JP3010107B2 - Encoder system - Google Patents

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 easily and accurately determine an initial origin position.

[0002]

2. Description of the Related Art Generally, a robot is provided with a servomotor or the like on each axis of a movable part such as a robot arm regardless of the type thereof.
By rotating each servomotor, the tip (working end) of the movable part is moved to a predetermined position.
In such a robot, an incremental encoder is disposed on the rotation axis of each motor, the number of rotations of each motor is detected by each of the encoders, and the tip (working end) of the movable portion is detected based on the detected data. The position is feedback-controlled and determined. For this reason, it is necessary to accurately obtain the origin of the detection data of the encoder.

Conventionally, as a device for detecting the origin position of an encoder, an incremental type encoder is provided on a rotating shaft of a motor, and a cam is provided on the rotating shaft via a speed reducer so that the device can be moved in the same manner as a movable part of a robot. And a protrusion is formed on the cam so that 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).

[0004] Since this origin detecting device is capable of detecting the origin of an actually movable portion with a cam or the like,
There is an advantage that the detection of the origin is reliable.

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

[0006] These disadvantages are eliminated by employing an absolute encoder. That is, it is possible to omit the mounting 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, the battery
In a home position detection system that uses a multi-turn absolute encoder such as a re-backup type , if the count value is reset or destroyed for some reason, it can be obtained based on the count value from the home position. There is a disadvantage that the operation data of the movable part cannot be used at all.

Accordingly, an object of the present invention is to provide an encoder system which can determine the initial origin position simply and accurately.

[0009]

To achieve the above object, an encoder system according to the first aspect of the present invention comprises:
Detects the motor that drives the moving parts and the number of rotations of the motor
The pulse count value from the encoder origin and the encoder
Encoder device that can output the
A mark indicating the mechanical origin position of the moving part
From the encoder index closest to the mark from the
The number of pulses up to the mark is stored in the storage
When the coder device loses the encoder home position,
After resetting the coder, move the moving parts to
From the encoder device when
The obtained pulse count value from the encoder origin,
From the number of pulses stored in the storage means, a new origin offset
The new origin offset in the storage means.
And a control device for remembering.

[0010] An encoder system according to a second aspect of the present invention provides a motor for driving a movable part and a motor for driving the motor.
The number of revolutions can be detected, and the pulse
Encoder that can output the print value and encoder index
And the mechanical device of the movable part
And a mark indicating the mechanical origin position of the movable part,
The number of pulses from hit to mark and mark to mark
Stores the number of pulses up to the nearest encoder index
Means, and the encoder device is
When the position is lost, after resetting the encoder device,
Turn the motor in a direction with a predetermined degree
By automatically moving the movable parts by turning
Output from the encoder device even if the
When the count value of Luz stops changing, the moving part
When it is determined that the moving part has stopped,
The encoder origin of the reset encoder device
Number of pulses from to every time the movable part stops
And from the hit point to the mark stored in the storage means
Number of pulses and encoder from mark to mark
From the number of pulses up to the index, a new home offset
The new origin offset and store it in the storage means.
And a control device for causing the control device to perform the control.

Further, in the encoder system according to the third aspect of the present invention, the sensor is formed by a contact switch with a degree contact.
It is what it was.

[0012]

According to the first aspect of the present invention, the mechanical element of the movable portion is provided.
A mark for indicating a point position is provided, and an encoder device is provided.
Mark from Mark from last encoder index
The number of pulses up to is stored in the storage means of the control device.
When the encoder device loses the encoder home position,
After resetting the encoder device, move the movable part
Encoder device when aligned with or near the mark
(That is, the pulse from the encoder origin)
New origin from the pulse count value) and the stored pulse number
Find the offset. This returns the previous origin
be able to.

According to the second aspect of the present invention, the machine of the movable portion is provided.
Hit as the target origin position and the mechanical origin of the movable part
A mark indicating the position is provided. In addition,
The pulse up to the peak is stored in the storage device of the controller.
The encoder device has lost the encoder home position
After resetting the encoder device,
When it is determined that the movable part has stopped
The pulse from the reset to the stop of the moving part
Origin position from the pulse stored in the storage means
Can be reproduced.

[0014] According to the third aspect of the present invention, the abutment is abutted.
The sensor consists of a switch, and this sensor detects the arm.
When the arm comes out, it comes back to the origin
Can be attributed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be described below in detail 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, a robot 1 is electrically connected to a control device 3 via a cable 5, and operates under the control of the control device 3. Although not shown, the robot 1 is composed of movable parts such as a base, an arm and a joint, a motor for driving these movable parts, and other parts, but only one movable part is shown for simplicity of explanation. Will be explained.

The arm 11 of the robot 1 is rotatably fixed to the base 12. The arm 11 is connected to a rotation 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 so that the encoder device 15 can detect the number of rotations and the rotation direction of the motor 14. The robot 1 has a mark 16 at the mechanical reference position of the arm 11.

The motor 14 of the robot 1 is electrically connected to the controller 3 via a cable 51, and a drive signal from the controller 3 is supplied to the motor 14 via the cable 51. . Also, the encoder device 1
Reference numeral 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 a 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,
Necessary operations, instructions, commands, and the like are given to the computer system, and necessary displays and the like can be performed.

This 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 an origin return process.

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 a Z-phase, and signals of A-phase (consisting of an A-phase and an inverted A-phase), B-phase (consisting of a B-phase and an inverted B-phase), and a Z-phase signal from the encoder And internal logic for processing and controlling Also,
The internal logic of the encoder device 15 is provided with an internal counter, and the value counted by this counter can be output as absolute data. The signal output from the encoder device 15 is A
The Z-phase itself is used only 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],
Control can be performed by E ₁ [V] and E ₂ [V]. That is, the encoder device 15 applies the applied voltage E ₀
At the time of [V], the stored value of the internal logic is reset,
In addition, the vehicle is completely stopped (see Aa and Ad in FIG. 2).
Further, when E ₁ [V], the encoder device 15
It is only a backup process and can only store absolute data and detect errors (Fig. 2
Ab)). Also, the encoder device 15
_{When the} voltage rises from ₁ [V] to E ₂ [V] (t in FIG. 2)
), The absolute data is notified using the phase B, and thereafter, the count value is transmitted by the phases A and B in the state of E ₂ [V], and the internal value is transmitted. The counter is updated (Ac and Ae in FIG. 2). Further, the encoder device 15
Are U, for commutation control of the AC motor 14,
The V and W phase states and the error state can be transmitted together with the absolute data by serial communication using the B phase. The error state output by the encoder device 15 also includes information on a sensor signal detected on the encoder side. When an error such as a sensor signal occurs, the encoder device 15 operates in the normal mode (E
₂ [V]), the phase B is set to a special state, and the occurrence of an error is notified to the outside. In this case, the count value cannot be output. When the power supply is interrupted, or when a speed of, for example, V _b [rpm] or more is detected during the backup, the absolute data in the encoder is erased or miscounted, and the data is destroyed. It has become so. In such a case, a process of clearing the absolute data is required. This encoder device 15 converts E ₀ [V] to E ₁ [V] → E
₂ [V], and after serial communication, E ₂ [V]
When the Z phase is detected for the first time in this state, 0 clear is performed.

The operation of such an embodiment will be described. <Initial Setting> First, the operation of storing the origin offset value will be described with reference to FIGS. Operation display panel 31
To give a "reset encoder device" command to the control device 3 (step 101). Thereby, the control device 3 sets the power supply voltage applied to the encoder device 15 to E
After having once set to ₀ [V], it is set to E ₂ [V] again (step 102). Then, the encoder device 15 sets E ₁
Since absolute data and the like are output when [V] → E ₂ [V] rises, the control device 3 confirms “power off” from the output signal (step 103). Control device 3
Indicates that the power-off confirmation has been completed (step 10).
3; Y), the power supply voltage of the encoder device 15 is E ₂ [V]
, The motor 14 is continuously rotated for one rotation or more (steps 104 and 105; N). If the reset is confirmed by the control device 3 (step 105; Y), 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] (step 106),
It is checked whether or not the absolute data is normal, and it is read (step 107, see Co in FIG. 4).

Next, the arm 11 is moved (step 108) until the predetermined mark of the arm 11 coincides with the mark 16 provided at a predetermined position of the robot.
Is moved (steps 108 and 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 "store" command to the control device 3 (step 11).
0). Thus, as shown in FIG. 4A, n encoder indexes (Z phases) are generated. In FIG. 4, Co indicates the encoder origin, mark 16 indicates the mechanical origin, M indicates the n-th encoder index In,
The number of pulses between the mark 16 is shown. These values are stored in the main memory 32 of the control device 3 (step 11).
1). As a result, 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).
Is stored in 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, for 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 data at the encoder origin is destroyed> The encoder device 15 is turned off (E
₀ [V]) or V _b at E ₁ [V].
If [rpm] or more is detected, the data is destroyed. When the encoder device 15 is reset in this way, in the conventional robot, various data created based on the machine origin (the mark 16) becomes 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 is turned off or the power supply voltage E
_{If a} count mistake is made by detecting V _b [rpm] or more at ₁ [V], the data from the encoder device 15 cannot be used.

When the arm 11 is at the encoder origin (C
Suppose that it has moved and stopped by mP from o) (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 once turns off the power supply to the encoder device 15 (step 202) and proceeds to the next step. . Further, when the power of the encoder device 15 is turned off to be in a reset state (step 2).
01; N) or the 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 calculates E ₁ [V] → E
_{2 Since} absolute data and the like are output at the time of startup of [V], the controller 3
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 with the power supply voltage of the encoder device 15 at E ₂ [V] (Step 204). 2
05, 206; N). The movement of the arm 11 is controlled by the control device 3
Drive control, or manually. If the reset is confirmed by the control device 3 (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 the absolute data 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 is moved.
The arm 11 is moved until the one predetermined mark substantially matches the mark 16 provided at a 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.
As shown in (1), q encoder indexes are generated from the encoder device 15, and the value between the q-th index and the mechanical origin (mark 16) is a value close to M pulses. The positional relationship between the encoder index near the mark and the mark is the same as that determined at the first time. Therefore, a relationship of qP + M must be established between the q encoder indexes and the mechanical origin.
Therefore, when the distance between the encoder index and the mark becomes a value close to M (within P) near the mark (step 211; Y), q at this time is stored in the storage device as M
When used together with a new origin offset, qP
It is stored again as + M. In other words, the operation display panel 31 is operated to give a "store" command to the control device 3 (step 21).
2) The value (qP + M) is stored in the main memory 32 of the control device 3.
Is stored (step 213). Note that the following relationship is established between the stored values. Since qP is mP + nP as shown in FIG. 6A, mP +
nP + M holds. That is, the new origin offset G ′ (= qP + M) is equal to the original origin offset G (= nP
+ M), the new encoder origin Co '
Thus, even if the current moving point is obtained using the new origin offset G ′, the correction from the original value of the encoder origin Co is possible, and the original moving data can be used as it is.

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

<Storing the Origin> The arm 11 is moved to a position near the mark 16. This movement may be performed by driving and controlling the motor 14 by the control device 3,
It may be moved manually. At an appropriate place, the operation display panel 31 is operated to give the controller 3 an "encoder device reset" command. Thus, the control device 3 once sets the power supply voltage to be 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 start of E ₁ [V] → E ₂ [V]. Therefore, the control device 3 confirms “power interruption” from the output signal. When the confirmation of the power-off is completed, the control device 3 continues to rotate the motor 14 by one or more rotations with the power supply voltage of the encoder device 15 at 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.
_{As 2} [V] → E ₁ [V] → E ₂ [V], it is confirmed whether or not the absolute data is normal, and the absolute data is read (see Co in FIG. 7).

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

On the other hand, an "encoder device reset" command is given to the control device 3 by operating the operation display panel 31 at an appropriate place. Thereby, the control device 3 sets the power supply voltage applied to the encoder device 15 to E ₀ [V] once,
It is set 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 that 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 by one or more rotations with the power supply voltage of the encoder device 15 at 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 from E ₂ [V] → E ₁ [V] → E ₂ [V].
Check whether the absolute data is normal and read it.

Next, a "motor JOG operation" command is given from the operation display panel 31 to the control device 3, and the motor 14
Make it work. When the arm 11 moves and reaches 19 per degree, the operation display panel 31 is operated at that time to give a “store” command to the control device 3. This allows
As shown in FIG. 7, a pulse A is obtained. Mark 16
Pulse D per degree is previously obtained from (AD)
Is formed into a value of (nP-M '). Next, the arm 11 is moved to the mark 16 side from 19 per degree,
Check the mark 16. Here, if it matches the mark 16, the storage operation is performed and the main memory 3 of the control device 3 is operated.
2, the value of (nP-M ') is stored as the origin offset G.

If the number 19 is used, an automatic operation can be performed with respect to the origin return. The control device 3 determines that the command is a hit and sets the command to a constant value when the accumulated pulse is equal to or more than a certain value or the command is equal to or more than a certain value and the speed is stopped (when the frequency detected by the encoder device 15 becomes close to 0) At this time, a hit flag is set 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. It can be performed by returning the command according to the absolute data.

Further, a sensor consisting of a contact switch or the like is provided at each contact 19, and when this sensor detects the arm, it is determined that the arm has contacted the contact 19 and the automatic operation for returning to the original position thereafter is performed. Can be done.

From the result of the automatic operation, the A pulse can be stored in the manner described with reference to FIG.

If the origin offset G can be obtained as described above, the origin can be returned in the same manner as in the first embodiment.

The above embodiment is a preferred embodiment of the present invention, but is not limited thereto, and can be variously modified without departing from the gist of the present invention. For example, in the above-described embodiment, a case where the present invention is applied to a robot has been described as an example. However, the present invention is not particularly limited thereto, and the present invention can be applied to all devices using a multi-turn absolute type encoder device such as a battery backup type .

[0041]

As is apparent from the above description, according to the first aspect of the present invention, the mechanical origin position of the movable portion is displayed.
Markings, and marks from the encoder device.
From the last encoder index to the mark
The number of resources is stored in the storage means of the control device, and the
When the encoder device loses the encoder home position,
After resetting the device, move the movable part to mark
Or from the encoder device when
Data (that is, the pulse
Count value) and the stored pulse number
In this case, the previous origin can be reproduced.

Further, according to the second aspect of the invention, whenever those
Set the mark and the pulse, and hit the pulse and the mark
Is stored, and the encoder device is
Automatically move the movable part when
Minute stoppage can be detected.
From the time when the moving part stops until the stop
The original origin position can be reproduced from the pulse
Wear.

[0043] Further, in the invention described in claim 3, in degrees per
Is a sensor consisting of a contact switch.
The arm abuts each time the sensor detects the arm
It is possible to return to the origin as a result.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an encoder system according to 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. 1;

FIG. 4 is a diagram for explaining an origin detecting operation of the embodiment of FIG. 1;

FIG. 5 is a flowchart for explaining the operation when the origin is lost in the embodiment of FIG. 1;

FIG. 6 is an explanatory diagram for explaining an operation when the origin is lost in the embodiment of FIG. 1;

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot 3 Control device 5 Cable 11 Arm 12 Base 13 Reducer 14 Motor 15 Encoder device 16 Mark 19 per degree 31 Operation display panel 32 Main memory (storage means)

Claims (3)

(57) [Claims] 1. A motor for driving a movable part, an encoder device capable of detecting the number of rotations of the motor and outputting a count value of a pulse from an encoder origin and an encoder index, and a machine for the movable part. The mark indicating the target origin position and the number of pulses from the encoder index to the mark nearest to the mark from the encoder device are stored in the storage means, and when the encoder device loses the encoder origin position, the encoder device After resetting, obtained from the encoder device when the movable part was moved to align with or near the mark
The count value of the pulse from the encoder origin and the memory
A controller for determining a new origin offset from the pulse number stored in the means and storing the new origin offset in the storage means. 2. A motor for driving a movable portion, an encoder device capable of detecting the number of rotations of the motor and outputting a count value of a pulse from an encoder origin and an encoder index, and a machine for the movable portion. And a mark indicating the mechanical origin position of the movable part, and a pulse from the hit to the mark.
Number and the encoder input from the mark
The number of pulses up to the index is stored in the storage means, when the encoder device has lost the encoder home position,
After resetting the encoder device, predetermined
Rotating the motor in the direction
Automatically moving the movable portion by the said motor
Output from the encoder device even if the
The movable part when the count value of the
Is determined to have stopped, and when it is determined that the movable part has stopped, the encoder of the reset encoder device is reset.
From the origin to the time when the movable part is stopped
The number of pulses and the degree of hit stored in the storage means
Number of pulses from the mark to the mark
To the encoder index closest to the mark
New origin offset from the number of
A controller for storing the point offset in the storage means . 3. The system according to claim 1, wherein said contact is formed by a contact switch.
3. The encoder system according to claim 2, wherein the encoder system is a sensor.