JP4538786B2 - Motor control device - Google Patents

Description

  The present invention relates to a motor control device that drives a machine, and more particularly to a motor control device that compensates for quadrant protrusions when the moving direction is reversed.

As a conventional control device for compensating for quadrant protrusions, there is a method of detecting a reversal of the moving direction and increasing the integral control gain of the speed control loop by a predetermined amount. (For example, refer to Patent Document 1).
FIG. 4 is a control block diagram of a conventional servo control device. In FIG. 4, reference numeral 11 denotes a position controller, which generates a speed command by performing a control process on a position command commanded by a host controller or the like and a position feedback signal of a position detector attached to the motor. A speed controller 12 receives a speed command and a speed feedback signal, performs control processing, and generates a torque command. A speed converter 21 performs a difference process on the position feedback signal at each sampling time to generate a speed feedback signal. A speed control integrator 13 integrates the deviation between the speed command and the speed feedback. 41 is a first speed control integral gain, and 42 is a second speed control integral gain. Reference numeral 15 denotes a speed control proportional gain. Reference numeral 16 denotes a current controller which controls the motor drive current from a torque command. Reference numeral 17 denotes a motor. Reference numeral 18 denotes a position detector. Reference numeral 19 denotes a compensation switch which switches the speed control integral gain when the moving direction is reversed.
Next, the internal block of the compensation switch will be described with reference to FIG. In FIG. 5, reference numeral 22 denotes a delay estimator 23 that estimates a position control delay by a position control estimator. A moving direction reversal discriminator 25 determines whether the moving direction is reversed from the output of the position control estimator 22. An end torque comparator 51 monitors the torque command and determines whether or not the torque command has reached a torque for ending the preset compensation. A compensation discriminator 27 controls on / off of compensation based on the discrimination result of the moving direction switching discriminator 25 and the judgment result of the end torque comparator 51.
The delay estimator 23 estimates a position control delay with respect to the position command. The position control delay is a delay mainly given as an inverse of the position loop gain Kp.
Next, the moving direction reversal discriminator 25 discriminates that the output of the position control estimator 22 has been switched from positive or zero to negative, or from negative or zero to positive, and notifies the compensation discriminator 27 of the discrimination result. . The compensation discriminator 27 determines whether the compensation is on or off according to the moving direction switching discriminating result and the comparison result of the end torque comparison 51, and sets the speed control integral gain, the second speed control integral gain, which is determined to be compensated. Switch to 42.
By setting first speed control integral gain <second speed control integral gain, the speed loop gain in the compensation-on section is increased, the moving direction is quickly reversed, and the position error is reduced.
Further, in Patent Document 2, a quadrant protrusion compensation amount is stored for each processing condition (for example, presence / absence of a function such as shape error compensation and a processing speed), and the quadrant protrusion compensation amount is switched depending on the processing condition.
Japanese Patent Laid-Open No. 07-005926 (FIG. 1) JP 08-99253 A (P2-3)

However, in the servo control system of Patent Document 1, quadrant protrusion compensation according to the moving speed cannot be performed because the speed loop integral gain is only increased by a certain amount. That is, for example, the amount of quadrant projections on the arc locus varies depending on the tangential speed of the arc locus, but cannot sufficiently compensate for frictional forces and the like that are affected by the speed of viscous friction and the like. When the gain increase amount is adjusted, compensation is not effective under the condition where the tangential speed is low, and the quadrant protrusion amount cannot be reduced. In addition, if the increase amount of the integral gain is adjusted under a condition that the moving speed before and after the moving direction is switched is low, there is a problem that overcompensation occurs when the moving speed before and after the moving direction is switched is high.
In the servo control system of Patent Document 2, the quadrant protrusion compensation amount is stored for each processing condition, and the quadrant protrusion compensation amount is switched according to the processing condition. In the case of a machine tool, the tangential speed is an arbitrary speed. The amount of compensation for quadrant protrusions for each machining condition (tangential speed) can be set, and the capacity of the storage medium increases. In addition, the amount of protrusion must be adjusted for each machining condition, which requires a lot of time and effort. Spend.
Furthermore, in the servo control method of Patent Document 1, since the end of compensation is determined by a torque command, when the frictional force changes due to temperature, aging, etc., and the output torque changes, the compensation end timing differs. It had an effect on the compensation effect. In addition, since the position control estimator was composed only of the delay of the position loop gain, there was an error in the actual position feedback and the output of the position control estimator for the system using velocity feedforward. As a result, the timing of quadrant protrusion compensation start was delayed, affecting the compensation effect.
The present invention has been made in view of such problems, and can determine whether or not quadrant protrusion compensation has been completed without being affected by the feed rate, temperature, or secular change. A motor control device with improved timing accuracy is provided.

According to the first aspect of the present invention, there is provided a position controller, a speed controller having an integral control means, a movement direction reversal detection means for detecting reversal of the movement direction of the position command, and the movement direction reversal detection means. In the motor control device having the movement direction reversal movement amount measuring means for measuring the movement amount after detecting the movement direction reversal, after the movement direction reversal detection means detects the movement direction reversal, the movement direction reversal is detected. The speed loop integral gain of the speed controller is increased as a function of time until the movement amount measured by the rear movement amount measuring means reaches a predetermined value. When the movement speed is high, the movement speed is low. to reduce the speed loop integral gain compared, when the moving speed is low and is characterized in that the moving speed is increased the speed integral loop gain than when the high-speed, performs the quadrant projections compensation according to the speed

  ADVANTAGE OF THE INVENTION According to this invention, the motor control apparatus which can perform quadrant protrusion compensation completion | finish discrimination | determination which is not influenced by feed rate, temperature, and secular change, and has improved the precision of the timing of a compensation start with respect to the system using feedforward is provided. To do.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. In the figure, 11 is a position controller that creates a speed command using a position command commanded from a host controller and the like and a position feedback signal from a detector attached to the motor, and 12 is a speed feedback signal for the speed command. speed controller to create a torque command Te, 13 an integrator for integrating the deviation between the speed command and the speed feedback, 14 speed loop integral gain to be multiplied by the output of the integrator 13, 15 is the speed loop integral gain in the integrator 13 14 is a speed loop proportional gain that multiplies the result obtained by multiplying 14 by the deviation of the speed feedback, 16 is a current control unit that controls the current that actually drives the motor in response to the torque command, 17 is a motor that is controlled by the motor control device, 18 is a position detector attached to the motor 17 or the machine, and 19 is quadrant projection compensation when the moving direction is switched. Compensation switch which controls the change of the speed loop integral gain 14 to 21 is a speed converter for converting the speed feedback signal from a position feedback signal.
FIGS. 2 and 9 are internal block diagrams of the compensation switch 19. 2 and 9, since the compensation switch 19 is the same, FIG. 2 will be described below. In FIG. 2, 22 is a position control estimator comprising a delay estimator 23 and a feedforward gain 24 for estimating a delay in position control, and 25 is used to determine whether or not the moving direction is reversed from the output of the position control estimator 22. movement direction reversal discriminator, 26 move amount counter which performs the moving distance measurement after the detection of the moving direction of the inversion in the direction of movement inversion discriminator 25, 27 of the determination result and the moving amount counter 26 in the movement direction reversal discriminator 25 It is a compensation classifier that controls on / off of compensation based on the value.
In the position control estimator 22 , a delay estimator 23 estimates a position control delay with respect to the position command. The position control delay is a delay mainly given as the reciprocal of the position loop gain Kp. Further, a position feedback for a position command is estimated, which is composed of a feed forward gain 24 having the same gain as the speed feed forward gain in the position controller 11.
Then, the movement direction reversal discriminator 25 discriminates that the output of the position control estimator 22 is positively inverted from negative positive or zero, or a negative or zero, and notifies the determination result to the compensation discriminator 27. The compensation discriminator 27 starts quadrant projection compensation when the moving direction is reversed as a result of the moving direction reversal discrimination, and ends quadrant projection compensation when the moving amount counter 26 exceeds a predetermined value.
In a section where quadrant protrusion compensation is determined to be on, the speed loop integral gain 14 is increased by a time function.

A method of increasing the speed loop integral gain 14 will be described with reference to FIG.
In FIG. 3, when the movement amount of compensation end is fixed, if the movement speed is high, the movement distance from the switching of the movement direction increases rapidly. finish. The compensation time at this time is a.
On the other hand, when the moving speed is low, the increase of the moving distance from the moving direction switching is slow, so that the compensation end moving amount line does not intersect with point B. The compensation time is b, and the compensation time increases as the speed decreases.
Therefore, by increasing the speed loop integral gain as a function of the compensation time, the speed loop integral gain can be relatively small at high speeds and can be increased at low speeds. Therefore, quadrant projection compensation according to speed becomes possible. An example of increasing the speed loop integral gain is shown in FIG. In FIG. 6, the speed loop integral gain varies according to equation (1). Equation (1) is a quadratic function with respect to time.

Ki (t) = (Kis-2 · K1 · Kie) · t ² + 2 · (K1 · Kis) · t + Kis
... (1)
Ki (t): Speed control integral gain at quadrant protrusion compensation time Kis: Speed control integral gain at the start of quadrant protrusion compensation Kie: Speed control integral gain at the end of quadrant protrusion compensation t: Normalization time (0 to quadrant protrusion compensation end time → 0 Normalized to ~ 1)
In FIG. 6, the speed loop integration time constant is switched to the quadrant protrusion compensation start integration gain (Kis) at the start of compensation. By providing an offset to the velocity loop integral gain at the start of compensation, the compensation effect is enhanced in a region where the tangential velocity is high.
Further, the protrusion compensation adjustment gain K1 has an effect of adjusting the speed loop integral gain during the compensation interval. This adjusts the compensation effect in the tangential speed range from medium to low speed. If the projection compensation adjustment gain K1 is increased or decreased to exceed the integral gain at the end of quadrant projection compensation or the integral gain at the start of quadrant projection compensation in the middle of the compensation interval, Clamp with integral gain or integral gain at the start of quadrant projection compensation.

Next, Embodiment 2 of the present invention will be described with reference to FIG.
In FIG. 7, a disturbance compensator 20 is added to FIG. When it is determined by the compensation switch 19 that quadrant protrusion compensation has started, a compensation torque obtained by multiplying the output of the disturbance compensator 20 by a coefficient is subtracted from the torque command created by the speed controller 12.
The torque command, estimated disturbance torque, and compensation torque will be described with reference to FIG.
FIG. 8B shows the driving torque when the quadrant protrusion compensation is not performed before and after the moving direction is reversed . After reversing the moving direction, it takes time compared to the ideal driving torque shown in FIG. Moreover, the estimated disturbance torque at this time is shown in FIG.8 (c). Disturbance torque is mainly torque due to friction.
Here, the difference between FIG. 8B and FIG. 8C is the torque necessary to drive the motor when there is no friction or the like.
Then, by compensating the torque command using the estimated disturbance torque in the quadrant projection compensation section as the compensation torque with the moving direction reversal as a reference, it is possible to approximate to FIG.
FIG. 9 is an example in which a compensation switching device is applied to the motor control device of the second embodiment.

  In the present invention, the end of quadrant projection compensation is determined without being affected by the feed rate, temperature, or secular change, and the accuracy of the compensation start timing is improved for a system using feedforward. It can also be used for control.

The block diagram which shows the structure of the motor control apparatus of this invention The block diagram which shows the structure which applies a compensation switching device with respect to the motor control apparatus of Example 1 of this invention. The conceptual diagram which shows the change of the speed loop integral gain of this invention Block diagram showing the configuration of a servo control device applying a conventional method The block diagram which shows the structure of the compensation switching device of the conventional method Example of change of speed loop integral gain of speed controller of the present invention The block diagram which shows the structure of the motor control apparatus of Example 2 of this invention. Conceptual diagram for explaining the compensation torque according to the second embodiment of the present invention. The block diagram which shows the structure which applies a compensation switch to the motor control apparatus of Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Position controller 12 Speed controller 13 Integrator 14 Speed loop integral gain 15 Speed loop proportional gain 16 Current control part 17 Motor 18 Position detector 19 Compensation switching device 20 Disturbance estimator 21 Speed converter 22 Position control estimator 23 Delay Estimator 24 Feed forward gain 25 Movement direction inversion discriminator 26 Movement amount counter 27 Compensation discriminator 41 First speed loop integral gain 42 Second speed loop integral gain 51 End torque comparator

Claims (1)

A position controller, a speed controller having an integral control means, a movement direction reversal detection means for detecting reversal of the movement direction of the position command, and the movement direction reversal detection means after detecting the movement direction reversal. In the motor control device provided with the movement amount measuring means after reversing the movement direction for measuring the movement amount,
After detecting the moving direction reversal by the moving direction reversal detecting means, the speed loop integral gain of the speed controller is set to the time until the moving amount measured by the moving amount measuring means after the moving direction reversal reaches a predetermined value. When the movement speed is high, the speed loop integral gain is reduced compared to when the movement speed is low, and when the movement speed is low, the speed integration loop gain is increased compared to when the movement speed is high. And a quadrant projection compensation according to the speed .

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