JP3304669B2 - Control compensator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control compensator for a servo mechanism, and more particularly, to a technique for improving control stability against a change in characteristics of a control target.

[0002]

2. Description of the Related Art In a control system of a servo mechanism, for example, a PI (Proportiona) is used to control the speed of a servomotor.
l Integral) Compensators are often used. FIG. 2 shows a general configuration example in this case. The PI compensator 51 is provided before the motor current control unit 55 for controlling the amount of current supplied to the servomotor 53. The load inertia J is applied to the servomotor 53. The motor angle of the servo motor 53 is detected by a pulse encoder 57, and the detected pulse is sent to a speed detector 59. Speed detector 59
Is composed of, for example, an F / V converter, and converts a detection pulse of an analog signal into a voltage representing a speed. The PI compensator 51 includes a P (proportional) element system 61, an I (integral) element system 63, a subtractor 65, and an adder 67.
A speed command signal ωr from a speed control unit (not shown) and a speed feedback signal ωf from a speed detector 59 are input to the PI compensator 51. Inside the PI compensator 51, the difference ωε between the signal ωr and the signal ωf is calculated by the subtractor 65 and sent to the P element system 61 and the I element system 63. The P element system 61 and the I element system 63 convert the signal ωε into signals up and ui according to their respective transfer functions and send the signals to the adder 67. The adder 67 outputs a compensation signal u obtained by adding the signals up and ui. The motor current control unit 55 is configured to input a three-phase current based on the compensation signal u.
3 is controlled. Thus, the deviation ω
The rotation speed of the servo motor 53 is controlled so that ε becomes zero.

In the above-described control system, the control loop gain changes as the load inertia J changes, and the control characteristics change. When the change of the load inertia J is large, the control system becomes unstable, and a trouble such as the hunting of the servo motor 53 may occur. As such a countermeasure, for example, "low-sensitivity robust control of a DC servomotor by passive adaptive control" (P707- 1987, IEEJ National Convention) has been proposed. An example of a configuration in which this technology (hereinafter, referred to as “proposed technology”) is applied to the control system of FIG. 2 will be described. In the control system of FIG. 2, the motor current control unit 55, the servo motor 53, the pulse encoder 57, and the speed detector 59 are represented by one element (hereinafter, referred to as "drive system") 71 as shown in FIG. In the figure, the transfer function of the drive system 71, that is, the transfer function of the input control signal u and the output speed feedback signal ωf is denoted by “G”. When the above proposed technique is applied to the control system shown in FIG. 3, the result is as shown in FIG. In the figure, the control compensator 81 is provided with a passive adaptive control system 82 in addition to the configuration of the control compensator 51 of FIG. The passive adaptive control system 82 includes a G ^* element system 83, a subtractor 84, a G ^{* -1} element system 85, a gain element system 87, and an adder 89. The transfer function G ^* of the G ^* element system 83 is a characteristic of the drive system 71 (hereinafter referred to as “motor characteristic”).
) Is an estimated value of the transfer function G. The transfer function G ^{* -1} of the G ^{* -1} element system 85 is the reciprocal of G ^* . Also,
The gain element system 87 gives a predetermined gain β to the output from the G ^{* -1} element system 85. These transfer functions G ^* , G ^{* -1}
And the gain β are set in advance in the respective element systems 83, 85, and 87.

[0004] In passive adaptive control system 82, G ^* element system 83 outputs a signal .omega.f ^* converts the compensated signal u of the output PI control from the adder 67 by the transfer function G ^*. The subtractor 84 subtracts the speed feedback signal ωf of the drive system 71 from the signal ωf ^* . The output ωf ^* −ωf from the subtractor 84 is converted by the G ^{* -1} element system 85, and the gain β is given by the gain element system 87 to be converted into the signal Δu. Δu generated in this manner
Is added to the compensation signal u by the adder 89, and the control signal u
+ Δu is input to the drive system 71. As described above, by using a signal obtained by adding the signal Δu generated by the passive adaptive control system 82 to the conventionally used compensation signal u of the PI control, the parameter sensitivity of the entire control system can be reduced. Even when a disturbance d such as a change in J is applied (indicated by an adder 91 in the figure), stable servo control can be performed by adjusting the value of the gain β.

[0005]

However, in putting the configuration shown in FIG. 4 into practical use, the following problems occur. FIG. 5 is a characteristic diagram of each signal in the control system of FIG. 4, and FIG. 5A shows a disturbance d and a control signal u + Δu,
(B) is an output signal ωf ^* from the G ^* element system 83, (c)
Denotes an output signal Δu from the passive adaptive control system 82. The disturbance d in FIG. 4 is a change in the load inertia J (see FIG. 2), which is generally a change in the load torque. FIG.
In (a), when a disturbance d represented by the load torque occurs, the control signal u + Δu changes to a level equivalent to the disturbance d in order to eliminate the rotational deceleration of the servomotor 53 due to the load torque. . At this time, Δu generated by the passive adaptive control system 82 changes as shown in FIG. On the other hand, when considering the signal ωf ^* for generating Δu, the transfer function G representing the motor characteristics is a value determined by the torque of the servo motor 53 and has an integral characteristic. Correspondingly, the transfer function G ^*, which is an estimated value of the transfer function G, must also be set so as to represent integral characteristics, so that ωf ^* becomes a signal that increases infinitely as shown in (b). . However, when actually assembling the apparatus, if the G ^* element system 83 is constituted by, for example, an OP amplifier or the like, the signal ω
f ^* may be saturated at a certain level, and the function for stabilizing the control as described above may not work sufficiently. The present invention has been conceived in view of the above circumstances, and an object of the present invention is to provide a control compensator capable of improving control stability with a configuration that can be easily put into practical use.

[0006]

In order to achieve the above object, a first aspect of the present invention provides a speed input unit for inputting a command speed of a motor, a speed detection unit for detecting the speed of the motor, A control value generation unit for generating a control value for the motor based on a deviation between an input value from the speed input unit and a detection value from the speed detection unit; and a control characteristic of the motor for the detection value from the speed detection unit. An inverse function multiplier that multiplies a value determined by an inverse function of the function representing the function, a subtractor that subtracts the output value of the inverse function multiplier from the control value, and a predetermined compensation gain multiplied by the output value from the subtractor. A gain multiplying unit, a control value adding unit that adds an output value from the gain multiplying unit to the control value, and a motor control unit that controls energization to the motor based on an output value from the control value adding unit. And including A control compensator. The second invention is
The function representing the control characteristic of the motor is a control compensator that is a transfer function of the output value from the speed detector to the output value from the control value generator. In a third aspect, the control value generator is a control compensator that outputs a PI control value based on the deviation.

[0007]

According to the first aspect of the present invention, the control value generation unit performs the control based on the deviation between the input value representing the command speed of the motor input from the speed input unit and the detected value of the motor speed detected by the speed detection unit. Generate motor control values. The inverse function multiplier multiplies the detection value from the speed detector by a value determined by the inverse function of the function representing the control characteristics of the motor, and then subtracts the output value of the inverse function multiplier from the control value by the subtractor. .
Then, the output value from the subtraction unit is multiplied by a predetermined compensation gain by the gain multiplication unit, and further, the output value from the gain multiplication unit is added to the control value of the motor by the control value addition unit. The energization of the motor is controlled by the motor control unit based on the output value from the control value addition unit, and the rotation speed of the motor is adjusted. According to the second aspect, the inverse function multiplication unit multiplies the detection value from the speed detection unit by a value determined by an inverse function of a transfer function of the output value from the speed detection unit to the output value from the control value generation unit. Output value. According to the third aspect, the control value generation section outputs the PI control value based on a deviation between the input value from the speed input section and the detection value from the speed detection section.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings to facilitate understanding of the present invention.
The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention. FIG. 1 is a block diagram of a control compensator 1 according to one embodiment of the present invention. Note that components having the same functions as those shown in FIGS. 2 to 4 are denoted by the same reference numerals,
The description of these will be omitted. The drive system 71
Represents the motor current control unit 55, the servo motor 53, the pulse encoder 57, and the speed detector 59 shown in FIG. 2 by one element, and its transfer function is "G". In the control compensator 1 of this embodiment, a passive adaptive control system 2 in which the passive adaptive control system 82 of FIG. 4 is suitably modified is provided. The speed feedback signal ωf output from the drive system 71 is directly input to the G ^{* -1} element system 85. Then, in the subtractor 3, the output signal ω of the G ^{* -1} element system 85 is calculated from the output signal (compensation signal) u of the adder 67.
f / G ^* is subtracted, and a gain element system 87
Gives a gain β to generate a signal Δu. When this Δu is represented by an equation, Δu = β · u−β · ωf / G ^* . On the other hand, in the conventional proposed technique shown in FIG.
Is expressed by Δu = β · (G ^* · u−ωf) / G ^* (= β · u−β ·
ωf / G ^* ). As described above, the control system of this embodiment is logically equivalent to the control system of FIG. 4, and satisfies the logical condition for stabilizing the servo control similarly to the control system of the proposed technique. Moreover, in the present embodiment, the transfer function G ^* representing the integral characteristic as shown in FIG. 4 is omitted, and the infinitely increasing signal ωf ^* , which is difficult to realize in the mounting circuit, is output. Since it is not necessary to use the G ^* element system 83, it is easy to put it into practical use.

The characteristic configuration of the embodiment will be described. The speed control unit constitutes a speed input unit for inputting a command speed of the motor. By the speed detector 59,
A speed detector for detecting the speed of the motor is configured. The P element system 61, the I element system 63, the subtractor 65, and the adder 67 control to generate a motor control value based on the deviation between the input value from the speed input unit and the detection value from the speed detection unit. A value generator is configured. In addition, G
^{The * -1} element system 85 constitutes an inverse function multiplying unit that multiplies the value detected by the speed detecting unit by a value determined by an inverse function of the function representing the control characteristics of the motor. The subtractor 3 constitutes a subtractor for subtracting the output value of the inverse function multiplier from the control value. The gain element system 87 constitutes a gain multiplication unit that multiplies the output value from the subtraction unit by a predetermined compensation gain. The adder 89 forms a control value adder that adds the output value from the gain multiplier to the control value. The motor control unit 55 controls the energization of the motor based on the output value from the control value adding unit by the motor current control unit 55. Further, the transfer function G ^* is a function representing a control characteristic of the motor, and corresponds to a transfer function of an output value from the speed detector with respect to an output value from the control value generator, and corresponds to an inverse function thereof. Is the transfer function G ^{* -1} . Further, the control value generating section composed of the P element system 61, the I element system 63, the subtractor 65 and the adder 67 outputs a PI control value, and the compensation signal u It corresponds to the control value.

[0010]

Since the control compensator according to the present invention is configured as described above, the transfer function representing the integral control characteristics of the motor as in the prior art is omitted, and an infinitely increasing value which is difficult to mount is output. Since it is not necessary to use a means for performing the operation, the motor can be stably controlled. This makes it possible to improve control stability with a configuration that is easy to put into practical use.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control compensator according to one embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a control system of a conventional general servo mechanism.

FIG. 3 is a block diagram illustrating a control system of a conventional general servo mechanism, in which a driving unit is represented by one element;

FIG. 4 is a block diagram showing a configuration in which a conventional proposed technique is applied to a control system of a servo mechanism.

FIG. 5 is a characteristic diagram of various signals in a circuit to which the conventional proposed technique is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Control compensator 3, 61 ... Subtractor 53 ... Servo motor 55 ... Motor current control part 57 ... Pulse encoder 59 ... Speed detector 61 ... P element system 63 ... I element system 67, 89 ... Adder 71 ... Drive system 83 ... G ^* element system 85 ... G ^{* -1} element system 87 ... gain element system

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05B 11/36 501 G05B 13/02

Claims (3)

(57) [Claims] A speed input unit for inputting a command speed of a motor; a speed detection unit for detecting a speed of the motor;
A control value generation unit that generates a control value of the motor based on a deviation between an input value from the speed input unit and a detection value from the speed detection unit; and a control value of the motor based on a detection value from the speed detection unit. An inverse function multiplier that multiplies a value determined by an inverse function of the function representing the characteristic; a subtractor that subtracts the output value of the inverse function multiplier from the control value; and a predetermined compensation gain to the output value from the subtractor. A gain multiplying unit for multiplying, a control value adding unit for adding an output value from the gain multiplying unit to the control value, and a motor control for controlling energization to the motor based on an output value from the control value adding unit And a control compensator. 2. The control compensator according to claim 1, wherein the function representing the control characteristic of the motor is a transfer function of an output value from the speed detector to an output value from the control value generator. 3. The control compensator according to claim 1, wherein the control value generator outputs a PI control value based on the deviation.