JP4471921B2 - Machine control device - Google Patents

Description

  The present invention relates to a machine control apparatus for moving a control target machine to a target position and stopping the machine, and more particularly to a machine control apparatus configured to suppress vibration of the control target machine due to inertial force at the time of stop.

There are various types of mechanical devices that accompany the movement. Among them, a mechanical control device that controls a machine that transports a heavy object mounted on the end of a long arm as shown in FIG. 14 is unique. There's a problem. Hereinafter, such problems will be described.
Here, FIG. 14 is a block diagram of a prior art machine control device, FIG. 15 is an explanatory diagram for explaining the operation of the machine control device, FIG. 15 (a) is a time-speed diagram, and FIG. It is a time-position diagram.

The machine control device shown in FIG. 14 includes a heavy object 1, an arm 2, a slide moving unit 3, a slide rail unit 4, a motor 5, a coupling 6, a feed screw 7, a position control device 8, And a position command device 9.
Among these, the heavy object 1, the arm 2, the slide moving part 3, the slide rail part 4, the motor 5, the coupling 6, and the feed screw 7 are included as controlled machines.

Next, the operation and function of each part will be outlined.
The slide rail unit 4 restrains the slide moving unit 3 to move only in the left and right moving directions in FIG. Further, the contact portion between the slide rail portion 4 and the slide moving portion 3 has a low friction so that the slide moving portion 3 can move smoothly on the slide rail portion 4.
The output shaft of the motor 5 is connected to a feed screw 7 via a coupling 6, and this feed screw 7 is screwed into a screw portion (not shown) attached to the slide moving portion 3.

  When the motor 5 rotationally drives the feed screw 7, the slide moving unit 3 moves in the left-right direction in FIG. A position control device 8 including a control circuit and a motor driver is connected to the motor 5, and the position control device 8 performs position control according to the position command value transmitted from the position command device 9.

  A long arm 2 is attached to the slide moving unit 3 where such position control is performed, and a heavy object 1 is attached to the tip of the arm 2. The position of the heavy object 1 at the tip of the arm 2 is also controlled by the position control of the slide moving unit 3.

Then, the control method in such a machine control apparatus is demonstrated.
When the slide moving unit 3 is moved, as shown in FIG. 15A, the moving speed of the slide moving unit 3 is increased at a predetermined acceleration from time a to time b, and the slide is moved at a constant speed from time b to time c. The moving unit 3 is moved, the moving speed of the slide moving unit 3 is decreased at a predetermined deceleration from time c to time d, and finally the movement of the slide moving unit 3 that has reached the target position is stopped at time d. The position command device 9 outputs a position command value U (s) that changes every moment so that the slide moving unit 3 moves at such a speed. U (s) is expressed as a function using a Laplace transform variable.

  Such a position command value U (s) is input to the position control device 8. When the position of the slide moving unit 3 is expressed as Xm (s), and the transfer function including the position control device 8 to the motor 5, the feed screw 7 and the slide moving unit 3 is G (s), Xm (s) is It is expressed as:

In such a machine control device, the slide moving unit 3 moves at a moving speed as shown in FIG. 18A according to the position command value U (s) and stops moving at time d. The heavy object 1 is conveyed to a predetermined target position.
The machine to be controlled according to the prior art is controlled by the position control device 8 as described above.

  In such a machine control device, it is possible to realize control for accurately moving the slide moving unit 3 to the target position by optimally designing the transfer function G (s) of the position control device 8 and the machine to be controlled. The arm 2 attached to the slide moving unit 3 moves in a state in which the deflection occurs, and even when the slide moving unit 3 stops at the target position, the heavy object 1 at the tip of the arm 2 is arm 2 by its own inertial force. Even after the slide moving unit 3 stops at the target position, it may vibrate without stopping immediately. For this reason, it has been difficult in the past to control the position of the heavy object 1 attached to the tip of the arm 2.

  Specifically, as shown in FIG. 15A, when the slide moving unit 3 is controlled to decelerate at a predetermined deceleration and finally stop at the target position at time d, the slide moving unit 3 is Despite stopping at the command position as shown by the solid line descending in the oblique direction of (b), the heavy article 1 vibrates around the target position as shown by the dotted line descending in the oblique direction of FIG. It will occur. Xw (s) that is the position of the heavy object 1 is expressed as the following expression when displayed as a transfer function using Xm (s) that is the position of the slide moving unit 3.

Here, Ks is the spring constant of the arm 2, and W is the mass of the heavy object 1.
When the above formulas 1 and 2 are put together to represent the overall system of the machine control device, the following formula is obtained.

  The transfer function related to the movement of the heavy object 1 has the following poles on the Laplace plane.

  When the transfer function has a pole as shown in Equation 4, it is known that the position of the heavy object 1 moves with a sinusoidal vibration waveform, and vibrates at a frequency represented by the following equation.

Thus, the heavy article 1 vibrates after reaching the target position as shown by the dotted line in FIG. 15B, and does not settle immediately.
Therefore, when the slide moving unit 3 stops at the target position, the original position of the slide moving unit 3 stops as instructed, but the heavy object 1 at the tip end of the arm 2 vibrates around the target position. There was a problem that it would occur. That is, since the heavy object 1 does not stop immediately, the time until it stops is a loss time.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to vibrate when stopping when a long arm with a heavy object attached to the tip is moved to stop at a target position. An object of the present invention is to provide a machine control device that can suppress the above-described problem.

In order to solve the above problem, the invention described in claim 1 suppresses vibration of the heavy object when the arm attached with the heavy object as a vibration element is moved to a target position by linear acceleration / deceleration and stopped. Machine control device for
A position command device for outputting a position command value ;
Differentiating means for obtaining a second order differential value of the position command value;
Gain means for outputting a value obtained by multiplying the second-order differential value output from the differentiating means by a gain constant obtained by dividing the mass of the heavy object by the spring constant of the arm, as a correction amount;
Adding means for adding the correction amount output from the gain means and the position command value to output a compensated position command value;
A position control device to which a compensated position command value output from the adding means is input;
And a controlled object machine that is controlled to move the arm to a target position under the control of the position control device .

According to a second aspect of the present invention, in the machine control device according to the first aspect, the second-order differential value has a characteristic of gradually increasing or decreasing from a constant value .

  According to the present invention, even when a machine having low rigidity is moved so as to move a long arm with a heavy object attached to the tip, it can be stopped at a target position in a short time without vibration. A machine control device can be provided.

Hereinafter, embodiments of the machine control device of the present invention will be described.
Figure 1 is a block diagram of implementation of the invention, corresponding to the embodiment of the invention described in claim 1. Figure 2 is a finely divided means, gain means is an explanatory view of a compensating element consisting of adding means. 3A and 3B are explanatory diagrams for explaining the operation of the machine control device. FIG. 3A is a time-speed diagram, and FIG. 3B is a time-position diagram.
4A and 4B are explanatory diagrams for explaining the operation of the slide moving unit. FIG. 4A is a time-speed diagram, and FIG. 4B is a time-acceleration diagram. 5A and 5B are explanatory diagrams for explaining the operation of the slide moving unit, in which FIG. 5A is a time-speed diagram, and FIG. 5B is a time-acceleration diagram.

The machine control device according to the implementation form of this, as shown in FIG. 1, is basically a heavy 1 which is a component of the prior art, an arm 2, the sliding movement portion 3, the slide rail section 4 , Motor 5, coupling 6, feed screw 7, position control device 8, and position command device 9.
Of these, the heavy object 1, the arm 2, the slide moving part 3, the slide rail part 4, the motor 5, the coupling 6, and the feed screw 7 are also included as controlled machines in the same manner as the prior art. is there.
Further, in this machine control device, the heavy object 1 is mounted at the tip of the long arm 2 and the deflection is caused by the movement of the arm 2 attached to the slide moving unit 3 as in the conventional case.

In this embodiment, in addition to these, a compensation element 10 is provided between the position control device 8 and the position command device 9 as a novel point.
Since the functions and the like from these heavy objects 1 to the position command device 9 are the same as those described in the prior art, description thereof will be omitted, and the compensation element 10 will be described below.
As shown in FIG. 2, the newly added compensation element 10 includes a differentiating means 10a, a gain means 10b, and an adding means 10c.

The differentiating means 10a is a means for performing second order differentiation on the position command value U (s) and outputting a second order differential value s ² · U (s).
The gain unit 10b multiplies the second-order differential value s ² · U (s) output from the differentiation unit 10a by a gain constant K, and outputs a correction amount K · s ² · U (s). Means.

The adding means 10c adds the correction amount K · U (s) · s ² and the position command value U (s) output from the gain means 10b to compensate the position command value U (s) + K · U (s ) · Means for outputting s ² .
The compensation position command value output by the compensation element 10 is (1 + K · s ² ) · U (s). When the gain constant K is K = W / Ks, a compensation position command value U ′ (s) expressed by the following equation is output.

Subsequently, control of the machine control device using such a compensated position command value will be described.
When the slide moving unit 3 is moved, as shown in FIG. 3A, the moving speed of the slide moving unit 3 is increased at a predetermined acceleration from time a to time b, and the slide is moved at a constant speed from time b to time c. The moving unit 3 is moved, the moving speed of the slide moving unit 3 is decreased at a predetermined deceleration from time c to time d, and finally the slide moving unit 3 is stopped at a predetermined target position at time d. This is the same as the prior art.

The position command device 9 outputs a position command value U (s) that changes from moment to moment so that the slide moving unit 3 has such a speed.
This position command value U (s) is input to the compensation element 10, converted to a compensated position command value U ′ (s), and input to the position control device 8. When the position of the slide moving unit 3 is expressed as Xm (s), and the transfer function including the position control device 8 to the motor 5, the feed screw 7 and the slide moving unit 3 is G (s), Xm (s) is It is expressed as:

  Further, the position Xw (s) of the heavy object 1 considering the deflection of the arm 2 is represented by the following expression when the position of the slide moving unit 3 is displayed as a transfer function using Xm (s).

  When Xm (s) and U '(s) are deleted from these mathematical expressions to represent the entire system of the machine control device, the following expression is obtained.

The compensation element 10 described above performs pole-zero cancellation that eliminates Ws ² + Ks in the denominator portion, thereby eliminating the vibration element. Therefore, as shown in FIG. 3B, the original position (indicated by the solid line) of the slide moving unit 3 and the position of the heavy object 1 (indicated by the dotted line) are stopped at the target position without vibration and settling. To do. As described above, since the heavy object 1 at the tip position of the arm 2 together with the original position of the slide moving unit 3 stops without vibrating, the conventional loss time can be eliminated and high-speed control can be realized. .

  In the present embodiment, the compensation element 10 is arranged between the position command device 9 and the position control device 8, but it is only necessary that the compensated position command value U ′ (s) can be finally obtained. Therefore, the position command device 9 integrated with the compensation element 10 may be used, or the position control device 8 integrated with the compensation element 10 may be used. These are the problems to which the added compensation element 10 belongs, and there is no substantial difference.

  When compensation is performed using the compensation element 10 described above, the moving speed of the slide moving unit 3 has a linear acceleration / deceleration characteristic as shown in FIG. 4A, that is, the differential value of the position command value is The characteristic changes linearly for a certain period. In this case, the acceleration of the slide moving unit 3, that is, the second-order differential value of the position command value, changes discontinuously at times a, b, c, and d as shown in FIG. This indicates that the slide moving unit 3 that is the original position of the arm 2 needs to be suddenly stopped. However, the rotational torque that the motor 5 applies to the feed screw 7 is actually insufficient, and such a stop is caused. May be difficult.

  Therefore, when the compensation is performed using the compensation element 10, as shown in FIG. 5A, the acceleration / deceleration characteristics such as a substantially S-shape before and after the movement speed of the slide moving unit 3 changes, that is, the position command Consideration was made so that the differential value of the value gradually increases or decreases from a constant value. In this case, the acceleration of the slide moving unit 3, that is, the second-order differential value of the position command value, changes as it gradually increases or decreases as shown in FIG.

Accordingly, since the acceleration applied to the slide moving unit 3 that is the original position of the arm 2 also gradually increases or decreases continuously, there is no situation where the rotational torque that the motor 5 applies to the feed screw 7 at this time is insufficient. The situation where an excessive burden is added is avoided.
The above point corresponds to the invention of claim 2 .

  The machine control device described above is based on the theory of preventing machine vibration by adding a zero point characteristic to the same point and canceling the pole to zero with respect to the pole on the Laplace plane of the vibration system. When an experiment for verifying whether or not such an effect is actually obtained is performed, an effect capable of preventing mechanical vibration has been confirmed.

  In addition, in this embodiment, the control object machine using a feed screw and a slide rail apparatus was demonstrated for the specific description. However, the machine to be controlled is not limited to such a machine. For example, the machine to be controlled is similar to a machine to be controlled that moves a slide rail device in which a ball screw is connected to a motor for rotation driving and moves a heavy object at the end of the arm. Further, the present invention can be applied to a control target machine using a rotational drive motor and a belt, a control target machine using a rack and pinion, a control target machine using a linear motor, and the like. These are locations included in G (s) of Equation 9, and even if these mechanisms change, only G (s) changes and there is no change in the point of canceling pole-zero. Can have an effect.

Next, FIG. 6 is a functional block diagram of the implementation of the invention. The correspondence between FIG. 6 and FIG. 1 will be described. The position command device 9, the compensation element 10, and the position control device 8 in FIG. 1 correspond to the blocks 21 to 29, 31 in FIG. 6, and the motor 5 in FIG. 6 and the mechanical system after the coupling 6 in FIG. 1 corresponds to the target machine 50 in FIG.

In FIG. 6, a position command block 21 is a block that outputs a position command value, and a correction block 22 is a block that generates a correction amount based on a second-order differential value (acceleration command value) generated from the position command value.
The correction block 22, the acceleration detecting means 23 corresponding to the differentiator 10a of FIG. 2, a parameter 24 phase to those on the gain K of Figure 2 that is set based like mechanical vibration frequency, in FIG gain means ( A correction term calculation means 25 corresponding to the multiplication means 10b, and the correction amount output from the correction block 22 is output from the position command block 21 in the adder 26 corresponding to the addition means 10c in FIG. It is added to the position command value.

The adder 26 in FIG. 6 outputs a compensated position command value, and this compensated position command value is input to the position adjuster 27. The position adjuster 27 performs an adjustment operation so that the position detection value from the motor encoder 31 attached to the motor 30 matches the compensated position command value, and the output is sent to the speed adjuster 28 as a speed command value. . The speed adjuster 28 performs an adjustment operation so that the speed detection value from the motor encoder 31 matches the speed command value, and the output is sent to the torque adjuster 29 as a torque command value.
In the torque adjuster 29, control is performed such that the motor 30 is driven according to the torque command value, and the slide moving unit 3 of the target machine 50 is moved to a predetermined position and stopped.

In the above you facilities embodiment obtains the correction amount is multiplied by a prescribed gain to second derivative value of the position command value, is carried out a compensation by adding the correction amount to the original position command value. That is, if the first-order differential value (speed command value) of the position command value is as shown in FIG. 7A, the second-order differential value (acceleration command value) of the position command value shown in FIG. It is corrected by adding to the original position command value. Accordingly, the differential value of the corrected position command value, that is, the corrected speed command value is as shown in FIG.
In other words, if the jerk command value shown in FIG. 8B obtained by multiplying the second-order differential value by a predetermined gain is added as a correction amount to the speed command value shown in FIG. Since the corrected speed command value as shown in c) is obtained, an operation equivalent to the correction for the position command value shown in FIG. 7 can be obtained.

The first reference embodiment of the present invention focuses on the above points, and FIG. 9 shows a control block diagram thereof. In addition, the same code | symbol is attached | subjected to the component same as FIG .
In FIG. 9, a position command value is input to the correction block 32, and a third acceleration value is calculated to obtain a jerk command value, which is multiplied by a predetermined gain to calculate a correction amount. Then, the speed command value is corrected by adding the correction amount to the speed command value output from the position adjuster 27 in the adder 26. The corrected speed command value is input to the speed adjuster 28, and thereafter the operation is the same as in FIG.

FIG. 10 is a control block diagram showing a second reference embodiment of the present invention .
In this reference form, the correction block 33 performs fourth-order differentiation of the position command value, and calculates the correction amount by multiplying the fourth-order differential value by a predetermined gain. Then, the torque command value is corrected by adding this correction amount to the torque command value that is the output of the speed adjuster 28 in the adder 26. The corrected torque command value is input to the torque adjuster 29, and thereafter the same operation as in FIG. 6 is performed.
Although not shown, the correction amount may be added to the thrust command value, and the position may be controlled based on the addition result.

Each form state described above, perform a full differential operation in the calculation of the correction amount, for example 2, it is assumed that obtain the correction amount as Ks ² in the example of FIG. 6, the correction amount Ks 2 ^{/ (1} + sT) Ya _{^{ks 2 / (1 + sT 1}} + s 2 T 2) may be obtained by incomplete differential form, such as.
The correction amount is not necessarily a function, as shown with respect to the embodiment in FIG. 11, detects a change in the original command value, the correction according to the timing of changing the value which has been prepared as a table pattern It may be output as a quantity.

  Summarizing the above, for each embodiment, the original command value (correction source) for generating the correction amount, the command value (correction target) to which the correction amount is added, a function example of the correction amount, and a representative example The relationship between various correction pattern examples (see FIG. 12) is as shown in FIG.

It is a block diagram of implementation of the invention. It is explanatory drawing of a compensation element. It is explanatory drawing explaining operation | movement of a machine control apparatus, Comprising: Fig.3 (a) is a time-speed diagram, FIG.3 (b) is a time-position diagram. 4A and 4B are explanatory diagrams for explaining the operation of the slide moving unit, in which FIG. 4A is a time-speed diagram, and FIG. 4B is a time-acceleration diagram. It is explanatory drawing explaining operation | movement of a slide moving part, Comprising: Fig.5 (a) is a time-speed diagram, FIG.5 (b) is a time-acceleration diagram. It is a functional block diagram of an embodiment of the present invention . It is a figure which shows the correction principle of the position command value in embodiment of this invention . It is a figure which shows the correction | amendment principle of the speed command value in the 1st reference form of this invention . It is a functional block diagram of the 1st reference form of the present invention . It is a functional block diagram of the 2nd reference form of the present invention . It is explanatory drawing in the case of producing | generating a correction amount based on a table pattern in embodiment of this invention . It is an explanatory view of a correction pattern in the form state. Each Model state correction source, corrected, example function is a diagram showing a correction pattern example. It is a block diagram of the machine control apparatus of a prior art. It is a figure explaining operation | movement of a machine control apparatus, Fig.15 (a) is a time-speed diagram, FIG.15 (b) is a time-position diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heavy object 2 Arm 3 Slide moving part 4 Slide rail part 5 Motor 6 Coupling 7 Feed screw 8 Position control device 9 Position command device 10 Compensation element 10a Differentiation means 10b Gain means 10c Addition means 21 Position command blocks 22, 32, 33 Correction block 23 Acceleration detection means 24 Parameter 25 Correction term calculation means 26 Adder 27 Position adjuster 28 Speed adjuster 29 Torque adjuster 30 Motor 31 Motor encoder 50 Target machine

Claims (2)

In the machine control device for suppressing vibration of the heavy object when the arm attached with the heavy object as the vibration element is moved to the target position by linear acceleration / deceleration and stopped,
A position command device for outputting a position command value ;
Differentiating means for obtaining a second order differential value of the position command value;
Gain means for outputting a value obtained by multiplying the second-order differential value output from the differentiating means by a gain constant obtained by dividing the mass of the heavy object by the spring constant of the arm, as a correction amount;
Adding means for adding the correction amount output from the gain means and the position command value to output a compensated position command value;
A position control device to which a compensated position command value output from the adding means is input;
A controlled object machine controlled to move the arm to a target position under the control of the position control device ;
A machine control device comprising: The machine control device according to claim 1,
The machine control device characterized in that the second-order differential value has a characteristic of gradually increasing or decreasing from a constant value .

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