JPS5833795B2 - Synchronous operation control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronous operation control system, and particularly to a synchronous operation control system in which a movable object is driven synchronously by two motors.

In Kant IJ machine tools, large drafting machines, etc., the movable parts are driven in the same direction by two motors.

In this case, unless the two motors are rotated synchronously, twisting or the like will occur in the movable part, and machining accuracy and drafting accuracy will decrease.

For this reason, synchronous operation has conventionally been performed using a configuration as shown in FIG.

In the figure, reference numeral 1 denotes a numerical control device (hereinafter referred to as NC), which has a pulse distributor inside, and generates a pulse train having a frequency according to the command speed based on a command from a paper tape or the like (not shown).

Note that this pulse train becomes a position command for each motor.

2 is a servo circuit for one motor M1, which outputs a position deviation signal P.
Position control circuit 2a that generates D1 and position deviation signal PD
A speed control circuit 2b that generates a drive voltage according to the difference between 1 and the actual speed of the motor M1, a tachogenerake 2C that generates a voltage that corresponds to the actual speed of the motor M1,
One feedback pulse F every time F rotates by a predetermined angle.
A position feedback loop PF1 and a feed feedback loop F1 are formed.

Now, the position control circuit 2a is a reversible counter RV1.
．． It has a DA converter DAC1 and an amplifier AMP1.

This reversible counter R■1 counts up every time the pulse PCMD, which is the position indicator ♦, is generated, and counts down every time the feedback pulse FP1 is generated.

That is, the contents of the reversible counter R11 are proportional to the positional deviation.

The contents of this reversible counter Rv1 are transferred to the DA converter D.
It is converted into an analog value by AC1, then amplified and output as a position deviation signal PD1.

The speed control circuit 2b outputs the position deviation signal PD1 and the actual speed signal■
1, and drives the motor M1 so that the drive voltage becomes zero.

With the above control, in a steady state, the positional deviation becomes a steady value, and -M rotates at a constant speed.

Reference numeral 3 denotes a servo circuit for the other motor M2, which has the same configuration as the servo circuit 1.

In addition, 3a is a position control circuit that generates a position deviation signal PD2, and 3b is a position deviation signal PD2 and the actual speed of the motor M2.
3C is a tachogenerator that generates a voltage 2 that corresponds to the actual speed of motor M2; 3d is a tacho generator that generates a voltage of 1 every time motor M2 rotates by a predetermined angle;
(1) F2 is a velocity feedback loop, PF2 is a position feedback loop, RV2 is a reversible counter, DAC2 is a DA converter, and AMP2 is an amplifier.

4 is a synchronization correction circuit, which includes an error voltage generator 4a that generates a voltage EV proportional to the difference in the number of pulses generated from the pulse coders 2d and 3d, and an amplifier 4 that amplifies the error voltage EV.
It has b.

4C is the position deviation voltage P of the motor M2.
This is an adder that adds to DV.

If the motors M1 and M2 rotate in complete synchronization, the output of the error voltage generator 4a is zero and no correction is performed.

However, if the synchronized rotation of the motors M19M2 breaks down and one of the rotations becomes faster, a difference occurs in the speed of the pulses generated from the pulse coders 2d and 3d, and the error voltage generator 4a has an amplitude corresponding to the speed difference. An error voltage EV is generated having a sign depending on the magnitude of the rotational speed of the motor M19M2.

Note that this sign is positive if ■1>■2, and negative if ■, <■2.

Therefore, the position deviation voltage PDV of the servo circuit 3 is corrected according to the speed difference between the two motors.

That is, if ■1>■2, the output voltage of the position control circuit 3a increases and the speed of the motor M2 increases to V until ■2, and if ■1 <■2, the output voltage of the position control circuit 3a increases. The voltage decreases and the speed of motor M2 is vl-V! It descends until it becomes .

From the above, the method shown in FIG. 1 allows for highly accurate synchronous control.

However, due to drift in the characteristics of the error voltage generator 4a and amplifier 4b, an error voltage EV may occur even if both mokes are completely synchronized.

In such a case, if the movable part driven by both motors is extremely hard, in other words, if the rigidity is large, an unreasonable force such as twisting will be applied to the movable part.

That is, considering the case where the above-mentioned drift occurs, the conventional method shown in FIG. 1 is not suitable for driving a rigid body once.
It can be said that it is suitable for synchronous control of relatively soft movable objects, that is, movable objects that can be restored even when a torsional force is applied.

Furthermore, the method shown in FIG. 1 requires two sets of position control circuits and position detectors (pulse coders), which increases the cost.

Accordingly, an object of the present invention is to provide an economical synchronous control system that is suitable for driving a movable object made of a rigid body and that uses a small number of parts.

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

FIG. 2 shows an embodiment for realizing the synchronous operation control system of the present invention, and the same parts as in the conventional example are given the same reference numerals, and detailed explanation thereof will be omitted.

The differences in Fig. 2 compared to the conventional example are: ■ The position control circuit 3a, the pulse coder 3d, and the position feedback loop PF2 are removed from the servo circuit 3 of the motor M2, and ■ The synchronization correction circuit 4 is deleted. (2) The motor M2 is driven so that the difference between the position deviation signal PD1 of the servo circuit 1 and the actual speed v2 of the motor M2 becomes zero.

That is, the servo circuit 1 of the motor M1 operates in exactly the same manner as the conventional example shown in FIG.

On the other hand, the servo circuit 2 of the motor M2 is formed by a speed control circuit 3b, a tacho generator 3c, and a speed feedback line LN, and the position deviation signal PD1 of the servo circuit 2 and the actual speed signal ■
Motor M2 so that the drive voltage according to the difference between M2 and M2 becomes zero.
to drive.

As is clear from this, in the present invention, motor M2
follows motor M and rotates synchronously.

In this embodiment of the present invention, the difference between the generated voltages of the tachogenerators 2c and 3c in both servo circuits 2.3 and the offset of the speed control circuits 2b and 3b, etc., or the magnitude of the load on both motors M12M2, Motor M
Even if the speed of motor M1 becomes smaller than the speed of motor M1 (vl
〉■2) If the movable object is a hard rigid body, the motor M2 becomes a load on the motor M1, in other words, the load on the motor M1 increases, the speed of the motor M1 decreases, and both motors can be synchronized.

Note that the same applies to cases (1) and (2). Furthermore, in the embodiment shown in FIG. 2, the position control circuit and pulse coder are removed from the servo circuit 3, and the synchronization correction circuit is also removed, so that a simple, low-cost synchronization control system with a small number of parts can be provided.

In the embodiment shown in FIG. 2, if the movable parts are soft, it becomes difficult to restore synchronization because one motor cannot effectively load the other motor when synchronization is lost.

FIG. 3 shows another embodiment of the invention.

In the figure, 5 and 6 are the armature current of DC Moke M12M2■1
．． A current detector 7 detects I2, a correction circuit, and an armature current 11. A differential current generating circuit 7a that generates a differential current signal 1d having a voltage according to the difference between the differential current signal I2 and the differential current signal I2, an amplifier 7b that amplifies the differential current signal d, and a differential current signal Id that converts the differential current signal Id into a driving voltage D■2 of the motor M2. It has an adder 7C that performs addition.

AD is an adder, APM is an amplifier, and the adder IC
and form a speed control circuit.

Note that the same parts as in the conventional example are given the same reference numerals, and detailed explanation thereof will be omitted.

Now, if the synchronization is broken and the speed ■2 of the DC motor M2 becomes smaller than the speed ■1 of the DC motor M1, if the movable object is a hard rigid body, the load on the motor M1 increases, and the armature current T1
increases, and T1>I2.

As a result, a positive difference current signal Td having an amplitude proportional to the current difference is generated and added to the drive voltage D2 by the adder 7c.

Therefore, the voltage applied to the DC motor M2 increases, the speed of the motor M2 increases, and the armature current T2 also increases. It becomes T2■1.

Conversely, in the case of vl<2, I1<I2, and a negative difference current signal Id is generated and added to the 1 drive voltage D2, so that the speed of the motor M2 decreases.

At the same time, the armature current T2 also decreases, and ■2=■1. ■
2-■ becomes 1.

That is, in the embodiment shown in FIG. 3, even if synchronization is lost for some reason, the load on one motor becomes larger than that on the other and the armature current T1. A difference occurs in I2, and the speed of motor M2 is increased or decreased depending on the difference in position.■1-■2. ■
1. I2, both motors can be synchronized and the loads on both motors can be made the same.

Also, compared to the one in Figure 2, it has a correction circuit that actively increases or decreases the speed of motor M2 when a speed difference occurs, so the restoring force for restoring synchronization is greater and the speed is shorter. Synchronization can be restored in time.

Further, the number of circuit components can be reduced compared to the conventional example.

In the above description, a pulse train is output from the NC as the position indicator ◆VCMD, but an analog voltage may also be output.

However, in this case, the position control circuits 2a and 3a are configured with differential amplifiers, etc., and the output voltage (speed) of a detector that generates an analog position signal, such as a tacho generator, is integrated instead of the pulse coders 2d and 3d. Therefore, it is necessary to use a position detector configured to generate an analog position signal.

As described above, according to the present invention, it is possible to control the synchronous operation of movable members that are hard, that is, have high rigidity, with a smaller number of parts than in the conventional system.

In addition, since the armature currents of both motors are compared and the drive voltage of one motor is corrected so that the current difference becomes zero, the load on both motors can always be the same, and even if a synchronization error occurs, it is possible to It has great resilience to synchronization recovery and can synchronize both motors in a short time.

[Brief explanation of drawings]

FIG. 1 is a block diagram explaining a conventional synchronous operation control system, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing another embodiment of the present invention. 1...NC12, 3... Servo circuit,
2a. 3a...Position control circuit, 2b, 3b...
... Speed control circuit, 2c, 3c... Tacho generator, 2d. 3d...Pulse coder, Rvl, Rv2...
...Reversible Count, DACl, DAC2...
...DA conversion, device, AMP1, AMP2...
・Amplifier, 4... Synchronization correction circuit, 5, 6...
...Current detector, 7...Correction circuit, 7a...
...Difference current generation circuit, 7b...Amplifier, I
C...Adder, M12M2...Motor.

Claims (1)

[Claims] In a synchronous operation control method in which 12 motors are rotated synchronously to move a movable part, a servo circuit having a position feedback loop and a speed feedback loop calculates the position, which is the difference between the command amount and the rotation amount of the first motor. Derive the deviation signal voltage,
The first motor is driven so that the difference between the position deviation signal voltage and the actual speed signal voltage of the first motor becomes zero, and the second motor is driven so that the difference between the position deviation signal voltage and the actual speed signal voltage of the second motor becomes zero. A synchronous operation control method characterized by driving so that the difference in speed signal voltage is zero.