JPH03169290A - Servo-control apparatus - Google Patents

Abstract

PURPOSE:To improve response delay when a servomotor starts a forward rotation or a reverse rotation by a method wherein a first corrected value obtained when the start of the forward rotation is instructed is corrected by a second corrected value obtained when the reverse rotation of the motor is instructed. CONSTITUTION:When a speed instruction instructs the start of a motor rotation, a first correcting means 60 replaces the integrated value of an integrating means 50 with a first corrected value. When the speed instruction instructs reverse rotation of the motor, a second correcting means 70 replaces the integrated value of the integrating means 50 with a second corrected value by a replacing means 74 in accordance with the reverse flag of a memory means 71, a reverse rotation judging means 72 and a region judging means 73. A third correcting means 80 corrects the first corrected value with the second corrected value. With this constitution, response-delay created when the servomotor starts rotation or the direction of rotation is reversed can be improved. Further, this improvement is effective even if a friction torque is varied by aging or environment.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention solves the problem of error in trajectory accuracy due to response delay when starting rotation of a servo motor or reversing direction of rotation due to frictional torque and hardware dead zone. The invention relates to servo control devices used in high-precision NC devices and robots.

BACKGROUND OF THE INVENTION FIG. 6 shows the basic structure of a general servo control method for controlling a -C servo motor using a foot bank loop. The position command generation circuit 1 calculates the amount of movement a per positioning time.
The subtracter 2 outputs the output pulse d per head position time of the rotary encoder 12 directly connected to the servo motor 11.
The speed command calculation circuit 3 calculates the difference between and the movement amount a, and calculates the difference between
The output of the subtracter 2 is manually amplified to output a speed command signal b, and a speed feed hack signal is generated by the speed signal detection circuit 8 which receives the output pulse (') per unit time of the rotary encoder 12 as an input. -M, e, and the subtracter 4 subtracts the speed feedback signal C from the speed command signal l].

Roughly speaking, the output of the subtractor 4 is human power}-The torque command calculation circuit 5 calculates and outputs the torque command C, and the subtracter 6 outputs the torque command C which is detected by the current detector 10 of the servo motor. Current fee 1 Hack value f
Subtract.

An amplifier 7 inputs the output of the subtracter 6 and converts it into PW.
M{Convert to M number and apply voltage to the servo motor 11. When voltage is applied to the motor 11, it rotates, movement #d per unit time is output from the rotary encoder 12, and this is repeated until the output of the speed command calculation circuit 3 becomes 0, and the motor 11 moves to the target position of 1q. let

Further, the portion 9 surrounded by a dotted line in FIG. 6 may be configured as software I/ware.

FIG. 7 shows the details of the torque command calculation circuit 5 and the subtracter 4 in a box diagram.

The subtracter 4 subtracts the speed foot pack signal ef2 from the speed command signal b and outputs the deviation value Δg, and the integrator 32 which uses the deviation value Δg as a manual input calculates the sum of the deviation value Δgj multiplied by the multiplier ki. is output as an integral value. In addition, the proportional device 33 uses the deviation value △g as human power, and the multiplier 1<1.
) and output. The adder 34 is an IRF integrator 3
Adding the output of 2 and the output of the proportional device 33 as human power,
Outputs torque command C.

This configuration has the advantage that even if the deviation value Δg is zero, the torque command C can be output based on the output of the integrator 32, and the speed fluctuation rate can be reduced.

Problems to be Solved by the Invention However, on the other hand, the integral value of the integrator 32 has a delayed response to non-linear loads such as the dead zone of friction l·ruk and ha 1ζ, resulting in errors in trajectory accuracy. Become.

That is, FIGS. 8(A), 8(C), and 8(C) show the waveforms of each part in FIG. 7 of the conventional example.

1, = 0, when a constant positive command is given to the speed command signal 1), when l(i do k p is negative, the torque command C gradually changes and the overshoe 1 - L, becomes negative). The speed feedback I/back signal e is initially zero, and when the torque command C exceeds the hard dead zone and friction torque, the output starts to be output rapidly and becomes a constant positive value.This is the speed command signal This shows that the servo motor starts rotating with a delay with respect to t. becomes smaller and becomes zero at t=t2.Furthermore,
When the value of the speed command signal h becomes negative and gradually changes to a constant negative value, the l/lux command C rapidly changes and becomes a constant positive shift.

The speed feedback signal C is initially zero, and when the torque command C exceeds the heart's dead zone and the friction torque, the output rapidly starts to be output and becomes a constant negative value.

This also indicates that the servo motor started rotating with a delay compared to the speed command signal b+.

An object of the present invention is to provide a servo control device that improves the response delay that occurs when the servo motor starts rotating or reverses the rotational direction due to the conventional friction torque and the dead zone of 1. shall be.

Means for Solving the Problems The present invention controls a servo motor using a torque command calculation circuit that outputs a torque command based on a value obtained by integrating the deviation between a speed command signal and a motor speed feedback signal using an integrating means. In the control device, a first correction means replaces the integral value of the integrating means with a first correction value when the speed command instructs the start of rotation of the motor; a second correction means for replacing the second correction value C when a command instructs to reverse the rotational direction of the motor; and a third correction means for correcting the first correction value by the second correction value. The servo control device is characterized in that the integral gain of the integrating means is increased by means.

According to the present invention, when the speed command instructs the start of rotation of the motor, the integral value of the integrating means is calculated as the first complement +E ff+
When the speed command instructs the reversal of the rotational direction of the motor, the integral value of the integral F stage is replaced with a second correction value, and the second correction value ζ 1 correction value [Thus, it is possible to improve the response delay that occurs when the servo motor starts rotating or when the direction of rotation is reversed.

It is also effective even if the friction torque changes due to aging or the environment.

EXAMPLES Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the main parts when an improvement plan is added to the lower/lower subtractor 4 and the torque command calculation circuit 5 in FIG. 6.

The first correction means 60 is means for replacing the integral value of the integration means 50 with a first correction value when the speed command instructs the moder to start rotating. The second correction means 70 is means for replacing the integral value of the 1,000 stages of integration 50 with a second correction value when the speed command instructs reversal of the rotational direction of the motor. The second correction stage 70 includes a storage means 71 for storing a reversal flag to be set when the speed command instructs reversal of the rotational direction of the motor, and a storage means 71 for storing a reversal flag to be set when the speed command instructs reversal of the rotational direction of the motor, and 1. A reversal determination f stage 72 that determines whether the back signal has been reversed, an area determination means 73 that determines whether the torque command is in a drive region or a brake region based on the result, and the integral and replacement means 74 for replacing the integral value of the means with the second correction value, and the third correction means 80 is
The value C is thus a means for correcting the first correction value.

FIG. 2 is a flowchart showing the operation of the present invention written in L.
3 does not show the detailed curve of its characteristic part. FIGS. 4 and 5 show the waveforms of the speed command signal 1), speed feedback signal e, and torque command C when the servo motor is controlled according to the flowcharts described in FIG.

First, in FIG. 2, in block 14, the speed command signal l]
Read block l5 and set speed fee 1 and back signal 5.
' Read the speed command signal b in block 1G.
and calculate the friction correction value from the speed feedback signal e,
Block 17 calculates the speed deviation value Δg, and block 18
In the integral term, the integral value SO is calculated as 1 (1 × Δg + sO), in block 19, the proportional term is calculated as 1《p × Δg, and in block 20, the l-lux command C is calculated as SO + k
Calculate and output tXΔg. Note that this loop is repeatedly calculated and output at fixed time intervals.

9. FIG. 3 is a flowchart C showing the operation of the friction compensation value calculation block 16, in which the block 21 determines whether the speed command signal b has changed from zero, and if it has changed, b>
o, the integral value SO of the integral term is set to the set value k in block 23.
When b<o, the block 24 sets the integral value SO of the integral term to -ka? Change the whistle.

Next, it is determined in block 25 whether the speed command signal 1] has been inverted, and if it has been inverted in block 26, an inversion flag is set in the storage means 71. Block 27 determines whether the reversal flag is set or not, and when it is set, block 28 determines whether the speed foot hack signal e is reversed, and if it is reversed, block 29 determines whether the speed command signal l
) and the torque command C have the same sign, that is, when only the speed command signal is reversed, it is determined whether the torque command C is in the brake region, and if it is in the brake region, the integral term is Replace the integral value SO with -SO, and then set it in block 31 {iffka as l< b
Replace with X SO. This is a process for estimating and correcting the friction torque at the time of starting from the friction torque 10- at the time of driving. In addition, the inversion flag is reset at block 35.

Further, when the speed command signal l) is inverted in block 29, and the torque command C is in the drive region, the inversion flag is reset to 1 in block 36.

In cases other than the above, the process moves to the next block.

By adding the friction torque correction as shown in the flowchart in Figure 4 (A), (C), (C),
As shown in , the startup starts without delay when 1 = 0, and when t = t. 2, when the speed command signal l] is reversed, the torque command C is reversed when the speed feedback signal C becomes zero, so no dead zone occurs even during the reverse.

Note that t = t. When restarting at step 4, the set value ka has been corrected, so the startup can be made more slowly than at the first startup.

In addition, as shown in Figure 5 (A), (Ex), and (C), startup starts without delay when 1 = 0, but
1 = 1; When the speed command signal 1] is rapidly reversed in 1, the torque command C is also rapidly reversed, and the motor operates in the rake region. When the speed command signal b is reversed, the torque command C has already been reversed. Since the area is in the driving region, the determination is made in block 29 of FIG. 3 and no correction is applied.

This can prevent abnormal operation from occurring due to correction being applied when correction is not necessary.

Effects of the Invention As described above, according to the present invention, since the correction is properly performed, it is possible to improve the response delay that occurs when the servo motor starts rotating or when the direction of rotation is reversed.

Another advantage is that even if the friction torque changes due to aging or the environment, it can be effectively corrected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main parts of a servo control device according to an embodiment of the present invention, and FIGS. 2 and 3 are flowcharts 1 and 4 showing the main operations of the servo control device. ,
Figure 5 is a waveform diagram of each part of the servo control device;
7 is a block diagram showing a conventional servo control device, and FIG. 8 is a waveform diagram of signals at various parts of the same device. l2 11... Servo motor, l2... Rotary encoder, 50... Integrating means, 60... First auxiliary IE means, 70... Second correction means, 7l... Storage means, 72
. . . Reversal determination means, 73 . . . Area determination means, 74.
... Substitution means, 80... Third correction means.

Claims (1)

[Claims] (1) A control device that controls a servo motor using a torque command calculation circuit that outputs a torque command based on a value obtained by integrating the deviation between a speed command signal and a motor speed feedback signal using an integrating means. , the integral value of the integrating means is
When the speed command instructs the motor to start rotating,
a first correction means for replacing the integral value of the integrating means with a first correction value; a second correction means for replacing the integral value of the integrating means with a second correction value when the speed command instructs reversal of the rotational direction of the motor; A servo control device comprising: third correction means for correcting the first correction value using the second correction value. (2) The servo control according to claim 1, wherein the first correction means converts the sign of the integral value of the integrating means to the same sign or a different sign from the sign of the speed command, and replaces the integral value. Device. (3) The second correction means includes a storage means for storing a reversal flag that is set when the speed command instructs to reverse the rotational direction of the motor, and a speed feedback signal that is inverted while the reversal flag is set. a reversal determination means for determining whether the torque command is in a drive region or a brake region based on the result, and a region determination means for determining whether the torque command is in a drive region or a brake region based on the result, The servo control device according to claim 1, further comprising replacement means for replacing the value with a value. (4) The servo control device according to claim 1, wherein the integrating means is a proportional-integral controller or an integral-proportional-derivative controller.