 305 has passed to the signal processing circuit 6a.

8, the signal processing circuit 6a includes a first position data detection circuit 61, a second position data detection circuit 62, a position data synthesis circuit 63a, a position data comparison / collation circuit 64a, an external communication circuit 65, a correction. A table generation unit 67, a storage unit 68, and a multi-rotation detection circuit 69 are provided.
The multi-rotation detection circuit 69 detects multi-rotation information indicating the number of rotations of the input shaft 10 based on the multi-rotation detection signal output from the magnetic sensor 304. The multi-rotation detection circuit 69 outputs the detected multi-rotation information to the position data synthesis circuit 63 and the position data comparison / collation circuit 64.

  The position data synthesis circuit 63a synthesizes the first position data detected by the first position data detection circuit 61, the second position data detected by the second position data detection circuit 62, and the multi-rotation information. Thus, the combined position data indicating the position displacement within one rotation is generated together with the number of rotations of the input shaft 10. Note that since the combined position data is combined based on the multi-rotation information, it corresponds to the case where the output shaft 11 rotates a plurality of times. The position data synthesis circuit 63a outputs the generated synthesized position data to the controller 8 through the communication line 9 via the external communication circuit 65. Other functions of the position data composition circuit 63 are the same as those of the position data composition circuit 63 shown in FIG.

  The position data comparison / collation circuit 64a is based on, for example, first position data, gear ratio information, resolution B1a of the first encoder 3a, resolution B2 of the second encoder 4, and multi-rotation information. Then, an estimated value (second estimated value) of the second position data is calculated. Then, the position data comparison / collation circuit 64a compares and collates the second position data detected by the second position data detection circuit 62 with the calculated estimated value of the second position data. Other functions of the position data comparison / collation circuit 64a are the same as those of the position data comparison / collation circuit 64 shown in FIG.

As described above, the encoder device 20a according to the present embodiment includes the multi-rotation detection circuit 69 that detects the number of rotations of the input shaft 10 based on the multi-rotation detection signal output from the first encoder 3a. Therefore, rotational position information corresponding to multiple rotations of the output shaft 11 can be detected.
In the present embodiment, the form in which the number of rotations of the output shaft 11 is detected by detecting the number of rotations of the input shaft 10 has been described. However, the form in which the number of rotations of the output shaft 11 in the second encoder 4 is detected. But you can. In this case as well, rotational position information corresponding to multiple rotations of the output shaft 11 can be detected.
In the present embodiment, the form in which the number of rotations is detected using the magnetic sensor 305 has been described. However, the form in which the number of rotations is detected using an absolute position detection signal may be used. In this case, it may be realized by counting the number of times the rotational position data “0” is passed.

  In addition, the drive device 1 in the embodiment of the present invention includes the encoder device 20 (or 20a) described above. Therefore, the same effect as that of the encoder device 20 (or 20a) can be obtained. Therefore, the drive device 1 can correct the displacement of the position information when the displacement of the position information occurs in the encoder device 20 (or 20a). Further, the encoder device 20 according to the present embodiment can detect the position information with high accuracy even when the displacement of the position information as described above occurs.

The drive device 1 can be applied to robot devices such as industrial robots and service robots. Next, an application example will be described.
FIG. 9 is a block diagram illustrating an example of the robot apparatus 5 including the driving apparatus 1 of FIG.
In this figure, the robot device 5 is a multi-axis drive type robot arm, and includes two drive devices (1A, 1B), two arm portions (51, 52), and a control device 55. In this figure, the driving device 1 shown in FIG. 1 is shown as a driving device (1A, 1B).

  The driving device 1B drives the arm unit 52, and the driving device 1A is provided in the arm unit 52 and drives the arm unit 51. The driving device 1 </ b> B is fixed to the pedestal 54 via the support column 53. The pedestal 54 includes, for example, wheels and may be movable in the horizontal direction.

  In addition, the end part of the arm part 51 on the side not connected to the driving device 1A is provided with a hand part that causes a mechanical action on the work target, for example. The hand part is, for example, a clamping part that clamps a work object, a welding part that welds the work object, a cutting part that cuts the work object, or an opening / closing part that opens or closes a screw or bolt that is the work object. is there. The arm portion 51 itself may be such a hand portion itself.

  The control device 55 controls the drive device (1A, 1B) based on the rotational position of the drive device (1A, 1B) input via the signal line 56. Thereby, the rotation position of the arm part (51, 52) is controlled, and the position of the hand part provided at the end of the arm part 51 is controlled. The control device 55 controls the drive devices (1A, 1B) via the control line 57. Further, the control device 55 may control the hand portion via the control line 57.

The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention.
In each of the above embodiments, the position data comparison / collation circuit 64 (or 64a) compares and collates the second position data and the estimated value of the second position data calculated from the first position data. Although the form to do was demonstrated, another form may be sufficient. For example, the position data comparison / collation circuit 64 (or 64a) compares the first position data with the estimated value (first estimated value) of the first position data calculated from the second position data. A form of matching may be used. In this case, the position data comparison / collation circuit 64 (or 64a) calculates the shift amount of the second position data using the shift amount (displacement amount) of the first position data. That is, the shift amount of the second position data can be calculated in both the form using the estimated value of the second position data and the form using the estimated value of the second position data.

Further, in each of the above embodiments, the encoder device 20 (or 20a) has been described in a form that does not include the motor 7 and the gear 2, but may include any one or both of the motor 7 and the gear 2.
Moreover, if it is a power transmission part, it will not be limited to the gear 2, For example, a reduction gear, a pulley, a transmission direction change etc. may be sufficient.
Further, in each of the embodiments described above, the encoder device 20 includes the correction table 681. However, the encoder device 20 may include the correction device 681, but the drive device 1 may include the correction table 681.

In each of the above embodiments, the example of the eccentric error due to the deviation between the center of the output shaft 11 and the center of the rotary disk 401 in the second encoder 4 has been described as the transmission error. However, the present invention is not limited to this. Instead, for example, an eccentricity error between the input shaft 10 and the output shaft 11 may be included. In other words, the eccentric error between the input shaft 10 and the output shaft 11 is, for example, the eccentricity between the input shaft 10 and the output shaft 11, and even if the shafts are intended to be assembled with high precision, the rigidity and meshing of the shaft members, Shows the error that occurs when rotating by load.
In each of the above embodiments, the storage unit 68 has been described as storing the correction table 681 and the eccentricity information 682. However, the correction table 681 and the eccentricity information 682 may be stored in different storage units.

In each of the above-described embodiments, the encoder device 20 (or 20a) has been described in the form of a combination in which an optical encoder is used for the first encoder 3 and a magnetic encoder is used for the second encoder 4. The form using other combinations may also be used. Note that the reliability can be improved by combining different types of encoders.
Further, in each of the above embodiments, the encoder device 20 (or 20a) has been described in the form in which the first encoder 3 and the second encoder 4 are absolute encoders, but other encoders may be used. Further, the optical encoder in the present embodiment may be a transmission type or a reflection type. In addition, the input shaft 10 in this embodiment may be a hollow shaft member. When the input shaft 10 is hollow, the output shaft 11 may be extended into the shaft of the input shaft 10, and the second encoder 4 may be disposed on the motor 7 side in the same manner as the first encoder 3. Further, the output shaft 11 in the present embodiment may be a hollow shaft member. Further, for example, the detection of the displacement of the relative positional relationship between the input shaft 10 and the output shaft 11 by the position data comparison / collation circuit 64 of the encoder device 20 (or 20a) in the present embodiment is synchronized with the detection of the position information. Alternatively, it may be performed in synchronization with a predetermined interval according to the resolution of the first encoder 3 or the second encoder 4.

  In each of the above embodiments, the signal processing circuit 6 and each circuit (each unit) of the signal processing circuit 6 may be realized by dedicated hardware, and may be a memory and a CPU (Central processing unit). And may be realized by a program.

  In each of the above embodiments, the correction table generation unit 67 has been described as generating the correction table using the first to fourth generation methods. However, the present invention is not limited to this. For example, when the relative positional relationship between the first encoder 3 and the second encoder 4 can be redefined, the correction table generating unit 67 uses the radius R and the eccentricity ε of the rotating disk 401 to generate The correction table 681 may be generated as shown in FIG. In this case, as shown in FIGS. 10B and 10C, the error value of the positive value is shifted from the error value of the negative value, and the error is “0” when the position data is “0”. Is generated (see waveform W11). As a result, the correction table generation unit 67 has the same effect as when the second generation method is used.

  DESCRIPTION OF SYMBOLS 1,1A, 1B ... Drive device, 2 ... Gear, 3, 3a ... 1st encoder, 4 ... 2nd encoder, 7 ... Motor, 10 ... Input shaft, 11 ... Output shaft, 20, 20a ... Encoder device, 61: First position information generation unit, 62: Second position information generation unit, 64, 64a: Position data comparison / collation circuit, 67: Correction table generation unit, 68: Storage unit, 401: Rotating disk

Claims (15)

A first encoder that outputs a first signal corresponding to the rotational position of the input shaft rotated by the drive unit;
A second encoder that outputs a second signal corresponding to a rotational position of an output shaft coupled to the input shaft via a power transmission unit;
A first position information generating unit that generates first position information indicating rotational position information of the first encoder based on the first signal;
A second position information generating unit that generates second position information indicating the rotational position information of the second encoder based on the second signal and a correction table indicating a correction value of the rotational position information of the second encoder. When,
A determination unit that detects a relative displacement of the second position information with respect to the first position information using the first position information and the second position information;
An encoder apparatus comprising: a correction table generation unit configured to generate the correction table according to the displacement of the second position information when the determination unit detects a relative displacement of the second position information. . The encoder apparatus according to claim 1, wherein the correction table generation unit generates the correction table based on a displacement amount of the second position information calculated by the determination unit. The correction table generation unit generates the correction table based on the first position information, the second position information, and transmission error information indicating a transmission error between the input shaft and the output shaft. The encoder device according to claim 1 or 2, wherein The transmission error information is a disk provided in the second encoder, the distance information from the center of the disk having a pattern indicating position information to the pattern, and the center of the input shaft measured in advance. The encoder device according to claim 3, wherein the encoder device is calculated based on an eccentric amount between the output shaft and the center of the output shaft. The transmission error information is
The encoder apparatus according to claim 4, wherein the encoder apparatus is acquired based on the first position information and the second position information detected by rotating the output shaft once. The transmission error information is
The position of the second encoder corresponding to the upper limit value and the lower limit value in the measurement error of the second encoder based on the first position information and the second position information detected by rotating the output shaft. Including information,
The correction table generation unit
The encoder apparatus according to claim 4 or 5, wherein the correction table is generated based on position information of the second encoder corresponding to the acquired upper limit value and the lower limit value. The determination unit calculates a displacement amount of the second position information based on the second position information and a second estimated value calculated from the first position information. The encoder apparatus as described in any one of Claim 6. The determination unit calculates a displacement amount of the second position information using a displacement amount of the first position information based on the first position information and a first estimated value calculated from the second position information. The encoder device according to claim 1, wherein the encoder device is calculated. The said correction table production | generation part produces | generates the said correction table, when it determines with the displacement amount of the said 2nd position information being more than the predetermined 1st threshold value by the said determination part. The encoder device according to any one of claims 1 to 8. The correction table generation unit
When the displacement amount is smaller than the first threshold value and greater than or equal to a predetermined second threshold value smaller than the first threshold value, the second threshold value is used as the displacement amount, and the second threshold value and the transmission error information The encoder device according to claim 9, wherein the correction table is generated based on: A storage unit for storing the correction table;
The correction table generation unit
The encoder device according to any one of claims 1 to 10, wherein the generated correction table is stored in the storage unit.   The encoder device according to claim 11, wherein the storage unit is a nonvolatile storage unit.   The encoder device according to any one of claims 1 to 12, wherein the first encoder is an absolute encoder that detects absolute position information in rotation of the input shaft.   A drive device comprising the encoder device according to any one of claims 1 to 13.   A robot apparatus comprising the driving apparatus according to claim 14.

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