JP2003204689A - Controller for servo motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a servo motor, which shortens the positioning time, even in autotuning. <P>SOLUTION: In the controller of the servo motor 8, the control gain is set according to the operating situation of the servo motor, so that a gain Kp proportional to position, a gain Kv proportional to speed, and estimated load inertia J are related by Kp<(Kv/J)/4, when the motor speed is under a certain set value, and the gain Kp is set proportional to position, the gain Kv proportional to speed, and estimated load inertia J are related by Kp>(Kv/J)/4, when the speed is not less than a certain set value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for positioning control of a servomotor, and more particularly to a controller for a servomotor that switches control gains and positions at high speed.

[0002]

2. Description of the Related Art A conventional servo motor control device for performing positioning control (hereinafter referred to as "conventional example 1") will be described. Figure 5
FIG. 6 is a block diagram showing a configuration of a conventional servo motor control device. In FIG. 5, 1 is a load inertia estimation unit, 2 is a gain table, 3 is a control gain setting unit, 4 is a position control unit, 5 is a speed control unit, 6 is a current control unit, 7 is a parameter setting unit, and 8 is a servo. Motor, 9 is encoder,
Reference numeral 10 is a mechanical load, and 11 is a position command generator. Here, the gain table 2 stores a position proportional gain for performing position control, a position integral gain, a velocity proportional gain for performing velocity control, a velocity integral gain, and the like. The load inertia estimation unit 1 estimates the estimated load inertia, which is the estimated value of the inertia of the mechanical system load 10 connected to the servomotor 8, and performs auto tuning. Auto-tuning is to estimate the estimated load inertia in real time and automatically set the optimum control gain according to the estimated value.

The gain table 2 is composed of a plurality of control gain sets such as a position proportional gain and a velocity proportional gain, and the control gain sets are associated stepwise in accordance with the parameters. For example, the control gain set is set so that the position proportional gain and the velocity proportional gain also increase as the parameter value increases. From the gain table 2, the control gain setting unit 3 automatically sets the control gain based on the gain set corresponding to the parameter set by the user in the parameter setting unit 7 and the estimated load inertia estimated by the load inertia estimation unit 1. It

The position command output from the position command generator 11 and the position which is a feedback signal to the encoder 9 are used to perform position PI control using the position proportional gain and the position integral gain in the position control unit 4, and the output signal thereof is output. Is used as the speed command, and the speed control unit 4 performs the speed PI control using the speed proportional gain and the speed integral gain. The current control unit 6 controls the current, and the load inertia estimation unit 1 estimates the load inertia using the motor current and the motor speed.

When the parameter value of the parameter setting unit 7 is increased to increase the response speed and the position proportional gain and the speed proportional gain are increased, the motor in a stopped state causes a vibration phenomenon. Increase the parameters in order from the smallest one, and set the parameter large within the range where vibration does not occur during stoppage. This set value is low in position proportional gain and speed proportional gain because it is based on stopping, so that the followability during movement is poor, and as a result, positioning takes time.

As a servomotor control device that solves the problem of the first conventional example, there is Japanese Patent Laid-Open No. 7-143783 (hereinafter, referred to as the second conventional example). In the conventional example 2, the control gain is estimated manually and the control gain is set by the parameter value. Instead, the control gain is manually set, and the control gain when the speed command is equal to or more than a predetermined speed command and the control gain when the speed command is less than that are set. Conventional example 2 for switching is variable speed control, but the same can be said for positioning control.

[0007]

However, the method of switching the control gain as in Conventional Example 2 has not been used in combination with auto tuning.

For this reason, since the control gain switching is not used in the case of performing the automatic tuning, the positioning time is longer in the case of performing the automatic tuning than in the case of manually adjusting the control gain.

Further, in the conventional example 2, the control gain switching is switched by the speed command, and the delay of the actual operation with respect to the speed command is not taken into consideration. Therefore, even if the speed command is completed, the actual motor operation may not be in the stopped range. If the gain is switched at this time, the control gain becomes low during the delay between the speed command and the actual motor operation, and thus the positioning time may become long.

[0010] Further, it is said that the control gain during operation is increased and the control gain during stop is decreased, but what is raised as a reference?
There is a case where it is too low or the positioning time cannot be shortened even though the intention is to set the gain during operation to a high value, although it is not mentioned below. On the contrary, even if the gain during the stop is set to be low, the vibration and sound may actually be too high.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a servo motor control device that appropriately switches the control gain and shortens the positioning time when performing auto tuning.

[0012]

In order to solve the above problems, a servo motor control apparatus according to the present invention includes a position control section for creating a speed command based on a position command, a position of the servo motor, and a position proportional gain. A speed control that creates a current command based on a speed command, a speed of the servo motor, and a speed proportional gain; a current control unit that controls a current flowing through the servo motor based on the current command; the speed; and the current. Load inertia estimation means for estimating an estimated load inertia, which is an estimated value of the inertia of a load connected to the servomotor based on a command or the current flowing through the servomotor, and the position proportional gain and the speed based on the estimated load inertia. Control of servo motor including control gain setting means for setting at least one of proportional gain In location, the control gain setting means, at least one of the position proportional gain based on the operation conditions of the servo motor and said speed proportional gain 1
One is to set one.

With the above configuration, the control gain is switched according to the operating condition of the servo motor, so that the positioning time can be shortened even during auto tuning.

Further, the servo motor control device of the present invention includes a position control section for creating a speed command based on a position command, a position of the servo motor and a position proportional gain, and a speed command and a speed proportional to the speed of the servo motor. A speed control that creates a current command based on the gain, and a current control unit that controls the current flowing through the servo motor based on the current command;
Load inertia estimation means for estimating an estimated load inertia which is an estimated value of the inertia of a load connected to the servomotor based on the speed and the current command or the current flowing through the servomotor, and the load inertia estimation means based on the estimated load inertia. In a servomotor control device including a control gain setting unit that sets at least one of a position proportional gain and the speed proportional gain, the control gain setting unit includes the position proportional gain based on the speed. At least one of the speed proportional gains is set.

With the above configuration, by switching the control gain according to the speed of the servo motor, the positioning time can be shortened even during auto tuning.

Further, the servo motor control device of the present invention includes a position control section for creating a speed command based on a position command, a position of the servo motor and a position proportional gain, and a speed command and a speed proportional to the speed of the servo motor. A speed control that creates a current command based on the gain, and a current control unit that controls the current flowing through the servo motor based on the current command;
Load inertia estimation means for estimating an estimated load inertia which is an estimated value of the inertia of a load connected to the servomotor based on the speed and the current command or the current flowing through the servomotor, and the load inertia estimation means based on the estimated load inertia. In a servomotor control device including a control gain setting unit that sets at least one of a position proportional gain and the speed proportional gain, the control gain setting unit is configured to control when the speed is less than a certain set value. The position proportional gain Kp, the speed proportional gain Kv, and the estimated load inertia J are Kp <(Kv / J) / 4.
When the speed is equal to or higher than a set value, the position proportional gain Kp, the speed proportional gain Kv, and the estimated load inertia J are set to Kp> (Kv /
J) / 4.

With the above configuration, since the optimum control gain can always be used, the followability during operation and the positioning time can be shortened, and vibration and noise can be made less likely to occur during stoppage.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the servo motor control device of the present invention will be described below with reference to the accompanying drawings.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A servo motor control device according to an embodiment of the present invention will be described below.

FIG. 1 is a block diagram showing the configuration of a servo motor control device according to an embodiment of the present invention. In FIG. 1, those having the same functions as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 1, the first gain table 20 and the second gain table 21 are configured to be switched by a changeover switch 22. First
The gain table 20 and the second gain table 21 store a plurality of control gain sets composed of position proportional gain, position integral gain, velocity proportional gain, velocity integral gain, etc. They are associated, and if you increase the value of the parameter,
The control gain set is set so that the position proportional gain and the speed proportional gain are also large.

FIG. 2 is a block diagram of position control. In FIG. 2, position integration control and speed integration control are omitted. From this figure, the closed loop transfer function G of the position control system is as shown in equation (1). Here, Kv is a velocity proportional gain, Kp is a position proportional gain, and J is the sum of the inertia of the servo motor 8 and the inertia of the mechanical system load 10.

[0022]

[Equation 1]

From the equation (1), the damping factor ξ is given by the equation (2). When the damping factor ξ is 1, it is an optimum value that does not cause overshoot in control theory.

[0024]

[Equation 2]

When the damping factor ξ is set to 1, a relational expression like the expression (3) can be obtained from the expression (2).

Kp = KvJ / 4 (3) It is better from the standpoint of vibration and sound to lower the position proportional gain during stop. Therefore, the position proportional gain Kp of the first gain table 20 is set to a lower value, for example, Kp = KvJ / 5.
Set to meet. On the other hand, during operation, it is better to increase the followability so that the positioning time is shortened.
Therefore, the position proportional gain K in the second gain table 21
For example, p is set to a higher value so that Kp = KvJ / 3 is satisfied.

Next, a method of switching the gain table will be described with reference to FIG. FIG. 3 is a time chart showing the gain switching method in the embodiment. When a position command is given from the position command generator 11 and a speed command is given as shown in (a) of FIG. 3 based on the position of the servo motor and the position proportional gain, the servo motor 8 is moved to (b) of FIG. However, when the motor speed becomes equal to or higher than a predetermined level V0 at this time, the changeover switch 22
Then, as shown in FIG. 3C, the first gain table 2
The control gain is switched from 0 to the second gain table 21, and the optimum control gain is calculated and set based on the second gain table 21. When the motor speed becomes less than V0, the second gain table 21 is switched to the first gain table 20, and the optimum control gain is calculated and set based on the first gain table 20.

In the example of FIG. 3, the changeover switch 22 switches between the first gain table selection and the second gain table even at the time of starting, but as shown in FIG. 4, at the time of starting, there is a speed command with and without a speed command. You may switch.

[0029]

As is apparent from the above embodiments, according to the servo motor control device of the present invention, the positioning time can be shortened even during auto-tuning by switching the control gain according to the operating condition of the servo motor. .

Further, according to the servo motor control device of the present invention, the positioning time can be shortened even during auto tuning by switching the control gain according to the speed of the servo motor.

Further, according to the servo motor control device of the present invention, since the optimum control gain can always be used, the followability during operation and the positioning time can be shortened, and vibration and noise are generated during stoppage. It can be difficult.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a servo motor control device according to an embodiment of the present invention.

FIG. 2 is a control block diagram of position control.

FIG. 3 is a time chart showing a gain switching method according to an embodiment of the present invention.

FIG. 4 is a time chart showing a gain switching method according to an embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional servo motor control device.

[Explanation of symbols]

1 Load inertia estimation section 2 gain table 3 Control gain setting section 4 Position control unit 5 Speed control section 6 Current control section 7 Parameter setting section 8 Servo motor 9 encoder 10 Mechanical load 11 Position command generator 20 1st gain table 21 Second Gain Table 22 Changeover switch

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomokuni Iijima             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Toru Tazawa             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Ichiro Oyama             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5H303 AA01 AA04 BB01 BB06 BB11                       CC04 DD01 EE03 EE07 FF08                       GG06 GG11 HH05 JJ01 KK02                       KK23 KK24 LL03                 5H550 BB05 GG01 GG03 GG05 GG10                       JJ04 LL14 LL36 LL48

Claims (3)

[Claims] 1. A position control unit that creates a speed command based on a position command, a position of a servo motor, and a position proportional gain, and a speed that creates a current command based on the speed command, the speed of the servo motor, and a speed proportional gain. Control, a current control unit that controls a current flowing through the servo motor based on the current command, and estimation of inertia of a load connected to the servo motor based on the speed and the current command or the current flowing through the servo motor. Servo comprising load inertia estimation means for estimating an estimated load inertia as a value, and control gain setting means for setting at least one of the position proportional gain and the speed proportional gain based on the estimated load inertia. In the motor control device, the control gain setting means is based on an operating condition of the servo motor. Control device for a servo motor and sets at least one of said speed proportional gain and the position proportional gain. 2. The control gain setting means is at least one of a position proportional gain and a speed proportional gain based on the speed.
2. The servo motor control device according to claim 1, wherein one of the two is set. 3. The control gain setting means, when the speed is less than a certain set value, the position proportional gain Kp and the speed proportional gain Kv.
And the estimated load inertia J are set to have a relationship of Kp <(Kv / J) / 4, and the position proportional gain Kp and the speed proportional gain K are set when the speed is a certain set value or more.
v and the estimated load inertia J are Kp> (Kv / J)
3. The servo motor control device according to claim 2, wherein the servo motor control device is set to have a relationship of / 4.