JPS58108983A - Controller for motor - Google Patents

Abstract

PURPOSE:To smoothly accelerate or decelerate a motor and to control the motor at a constant speed by reducing the reduction rate of a motor drive signal when the driving amount of the motor enters the prescribed driving amount range. CONSTITUTION:A microcomputer 1 outputs an instruction pulse CP which contains the total rotation amount of a DC motor 2 and speed information and potentiodata P0, -P0 which indicate the driving mount range for reducing the reduction rate of the drive signal of the motor 2. A deviation counter 3 produces a deviation amount DS between the number of pulses of the pulse signal CP and the number of pulses of a feedback signal FP from a pulse generator 5. When the rotating amount of the motor 2 enters the preset rotating amount range, only an analog switch 10 closes, and the reduction rate of the reference input of a servo amplifier 12 decreases. Accordingly, even if the rotating amount of the motor 2 approaches the target value, necessary torque can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a closed-loop motor control device that controls the drive of a motor based on the amount of deviation between a command signal and a feedback signal from a position detector.

Conventional closed-loop motor control devices include analog and digital sensors. There are two methods:
In both cases, the command signal and the feedback signal from a position detector such as a pulse generator (sometimes it is attached to the output shaft of the motor, and sometimes it is attached directly to the driven part driven by the motor). According to the amount of deviation, a motor drive signal is generated to drive and control the motor.

By the way, the following problems are listed as problems with such a conventional motor control device.

In other words, 1. Since the motor drive signal (current) is generated according to the amount of deviation between the command signal and the feedback signal, when the motor drive amount approaches the target value, the drive signal becomes extremely small and the motor The generated torque also becomes very small.

Therefore, when such a motor control device is applied to drive a logget, which has been actively developed in recent years, the following problems occur.

For example, when a robot is used to assemble a workpiece, the movable parts of the robot (such as an arm or a mechanical hand) must exert a certain amount of force even when they approach the target movement position. If such a motor control device is used as a drive motor for a movable part, this cannot be achieved due to the reasons mentioned above.

As a solution to this problem, it is possible to prepare an amplifier with high drive signal generation characteristics (for example, amplifier gain characteristics) with respect to the deviation amount so that the necessary torque is generated even when the motor drive amount approaches the target value. Conceivable.

However, when doing so, there is a problem that when speed control is performed together with rotation amount (position) control of the motor, acceleration/deceleration and constant speed control cannot be performed smoothly.

This invention was made in view of the above-mentioned problem, and when the motor drive amount enters a preset drive amount range, the motor drive signal generated according to the deviation amount between the command signal and the feedback signal. An object of the present invention is to provide a motor control device that slows down the rate of decrease in the rate of decrease in the rate of decrease, thereby solving the above-mentioned problems.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention.

In the figure, the microcomputer 1 generates a command pulse signal CP including the total rotation amount and speed information of the DC motor 2;
Position data Po, Po (see FIG. 2) indicating a drive amount region in which the rate of decrease of the drive signal of the DC motor 2 is slowed down is output.

The deviation counter 6 calculates the /'P pulse number of the command pulse signal CP from the microcomputer 1 and the feedback signal FP from the pulse generator 5 attached to the output shaft 2a of the DC motor 2 via the coupling 4. The deviation amount (accumulation amount) DS from the basic Luss number is created.

Note that the deviation amount DS, which is the output of the deviation counter 3, has positive and negative values, and the DC motor 2 rotates, for example, clockwise in the case of +DS, and counterclockwise in the case of -DS.

Further, since the deviation amount DS is inversely proportional to the rotation amount of the DC motor 2, the deviation counter 3' also serves as a rotation amount detection means for detecting the rotation amount of the DC motor 2.

The D/A converter 6 converts the deviation amount DS from the deviation counter 6 into a voltage signal SO which is an analog value.

The first preamplifier 7 has a gain characteristic between the input voltage signal SO and the output voltage signal S1 as shown by the straight line ■ in FIG.
It has a gain characteristic between O and the output voltage signal S2 as shown by the straight line ■ in FIG.

That is, the second preamplifier 8 has a higher dyne than the first preamplifier 70 dyne.

Analog switches 9 and 10 as characteristic switching means are turned on and off by the output a of a comparator circuit 15 as reach detection means, which will be described later.When the output a is at low level 'L', the analog switch 9 The analog switch 10 is turned on only when the output a is at high level 1H#.

The amplifier 12 is the first one. Voltage signal S1 or 82 as a drive signal for the motor from the second preamplifier 7.8
(reference input) and the speed feedback signal S3 obtained by converting the feedback signal FP from the Noyalus generator 5 into a voltage signal by the F/V converter 16. A voltage signal S4 is output to the DC motor 2 according to the deviation amount. do.

The position register 14 is for writing position data Pa, -PG output from the microcomputer 1 before starting the DC motor 2.

The comparison circuit 15 as an arrival detection means has a deviation color/ri3.
By inputting the deviation amount DS from DS and the position data Po, Po from the position register 14, the deviation amount DS is
>Po or DS (when -Po, output a is low level 1L'
When -PO≦Ds≦Pa, output a is set to high level 1H#
Make it.

Therefore, when the rotation amount of the DC motor 2 is set in advance and is not yet within the normal rotation amount region, that is, when the deviation amount DS is D
When S>Pa or DS (-Po, only the analog switch 9 is turned on, so at this time the first preamplifier 7
Is the voltage signal S1 from sir? When the reference input of the amplifier 12 and the rotation amount of the DC motor 2 enter a preset rotation amount range, that is, the deviation amount DS is −Po≦DS≦Pa.
At this time, only the analog switch 10 is turned on, so at this time, the voltage signal S2 from the second preamplifier 8 is turned on. This becomes the amplifier 120 reference input.

Therefore, the characteristics of the reference input of the servo amplifier 12 are
The solid line in the figure shows that DS>Pa or DS(-
When moving from Po to -Pa≦D, S≦P, the rate of decrease in the reference input slows down.

Therefore, the rotation amount of the DC motor 2 is set to the target value (DS=O
), the voltage signal S4 does not become extremely small;
The necessary torque can be secured.

Moreover, as shown in FIG. 2, the control range (size of deviation amount DS) can be made wider than when controlling only with the characteristic shown by the straight line ■, so the speed of the DC motor 2 in FIG. FIG. 2 is a block configuration diagram showing a second embodiment.

In FIG. 3, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and explanations of those parts will be omitted.

This second embodiment differs from the first embodiment described above in the first embodiment. The second preamplifier 7.8 is replaced with one preamplifier 16, the analog switches 9 and 10 are omitted, and the data for the upper 4 bits of the deviation amount DS, which is 8-bit digital data from the deviation color/reference 6, is The DS is directly input to the D/A converter 6, and the lower 4 bits of data are converted into data DS' by the data conversion circuit 17, which is a characteristic switching circuit, and then input to the D/A converter 6. It is characterized by the fact that it is

However, in this second embodiment, since the DC motor 2 is designed to rotate only in the clockwise direction, the position data is only Pa.

That is, as shown in FIG. 4, for example, the data conversion circuit 17 includes an AND circuit 18 that takes the AND between the output a of the comparison circuit 15 and the bit data DSx of the deviation amount DS, and an AND circuit 18 that takes the AND between the output a of the comparison circuit 15 and the bit data DSx of the deviation amount DS, and the bit data DS2°D of the deviation amount DS. S + ID
OR circuits 19 to 21 that take an OR between each of S o and the output of the AND circuit 18, and bit data DS of the deviation amount DS.
3 and the outputs of the OR circuits 19 to 21 in sequence, four terminals B to which each output of the OR circuits 19 to 21 and the ground level were input in sequence, and the comparison circuit 15. When the output a is low level 'L', the terminal At is selected, and when the output a is 'H', the terminal B is selected, and each data DS/~DS6 output from the selected terminal is sent to the D/A converter. 6, and a selection circuit 22 constituted by selection means C1 to C4.

By doing this, when the output a of the comparator circuit 15 is at the low level 1L', the deviation amount DS
is input to the D/A converter 6 as it is without being converted, and when the output a is 'H', the data for the lower 4 bits of the deviation amount DS from the deviation counter 3 is shown in the table on the next page. It will be converted as follows.

However, the position data PO is set to "15"('1111
').

Therefore, the signal is the reference input S' of the amplifier 12.

The characteristics of the output So of the D/'A converter 6, which is the value before amplification, are as shown in FIG. 5, and the deviation amount DS is D S )
When moving from Po to O≦DS≦Po, the output is S.

The rate of decline will slow down.

Even in this case, the same effects as in the first embodiment can be achieved.

In the second embodiment, an example was described in which the DC motor 2 was rotated only in the clockwise direction, but by changing the logic of the data conversion circuit 17, the characteristics can also be switched in the counterclockwise direction. can.

Also, the above 1. In the second embodiment, an example was described in which the deviation counter 3 was used as the rotation amount detection means, but a counter may be provided separately from the deviation counter 3 and used as the rotation amount detection means.

Furthermore, the motor control device according to the present invention can also be applied to a linear motor.

As described above, the motor control device according to the present invention has
When the motor drive amount enters the preset drive amount range,
The reduction rate of the motor drive signal that occurs depending on the amount of deviation between the command phalanx and the feedback signal is slowed down, so even if the motor drive amount approaches the target value, the drive signal does not simply decrease, and the required torque can be ensured.

Moreover, since the control range can be wider than when an amplifier with high drive signal generation characteristics is used in advance, the speed of the motor can be controlled smoothly.

Therefore, if such a motor control device is applied to, for example, a rodet, it will be effective especially when the rodet performs the work of assembling a workpiece.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing a first embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of the embodiment of FIG. 1, and FIG. 3 is a diagram showing a second embodiment of the invention. FIG. 4 is a circuit diagram showing details of the data conversion circuit of FIG. 3, and FIG. 5 is a diagram for explaining the operation of the embodiment of FIG. 3. 1...Microcomputer 2...DC motor 3...Deviation counter (rotation amount detection means) 5...Medium pulse generator (position detector) 6...D/A converter 7...No. 1 preamplifier 8...second preamplifier 9.10...analog switch (characteristic switching means) 12
...Sir is an amplifier 16...F/V converter 14.
...Position register 15...Comparison circuit (arrival detection means) 16...Preamplifier

Claims (1)

[Claims] 1. In a closed-loop motor control device that controls the drive of a motor based on the amount of deviation between a command signal and a feedback signal from a position detector, a drive amount detection means for detecting the drive amount of the motor, and the drive amount arrival detection means for detecting that the drive amount of the motor detected by the detection means has entered a preset drive amount region; 1. A motor control device comprising: characteristic switching means for slowing down the rate of decrease in a drive signal.