JPH0595695A - Numerical value controller - Google Patents

Abstract

PURPOSE:To prevent deviation of a track due to a load change, etc., by comparing a current command to a motor with a predetermined set current, reducing a target speed if the command is larger than the set current, and regulating the command to each motor to the set current or less. CONSTITUTION:Current command comparators 28X, 28Y compare a current command to motors 10X, 10Y with a predetermined set current. As a result of comparison, if the command is larger than the set current, the command to the motors 10X, 10Y is regulated to the set current or less by a target speed regulator 30. Thus, even if tracking becomes difficult due to an overload, etc., the target speed is reduced. As a result, the tracking is secured, and a target locus can be drawn. Thus, a deviation of the locus due to the load change, etc., can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a numerical controller for driving a plurality of motors to draw a predetermined locus.

[0002]

2. Description of the Related Art FIG. 5 shows the configuration of a numerical controller according to a conventional example. The device shown in this figure is a device that drives an X-axis motor 10X and a Y-axis motor 10Y to draw a predetermined locus. The apparatus shown in this figure includes a position command generator 12 that issues a position command based on a target trajectory and target speed patterns of the motors 10X and 10Y, and an X-axis control unit 14X and a Y-axis that drive the motors 10X and 10Y according to the position command. It is composed of a control unit 14Y.

The X-axis control unit 14X is a position control unit 16 which issues a speed command based on a position command and position feedback.
X, a speed control unit 18X which issues a current command based on the speed command and the speed feedback, and a current control unit 20X which controls the drive current of the motor 10X based on the current command and the current feedback. A current detecting unit 22X for detecting, a position detecting unit 24X for detecting the behavior of the motor 10X as a position, and a position-speed converting unit 26X for converting the detected position into a speed are provided. The current detected by the current detection unit 22X is fed back to the current control unit 20X, the position detected by the position detection unit 24X is input to the position-speed conversion unit 26X and fed back to the position control unit 16X,
The speed obtained by the position-speed conversion unit 26X is fed back to the speed control unit 18X. That is, three feedback loops of position, velocity and current are formed.

Similarly, the Y-axis controller 14Y includes a position controller 16Y, a speed controller 18Y, a current controller 20Y, a current detector 22Y, a position detector 24Y, and a position-speed converter 26.
It is composed of Y.

The operation of this embodiment will be described with reference to an example of drawing an arc locus as shown in FIG. That is,
The arc locus of FIG. 6 is used as the target locus, and the tangential velocity pattern as shown in FIG. 7 is used as the target velocity pattern.
When trying to drive 0Y, the position command generator 12 issues a position command for each of X and Y based on the target trajectory and the target speed pattern, and supplies the position command to the X-axis control unit 14X and the Y-axis control unit 14Y. Here, since the target locus is an arc locus, the X and Y position commands have values corresponding to the X and Y target loci shown in FIGS. 8 and 9, that is, the values of the following equations. However, V _XY is a tangential velocity and R is a radius.

X = Rsin (V _XY t / R) Y = R cos (V _XY t / R) In the X-axis control unit 14X and the Y-axis control unit 14Y, the above three feedback loops of position, speed and current are used. Thus, the driving of the motors 10X and 10Y is controlled. That is, the motors 10X and 10Y drive the drive target (load) under the control of the device of FIG. Such driving is repeated until the end point (target position) of the target trajectory is reached. In the above operation, the position command,
The speed command, the current command, and the current generation may be executed at the same time.

In this embodiment, the current controllers 20X and 20Y operate as shown in FIG. 10 in order to prevent the motors 10X and 10Y from being driven with a current larger than the maximum allowable current. As shown in this figure, the current controller 20X
And 20Y indicate the current command to the speed controller 18X or 18Y.
(100), the current command Im is received from the motor 1
It is judged whether or not it is larger than the allowable maximum current Imax of 0X or 10Y (102).
Is limited to the allowable maximum current Imax (104), and the drive current of the motor 10X or 10Y is controlled based on the current command Im (106).

When the current command Im is limited as described above,
As a result, a delay occurs in the drive control of the motor 10X or 10Y. In this embodiment, when the deviation of the locus exceeds a predetermined value, it is determined that the operation is abnormal and the motor 1
The driving of 0X and 10Y is stopped. As shown in FIG. 11, the position control unit 16X calculates the difference between the value of the position command (command position) and the value of the position feedback (current position) (200), and sets the position deviation that is the calculated difference. It is judged whether or not it is less than or equal to the allowable value (202), and if this condition is not satisfied, it is judged to be abnormal and the display to that effect and the driving of the motors 10X and 10Y are stopped (2).
04).

[0009]

In the conventional numerical control apparatus, the deviation of the locus due to the current limitation is monitored, and the processing for stopping the driving is executed as described above, which is regarded as an abnormal operation. However, for example, when the load becomes large and a thrust force larger than the maximum thrust force of the motor is required, the locus also shifts. Further, even if the deviation of the trajectory can be detected, the deviation cannot be corrected.

In the case where the arc locus as shown in FIG. 6 is used as the target locus, if a load fluctuation or the like occurs during driving of the motor, a delay occurs with respect to the position command, and a necessary thrust force for recovering this delay is generated. It becomes larger than the maximum torque generated by the motor. Then, for example, when considering the X-axis motor, the locus shown by the solid line in FIG. 12A is obtained, and the deviation shown in FIG. 12B deviates from the command shown by the broken line. At this time, the operation shown in FIG. 11 limits the drive current of the motor for a certain time (FIG. 12 (C)). As a result, the actual locus becomes significantly different from the arc as shown in FIG.

The present invention has been made to solve the above problems, and it is an object of the present invention to prevent the deviation of the locus due to load fluctuation or the like.

[0012]

In order to achieve such an object, the present invention provides a plurality of current command comparison units for comparing a current command to each motor with a predetermined set current and a current command as a result of the comparison. Is greater than the set current, the target speed is reduced, and a target speed adjusting unit that adjusts the current command to each motor to be equal to or less than the set current is provided.

[0013]

In the present invention, the current command is compared with a predetermined set current, for example, the maximum allowable current of the motor. As a result, when the former is large, the target speed is adjusted so that the former is equal to or less than the latter. As described above, even when tracking is difficult due to overload or the like, the target speed is reduced, and as a result, tracking can be secured and a target trajectory can be drawn.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. The same components as those in the conventional example shown in FIGS. 5 to 13 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 shows the configuration of a numerical controller according to an embodiment of the present invention. This apparatus adds current command comparison units 28X and 28Y to the X-axis control unit 14X and the Y-axis control unit 14Y, respectively, and sets the position command generator 12 to the target speed adjustment unit 30 and the position command generation units 32X and 32Y.
The device is configured to include.

The current command comparison units 28X and 28Y respectively have an allowable maximum current Imax of the motor 10X or 10Y.
The current value set below is compared with the current command Im, and if the latter is larger than the former, a speed reduction command is issued. The target speed adjusting unit 30 gives the target speed to the position command generating unit 32X or 32Y, while the current command comparing units 28X and 28Y.
Is monitored, and if a speed reduction command is issued, the target speed is reduced by a constant amount ΔV. Position command generator 32X
And 32Y are the target speed V from the target speed adjusting unit 30.
The position command of the corresponding axis is issued based on _{obj and a} predetermined target locus. Further, the current control units 20X and 20Y perform the same drive current control as the conventional one on the motor 10X or 10Y only when the speed reduction command is issued.

That is, the feature of this embodiment is that the target speed V _obj is gradually reduced when the current command Im tries to exceed the set current.

The operation of this embodiment is shown in FIG. Although this figure illustrates the X axis, the same applies to the Y axis. As shown in this figure, initially, the target speed V _obj is set to the maximum speed Vm (30
0). Next, the position command generator 32X determines the target speed V
_A position command is generated based on _obj (302). When the target locus is as shown in FIG. 6, the generation formula is as follows.

X = Rsin (V _obj t / R) The position control unit 16X has the position command and position detection unit 24.
A speed command is issued based on the position feedback from X (304). Further, the speed control unit 18X issues the current command Im based on the speed command and the speed feedback via the position-speed conversion unit 26X (306). At this time, the current command comparison unit 28X determines whether the current command Im is larger than a predetermined set current (308). The current command comparison unit 28X issues a speed decrease command when the current speed is large, and the target speed adjustment unit 30 responds to this by issuing the target speed V.
Decrease _obj by ΔV (310). That is, V _obj ← V _obj −ΔV. After this, the process returns to step 302.

Therefore, even if the current command Im is initially larger than the predetermined set current, the current command Im becomes equal to or less than the set current by repeating the above operation. When the current command comparison unit 28X determines that the current command Im is less than or equal to the set current, the current control unit 20X proceeds to drive current control of the motor 10X (312).

In other words, the current control unit 20X controls the motor 1 while the current command Im is limited to the set current or less.
Control 0X drive current. After this, the time variable t is updated (314) and the process returns to step 300.

FIG. 3 shows the structure of the target speed adjusting unit 30 in this embodiment. As shown in this figure, the target speed adjustment unit 30 includes a calculation unit 34 that receives a speed reduction command from the current command comparison units 28X and 28Y and adjusts the target speed V _obj . A maximum speed storage memory 36, a target speed storage memory 38, and a deceleration amount storage memory 40 are provided as memories for storing various amounts used for processing. The calculation unit 34 includes a speed reduction command receiving unit 42 having a function of inputting a speed reduction command,
It has a target speed decrease calculation unit 44 having a function of performing the calculation of step 310, and a target speed sending unit 46 having a function of outputting the adjusted target speed V _obj to the position command generation units 32X and 32Y.

FIG. 4 shows a flow of the operation of the target speed adjusting section 30. As shown in this figure, first, the maximum speed Vm is read from the maximum speed storage memory 36 so as to correspond to step 300 described above, and the arithmetic unit 3 is read.
The target speed V _obj is set by 4 (400). Next, the target speed V _obj is output to the position command generators 32X and 32Y by the target speed sending unit 46 and is stored in the target speed storage memory 38 (402). Further, the speed command receiving unit 42 causes the current command comparing unit 28X
And 28Y, it is determined whether or not a speed reduction command is received (404). If not, return to step 402. If a speed reduction command is received from any of the current command comparison units, step 40
Since the current command Im corresponding to the target speed V _obj sent in 2 exceeds the set current (30
8), the calculation related to step 310 is executed by the target speed decrease calculator 44 (406). This calculation is executed based on the target speed V _obj stored in the target speed storage memory 38 and the ΔV stored in the deceleration amount storage memory 40. The target speed V reduced in this way
_{obj is} also the position command generator 32X by the target speed transmitter 46
And 32Y and are stored in the target speed storage memory 38. Then, the process returns to step 402.

As described above, according to the present embodiment, the target velocity V _obj that cannot draw a predetermined target trajectory is reduced to a velocity that can follow the target trajectory, so that the actual trajectory can be brought close to the target trajectory. it can. That is, there is no problem that the locus is broken due to overload.

Further, according to the present embodiment, the target speed V is automatically adjusted so that the target trajectory can be followed and the maximum speed can be obtained.
_{Since obj} is set, if the maximum speed Vm is set higher in advance, the cycle time becomes the shortest and the adjustment man-hour is reduced.

In addition, the target locus can be followed even when a motor having a small maximum thrust is used. Since a small motor can be used in this way, when the load of the motor and a person come into contact with each other, the thrust can be reduced to a safe thrust, and the safety is further improved. Further, the cost can be reduced by downsizing the motor.

[0027]

As described above, according to the present invention,
Since the target speed is adjusted by comparing the current command Im with the set current, the target locus is followed even in the case of overload,
It is possible to prevent the deviation of the synthetic trajectory. Furthermore, since the target speed is automatically adjusted, the number of steps involved in setting the target speed is reduced. Further, since the thrust of the motor can be reduced, it is possible to improve safety and reduce costs.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a numerical control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the overall operation of this embodiment.

FIG. 3 is a block diagram showing a configuration of a target speed adjusting unit in this embodiment.

FIG. 4 is a flowchart showing an operation of a target speed adjusting unit in this embodiment.

FIG. 5 is a block diagram showing an overall configuration of a numerical control device according to a conventional example.

FIG. 6 is a diagram showing an example of a target trajectory.

FIG. 7 is a diagram showing an example of a target speed pattern.

FIG. 8 is a diagram showing an example of an X-axis target trajectory.

FIG. 9 is a diagram showing an example of a Y-axis target trajectory.

FIG. 10 is a flowchart showing the operation of the current control unit in this conventional example.

FIG. 11 is a flowchart showing an abnormal stop operation in this conventional example.

FIG. 12 is a diagram showing a deviation of a locus due to overload and the like in this conventional example. (A) is a deviation between an actual X-axis locus and a target locus, (B) is a deviation, and (C) is a current. It is a figure which shows a value, respectively.

FIG. 13 is a diagram showing an actual trajectory in this conventional example.

[Explanation of symbols]

10X, 10Y Motor 12 Position command generator 14X X-axis control section 14Y Y-axis control section 16X, 16Y Position control section 18X, 18Y Speed control section 20X, 20Y Current control section 22X, 22Y Current detection section 24X, 24Y Position detection section 26X , 26Y Position-speed conversion unit 28X, 28Y Current command comparison unit 30 Target speed adjustment unit 32X, 32Y Position command generation unit 34 Calculation unit 36 Maximum speed saving memory 38 Target speed saving memory 40 Deceleration amount saving memory 42 Speed decrease command receiving unit 44 target speed drop calculation unit 46 target speed sending unit V _obj target speed Vm maximum speed ΔV target speed deceleration amount

Claims (1)

[Claims] 1. A position command generator for issuing a position command for each of a plurality of motors according to a target speed and a target trajectory, and a plurality of position control units for issuing a speed command for each motor based on the position command and position feedback. A plurality of speed control units that issue a current command for each motor based on the speed command and the speed feedback, a plurality of current control units that control the drive current of each motor based on the current command and the current feedback, and the position, speed, and speed of each motor. And a means for feeding back currents to the corresponding position control section, speed control section and current control section, and controlling the drive currents of the plurality of motors so that the combined trajectory of the plurality of motors draws a target trajectory. , A plurality of current command comparison units that compare the current command to each motor with a predetermined set current, and Of If the result current command is larger than the set current reduces the target speed, the numerical control device, wherein the target speed adjusting unit that adjusts the current command below the set current, in that it comprises for each motor.