JP5840995B2 - Encoder system - Google Patents

Description

  The present invention relates to an encoder system that detects a rotational position of a motor and a rotational position of a load by an encoder in a configuration in which a load is driven by a motor via a speed reducer.

For example, when controlling the rotational position of the arm in a configuration that drives the joint of the robot, as a result of controlling the motor according to the rotational position detected by the encoder, the actual rotational position of the arm via the speed reducer You may want to check if it is. For example, Patent Document 1 discloses a configuration in which a rotational position of an arm is detected by a potentiometer when a motor and an arm are connected via a torque cutter.
Japanese Patent No. 4369886

  In the configuration as described above, it is assumed that the encoder is used in the same manner as the motor side instead of the potentiometer on the arm side in order to handle the rotational position with digital data. In this case, if the encoder on the arm side is arranged between the speed reducer and the arm on the tip end side of the rotating shaft of the motor as in Patent Document 1, it is necessary to secure an arrangement space correspondingly, and the robot This hinders the construction of a small size.

  That is, an apparatus having an arm, such as a robot or a machine tool, may introduce the tip end side of the arm into a narrow region because of its work characteristics, and there is a demand for making the arm as thin and small as possible. If a part such as a potentiometer or an encoder instead of the potentiometer is additionally mounted as in Patent Document 1, the volume on the arm side is enlarged by the arrangement space.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an encoder system capable of downsizing a configuration in which the rotational positions of a motor and a load are detected by an encoder.

  According to the encoder system of the first aspect, the rotating shaft (input shaft) of the motor is formed in a hollow shape, the output shaft is directly connected to the load at the rear end thereof, and is inserted into the hollow portion of the input shaft. Derived to the rear end side of the input shaft. That is, the tip of the output shaft that rotates with the rotation of the load faces the rear end side of the motor through the inside of the input shaft. The rotational position of the motor and the rotational position of the load via the speed reduction mechanism are detected by the optical input side and output side encoders, respectively, but these rotating plates are shared and fixed to the rear end side of the input shaft. . And the detection part (namely, light projection part and light-receiving part) of an output side encoder is attached to the front end side of an output shaft, and the detection part of an input side encoder is attached to a fixed part.

  If comprised in this way, the rotation position of a motor can be acquired as usual based on the detection result of the detection part of an input side encoder. On the other hand, the rotational position of the load is detected as follows. Since the rotating plate rotates with the input shaft and the detection unit of the output encoder rotates with the output shaft, the detection unit detects the rotational position corresponding to the difference in rotational speed between the input shaft and the output shaft. Become. Therefore, in the control unit that reads and processes the data from the detection units of the two encoders, if the difference between the rotation position detected by the input side encoder and the rotation position detected by the output side encoder is obtained, the rotation of the load is obtained. The position can be obtained.

  That is, since the input side and output side encoders detect the rotational position based on the rotation of the same rotating plate, it is difficult to generate a detection error due to the deviation of the axis. Since these encoders are collectively arranged on the rear end side of the motor, the load side arrangement space can be reduced as much as possible, and the encoder system using two encoders and the configuration combining the encoder system and the load are compact. Can be.

  According to the encoder system of the second aspect, the detection unit of the input side encoder is attached to the fixed unit located on the opposite side of the rotation plate with respect to the detection unit of the output side encoder. If comprised in this way, there will be no possibility that the optical signal which each of the two optical encoders output in order to detect the rotational position will be received by the mutual detection unit, and erroneous detection can be prevented.

  According to the encoder system of the third aspect, the first surface of the rotating plate has a position detection pattern for the output side encoder, and the input is input to the second surface which is a surface different from the first surface. A position detection pattern for the side encoder is provided. If comprised in this way, it will become possible for the detection part of each of an output side and an input side encoder to receive the reflected light for performing a rotational position detection in the state which does not mutually interfere.

Functional block diagram illustrating the configuration of the data processing unit in the detection unit of the encoder according to the first embodiment. Flowchart showing the rotational position data transfer process between the input EC detection unit and the output EC detection unit Timing chart showing a state in which rotational position data Pin (t), Pout (t) changes Functional block diagram showing the internal configuration of the motor control controller, and the connection state between the three input EC detection units and the controller Flowchart showing processing contents when control CPU controls 3-axis robot FIG. 5 is a timing chart showing a transfer state of rotational position data corresponding to the processing of FIG. Vertical side view of FIG. The perspective view which shows the structure which drives one of the joint axes of a robot with a motor. FIG. 7 equivalent diagram showing the second embodiment. Longitudinal side view of turntable Diagram explaining calculation of output angle θout Flow chart showing calculation process of output angle θout FIG. 4 equivalent view showing the third embodiment

(First embodiment)
Hereinafter, a first embodiment will be described with reference to FIGS. FIG. 8 is a perspective view showing a configuration in which one of the joint axes of the robot is driven by a motor, and FIG. 7 is a vertical side view (however, slightly simplified). The motor 1 is, for example, an inner rotor type permanent magnet synchronous motor, and is arranged inside a cylindrical base 2 with the tip of the rotary shaft 3 facing upward in the drawing. The stator 4 of the motor 1 is composed of a stator core and windings (not shown), and is fixed so that its upper end surface is in contact with the back of the top plate of the base 2. The rotor is composed of a rotating shaft 3 and permanent magnets arranged so as to face the rotor core and the stator side windings (none of which are shown). In FIG. 6 is shown as being rotatably supported.

  The rear end portion of the rotating shaft 3 protrudes downward from the rear end surface of the stator 4, and the front end portion protrudes outside through a through hole 7 formed in the top plate of the base 2. The tip portion is connected to the input portion 8I of the speed reducer 8, and the robot arm 9 (control object, load) is connected to the output portion 8O. The detailed configuration of the speed reducer 8 is also not shown. On the rear end surface of the rotary shaft 3, a turntable 11 constituting an optical rotary encoder (hereinafter referred to as an input encoder (input EC)) 10 is attached.

  Below the turntable 11, an input EC detection unit 12 including a data processing unit including a light projecting element, a light receiving element, a counter (not shown), a register described later, and the like is formed in a cup shape after the stator 4. It is attached to the bottom surface of the encoder support member 13 fixed to the end surface. That is, the input EC detection unit 12 detects the rotational position of the motor 1 by projecting light toward a slit (not shown) of the upper turntable 11 and receiving the reflected light.

  A rear end portion of the arm rotation shaft 14 (output shaft) is attached to the upper surface side of the arm 9 so as to be coaxial with the rotation shaft 3 (input shaft) of the motor 1. A shaft support member 15 comprising a vertical portion 15V extending upward and a horizontal portion 15H disposed parallel to the arm 9 at the tip of the vertical portion 15V is disposed at the right end of the top plate of the base 2 in FIG. ing. The arm rotation shaft 14 passes through the horizontal portion 15H and is rotatably supported by a bearing 16 disposed in the horizontal portion 15H.

  A rotating disk 18 constituting an optical encoder 17 (hereinafter referred to as an output encoder (output EC)) is attached to the tip surface of the arm rotating shaft 14. The output encoder 17 has the same configuration as that of the input encoder 10, and an output EC detection unit 19 including a light projecting element, a light receiving element, a counter, and the like is disposed above the turntable 18 with a horizontal part 15 </ b> H in a shape with the cup turned down. Are attached to the back of the top plate of the encoder support member 20 fixed to the upper surface of the encoder. In other words, the output EC detection unit 19 detects the rotational position of the arm 9 by projecting light toward the slit of the lower rotating disk 18 and receiving the reflected light.

  The input EC detection unit 12 of the input encoder 10 is connected to the output EC detection unit 19 of the output encoder 17 via the relay bus 21, and the rotational position data detected by the output EC detection unit 19 is the input EC detection unit 12. Forwarded to The output EC detection unit 19 transmits an edge pulse signal for data latch to the input EC detection unit 12 via the relay bus 21. When the input EC detection unit 12 integrates the rotation position data and the rotation position data detected by itself, the input EC detection unit 12 outputs the data to the motor control controller 23 (see FIGS. 1 and 3) via the data bus 22. The relay bus 21 and the data bus 22 are led out to the inside and outside of the base 2 through a through hole 24 formed in the base 2.

  FIG. 1 is a functional block diagram mainly showing the configuration of the data processing unit in the detection units 12 and 19. The input EC detection unit 12 includes, for example, a 20-bit input EC value holding register 31 (input data latch) that holds counter data for counting the number of pulses output from the light receiving unit. Similarly, the output EC detection unit 19 includes an output EC value holding register 32 (output data latch) that holds counter data. The rotation position data of the arm 9 is, for example, 9 bits (the size is smaller than the input side because of the speed reducer 8), but the counter overflows when the rotation speed of the arm 9 is 1 rotation or more. Multi-rotation data (for example, 2 bits) indicating the number of times the image is recorded is also stored. However, this embodiment does not handle multi-rotation data.

  In the output EC detection unit 19, the output EC value register monitoring unit 34 constituting the data change detection unit 33 monitors whether or not the LSB (Least Significant Bit) of the output EC value holding register 32 has changed, and there is a change. (That is, when the counter value is incremented), an edge pulse is output to the output EC value holding register 32 and a pulse output command is issued to the edge pulse output unit 35 (latch signal output unit). Then, the edge pulse output unit 35 transmits a latching edge pulse (latch signal) to the input detection unit 12.

  The data change output value holding register 36 stores and holds the 9-bit rotational position data Pout (t) latched in the EC value holding register 32 at the rising edge of the edge pulse. The held rotational position data Pout (t) is transmitted to the input EC detection unit 12 via the holding data output unit 37. That is, the edge pulse output unit 35 and the hold data output unit 37 are drivers for transmitting the edge pulse and the rotation position data Pout (t) to the input EC detection unit 12, respectively.

  On the input EC detection unit 12 side, the edge pulse transmitted from the edge pulse output unit 35 is received by the edge pulse input unit 39 of the data latch unit 38 and output to the input value holding register 31. As a result, the rotational position data Pout (t) in the data change output value holding register 36 and the rotational position data Pin (t) in the input value holding register 31 are latched by the rising edge of the same edge pulse. .

The rotational position data Pin (t) is output to the motor control controller 23 (control device) via the input value data bus 40 forming a part of the data bus 22 described above, and input / output of the data latch unit 38. It is transferred to the value holding register 41 (input / output data latch). Further, the rotational position data Pout (t) transmitted from the held data output unit 37 of the output EC detection unit 19 is also transferred to the input / output value holding register 41. The total 29-bit rotational position data Pin (t) and Pout (t) stored in the input / output value holding register 41 is used for motor control via the input / output value data bus 42 that forms part of the data bus 22. It is output to the controller 23.
The data buses 40 and 42 are actually 32 bits in size, and the bits of data not used for transmission are pulled up or pulled down. Hereinafter, the 20-bit rotational position data Pin (t) is referred to as an input EC value, and the 29-bit rotational position data Pin (t) and Pout (t) are referred to as input / output EC values.

  FIG. 4 is a functional block diagram showing the internal configuration of a motor control controller (hereinafter simply referred to as a controller) 23, and assumes that it is applied to a multi-axis configuration, for example, each axis of a 3-axis robot. The connection state of the input EC detection units 12 (1 to 3) and the motor control controller 23 when there are three sets of configurations shown is shown. Reference numerals (1) to (3) correspond to the first to third axes of the robot. The two are connected via a communication interface (not shown).

  The controller 23 is composed of a microcomputer including a ROM, RAM and other peripheral circuits (not shown) with a control CPU 43 as a center. The input EC value holding register 44 (1 to 3) is a register in which the 20-bit input EC value (1 to 3) transmitted from the input EC detection unit 12 (1 to 3) is written via the communication interface. . The input / output EC value holding registers 45 (1 to 3) receive the 29-bit input / output EC values transmitted from the input EC detection units 12 (1 to 3) via the input / output EC value transmission switch 46. The register to be written. Further, the communication interface and the input / output EC value transmission switching unit 46 are configured by, for example, an FPGA (Field Programmable Gate Array).

  The controller 23 outputs a data transfer request to the input EC detection unit 12 (1 to 3). In the figure, “control data request” is a transfer request for input EC values for three axes, and “correction data request” is a transfer request for input / output EC values for one axis. The control CPU 43 has, for example, a 32-bit configuration, reads the rotational position data stored in the input EC value holding register 44 and the input / output EC value holding register 45, and controls the robot as described later.

  Next, the operation of this embodiment will be described with reference to FIG. 2, FIG. 3, FIG. 5, and FIG. FIG. 2 is a flowchart showing a rotational position data transfer process between the input EC detection unit 12 and the output EC detection unit 19 shown in FIG. As a result of the control CPU 43 executing the control described later, the motor 1 is driven to move the robot arm 9 (S1). When the output EC value monitoring unit 34 detects that the LSB of the output EC value holding register 32 has changed (Pout (t−1) → Pout (t)) (S2: YES), the edge pulse output unit 35 An edge pulse is output and the rotational position data Pout (t) is latched in the output EC value holding register 32 (S3).

  The edge pulse is transmitted to the input EC detection unit 12 (S4), is output to the input EC value holding register 31 via the edge pulse input unit 39, and the rotational position data Pin (t) is latched (S5). Further, the rotation position data Pout (t) is transmitted from the held data output unit 37 of the output EC detection unit 19 to the data latch unit 38 (S6), and the rotation position data Pin (t) and Pout (t) are input / output values. It is stored in the holding register 41 (S7). Then, the rotational position data Pin (t) stored in the input EC value holding register 31 and the rotational position data Pin (t) and Pout (t) stored in the input / output value holding register 41 are respectively data buses. The data is transmitted to the motor control controller 23 via 40 and 42 (S8).

  FIG. 3 is a timing chart showing a state in which the rotational position data Pin (t) and Pout (t) change in the above-described processing. In the output encoder 17, when the rotational position data Pout (t) changes, an edge pulse is generated (see (a) and (b)), the rotational position data Pout (n) at that time and the rotational position data on the input encoder 10 side. Pin (n) is latched (see (e) and (f)). FIG. 3C shows a delay when the input encoder 10 receives the rotational position data Pout (t) transmitted from the output encoder 17. Thereby, the latched rotational position data PinL and PoutL become data detected at the same timing.

  Next, FIG. 5 is a flowchart showing the processing contents when the control CPU 43 of the motor control controller 23 controls the three-axis robot. Hereinafter, the rotational position data Pin (n) is referred to as “input EC value”, and the rotational position data Pout (t) is referred to as “output EC value”. First, when the operation pattern of each axis motor is determined from the target position of the hand of the robot (S11), the control CPU 43 sets the input EC value (all-axis input EC value) for three axes from the input EC value holding register 44 to three. The read cycle is executed and read (S12).

  Subsequently, when the input / output EC value of the first axis is read from the input / output EC value holding register 45 (1) (S13), the motors 1 (1 to 3) of the respective axes are based on the all-axis input EC value acquired in step S12. ) To control the current and speed. Here, the current control and speed control mean that, when the motor 1 is driven by a drive circuit such as an inverter, PI (proportional integration) control or the like is performed based on the deviation between the speed command and the actual speed.

  Subsequent steps S15 to S17 have the same processing pattern as steps S12 to S14. However, in step S16, the input / output EC values of the second axis are read instead of the first axis in step S13. The same applies to the subsequent steps S18 to S20. In step S19, the input / output EC value of the third axis is read instead of the second axis in step S16.

  In the next step S21, using the input / output EC values of the first to third axes acquired in steps S13, S16, S19, the difference (deviation) between the input EC value and the output EC value for each axis is calculated, The position control of the hand of the robot is performed based on the input EC values of all axes (S22). At this time, the position control is corrected according to the deviation value calculated in step S21 (S23). If the hand of the robot has reached the target position (S24: YES), the operation is terminated, and if it has not reached the target position (NO), the process returns to step S12 and the above processing is repeated.

In the processing shown in FIG. 5, the processing until the controller 23 acquires data from the input EC detection unit 12 and stores the data in the input EC value holding register 44 and the input / output EC value holding register 45 is the communication interface described above. Is running at a constant cycle. When the data is stored in the registers 44 and 45, for example, the communication interface generates an interrupt, so that the control CPU 43 starts the processing from step S12 and accesses the input EC value holding register 44.
As a result of executing the processing as described above, the input EC value and the input / output EC value of each axis are transferred to the controller 23 as shown in FIG. That is, the input EC values for all axes are transferred at each transmission cycle, and the input / output EC values for each axis are sequentially transferred at different transmission cycles.

  As described above, according to the present embodiment, the joint axis of the robot includes the input encoder 10 that detects the rotational position of the motor 1 and the output encoder 17 that detects the rotational position of the arm 9 via the speed reducer 8. The controller 23 acquires each rotational position data (EC value) detected by the input encoder 10 and the output encoder 17 and controls the motor 1. An input EC value holding register 31 that latches the input EC value is disposed in the input encoder 10, and an output EC value holding register 32 that latches the output EC value is provided in the output encoder 17, each time the output EC value changes. And an edge pulse output unit 35 for outputting edge pulses to the registers 31 and 32.

  That is, the input encoder 10 on the motor 1 side and the output encoder 17 on the arm 9 side are arranged at a certain distance in structure, and in order for the controller 23 to correct the rotational position of the arm 9, It is necessary to obtain an EC value and an output EC value. Since the arm 9 is driven via the speed reducer 8, the resolution of the output EC value is lower than the input EC value. Therefore, if the edge pulse output unit 35 is disposed in the output encoder 17 and an edge pulse is output to the registers 31 and 32 each time the output EC value changes, the above change can be achieved even in the input encoder 10 that is far away. The input EC value can be latched and held at the same timing.

  Moreover, the controller 23 acquires each EC value detected by the input encoders 10 (1 to 3) and the output encoders 17 (1 to 3) for a plurality of axes, and controls each motor 1 (1 to 3). In order to perform the control, the controller 23 acquires the input EC values of all the axes at regular intervals and sequentially acquires the input EC value and the output EC value of one axis. That is, the input EC values for each axis are all acquired at regular intervals because they are necessary for controlling the position of the hand of the robot. If an error occurs in the output EC value obtained via the speed reducer 8 with respect to the input EC value in one axis, it is necessary to correct the error. Therefore, the input EC value and the output EC value for performing correction are obtained by switching only one axis at regular intervals and sequentially switching, thereby correcting the output rotation position of each axis while suppressing the data transfer size.

  Moreover, it is preferable to use the data acquired at the same time as the data for correcting the rotational position. Therefore, even if the input EC values of all the axes are acquired in the same cycle, the correction is performed with high accuracy by separately acquiring the data used for the correction as a set of the input EC value and the output EC value for each axis. be able to.

  The output EC value is once transferred from the output encoder 17 to the input encoder 10 and then transferred to the controller 23 via the input encoder 10. That is, it is efficient to integrate the input EC value and the output EC value of each axis and transfer them to the controller 23 at the same time. As described above, since the resolution of the output EC value is low and the data size is small, if the output EC value is transferred to the input encoder 10 and then transferred to the controller 23, the output encoder 17 and the input encoder 10 are connected. The bus width of the relay bus 21 is reduced.

  In this case, the input encoder 10 includes an input value holding register 31 for transferring the input EC value to the controller 23, and an input / output value holding register 41 for transferring the input EC value together with the output EC value to the control device. Prepare. Therefore, the data transferred as a set of the input EC value and the output EC value of one axis only once in a plurality of periods and the input EC value transferred to the controller 23 as a part of all the axes at a constant period. And can be transferred efficiently. Moreover, the controller 23 can acquire and process each data quickly.

(Second embodiment)
9 to 12 show a second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, different parts will be described. In the second embodiment, a configuration corresponding to the input encoder 10 and the output encoder 17 of the first embodiment is integrally arranged on the rear end side of the motor rotation shaft. FIG. 9 shows a state in which the top and bottom of FIG. 7 are inverted (the rear end side of the motor is upward). The motor 51 is an inner rotor type permanent magnet type synchronous motor similar to the motor 1, and a rotating shaft (rotor) rotatably supported by a stator 52 and a bearing 53 disposed on the inner peripheral side of the stator 52. 54. An encoder accommodating portion 55 is disposed on the rear end side of the motor 51.

  The encoder housing portion 55 includes an annular side wall 56 attached to the rear end of the stator 52 and a disk-like support member 57 (fixed portion) that is fixed so as to be inserted into the middle portion of the side wall 56. I have. The support member 57 has a through hole 57a formed at the center thereof, and has a so-called donut shape. A rear end portion of the rotary shaft 54 (input shaft) is inserted into a through hole 57a of the support member 57, and a rotary disc (rotary plate) 58 constituting an encoder is fixed to the rear end thereof. The input EC detection unit 12 is disposed on the upper surface side of the support member 57 so as to face the rotating disk 58. That is, the turntable 58 and the input EC detection unit 12 constitute an input encoder unit 59 corresponding to the input encoder 10 of the first embodiment.

  The rotating shaft 54 is formed of a hollow member, and the tip thereof is fixed to the inner peripheral side of the hollow portion of the input portion 60I constituting the speed reducer 60. The arm 9 is attached to the output portion 60O of the speed reducer 60. Are connected. An output shaft 61 whose rear end is fixed to the arm 9 is inserted into the hollow portion of the rotating shaft 54. A bearing 62 is disposed on the inner peripheral side of the rotating shaft 54, and the output shaft 61 is rotatably supported.

  An insertion hole 58a having the same diameter as the hollow portion of the rotary shaft 54 is formed in the rotary disk 58, and the tip of the output shaft 61 protrudes into the space inside the encoder housing portion 55 via the insertion hole 58a. . A rotating disc 63 having a diameter larger than that of the hollow portion of the rotating shaft 54 is fixed to the tip. An output EC detection unit 19 is disposed on the lower surface side of the turntable 63 so as to face the turntable 58. That is, the turntable 58 and the output EC detection unit 19 constitute an output encoder unit 64 corresponding to the output encoder 17 of the first embodiment.

  In the second embodiment, light is projected from both the lower surface side and the upper surface side of the turntable 58 in order to detect the rotational position. Therefore, a pattern (for example, a slit) for position detection is formed on the rotary disk 58 on the first and second surfaces (for example, both surfaces, the upper surface and the side surfaces). FIG. 10 shows a cross-sectional structure (a part) of the turntable 58. The turntable 58 has a five-layer structure. Glass plates 58b and 58c are arranged above and below the light shielding plate 58a, and slit films 58d and 58e are arranged above and below the glass plates 58b and 58c. The slit is formed in both the slit films 58d and 58e.

  Although not shown, power is supplied to the output EC detection unit 19 disposed on the turntable 63, and edge pulses and rotation position data are transferred to the input EC detection unit 12 by wire connection. Even if the arm 9 makes multiple rotations, the number of rotations is about 3 at most. A cover 65 that covers the opening is attached to the top of the encoder housing 55.

Next, the operation of the second embodiment will be described with reference to FIGS. FIG. 11 shows the reduction gear 60 and the arm 9 omitted. When the motor 51 is driven to rotate the arm 9, the rotating disk 58 rotates with the rotation of the rotating shaft 54, so that the input encoder unit 59 rotates the motor just like the input encoder 10 of the first embodiment. The position can be detected. On the other hand, the rotating disk 63 rotates as the arm 9-output shaft 61 rotates. Here, assuming that the rotation angle of the rotating disk 58 is θrot1 and the rotating disk 63 rotates in the same direction as the rotating disk 58, and that rotation angle is θrot2, the angle θ1 detected by the input EC unit 12 is equal to θrot1. The angle θ2 detected by the output EC detection unit 19 is
θ2 = θrot1−θrot2
It becomes.
Therefore, the rotation angle θin of the motor 51 is
θin = θ1 = θrot1
The rotation angle θout of the arm 9 is
θout = θ1−θ2 = θrot1− (θrot1−θrot2) = θrot2
Can be obtained as

Specifically, for example, when the control CPU 43 reads the input / output EC value in steps S13, S16, and S19, the processing shown in FIG. 12 is performed to calculate the rotation angle θout. First, the rotation angle θ1 is calculated from the input EC value Pin (t) by the following equation (S31). However, a is the reduction ratio of the reduction gear 8.
θ1 = 360 × Pin (t) / (2 ²⁰ × a) [deg]
Next, the rotation angle θ2 is calculated from the output EC value Pout (t) by the following equation (S32).
θ2 = 360 × Pout (t) / 2 ⁹ [deg]
Then, the rotation angle θout is obtained by subtracting the rotation angle θ2 from the rotation angle θ1 (S33). The above processing may be performed by hard logic.

  As described above, according to the second embodiment, the rotating shaft 54 of the motor 51 is formed in a hollow shape, the output shaft 61 is directly connected to the arm 9 at the rear end, and is inserted through the hollow portion of the rotating shaft 54, The front end is led out to the rear end side of the rotation shaft 54. The rotation position of the motor 51 and the rotation position of the arm 9 via the speed reducer 60 are detected by the optical input encoder unit 59 and the output encoder unit 64, respectively. And fixed to the rear end side of the rotating shaft 54. Then, the detection unit 19 of the output encoder unit 64 is attached to the distal end side of the output shaft 61, and the detection unit 10 of the input encoder unit 59 is supported on the opposite side of the detection unit 19 with the rotating disk 58 interposed therebetween. It was made to attach to the member 57. For example, the detection unit 10 of the input encoder unit 59 may be attached to the side wall 56 as a fixed unit.

If comprised in this way, the rotation position of the motor 51 can be acquired normally based on the detection result of the detection part 10 of the input encoder part 59. FIG. On the other hand, the rotational position of the arm 9 is detected by the input encoder 59 and the rotational position detected by the output encoder 64 in the controller 23 that reads and processes data from the two detectors 10 and 19. And can be obtained by the difference. That is, since the input and output encoder units 59 and 64 detect the rotational position based on the rotation of the same rotating disk 58, it is difficult for a detection error due to the deviation of the axis to occur. And since these encoder parts 59 and 64 are collectively arrange | positioned at the rear-end side of the motor 51, arrangement | positioning space can be reduced as much as possible, The structure which combined the encoder system and load which used two encoders Can be reduced in size.
That is, as in the second embodiment, by using the rotating shaft 54 formed in a hollow shape, the encoder parts 59 and 64 can be collectively arranged on the rear end side of the motor 51, and the output encoder part 64 is reduced. It is not necessary to arrange between 60 and the arm 9.

  And since the detection part 10 of the input side encoder 59 is attached to the fixed part located on the opposite side of the rotation disk 58 with respect to the detection part 19 of the output side encoder 64, the two optical encoders 59, 64 There is no possibility that the optical signals output for detecting the rotational position of each of them will be received by the mutual detectors 19 and 10, and erroneous detection can be prevented. Further, since the slit for the output side encoder 59 is provided on one surface of the rotating disk 58 plate and the slit for the input side encoder 64 is provided on the other surface, each of the detection units 10 and 19 detects the rotational position. It is possible to receive reflected light to be performed without interfering with each other.

(Third embodiment)
FIG. 13 shows a third embodiment, and only differences from the first embodiment will be described. The third embodiment shows a configuration in which a data transfer processing unit 71 is disposed between the input EC detection units 12 ′ (1 to 3) and output EC detection units 19 (1 to 3) and the controller 23. The data transfer processing unit 71 has an input / output EC value holding register provided in the input EC detection unit 12 and a communication interface function. Therefore, the output EC detection unit 19 makes the 9-bit output EC value directly to the data transfer processing unit 71.
The data transfer processing unit 71 outputs a 20-bit input EC value and a 29-bit input / output EC value to the controller 23 in response to a request from the communication interfaces 43R and 44 on the controller 23 side. In the case of the third embodiment configured as described above, the same effect as that of the first embodiment can be obtained.

The present invention is not limited to the embodiments described above or shown in the drawings, and the following modifications or expansions are possible.
The number of bits of the input encoder and output encoder may be appropriately changed according to the individual design.
The data transfer method performed between the input EC detection unit 12 and the controller 23 for the three axes shown in FIG. 4 may be changed as appropriate. For example, two 32-bit buses are connected between them, and an input EC value for 3 axes (20 bits) and an input / output EC value for 3 axes (29 bits) are selected and A communication interface that transfers only data for one axis to the controller 23 side by communication may be used.

Further, the bus size is not limited to 32 bits, and may be 20 bits and 29 bits as the minimum required sizes. Alternatively, the input EC value and the input / output EC value may be transferred by a common 32-bit (or 29-bit) bus.
In the second embodiment, depending on the configuration of the speed reducer 60, the rotating shaft 54 and the output shaft 61 may rotate in opposite directions.
You may apply to the robot of 4 axes or more. Further, the present invention is not limited to a multi-axis robot, and may be applied to single motor control.

  1 is a motor, 8 is a reduction gear, 9 is an arm (load), 10 is an input encoder, 12 is an input EC detection unit, 17 is an output encoder, 19 is an output EC detection unit, 21 is a relay bus (data bus), 23 Is a motor control controller (control device), 31 is an input EC value holding register (input data latch), 32 is an output EC value holding register (output data latch), 35 is an edge pulse output unit (latch signal output unit), 41 Is an input / output value holding register (input / output data latch), 51 is a motor, 54 is a rotating shaft (input shaft), 57 is a support member (fixed portion), 58 is a rotating disk, 59 is an input encoder portion, and 60 is a reducer. , 61 is an output shaft, and 64 is an output encoder section.

Claims (3)

The load is driven by a motor through a speed reducer.
In the motor, the rotation shaft has a hollow portion,
When the rotary shaft is an input shaft, the rear end is directly connected to the load, the output shaft is inserted into the hollow portion of the input shaft and the front end is led out to the rear end side of the input shaft,
Detecting the rotational position of the motor, and an optical input-side encoder disposed on the rear end side of the input shaft;
It detects the rotational position of the load via the speed reduction mechanism, and comprises an optical output side encoder,
The rotating plate constituting the input side encoder and the output side encoder is shared, and is fixed to the rear end side of the input shaft,
The detector of the output side encoder is attached to the tip side of the output shaft,
An encoder system, wherein the detection unit of the input side encoder is attached to a fixed unit.   2. The encoder according to claim 1, wherein the detection unit of the input-side encoder is attached to the fixed unit located on the opposite side of the rotation plate with respect to the detection unit of the output-side encoder. system.   The rotary plate has a position detection pattern for the output encoder on a first surface, and a position detection pattern for the input encoder on a second surface that is different from the first surface. The encoder system according to claim 1, further comprising:

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