JP2000181521A - Controller for automatic machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make removable the cause of an abnormal operation by avoiding the occurrence of an abnormal operation of a robot just after start because of an erroneous connection, etc., of various kinds of units in a servo system. SOLUTION: A forced power supply breaking mode is confirmed (S1), and a brake is canceled (S2). When the forced power supply breaking mode is canceled, ordinary operation is performed (S16). A timer is reset/started (S3) and the conduction of a servo amplifier is turned on (S4). A moving command is outputted to a servo controller (S5) and an abnormality judgement index is stored (S6). After time t0 (S7), conduction to the servo amplifier is forcedly turned off and the brake is validated (S8 and S9). The mat relation of latest torque command value icj, current feedback value ifj, position command value xcj and position feedback value xfj is checked for every shaft and the message of the result is outputted/displayed (S10-S15). The display content includes the number of a shaft where an abnormality is detected. By omitting S5 and S6, a case in which a load is applied by gravity can be dealt with as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic machine having a plurality of servo-controlled axes, such as an industrial robot (hereinafter simply referred to as "robot") and a machine tool. More specifically, the present invention relates to a technique for avoiding the danger caused by abnormal operation immediately after the start of the automatic machine and contributing to eliminating the cause.

[0002]

2. Description of the Related Art When a failure occurs in a robot or a machine tool due to deterioration of an electronic component in a servo amplifier or the like, measures such as replacement of a unit including the component are taken. At that time, the connection between the servo amplifier and the servomotor, the connection between the servo controller and the pulse coder (position detector), and the like are temporarily released, and a reconnection operation is performed after replacing the unit.
However, there is a case where the connection is incorrectly performed for each axis during the reconnection operation.

FIG. 1 shows an example of such an erroneous connection. In this example, an erroneous connection related to the first axis and the second axis is illustrated.

First, as is well known, a servo controller # 1,
# 2, servo amplifiers A1, A2, servo motors M1, M
2. If the connection state between the pulse coder P1 and the pulse coder P2 is normal, the servo controller # 1 of the first axis receives the movement command of the first axis created in the control device (not shown). And a servo amplifier A together with a feedback signal from a pulse coder P1 attached to the first axis servomotor M1.
1 outputs a torque command. The servo amplifier A1 supplies a drive current for the first servo motor M1 based on the torque command. The first axis pulse coder P1 is
Information on the position or speed of the axis is output as a feedback signal to the servo controller # 1 of the first axis.

On the other hand, in the erroneous connection example 1, there is an error (replacement) in the axis correspondence of the connection relationship between the servo controller and the servo amplifier. When the machine is started in such a state, the second
While the output of the first axis servo controller # 1 is sent to the axis servo amplifier A2, the output of the second axis servo controller # 1 is sent to the first axis servo amplifier A1.

Therefore, the first axis servo motor M1 attempts to operate in accordance with the second axis movement command. On the other hand, the pulse coder P1 outputs the position information of the servo motor M1 that is to operate as such to the servo controller # 1. The servo controller # 1 creates an output for trying to reduce the position deviation to 0, and the output is the servo amplifier A1 of the first axis.
Without being sent to the servo amplifier A2 of the second axis. Therefore, the servo system that attempts to reduce the position deviation to 0 does not operate, and the servo motor M1 is highly likely to cause unexpected unexpected irregular operation, or in some cases, runaway. Second
Similarly, there is a risk of runaway operation of the shaft servomotor M2. Further, in a case where a gravity or a moment due to gravity is applied to the second axis in a robot or the like, an output for supporting the gravity or the moment due to gravity and trying to reduce the position deviation to zero even if a command is not input. Is sent to the first axis, and the servomotor M1 of the first axis may run away.

Next, in the erroneous connection example 2, there is an error (replacement) in the axis correspondence of the connection relationship between the servo amplifier and the servomotor. Further, in the erroneous connection example 3, there is an error (replacement) in the axis correspondence of the connection relationship between the servo motor and the servo controller. In both of these cases, the servo system does not operate normally, and the servo motors M1 and M2 are at risk of runaway operation, as in the case of the erroneous connection example 1.

The abnormal operation due to such erroneous connection occurs immediately after the start of the machine due to the nature of the servo system, more specifically, immediately after the brake is released when the shaft to which gravity or a moment due to gravity is applied is involved. If the axis to which the moment due to gravity is applied is not entangled, it is highly likely that the error will occur immediately after the operation command is input. because,
This is because the servo controller creates an output so as to converge the deviation to 0 as soon as possible. Therefore, if there is an erroneous connection as described above, there is a high possibility that the system does not converge and rapidly diverges.
Even if there is no erroneous connection as described above, the same abnormal operation may occur even when the operator starts the machine without noticing the occurrence of deterioration, failure or the like of the electronic component.

In order to prepare for an abnormal operation, the robot controller is connected to a teach pendant equipped with a deadman switch, and the robot is urgently stopped when the worker releases (stops pressing) the deadman switch. However, if a runaway occurs immediately after the start of the robot due to various causes as described above, there is a high risk that an operator will be unable to respond in time and an accident will occur. Even in a machine tool, there is no known means capable of reliably coping with an unexpected abnormal operation immediately after the start of the machine tool.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention, as described above, is to start an automatic machine immediately after an automatic machine start which may occur due to erroneous connection of various devices (including a servo motor) of a servo system. An object of the present invention is to provide a control device which can be prepared for abnormal operation, especially runaway operation, and can prevent it before it expands to a serious situation. A further object of the present invention is to make it possible to estimate the cause of the abnormal operation and to notify the worker of the cause, in addition to the prevention of the expansion of the abnormal operation.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a control device for servo-controlling a plurality of axes of an automatic machine such as a robot or a machine tool is forcibly energized with a servo amplifier immediately after the start of each axis servo system. The above-mentioned technical problem has been solved by providing a means for shutting off. Further, it is determined whether or not an inconsistency that causes an abnormal operation has occurred in the servo system, and the result of the determination is output as a message so that the cause of the abnormal operation can be eliminated. It was done.

That is, according to the present invention, a control device for an automatic machine having a plurality of axes driven by a servomotor is provided with a servo controller for inputting position information fed back from a position detector of the servomotor. A servo amplifier for supplying electricity to the servomotor; and a forced power cutoff means for forcibly interrupting power supply to the servo amplifier.

The forcible energization cutoff means energizes the servo amplifier at a predetermined time after the energization of the servo amplifier is started and after a movement command is input to the servo controller. Forcibly shut off. However, when the predetermined time point at which the energization is forcibly cut off is determined, the condition "after the movement command is input to the servo controller" can be removed. Such a method of determining the forcible cutoff point is suitable for a case where abnormal operation may occur immediately after energization in relation to an axis on which gravity or a moment due to gravity is applied even if a movement command is not input. I have.

While the servo amplifier is energized, it is preferable that data in the servo system, which is used as an index for judging whether or not each axis operates abnormally, is stored. Some or all of the stored data may be output as a message. It is further preferable that the presence or absence of an abnormality in each axis is estimated based on the stored data, and the estimation result is output as a message.

Normally, the forced power cutoff means can be disabled for normal operation after the cause of the abnormality is removed. Immediately after the power supply to the servo amplifier is forcibly shut off, the brakes attached to each axis are activated to cause a fall accident (for a robot, a machine tool having a Z-axis in the direction of gravity). Can be reliably prevented.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The control device of the present invention can be embodied by equipping a control device having a normal hardware configuration with software for executing processing described later. FIG. 2 is a block diagram of a main part of a general hardware configuration of a control device, taking a robot as an example.

A RAM, an RO, and the like are connected to a bus 107 connected to a main CPU (hereinafter, simply referred to as a CPU) 101.
M, a memory 102 such as a nonvolatile memory, an interface 103 for a teaching operation panel, an input / output interface 106 for an external device, and a servo control unit 105 are connected in parallel.

The teaching operation panel 104 connected to the teaching operation panel interface 103 has a normal display function. The operator can create, modify, and operate the operation program of the robot through manual operation of the teaching operation panel 104. In addition to registration or setting of various parameters,
The playback operation and the jog feed of the taught operation program are executed. The display is also used for displaying an abnormality check result immediately after the start of the robot (described later).

The system program supporting the basic functions of the robot and the robot controller is stored in the ROM of the memory 102.
Is stored in The operation program of the robot and the related setting data taught according to the application are stored in the nonvolatile memory 102 of the memory 102. The non-volatile memory 102 mainly stores program-related data for forced measures immediately after the start of the robot, which will be described later.
Is stored in The RAM of the memory 102 is a CPU 101
Is used as a storage area for temporary storage of data in various arithmetic processes performed by.

The servo control unit 105 includes servo controllers # 1 to # 1.
#N (n: total number of robot axes), receives a movement command created through arithmetic processing for robot control (trajectory planning, interpolation and inverse transformation based on it, etc.), and receives a pulse coder attached to each axis. A torque command is output to the servo amplifiers A1 to An together with the feedback signals received from P1 to Pn. Each of the servo amplifiers A1 to An supplies a current to the servomotor of each axis based on each torque command to drive them.

However, as described above, the servo controller # 1
To #n, servo amplifiers A1 to An, servomotors M1 to
An error may occur in the connection state between Mn and the pulse coders P1 to Pn. In that case, the connection relationship as shown in FIG. 2 is not realized for those devices. Although not shown, as is well known, each axis is provided with a brake mechanism such as an electromagnetic brake, which is released (opened) / at any time by a command from the robot controller.
It can be activated (closed).

In this embodiment, the power supply to the servo amplifier is forcibly stopped immediately after the start of the robot, and at this time, data for safety confirmation is displayed on the display of the teaching operation panel 104. FIG. 3 is a flowchart showing an outline of the processing for that.

The processing described here is performed by the main CPU 10
1 and the CPU (servo CP) of the servo controllers # 1 to #n.
U) is performed jointly. Further, forcible energization cutoff immediately after starting the robot, which is a feature of the present invention, is performed by the mode flag
It is assumed that the setting can be canceled by the prior setting of selecting the value. When F = 1, the forced energization cutoff mode is enabled, and F
When = 0, the forced energization cutoff mode is invalidated. To ensure safety, it is preferable that F = 1 be a normal value when the robot is started.

Referring to FIG. 3, the operation of teaching operation panel 104 instructs the robot controller to start the operation of reproducing the operation program, and the time after the servo controller 105 including servo amplifiers A1 to An is energized is turned on. Will be described. The main points of each step are as follows. Here, first, an example of a process (corresponding to claim 1) suitable for a case where there is no axis affected by gravity or a moment due to gravity, or a case where such an axis can be neglected even if it exists.

Step S1: Check the value of the mode flag F. The process proceeds to step S2 unless the forced power cutoff mode is released. If canceled (F =
0) Proceed to step S16 (normal operation). Step S2: Release (open) the brake. Step S3: Reset and start a timer set for measuring the elapsed time from the start.

Step S4: The power supply to the servo amplifiers A1 to An is turned on.

Step S5: For each axis (1st axis to nth axis), 1ITP created by the numerical control function of the robot controller (operation program decoding, trajectory planning, interpolation, acceleration / deceleration processing, distribution of each axis, etc.) Movement commands for (one calculation cycle) are output to the servo controllers # 1 to #n. Each of the servo controllers # 1 to #n controls the servo amplifier A1 together with a feedback signal received from the pulse coder P1 to Pn.
To An.

Each of the servo amplifiers A1 to An supplies a drive current to the servomotors M1 to M6 of each axis based on each torque command. Thereby, the actual operation of the robot is started. However, it should be noted that there may be errors as described above in connection axis correspondence.

Step S6: Internal data serving as an abnormality determination index is stored in order to determine whether there is any abnormality in the state of the servo system that has started running by executing step S5. Specifically, here, each axis (j = 1, 2,...)
n) The latest torque command value (current command value) icj, the latest current feedback value ifj, the latest movement command value (integrated value) xcj, and the latest position feedback value xfj are stored.

Step S7: The count value t of the timer is checked. If it is equal to or smaller than the set value t0, steps S5 and S6 for the next ITP are executed. If t> t0, the process proceeds to step S8. Here, the set value t0 is generally an extremely short time, and is determined by design within a range in which abnormal operation of the robot does not increase even if there is an erroneous connection. For example, the size is such that t> t0 for the first time immediately after the movement command for several ITP to several tens ITP (step S5) is output.

Step S8: Forced servo amplifier A1
To turn off the current to An. However, servo controllers # 1 to # 1
The energization for signal processing such as the operation of the servo CPU in #n is maintained.

Step S9: The brake is activated (closed). Step S10: A matching relationship between the latest torque command value (current command value) icj and the latest current feedback value ifj is checked for each axis (j = 1, 2,..., N). For example, if the erroneous connection example 1 occurs due to a work error, the first axis and the second axis are (j = 1,
2) It is highly possible that an abnormal shift between icj and ifj (ie, a shift exceeding a normal deviation) is detected. If i
If an alignment error between cj and ifj is detected, step S
The process proceeds to step S11, and if no matching abnormality is detected, the process proceeds to step S12.

Step S11: An abnormal message 1 is output and displayed on the display of the teaching operation panel 104, for example. It is preferable that the display contents include the axis number at which the abnormality is detected. Further, part or all of the data stored for abnormality determination may be included in the display (generally, a message output).

Here, the abnormal message 1 is a message indicating a connection error between the servo controller and the servo amplifier. However, there may be a case where the current feedback value ifj itself is not normal due to another abnormality, for example, a failure of the electronic component. After the processing in step S11 is completed, the process proceeds to step S13.

Step S12 / Step S13: For each axis (j = 1, 2,..., N), the matching relationship between the latest position command value (integrated value) xcj and the latest position feedback value xfj is checked. For example, if the erroneous connection example 2 or the erroneous connection example 3 occurs due to a work error, an abnormal shift between xcj and xfj for the first axis and the second axis (j = 1, 2) ( That is, there is a high possibility that a deviation exceeding a normal deviation is detected. If an alignment error between xcj and xfj is detected, the process proceeds to step S15,
If no matching abnormality is detected, the process proceeds to step S14.

Step S14: A servo normal message is output and displayed on, for example, the display of the teaching operation panel 104, and the process is completed.

Step S15: Output the abnormal message 2 and display it on the display of the teaching operation panel 104, for example.
Complete the process. It is preferable that the display contents include the axis number at which the abnormality is detected. Further, part or all of the data stored for abnormality determination may be included in the display (generally, a message output).

Here, the abnormal message 2 is a message suggesting an error in connection between the servo amplifier and the servomotor or between the pulse coder and the servo controller. However,
There may be a case where the position feedback value xfj itself is not normal due to another abnormality such as a failure of the pulse coder itself.

Step S16: Normal operation is executed. The details of the process for normal operation are well known, and there is no particular relationship with the gist of the present invention, so the description is omitted.
After the above processing, the operator may take the following measures, for example, according to the output status of the abnormal messages 1, 2 / normal messages.

1. When outputting / displaying a normal message (step S14): After changing the value of the mode flag F from "1" to "0" and disabling the forcible power cutoff mode,
Perform normal operation.

2. At the time of outputting / displaying the abnormal message 1 (step S11); check the connection relationship between the servo controller and the servo amplifier. Particular attention should be paid to the axis where the abnormality is detected (determined from the display data). If an incorrect connection is found, correct the connection. Then, the above process (FIG. 3) is executed again just in case. 2a; As a result, when a normal message output / display time is obtained (step S14), the forced power cutoff mode is invalidated (F; 1 → 0), and normal operation is performed.

2b; Should the abnormal message 1 be displayed again, it is presumed that the cause is other than an erroneous connection, and a measure (circuit inspection, etc.) is taken accordingly.

2c; If no erroneous connection is found, it is also presumed that the cause is other than erroneous connection, and a measure (circuit inspection or the like) is performed accordingly.

3. At the time of outputting / displaying the error message 2 (step S15); the connection relation between the servo amplifier and the servomotor is checked. Particular attention should be paid to the axis where the abnormality is detected (determined from the display data). If no misconnection is found, check the connection between the pulse coder and the servo controller. Again, particular attention should be paid to the axis where the abnormality was detected (determined from the display data).

If an erroneous connection is found in any of them, the state is corrected to a correct connection state. Then, the above process (FIG. 3) is executed again just in case. 3a; As a result, when a normal message output / display time is obtained (step S14), the forced power cutoff mode is invalidated (F; 1 → 0), and normal operation is performed.

3b; If the abnormal message 2 is displayed again, it is presumed that the cause is other than the incorrect connection, and a corresponding measure (circuit inspection, inspection of the pulse coder itself, etc.)
Perform

3c; If no erroneous connection is found, it is presumed that the cause is other than the erroneous connection, and accordingly, measures (circuit inspection, inspection of the pulse coder itself, etc.) are performed.

The processing described above is suitable for the case where there is no axis affected by gravity or the moment due to gravity, or the case where the influence is negligible even if it exists.
This is an example). The processing (corresponding to claim 2) in the case where there is an axis affected by gravity or a moment due to gravity and the influence cannot be ignored (corresponding to claim 2) may be performed by slightly modifying the above processing (flowchart in FIG. 3). That is, of the above processing, step S5 becomes unnecessary as the processing for forcibly interrupting the energization. In other words, step S5 is skipped and the process proceeds from step S6 to step S7, and if t ≦ t0, waits for state reversal to t> t0 irrespective of the presence or absence of the output of the movement command (step S6 for each ITP). S7 repeat). When the determination output of t> t0 is obtained, the process proceeds to step S8 and subsequent steps. Here, the set value t0 is a short time, and is designed by design so that even if there is an erroneous connection, for example, the expansion of an abnormal operation derived from the gravitational dropping motion of the robot arm can be prevented.
Step S6 can also be skipped to simplify the processing. In that case, step S10 and subsequent steps are also skipped. The determination of normal / abnormal is made by visually observing the posture of the robot at the time of stop immediately after the elapse of the set time t0. Further, in the flowchart of FIG. 3, steps S2 to S9 (part or all) can be performed by hardware (circuit operation not depending on CPU processing) instead of software processing. As described above, the embodiment has been described assuming a robot having an n-axis configuration (n ≧ 2) as the automatic machine. However, it is needless to say that an automatic machine other than the robot can have the same operation as the above embodiment by the same configuration. No.

[0049]

According to the control device of the present invention, the robot or the machine tool causes abnormal operation immediately after the start due to erroneous connection of various devices (including the servo motor) of the servo system, and causes a personal injury or a physical injury. It is possible to avoid situations such as damage to peripheral devices. In addition, an error message can be output in a form that includes information such as the axis where an error has occurred.
Elimination of the cause of abnormal occurrence or investigation of the cause became easy.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an example of an erroneous connection related to a device in a servo system.

FIG. 2 is a main block diagram showing a general hardware configuration of the robot control device.

FIG. 3 is a flowchart illustrating a main point of processing executed in the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 101 Central processing unit (CPU) 102 Memory 103 Teaching operation panel interface 104 Teaching operation panel 105 Servo control unit 106 External device input / output interface 107 Bus

Claims (7)

[Claims] 1. A control device for an automatic machine having a plurality of axes driven by a servo motor, the control device comprising: a servo controller for inputting position information fed back from a position detector of the servo motor; A servo amplifier for supplying electricity to the servo motor, and a forced energization cutoff means for forcibly interrupting energization of the servo amplifier, wherein the forced energization cutoff means energizes the servo amplifier. A control device for the automatic machine, wherein the power supply to the servo amplifier is forcibly cut off at a predetermined time after the start of the operation and at the predetermined time after the movement command is input to the servo controller. 2. A control device for an automatic machine having a plurality of axes driven by a servomotor, the control device comprising: a servo controller for inputting position information fed back from a position detector of the servomotor; A servo amplifier for supplying electricity to the servo motor, and a forced energization cutoff means for forcibly interrupting energization of the servo amplifier, wherein the forced energization cutoff means energizes the servo amplifier. A control device for the automatic machine, which forcibly cuts off the power supply to the servo amplifier at a predetermined time after the start of the operation. 3. The servo system according to claim 1, wherein during power supply to the servo amplifier, data in the servo system used as an index for determining whether or not there is an operation abnormality of each axis is stored. Control device for the described automatic machine. 4. An internal servo system data used as an index for judging whether or not each axis operates abnormally while the servo amplifier is energized, wherein the stored data is output as a message. A control device for an automatic machine according to claim 1 or claim 2. 5. An internal servo system data used as an index for determining whether or not there is an operation abnormality of each axis during energization of the servo amplifier, and based on the stored data, 3. The control device for an automatic machine according to claim 1, wherein the presence or absence of an abnormality in each axis is estimated, and the estimation result is output as a message. 6. The control device for an automatic machine according to claim 1, wherein said forcible power cutoff means can be disabled. 7. The system according to claim 1, wherein immediately after the power supply to said servo amplifier is forcibly cut off, a brake means attached to each of said shafts is activated. Control device for an automatic machine described in the paragraph.