JPH05268785A - Servo motor controller - Google Patents

Abstract

(57) [Summary] [Objective] To provide a controller for a servo motor that automatically adjusts various gains and time constants by fuzzy reasoning. [Structure] The accumulated pulse amount ε1 of the deviation counter 22 t seconds after the position command is issued, the accumulated pulse amount ε2 of the deviation counter 22 when the position command is completed, and the settling time T of the current command (torque monitor). As an input to the fuzzy reasoner 28,
Position feedback loop gain K by fuzzy reasoning
P, velocity feedback loop gain P, and velocity feedback loop time constant I are determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servomotor control device having a fuzzy reasoner for automatically determining a position feedback gain KP, a velocity feedback gain P, and a velocity feedback time constant I.

[0002]

2. Description of the Related Art A conventional servo motor controller will be described with reference to FIG. A servomotor control device having a position feedback loop provides a speed feedback loop for controlling the rotation speed of the motor 1 and a motor current in addition to a position feedback loop for controlling the rotation position of the motor 1 or the position of a mechanical moving part. It has a current feedback loop for controlling. The current amplifier 8 controls in the current feedback loop so that the deviation between the motor current I ₁ detected by the current detector 9 and the current command value I ₀ from the proportional-plus-integral controller 7 becomes zero. The proportional-plus-integral controller 7 converts the motor speed detected by the speed detector 2 such as an encoder into a voltage V ₁ by the F / V converter 10 in the speed feedback loop and the speed command from the D / A converter 6. The current command value I ₀ is determined so that the deviation from the value V ₀ becomes zero. D
The / A converter 6 is a position detector 3 such as a resolver or encoder.
The speed command value V ₀ is determined so that the difference between the motor position L ₁ detected in step ₁ and the position command value L ₀ given from the command pulse generation circuit 5 becomes zero, and the position of the servo motor 1 is determined by the position feedback loop. Control. In the figure, 4a,
4b and 4c are adders.

FIG. 5 shows the velocity feedback loop of FIG.
It is a block diagram which shows a structure. 11 is a proportional-integral controller
Servo motor, 12 is load, 13 is disturbance torque T_L1
4 is the speed command signal V₀, 15 is the speed V of the servo motor₁,
16 is a speed deviation ε. First the motor is stopped, ie
V₁= 0. Positive speed command V₀Is given, V ₀
And V₁, The velocity deviation ε is a positive value
It This produces a positive torque value that accelerates the axis and
The degree goes up. The deviation ε approaches zero as the speed increases.
Come on. Therefore, the torque also decreases and the acceleration of the shaft does not become weak.
It When the motor speed matches the command speed, the torque becomes zero.
Will not accelerate. Disturbance torque T_LIs as it is
Then it will continue to rotate at this speed. That is,
The speed of the motor is controlled at a constant speed to the desired value.

[0004]

Conventionally, the position feedback gain KP in the position feedback, the speed feedback gain P in the speed feedback loop and the speed feedback time constant I are conventionally taken by an adjuster while listening to the waveform and listening to the sound. The adjustment value was decided. Therefore, in the conventional adjustment method, the adjustment value varies depending on the skill level because of the experience and intuition of the adjuster. Also,
Since the adjustment value is a constant value, the adjustment value may be inappropriate when the usage conditions such as the load change.

The present invention provides a controller for a servo motor, which has a function of automatically determining the adjustment values of KP, P, I by fuzzy reasoning and having a function of responding to changes in operating conditions without variations in the adjustment values. The purpose is to

[0006]

In order to achieve the above object, the servo motor control apparatus according to the present invention accumulates the deviation counter in the sampling time t seconds after the position command is issued in the operation pattern in the gain adjustment mode. Pulse amount ε
1 and the amount of accumulated pulse ε2 of the deviation counter when the position command is completed and the settling time T of the current command (torque monitor) as the input variables of the antecedent part, and the above inference result shows that K
A fuzzy reasoner for automatically determining P, P and I is provided.

[0007]

With the above structure, the position feedback gain KP, the speed feedback gain P, and the speed feedback time constant I of the servo motor control device of the present invention are automatically adjusted.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a servo motor control device of the present invention. 17 is a servo motor, 18
Is a speed detector, 19 is a position detector, and 20a, 20b, 2
0c is an adder, 21 is a position commander, 22 is a deviation counter, 23 is a D / A converter, 24 is a proportional integral controller, 25
Is a current amplifier, 26 is an F / V converter, 27 is a settling time determiner, and 28 is a fuzzy reasoner which is the essence of the present invention.

First, the fuzzy inference means will be described. As is well known, fuzzy inference is an inference method that determines output according to linguistically described control rules, and by reflecting the knowledge based on human experience and intuition, and the know-how of skilled operators in rules, the requirements can be met. You can design a control system that suits you. The fuzzy inference unit 28 uses ε1 as the first variable of the antecedent portion for the accumulated pulse amount of the deviation counter at the sampling time t seconds after the position command is issued. Similarly, the accumulated pulse amount ε2 of the deviation counter when the position command is completed is used as the second variable of the antecedent part. The settling time T of the current command (torque monitor) is the third variable. By performing a fuzzy calculation using these three variables, the velocity feedback gain P of the proportional-plus-integral controller,
The velocity feedback time constant I and the position feedback gain KP are determined, and ε1, ε2, T, KP, P, I are represented by fuzzy variables that are vague expressions such as small or very large, and each fuzzy variable is It is defined by a membership function as shown in FIG.
The accumulated pulse amount ε1 is normalized to the interval of [−1 to 1] as shown in FIG. 2A and defined by seven fuzzy variables from NL (very large in negative) to PL (very large in positive). .. Similarly, the accumulated pulse amount ε2 is as shown in FIG. 2b, the settling time T is as shown in FIG. 2c, and the velocity feedback gain P is as shown in FIG. 2d.
Thus, the velocity feedback time constant I is defined by each of the seven fuzzy variables as shown in FIG. 2e, and the position feedback gain KP is defined by each of the seven fuzzy variables as shown in FIG. 2f. As the control rule using these fuzzy variables, for example, the following can be considered.

In the case of the gain KP of the position feedback loop, (1) if the deviation counter droop pulse amount ε1 is very large (PL) and the deviation counter droop pulse amount ε2 is very large (PL). If the settling time T is just very large (PL), then the position feedback loop gain (KP) should be very large (PL).
(2) If ε1 is very large (PL), ε2 is very large (PL), and T is mediumly large (P).
If M), then KP should be just moderately large (PM).
(3) If ε1 is positively very large (PL), ε2 is positively medium large (PM), and T is positively medium large (PM).
If so, make KP just moderately large (PM).
(4) If ε1 is positively large (PM), ε2 is positively large (PM), and T is positively large (PM), KP is positively large (PM). do it. (5)
If ε1 is positively large (PM), ε2 is positively large (PM), and T is slightly large (PS),
Make KP just a little bigger (PS). (6) If
If ε1 is positively moderately large (PM), ε2 is positively slightly large (PS), and T is positively slightly large (PS), then KP should be positively slightly large (PS). (7) If ε1 is slightly larger (PS), ε2 is slightly larger (P)
If S) and T are just slightly larger (PS), then KP should be just slightly larger (PS). (8) If ε1 is slightly larger (PS), ε2 is slightly larger (PS),
If T is proper (ZR), make KP proper (ZR). (9) If ε1 is just slightly larger (PS), ε2
If is appropriate (ZR) and T is appropriate (ZR), make KP appropriate (ZR). (10) If ε1 is appropriate (Z
R), ε2 appropriate (ZR), and if T is appropriate (ZR), K
Make P appropriate (ZR).

The control rule of the speed feedback gain P and the speed feedback time constant I can be similarly considered. Next, the process of fuzzy inference will be described with reference to FIG. Although the fuzzy inference MIN-MAX-centroid method (also called the head-cutting method) in this embodiment is used, the area method, the height method, etc. may be used in some cases. First, find the conclusion for each rule. For example, rule 1 (if ε1 = PL
and ε2 = PLandT = PM, thenKP = P
For M), the suitability of the antecedent part is obtained by taking the minimum (MIN) of the antecedent part as shown in Fig. 3 ○ 1, and the head of the consequent part variable is shown as shown in Fig. 3 ○ 2. The conclusion of this rule is to cut (at the shaded part) the conformance of the antecedent part. After applying the same steps to each rule and obtaining the conclusion for each rule, take the maximum (MAX) of the previous conclusions as shown in Fig. 3 ○ 3 and correspond to the center of gravity of the shaded area as shown in Fig. 3 ○ 4. The value to be determined is determined as the inference result.

KP, P, determined by these inferences
As a criterion for judging that I is appropriate, when ε2 and T are adjusted within a preset rule, KP, P, I
Is judged to be appropriate and the adjustment is completed. Such inference can be performed by using a general-purpose microcomputer or digital signal processor, or by using a dedicated fuzzy arithmetic chip.

[0013]

As is apparent from the above description, the servo motor control device of the present invention can automatically adjust the adjustment process performed by human experience and intuition by using fuzzy control. It is possible and its practical effect is great.

[Brief description of drawings]

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

FIG. 2 is a schematic diagram showing the definition of fuzzy variables.

FIG. 3 is a schematic diagram showing the definition of fuzzy inference.

FIG. 4 is a block diagram of a conventional servo motor control device.

FIG. 5 is a block diagram of a velocity feedback loop.

[Explanation of symbols]

17 Servo Motor 22 Deviation Counter 26 F / A Converter 28 Fuzzy Reasoning Device T Current Command (Torque Monitor) Settling Time ε1 Deviation Counter Drooping Pulse Amount (Position Deviation) ε2 Position Command Completes t seconds after a position command is issued Droop pulse amount of the deviation counter (position deviation)

Claims (1)

[Claims] 1. A position feedback loop, a velocity feedback loop, and a fuzzy inference device are provided, and the fuzzy inference device uses position deviation and settling time of a current command (torque monitor) as input variables of the antecedent part, and position feedback is performed by fuzzy inference. Gain KP, velocity feedback gain P,
A servomotor control device characterized by automatically adjusting a speed feedback time constant I.