JPH01113809A - Servo controller - Google Patents

Abstract

PURPOSE:To extremely reduce the impacts and vibrations of a machine by deciding an array of moved variables via a distribution means without performing distribution of pulses via a pulse distributor so that the distribution data are averaged twice. CONSTITUTION:Three time units having moved variables 0 are put into the positions before and after the distribution data. Then the average moved variable 60/4 of time units T1-T4 is calculated for acquisition of an average moved variable 15. Then the average moved variable {(60+60)/4} of the time units T2-T5 is calculated for acquisition of an average moved variable 30. Thus operations are repeated for output of the averaged distribution data (speed data). Then the second averaging process is carried out so that more averaged distribution data can be obtained. This distribution data is given to a subtractor from a control part 10 for each time unit as a speed command. Thus a control subject is driven at a proper speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a servo control device for moving a controlled object to a target position with high precision.

[Conventional technology]

Servo control devices are used in many fields such as automatic drafting machines, machine tools, and robot control. The outline of such a servo device will be explained using figures.

FIG. 5 is a block diagram of a conventional servo control device. In the figure, 1 is a microcomputer that outputs the target movement amount and target speed of the controlled object.

A pulse distributor 2 generates pulses corresponding to the target movement amount output from the microcomputer 1. At this time, the frequency of these pulses is converted according to the commanded target speed. A comparator 3 outputs the difference between the phase of the pulse from the pulse distributor 2 and a phase signal corresponding to the current position output from a position detector 9, which will be described later. 4
5 is a subtracter that calculates the difference between a phase difference signal from the comparator 3 and a speed signal from a speed generator, which will be described later, and an amplifier 5 that amplifies the difference signal from the subtracter 4. Reference numeral 6 denotes a servo motor, which is always driven by a signal from the amplifier 5 at a speed commensurate with the command. Reference numeral 7 indicates a load connected to the servo motor, that is, an object to be controlled. A speed generator 8 is connected to the servo motor 6 and outputs the current speed of the servo motor 6. 9 is a position detector connected to the servo motor 6;
Outputs the current position data of the load 7.

With such a configuration, the controlled object is moved to the target position at a speed commensurate with the command value.

[Problem that the invention seeks to solve]

In the conventional servo control device described above, speed control is performed by generating pulses in the pulse distributor 2 and converting these pulses into pulses with a frequency according to a speed command value. That is, the configuration was such that each pulse was output at intervals commensurate with the speed. In order to obtain such an output, it is necessary to provide a wideband conversion function of the pulse frequency, which has the disadvantage that the circuit configuration of the pulse distributor 2 becomes extremely complicated and large.

Furthermore, with conventional servo control devices, there are large changes in acceleration, which causes shock and vibration to the machine.

This not only reduces the lifespan and accuracy of the equipment by causing loosening of screws and peeling of adhesive parts, but also the vibration during movement, which makes it difficult for automatic drawing machines to accurately draw desired line segments. In addition, machine tools tend to have problems such as not being able to perform the desired cutting, and as a countermeasure for this, a pulse frequency determination mechanism is required, making the equipment complex and complicated.
It becomes expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a servo control device that solves the problems of the prior art described above, has a simple structure, and can significantly suppress shocks and vibrations.

[Means for solving problems]

In order to achieve the above object, the present invention includes a driving ear structure that drives a controlled object, and an instruction section that instructs a target movement amount and a target speed of the controlled object, and according to instructions from the instruction section, the In a servo control device for operating a drive mechanism, a distributing means determines an array of maximum travel amounts per unit time based on the target travel amount and the target speed, and a unit of travel amount equivalent to 0 before and after the array. A first averaging means that calculates speed data by adding a predetermined number of times and averaging the movement amount in the order of arrangement, and a method equivalent to O before and after the arrangement of speed data obtained by this first averaging means. The present invention is characterized in that a second averaging means is provided which calculates a speed command by adding a predetermined number of units of movement amount and averaging the movement amount in the order of arrangement.

[Effect]

When the target movement amount and target speed are given by the instruction unit,
The distributing means first obtains the amount of movement per unit time from both of them, arranges them in the same number of units of time, and then calculates a predetermined number of movement amounts before and after the array of movement amounts arranged in this way. Performs an array with a movement amount of 0 or close to 0. Next, the first averaging means extracts a predetermined number of the arrayed movement amounts from one end of the array and calculates the average value thereof. This calculation of the average value is performed sequentially toward the other side of the array while shifting the array one by one. With respect to the thus obtained array of velocity data for each unit time, a predetermined number of 0 or close to 0 movement amounts are further arrayed before and after the array. Then, like the first averaging means, the second averaging means extracts a predetermined number from one end of the array and calculates the average value, and this calculation is performed by shifting the array one by one. is executed in one jet toward the other side. In this way, a speed command is calculated for each unit time, and the controlled object is driven at an appropriate speed based on this speed command.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a block diagram of a servo control device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 5 are given the same reference numerals and explanations will be omitted.

Reference numeral 10 denotes a control section composed of a microcomputer. In this embodiment, the functions of the microcomputer 1, pulse distributor 2, and comparator 3 are performed by the control section 10 in the apparatus shown in FIG.

Next, the operation of the control section 10 will be explained with reference to the graphs shown in FIGS. 2(a) to 2(e). Here, for ease of understanding, a specific example will be described in which commands are input such that the moving distance is 600 mm in the X-axis direction and the moving speed is 60 m/sec. When such commands are input to the control unit 10, the control unit 10 calculates distribution data for the X-axis and Y-axis based on these values.

Distribution data is data on the amount of movement output per unit time (since it is the amount of movement per unit time, it is equal to speed data).

). Here, x: target distance in the X-axis direction, y: target distance in the Y-axis direction, l: distance between positions A and B, V, command speed, N: travel time, distribution data on the X-axis, D, on the Y-axis. Distribution data D
Each of V is expressed by the following formula.

v v v ■ In the above example, x=600. )'=O, v=60, so N=10. Δx=60. Δy=o. That is, the distribution data becomes the movement amount DX (60) every N times (10 times) in the unit time.

Note that x/N and y/N are usually not integers.

The arithmetic processing of distribution data in such a normal case will be described later.

FIG. 2(a) shows the above N=10. The arrangement of distribution data when DX=60 is shown. In the figure, time is plotted on the horizontal axis, and movement amount is plotted on the vertical axis, and it is shown that the movement ff160 is output 10 times per unit time.

The distribution data shown in FIG. 2(a) obtained by such distribution processing is subjected to the first averaging process shown below. The explanation will be based on the graph shown in .First, before and after the distribution data,
Insert three time units each with a movement amount of 0. Then the average movement of time units T I' - T 4! (60
/4) to obtain an average movement amount of 15. Next, the average movement amount ((60+60)/4) of the time units T2 to T is calculated to obtain the average movement amount 30. By repeating such calculations, averaged distribution data (referred to as speed data) as shown in FIG. 2(C) is output.

The speed data obtained by the first averaging process is further subjected to a second averaging process.

This second averaging process is also performed by the same means as the first averaging process. That is, as shown in FIG. 2 Tdl, two time units each having a movement amount O are inserted before and after the speed data. Next, the average movement ffi (15/3) of the time units T1 to T3 is calculated and the average movement amount 5 is calculated.
get. Next, the average movement amount (
(15+30)/3) is calculated to obtain the average movement 1115. By repeating such calculations, the result shown in Figure 2 (
Further averaged distribution data as shown in e) is obtained. This data is output from the control unit 10 to the subtracter 4 in units of time as a speed command.

FIG. 3 is a characteristic diagram of the speed command. In the figure, time is plotted on the horizontal axis, and speed command value is plotted on the vertical axis.

This figure is a diagram depicting the amount of movement shown in FIG. 2 (8) as a characteristic curve, and as is clear from both figures, T at the time of startup.

The time 'rs to transition from the acceleration zone to the constant velocity zone, the time T8 to transition from the constant velocity zone to the deceleration zone, and the time TI at stop.
When the acceleration and deceleration of S suddenly change, the speed command value changes gradually. Therefore, the above-mentioned respective times T r and T s of the actual servo motor 6.

T11. Changes in acceleration and deceleration in the TIS become gentler, and shock and vibration applied to the machine are significantly reduced.

Here, the distribution processing for obtaining distribution data in the control unit 10 will be explained with reference to the flowchart 10 shown in FIG. In this distribution process, each amount of movement for each unit time, ie, distribution data, is expressed by I)vt for the X axis, . This subscript riJ indicates the number of unit time. Therefore, first, in the distribution process, the subscript ri
Let J be 1 (procedure S+ shown in FIG. 4). Then, it waits until one unit time has elapsed (until the sampling time signal is input) before moving to the next step S2. After this time has elapsed, it is determined whether movement data based on the movement command exists in the control unit 10 (step S2).

When there is no movement data, distribution data D X i
To output rD V i as O, procedure S'l), subscript i
is incremented by 1, and after 1 unit of time has elapsed, step S2 is executed again.

If it is determined in step S2 that there is movement data, the movement data, that is, the distance X in the X-axis direction and the distance y in the Y-axis direction.
is taken in (step SS), and the moving distance 1<1=, βr7T]11) from the current position to the target position is calculated (step S6). Next, a moving time N (number of unit times) is calculated from the calculated moving distance l and the moving speed V commanded to the control unit 10 (step S?). Note that the above-mentioned moving speed V (60 m/5 ec in the previous embodiment) is determined in advance based on the performance of the machine and the attached tools (for example, what type of writing instrument is used in an automatic drafting machine). The travel time N is determined by l/v, but as mentioned above, it is rarely an integer.

Therefore, the fraction of the travel time N determined in step S is rounded up. Hereinafter, the process of step 5e=317 is a process for determining distribution data when the amount of movement per unit time is not an integer.

If the amount of movement per unit time is not an integer, the difference in distribution data for each unit time needs to be made as small as possible and averaged over the entire movement time N. Therefore, in the following process, the distribution data is sequentially increased or decreased by the minimum value for each unit time. In order to perform this process, a number J for determining the number of outputs of distribution data and a number gX1gy for determining an increase/decrease in the previous distribution data are provided. These numbers J=gx9gy are actually numerical values stored at predetermined addresses in the memory.

In the following explanation, only the simplest numerical value will be exemplified regarding the X-axis. Now x=10. If N=4, the following process is performed in step S8.

That is, the absolute value of distance X is divided by the travel time °N, the quotient is ΔX, and the remainder is ? ' The number gx, (gx+2・
rx), and the distribution data Dxi is determined to be ΔX.

In the above example, the new number gx is (0+2 x 2), which is 4, and the distribution data D 11i is 2.

Next, the numerical value g8 and the travel time N are compared (step Sz
). In the above example, g,=4. Since N=4, gx
>N, the process moves to step StZ, and after similar processing is performed for the Y-axis, the process moves to step 313. In step SI3, distribution data D determined in step SIO,
1 (=2) is given a sign in the X-axis direction, and this is output as distribution data.

Next, add 1 to the number i, and add 1 to the number J (
Step 5I4), compare this new number J with the travel time N (step S1.). If the number J has not reached the travel time N, the process returns to step S. Return to

In this case, since the number gx was gx=4 in the previous procedure SIO, the new number gx is 8 (4+2X2). Moreover, the distribution data is expressed as Dx(ion), and Dx(1
+++=Δx=2.

In procedure SII, gx =8. Although N=4, gx
>N, and the process moves to step 516.

In step S16, 1 is added to Dx(i,)=2 to set distribution data Dx(i+1> to 3, and gIl-2xN=8-2x4=0 is determined as a new number gx.

After the same process (steps S1□, Sl?) is executed for the Y axis, the distribution data DX, . . . in step S13.

Output with a sign. The same procedure is repeated thereafter. As a result, in the above example, the X-axis distribution data D
xi becomes r3J, r2J, r3J, r2J. Similarly, for the Y-axis, step S and the following processing are executed.

In this way, in this embodiment, the distribution data is obtained by the calculation and control processing of the control unit based on the given movement data and specified speed, so the configuration is simpler than that of the conventional pulse distributor. It can be done. Also, since the obtained distribution data is averaged twice, changes in acceleration/deceleration can be made gentler.
In turn, it is possible to significantly reduce the stiffness and vibrations that are applied to the machine, and it is possible to improve the accuracy and extend the life of the machine.

〔Effect of the invention〕

As described above, in the present invention, the arrangement of movement amounts is determined by the distribution means without performing pulse distribution by the pulse distributor, so that the configuration can be simplified and the distribution data can be Since it is averaged twice, it is possible to significantly reduce the shock and vibration generated in the machine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a servo control device according to an embodiment of the present invention, and FIGS. 2(a), (b), (e), (d),
(e) is a graph explaining the operation of the control unit shown in Fig. 1, Fig. 3 is a characteristic diagram of the speed command, Fig. 4 is a flowchart of distribution processing, and Fig. 5 is a block diagram of a conventional servo control device. be. 4... Subtractor, 6... Servo motor,
7...Load, 8...Speed generator, 9.
...Position detector, 10...Control unit. Figure 1 n Figure 3 Procedural Amendment (White side, January 21, 1988)

Claims (1)

[Claims] A servo control device that includes a drive mechanism that drives a controlled object, and an instruction section that instructs a target movement amount and a target speed of the control object, and that operates the drive mechanism in accordance with instructions from the instruction section. distribution means for determining an arrangement of movement amounts per unit time based on the amount and the target speed; and adding a predetermined number of movement amount unit times equivalent to 0 before and after the arrangement to average the movement amounts in the order of the arrangement. a first averaging means for calculating speed data using the first averaging means; and a predetermined number of units of movement amount equivalent to 0 are added before and after the array of speed data obtained by the first averaging means, and the speed data is moved in the order of the array. A servo control device comprising: second averaging means for calculating a speed command by averaging the amounts.