JPH0749246A - Encoder system - Google Patents

Abstract

PURPOSE:To establish an initial origin position easily and highly accurately by saving a pulse value obtained from an encoder device as an origin offset in a memory means (memory). CONSTITUTION:The arm 11 of a robot 1 is rotatably jointed to a base 12. The arm 11 is connected to and driven with a motor 14 via a reducer 13. Also, an encoder device 15 is connected to the rotating shaft of the motor 14, thereby detecting the speed and rotating direction of the motor 14. A mark is applied to the arm 11 at a mechanical reference position. Furthermore, a control device 3 calculates the operating position of the arm 11 on the basis of a detection signal from the encoder device 15. The control device 3 stores a pulse value obtained from the encoder device 15 in a main memory 32 as an origin offset value, as a result of the travel of the arm 11 from an encoder origin position to the mark 16. According to this construction, the origin offset value can be reproduced, even if the internal count value of the encoder device 15 is lost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder system used for robots and other industrial machines. More specifically, the present invention relates to an encoder system that can determine the initial origin position simply and with high accuracy.

[0002]

2. Description of the Related Art Generally, regardless of the type of robot, a servo motor or the like is provided on each axis of a movable part such as a robot arm,
By rotating each servo motor, the tip (working end) of the movable portion is moved to a predetermined position.
Further, in such a robot, an incremental encoder is arranged on the rotary shaft of each motor, the number of revolutions of each motor is detected by each encoder, and the tip (working end) of the movable part is detected based on the detected data. The position is confirmed by feedback control. Therefore, it is necessary to accurately obtain the origin of the detection data of the encoder.

Conventionally, as a device for detecting the origin position in an encoder, an incremental encoder is provided on the rotary shaft of a motor, and a cam is provided on the rotary shaft via a speed reducer so that it can move in the same manner as a movable part of a robot. And a protrusion is formed on the cam, the protrusion of the cam can be detected by a proximity sensor, and an origin position detection signal is obtained from a detection signal from the proximity sensor and an index pulse from the encoder. (For example, Japanese Patent Application No. 2-30194).

Since this origin detecting device is capable of detecting the origin of a portion which is actually moving by a cam or the like,
There is an advantage that the origin can be detected reliably.

However, in the above-mentioned conventional origin position detecting device, since the origin is mechanically detected by the cam, it takes a long time to attach the proximity sensor and to perform adjustment work. was there.

Such a drawback is solved by adopting an absolute encoder. That is, it is possible to omit the attachment and adjustment work of the proximity sensor. By resetting the absolute encoder at the mechanical origin position of the movable part, the current position of the movable part of the robot can be estimated from the rotation pulse count value of the motor from the encoder origin.

[0007]

However, in the origin position detection system using the absolute encoder, when the count value is reset or destroyed due to some reason, the count value from the origin position is changed. There is a drawback in that the motion data of the movable part, which has been obtained based on this, cannot be used at all.

Therefore, it is an object of the present invention to provide an encoder system that can determine the initial origin position simply and with high accuracy.

[0009]

In order to achieve this object, an encoder system according to the invention of claim 1 is
A motor that drives a movable part, an encoder device that can detect the number of rotations of the motor, and can output a count value from an encoder origin, a mark that displays a mechanical origin position of the movable part, and an operation of the encoder device. A control device that can be controlled and that can store the pulse value obtained from the encoder device by the moving of the movable portion from the encoder origin position of the encoder device to the mark as the origin offset in the storage means is provided.

The encoder system according to a second aspect of the present invention includes a motor for driving a movable part, an encoder device capable of detecting the rotation speed of the motor and outputting a count value from an encoder origin, and the movable part. A mark for displaying the mechanical origin position of the, and the number of pulses from the encoder device to the mark closest to the encoder index to the mark is stored in the storage means, and when the encoder device loses the encoder origin position, After resetting the encoder device, a new origin offset is obtained from the data obtained from the encoder device and the stored pulse number when the movable part is moved to match the mark or its vicinity, and this new origin offset is obtained. And a control device for storing the information in the storage means.

Further, in the encoder system according to the third aspect of the present invention, the motor for driving the movable part, the encoder device capable of detecting the rotation number of the motor and outputting the count value from the encoder origin, and the movable part. As a mechanical origin position, a mark indicating the mechanical origin position of the movable part, and the pulse up to the mark and the mark are stored in a storage unit, and the encoder device sets the encoder origin position. , When the encoder device is reset, the movable part is automatically moved, and when it is determined that the movable part has stopped,
A control device capable of reproducing the original origin position from the pulse from the reset to the stop of the movable part and the pulse stored in the storage means is provided.

[0012]

According to the first aspect of the present invention, a mark for indicating the mechanical origin position of the movable part is provided, and a pulse obtained from the encoder device by moving the movable part from the encoder origin position of the encoder device to the mark. The value is stored in the storage means as the origin offset. Therefore, even if the internal count value of the encoder device is lost, the origin offset value can be reproduced.

According to a second aspect of the present invention, a mark for indicating the mechanical origin position of the movable portion is provided, and the number of pulses from the encoder device closest to the mark to the mark from the encoder index to the mark is set by the control device. It is stored in the storage means. When the encoder device loses the encoder origin position, after resetting the encoder device, a new data is obtained from the data obtained from the encoder device and the stored pulse number when the movable part is moved to align with or near the mark. Find a proper origin offset.
As a result, the previous origin can be restored.

According to the third aspect of the present invention, a hit as a mechanical origin position of the movable portion and a mark indicating the mechanical origin position of the movable portion are provided. Further, the hit and the pulse up to the mark are stored in the storage means of the control device, and when the encoder device loses the encoder origin position, the movable part is automatically moved after the encoder device is reset. Then, when it is determined that the movable part has stopped, the original origin position can be reproduced from the pulse from the reset until the movable part stops and the pulse stored in the storage means. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 shows an embodiment of the encoder system of the present invention. In the figure, the robot 1 is electrically connected to the control device 3 through a cable 5, and operates under the control of the control device 3. Although not shown, the robot 1 is composed of a base, movable parts such as arms and joints, a motor for driving these movable parts, and other parts, but only one movable part is shown for simplification of description. I will explain.

The arm 11 of the robot 1 is rotatably fixed to the base 12. The arm 11 is connected to a rotating shaft of a motor 14 via a speed reducer 13, and is moved by the operation of the motor 14. An encoder device 15 is connected to the rotation shaft of the motor 14, and the encoder device 15 can detect the rotation speed and rotation direction of the motor 14. The robot 1 is provided with a mark 16 at a mechanical reference position of the arm 11.

The motor 14 of the robot 1 is electrically connected to the control device 3 via a cable 51, and a drive signal from the control device 3 is supplied to the motor 14 via the cable 51. . Also, the encoder device 1
5 is electrically connected to the control device 3 via cables 52 and 53. The power supply voltage from the control device 3 is supplied to the encoder device 15 via the cable 52. The detection signal from the encoder device 15 is supplied to the control device 3 via the cable 53.

The control device 3 is composed of a computer system including a central processing unit, a main memory, an input / output device, etc., and can calculate the operating position of the arm 11 based on the detection signal from the encoder device 15, and The power supply voltage supplied to the encoder device 15 can also be adjusted. The control device 3 includes an operation display panel 31,
It is designed to give necessary operations, instructions, commands, etc. to the computer system and to perform necessary displays.

The present embodiment comprises an encoder device 15, a mark 16 indicating a mechanical reference position of the arm 11, and a control device 3 capable of executing an offset value of the encoder device 15 and origin return processing.

Next, FIG. 2 shows the relationship between the operation of the encoder device used in this embodiment and the applied voltage.

Encoder device 15 used in this embodiment
Although not shown, an incremental encoder with Z phase and signals of A phase (consisting of A phase and inverted A phase), B phase (consisting of B phase and inverted B phase), and Z phase from this encoder And internal logic that processes and controls the. Also,
An internal counter is provided in the internal logic of the encoder device 15, and the value counted by this counter can be output as absolute data. The signal output from this encoder device 15 is A
There are two systems, the phase and the B phase, and the Z phase itself is used internally and is not output to the outside. This encoder device 15
As shown in FIG. 2, for example, when the applied voltage is E ₀ [V],
It can be controlled by E ₁ [V] and E ₂ [V]. That is, in the encoder device 15, the applied voltage is E _0.
At [V], the stored value of the internal logic is reset,
In addition, the state is completely stopped (see Aa and Ad in FIG. 2).
The encoder device 15, when the E ₁ [V],
Only backup processing is available, and only absolute data storage and error detection can be performed (Fig. 2
Ab)). In addition, the encoder device 15 is
When rising from ₁ [V] to E ₂ [V] (t in FIG. 2)
, B) to notify absolute data and the like, and thereafter, in the state of E ₂ [V], while transmitting the count value by A phase and B phase as in the normal encoder device 15, The counter is updated (Ac and Ae in FIG. 2). Furthermore, the encoder device 15
Is U for commutation control of the AC motor 14,
The state of the V and W phases and the error state can be transmitted together with the absolute data by serial communication using the B phase. Further, the error state output by the encoder device 15 also includes information on the sensor signal detected on the encoder side. This encoder device 15 is used in the normal mode (E
_{In 2} [V]), the phase B is set to a special state to notify the outside of the occurrence of an error, and in this case, the count value cannot be output. When the encoder device 15 cuts off the power supply or detects a speed of _Vb [rpm] or more during backup, the absolute data in the encoder is erased or miscounted to destroy the data. It has become so. In such a case, processing for clearing the absolute data is necessary. This encoder device 15 has E ₀ [V] to E ₁ [V] → E
Start up with ₂ [V], and after serial communication, E ₂ [V]
When the Z phase is first detected in this state, 0 is cleared.

The operation of such an embodiment will be described. <Initial Settings> First, the operation of storing the origin offset value will be described with reference to FIGS. Operation display panel 31
Is operated to give a "reset encoder device" command to the control device 3 (step 101). As a result, the control device 3 controls the power supply voltage applied to the encoder device 15 to E
After once setting to ₀ [V], it is set to E ₂ [V] again (step 102). Then, the encoder device 15 displays E ₁
Since absolute data and the like are output at the rise of [V] → E ₂ [V], the control device 3 confirms “power off” from the output signal (step 103). Control device 3
When the confirmation of power off is completed (step 10
3; Y), the power supply voltage of the encoder device 15 is E ₂ [V]
Then, the motor 14 is continuously rotated for one rotation or more (steps 104, 105; N). When the controller 3 confirms the reset (step 105; Y), the controller 3
Is the power supply voltage applied to the encoder device 15 E ₂ [V]
→ E ₁ [V] → E ₂ [V] (step 106),
It is confirmed whether or not the absolute data is normal, and this is read (step 107, see Co in FIG. 4).

Next, the arm 11 is moved (step 108) until the predetermined mark on the arm 11 matches the mark 16 provided at the predetermined position on the robot.
Is moved (steps 108, 109; N). When the mark on the arm 11 and the mark 16 surely coincide with each other (step 109; Y), the operation display panel 31 is operated to give a "memorize" command to the control device 3 (step 11).
0). As a result, n encoder indexes (Z phases) are generated as shown in FIG. 4, Co is the encoder origin, mark 16 is the mechanical origin, M is the nth encoder index In,
The number of pulses with respect to the mark 16 is shown. These values are stored in the main memory 32 of the control device 3 (step 11).
1). Accordingly, the origin offset G (= n × P + M; where n is an integer) is provided between the encoder origin of the encoder device 15 and the mechanical reference position (mark 16).
Of the main memory 32. Note that P is the number of pulses per rotation of the encoder device 15, and is, for example, 81
92.

Therefore, with respect to the movable part of the robot 1, for example, the range in which the arm 11 operates, the control device 3
The movement data of the arm 11 is stored based on the origin offset G, the absolute data from the encoder device 15, and the A-phase and B-phase signals.

<Operation when the data at the encoder origin is destroyed> The encoder device 15 is powered off (E
₀ [V]) to reset or E ₁ [V] to V _b
Data is destroyed when [rpm] or more is detected. When the encoder device 15 is reset or the like in this way, in the conventional robot, various data created based on the machine origin (mark 16) become unusable, and it is necessary to recreate these data.

However, according to this embodiment, since the origin offset G between the encoder origin (Co) and the mechanical reference position (mark 16) is stored in the main memory 32 of the control device 3, Based on these, the mechanical origin position before resetting can be determined.

That is, the power supply is cut off or the power supply voltage E is set.
_{If a} count error occurs by detecting V _b [rpm] or more at ₁ [V], the data from the encoder device 15 cannot be used.

The arm 11 is, for example, an encoder origin (C
It is assumed that the vehicle has moved by mP from o) and stopped (Fig. 6).
(See (a)). It is assumed that the data of the encoder device 15 cannot be used at this point.

In the case of a count error (step 20
1; Y), when the operation display panel 31 is operated to give a "reset" command to the control device 3, the control device 3 temporarily cuts off the power supplied to the encoder device 15 (step 202), and proceeds to the next step. . Further, when the power of the encoder device 15 is cut off and the encoder device 15 is reset (step 2
01; N), or a process of temporarily turning off the power (step 2)
02), the control device 3 changes the power supply voltage from E ₁ [V] to E ₂ [V] (step 20).
3). Then, the encoder device 15 uses E ₁ [V] → E
_{2 Since} absolute data etc. are output when [V] is started up, the control device 3 outputs "power off" from the output signal.
Is confirmed (step 204). When the confirmation of the power-off is completed (step 204; Y), the control device 3 continues to rotate the motor 14 for one rotation or more while the power-supply voltage of the encoder device 15 is E ₂ [V] (step). Two
05, 206; N). The movement of the arm 11 is controlled by the control device 3
Drive control by, or manually. When the control device 3 confirms the reset (step 206; Y), the control device 3 sets the power supply voltage applied to the encoder device 15 to E.
₂ [V] → E ₁ [V] → E ₂ [V] (Step 2
07), it is confirmed whether or not the absolute data is normal (step 208), and this is read (step 20).
9, see Co 'in FIG. 6 (b)). Next, the arm 11 is moved to the mark 16 side (step 210), and the arm 1
The arm 11 is moved until the predetermined mark No. 1 substantially coincides with the mark 16 provided at the predetermined position of the robot (steps 210, 211; N). It is assumed that the mark on the arm 11 and the mark 16 substantially match. Then, FIG. 6 (a)
As shown in, the encoder device 15 generates q encoder indexes, and the value between the qth index and the mechanical origin (mark 16) is close to M pulses. The encoder index near the mark and the positional relationship of the mark are the same as the ones initially decided. Therefore, the qP + M relationship must be established between the q encoder indexes and the mechanical origin.
Therefore, when the distance between the encoder index and the mark is close to M (within P) near the mark (step 211; Y), q at this time is stored in the storage device as M.
By using this together with the new origin offset, qP
Re-store as + M. That is, the operation display panel 31 is operated to give a “memorize” command to the control device 3 (step 21
2), the value (qP + M) in the main memory 32 of the control device 3
Is stored (step 213). The stored values have the following relationship. Since qP is mP + nP as shown in FIG. 6A, mP +
nP + M is established. That is, the new origin offset G '(= qP + M) is equal to the original origin offset G (= nP
+ M) is included, new encoder origin Co '
Then, even if the current movement point is obtained using the new origin offset G ′, the correction from the original encoder origin Co value is possible, and the original movement data can be used as it is.

Next, a second embodiment will be described with reference to FIGS. 1, 2 and 7. Also in the second embodiment, the configurations of the robot 1 and the control device 3 are similar to those of the first embodiment. In the second embodiment, the origin is returned by using the movement of the arm 11 to the mechanical collision point.

<Origin Storage> The arm 11 is moved to a position near the mark 16. For this movement, the motor 14 may be driven and controlled by the control device 3 to move,
It may be moved manually. At a suitable place, the operation display panel 31 is operated to give a "reset encoder device" command to the control device 3. As a result, the control device 3 once sets the power supply voltage applied to the encoder device 15 to E ₀ [V] and then sets it to E ₂ [V] again. Then, the encoder device 15 outputs absolute data and the like at the rise of E ₁ [V] → E ₂ [V], so the control device 3 confirms “power-off” from the output signal. When the confirmation of the power-off is completed, the control device 3 continues to rotate the motor 14 for one rotation or more while the power-supply voltage of the encoder device 15 is E ₂ [V]. When the reset is confirmed by the control device 3 (this point is the encoder origin Co), the control device 3 sets the power supply voltage applied to the encoder device 15 to E.
₂ [V] → E ₁ [V] → E ₂ [V], it is confirmed whether or not the absolute data is normal, and this is read (see Co in FIG. 7).

Then, when a "motor JOG operation" command is given from the operation display panel 31 to the control device 3, the motor 14 is controlled by J.
Since the OG operation is performed, the arm 11 moves. The mark 1 on the arm 11 is provided at a predetermined position on the robot 1
When it is coincident with 6, the operation display panel 31 is operated to give a "memorize" command to the control device 3. As a result, n encoder indexes are generated as shown in FIG. 7, and the n encoder indexes and the pulse number M ′ between the encoder index and the mark 16 are stored in the main memory 32 of the control device 3. Let As a result, the origin offset G (= n × P−) between the encoder origin of the encoder device 15 and the mechanical reference position (mark 16).
M ′) is stored in the main memory 32 of the control device 3. Note that P is the number of pulses per one rotation of the encoder device 15, and is 8192, for example.

On the other hand, at a suitable place, the operation display panel 31 is operated to give a "encoder device reset" command to the control device 3. As a result, the control device 3 once sets the power supply voltage applied to the encoder device 15 to E ₀ [V], and then
Set it to E ₂ [V] again. Then, the encoder device 15
Outputs absolute data and the like at the rise of E ₁ [V] → E ₂ [V], the control device 3 confirms “power off” from the output signal. When the confirmation of the power-off is completed, the control device 3 continues to rotate the motor 14 for one rotation or more while the power-supply voltage of the encoder device 15 is E ₂ [V]. When the reset is confirmed by the control device 3 (Co in FIG. 7), the control device 3 changes the power supply voltage applied to the encoder device 15 to E ₂ [V] → E ₁ [V] → E ₂ [V].
Confirm that the absolute data is normal and read it.

Then, a "motor JOG operation" command is given from the operation display panel 31 to the control device 3 so that the motor 14 is operated by the JOG.
To operate. When the arm 11 moves and the arm 11 reaches 19 degrees per degree, the operation display panel 31 is operated at that time to give a “memorize” command to the control device 3. This allows
As shown in FIG. 7, pulse A is obtained. Also, mark 16
Pulse D is obtained in advance from (A-D)
Is formed into a value of (nP-M '). Next, the arm 11 is moved from 19 to the mark 16 side,
Check the mark 16. Here, if the mark 16 is matched, the main memory 3 of the control device 3 is operated by performing a storage operation.
In 2, the value of (nP−M ′) is stored as the origin offset G.

If 19 is used for this time, an automatic operation can be performed in regard to the above origin return. When the accumulated pulse is equal to or greater than a certain value or the command is equal to or greater than a certain value, and the speed is stopped (the frequency detected by the encoder device 15 is close to 0, the control device 3 determines that it is a hit and the instruction is a certain value. At this time, a flag is set every time in the control device 3. At this time, the internal state of the control device 3 is a servo-free state in which only the command is clamped. This can be done by returning the command according to the absolute data.

Further, a sensor including a contact switch or the like is provided for each degree 19, and when this sensor detects the arm, it is assumed that the arm has come into contact with the degree 19 and the subsequent automatic operation for returning to the origin is performed. Can be made.

Then, from the result of the automatic operation as described above, the A pulse can be stored by performing as described in FIG.

If the origin offset G can be obtained as described above, the origin return can be performed as in the first embodiment.

The above embodiment is one example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the case where the invention is applied to the robot has been described as an example, but the invention is not particularly limited to this, and the invention can be applied to all devices using the absolute encoder device.

[0041]

As is apparent from the above description, according to the first aspect of the present invention, a mark for indicating the mechanical origin position of the movable portion is provided, and from the encoder origin position of the encoder device to the mark. Since the pulse value obtained from the encoder device due to the movement of the movable part is stored in the storage means as the origin offset, the origin offset value can be reproduced even if the internal count value of the encoder device is lost.

According to the second aspect of the present invention, a mark for indicating the mechanical origin position of the movable part is provided, and the number of pulses from the encoder index closest to the mark from the encoder device to the mark is displayed. The encoder device is stored in the storage means of the control device, and when the encoder device loses the encoder origin position, the encoder device is reset, and then the movable part is moved to align with the mark or the vicinity thereof. Since a new origin offset is obtained from the data obtained from the above and the stored number of pulses, the former origin can be reproduced.

Further, in the invention according to the third aspect, a hit point and a mark are provided, and the hit point and the pulse to the mark are stored, and when the encoder device loses the encoder origin position, the movable part is moved. Is automatically moved to detect the stop of the movable part, so that the original origin position is reproduced from the pulse from the reset until the movable part stops and the pulse stored in the storage means. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an encoder system of the present invention.

FIG. 2 is a diagram for explaining the operation of the encoder device used in the embodiment of FIG.

FIG. 3 is a flowchart for explaining an origin detection operation of the embodiment of FIG.

FIG. 4 is a diagram for explaining the origin detection operation of the embodiment of FIG.

5 is a flow chart for explaining the operation when the origin is lost in the embodiment of FIG.

FIG. 6 is an explanatory diagram for explaining an operation when the origin is lost in the embodiment of FIG.

FIG. 7 is an explanatory diagram for explaining the operation of the second embodiment.

[Explanation of symbols]

 1 Robot 3 Control Device 5 Cable 11 Arm 12 Base 13 Speed Reducer 14 Motor 15 Encoder Device 16 Mark 19 Per Degree 31 Operation Display Panel 32 Main Memory (Storage Means)

Claims (3)

[Claims] 1. A motor for driving a movable part, an encoder device capable of detecting a rotation speed of the motor and outputting a count value from an encoder origin, a mark for displaying a mechanical origin position of the movable part, and An encoder provided with a control device capable of controlling the operation of the encoder device and capable of storing a pulse value obtained from the encoder device by moving the movable portion from the encoder origin position of the encoder device to the mark in the storage means as an origin offset. system. 2. A motor for driving a movable part, an encoder device capable of detecting a rotation speed of the motor and outputting a count value from an encoder origin, a mark for displaying a mechanical origin position of the movable part, and The number of pulses from the encoder device to the mark closest to the mark from the encoder device is stored in the storage means, and when the encoder device loses the encoder origin position, the encoder device is reset and then the movable part is moved. And a control device for determining a new origin offset from the data obtained from the encoder device and the stored pulse number when the mark is aligned with the mark or the vicinity thereof, and storing the new origin offset in the storage means. Encoder system. 3. A motor for driving a movable part, an encoder device capable of detecting a rotation speed of the motor and outputting a count value from an encoder origin, a degree as a mechanical origin position of the movable part, and A mark indicating the mechanical origin position of the movable part, the hit and the pulse up to the mark are stored in the storage means, and when the encoder device loses the encoder origin position, after resetting the encoder device, When the movable part is automatically moved and it is determined that the movable part has stopped,
An encoder system comprising a control device capable of reproducing the original origin position from the pulse from the reset until the movable part stops and the pulse stored in the storage means.