JPH05248407A - Control method and device for linear actuator - Google Patents

Abstract

PURPOSE:To carry out precise positioning control by compensating a feedback signal as a compensating current for detent force which is static thrust at zero ampere of an exciting signal at the time of adding an output shaft displacement detecting signal as a feedback signal to the exciting signal. CONSTITUTION:A detent force compensating circuit 19 inputs a displacement signal of an output shaft 13 from a differential transformer 15 to a detent force compensating function circuit 2 as a displacement feedback signal (b). The displacement feedback signal (b) output from the detent force compensating function circuit 21 compensates for the detent force as a detent force compensating current signal (b1), and the signal (b1) and a current command signal (a1) are added by an adder 25 and input to a current amplifier circuit 25. The output current of the current amplifier circuit 25 is input as an exciting current (a2) to coils 9A, 9B of a linear actuator 1. The exciting current (a2) shows a smooth characteristic in the distribution of thrust. Accordingly, high speed and high performance positioning control can be conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for hydraulic or pneumatic direct acting valves (hydraulic / pneumatic direct acting valves), etc., and controls the hydraulic / pneumatic direct acting valves etc. at high speed, with high response and high performance. The present invention relates to a method and apparatus for controlling a near actuator that can be used.

[0002]

2. Description of the Related Art Conventionally, linear actuators have been used as actuators for hydraulic / pneumatic direct-acting valves. Center yokes are provided in the yoke so as to face each other. Central magnetic poles are provided so as to face each other in the yoke, and a movable element that is interposed between the central magnetic poles and is displaceable between the central magnetic poles is provided.

Permanent magnets are mounted on both side surfaces of the mover facing the center yoke, and one end of the mover penetrates the center yoke, and an output shaft connected to, for example, a hydraulic / pneumatic direct-acting valve is connected to the mover. It is provided for controlling the thrust to the hydraulic / pneumatic direct-acting valve and the like by the exciting current to the coil.

[0004]

By the way, FIG. 6 shows static thrust characteristics of a conventional linear actuator. In the figure, when the exciting current flowing in the coil is expressed as a parameter,
The static thrust distribution has a positive slope and is an unstable system. Therefore, it is difficult to perform precise hydraulic / pneumatic valve control when the linear actuator is used for driving the hydraulic / pneumatic valve. The static thrust force at zero ampere of the exciting current is called detent force.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a linear actuator control method and apparatus which have a flat static thrust characteristic to enable precise positioning control in order to solve the above problems.

[0006]

In order to achieve the above object, the present invention is directed to a center yoke provided in the yoke so as to face each other, a coil wound around the center yoke, and the center yoke. Central magnetic poles that are orthogonal to each other and are provided to face each other in the yoke, and a mover that is interposed between the central magnetic poles and that is movable between the central yoke and the center yoke.
Permanent magnets attached to both side surfaces of the mover facing the center yoke, and an output shaft provided at the mover and having one end penetrating through the center yoke and controlled by an exciting current to the coil. A linear actuator having, as a compensation current for compensating a detent force, which is a static thrust force at zero ampere of the excitation signal, when a displacement detection signal for detecting the displacement of the output shaft is added to the excitation signal as a feedback signal. A method of controlling a linear actuator, wherein the feedback signal is compensated.

Further, according to the present invention, a center yoke provided in the yoke so as to face each other, a coil wound around each of the center yokes, and a coil orthogonal to the center yoke and provided in the yoke so as to face each other. A center magnetic pole, a mover interposed between the center magnetic pole and displaceable between the center yoke, and permanent magnets attached to both side surfaces of the mover facing the center yoke, A linear actuator having an output shaft provided at the mover and having one end penetrating the inside of the center yoke and being controlled by an exciting current to the coil, wherein a displacement detection signal for detecting displacement of the output shaft is fed back as a feedback signal. As the compensation current for compensating for the detent force, which is the static thrust force at zero ampere of the excitation signal, is added to the excitation signal as the feedback current No. is a control system for a linear actuator, characterized in that it comprises a detent force compensation circuit to be compensated.

[0008]

By adopting the linear actuator control method and apparatus of the present invention, when the displacement detection signal for detecting the displacement of the output shaft is added as a feedback signal to the excitation signal, the static thrust force at zero ampere of the excitation signal is obtained. By compensating the feedback signal as a compensating current for compensating the detent force, the static thrust characteristic becomes flat and precise positioning control is possible.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 4 is a schematic diagram of a linear actuator embodying the present invention, and FIG. 5 is an enlarged view of a portion A of FIG.
In FIGS. 4 and 5, the linear actuator 1 is
It is mainly composed of a yoke 3 and a mover 5.

The yoke 3 is formed by laminating a large number of cores, and a center yoke 7 is provided inside the yoke 3 so as to face each other.
A, 7B, center electrodes 8A, 8B provided orthogonal to the center yokes 7A, 7B and facing each other, and coils 9A, 9B wound around the center yokes 7A, 7B, respectively.

The mover 5 is interposed between the center electrodes 8A and 8B and is provided so as to be displaceable between the center yokes 7A and 7B. The center yokes 7A and 7B are provided on both side surfaces of the mover 5. Permanent magnets 11 fixed to face each other
A, 11B and a center yoke 7 directly connected to the mover 5
And an output shaft 13 that movably penetrates through the inside of A and 7B. It is assumed that one end of the output shaft 13 is connected to a spool of a hydraulic / pneumatic valve (not shown) and the other end is inside a differential transformer 15 provided outside the yoke 3.

The linear actuator 1 includes a coil 9A,
By controlling the exciting current to 9B, the permanent magnet 1
1A, 11B and the center yoke 7A, 7B between the attraction force and the thrust force F is a repulsive force generated by the displacement X,
The hydraulic / pneumatic valve can be controlled.

At this time, the displacement of the output shaft 13 is detected by the differential transformer 15 and is fed back to the control device (FIG. 1) of the hydraulic / pneumatic valve. In addition, the output shaft linear bearing 17 is provided in the yoke 3,
Smooth the displacement of the output shaft 13.

Next, FIG. 1 shows a block diagram of a detent force compensation circuit which is an embodiment of the present invention. In the figure, the detent force compensation circuit 19 uses the displacement signal of the output shaft 13 from the differential transformer 15 as the displacement feedback signal b,
Input to the detent force compensation function circuit 21.

The displacement feedback signal b output from the detent force compensation function circuit 21 compensates the detent force as a detent force compensation current signal b1 and the current command signal a1 is added by the adder 25, and the current amplifier circuit is obtained. 25 is input. The output current of the current amplifier circuit 25 is input to the coils 9A and 9B of the linear actuator 1 as an exciting (driving) current a2. This exciting current a2
Shows a characteristic that the thrust distribution is smooth as shown in FIG.

Next, FIG. 3 shows a block diagram of a control circuit for a hydraulic / pneumatic valve of a linear actuator according to the present invention.
In the figure, the linear actuator control circuit is a control system having a velocity field back and a displacement field back, and a detent force compensation circuit 19 is inserted in the velocity feedback inner loop.

The opening command signal a to the spool of the hydraulic / pneumatic valve 27 is compared with the displacement field back signal b of the differential transformer 15 by the comparator 29, and then amplified by the position amplifier circuit 31.

The current command signal a0 output from the position amplifier circuit 31 is converted into the velocity field back signal b2 by the differentiator 33 from the displacement field back signal b and then compared by the comparator 35 and compared by the velocity amplifier circuit 37. Is amplified.

The current command signal a1 amplified and output by the speed amplifier circuit 37 is input to the adder 39 of the detent force compensating circuit 19 and the detent force is an exciting current having a flat and stable characteristic as shown in FIG. It is input to the coils 9A and 9B of the linear actuator 1 as a2, and at high speed to the hydraulic / pneumatic valve 27, high-performance positioning accuracy is improved, and high-speed and high-performance positioning control is possible.

The present invention is not limited to the above embodiments, but can be implemented in other modes by making appropriate design changes.

[0022]

As is apparent from the above description, the linear actuator control method and apparatus of the present invention are:
When adding the displacement detection signal for detecting the displacement of the output shaft to the excitation signal as a feedback signal, by compensating the feedback signal as a compensation current for compensating for the detent force, which is the static thrust at zero ampere of the excitation signal, The problems of the conventional technology are effectively solved, the static thrust characteristics become flat, and high-speed and high-performance positioning control is possible.

[Brief description of drawings]

FIG. 1 is a block diagram of a detent force compensation circuit that is an embodiment of the present invention.

FIG. 2 is a static thrust force characteristic diagram when detent force is compensated.

FIG. 3 is a block diagram of a control circuit of a hydraulic / pneumatic valve of a linear actuator according to the present invention.

FIG. 4 is a schematic configuration diagram of a linear actuator in which the present invention is implemented.

5 is an enlarged view of part A of FIG.

FIG. 6 is a static thrust characteristic diagram of a conventional linear actuator.

[Explanation of symbols]

 1 linear actuator 3 yoke 5 mover 7A, 7B center yoke 9A, 9B coil 11A, 11B permanent magnet 13 output shaft 15 differential transformer 19 detent force compensation circuit 21 detent force compensation function circuit 25 current amplifier circuit 27 hydraulic / pneumatic valve

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[Procedure amendment]

[Submission date] May 28, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The yoke 3 is formed by laminating a large number of cores, and a center yoke 7 is provided inside the yoke 3 so as to face each other.
A, 7B, center magnetic poles 8A, 8B provided orthogonal to the center yokes 7A, 7B and facing each other, and coils 9A, 9B wound around the center yokes 7A, 7B, respectively.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

The mover 5 is interposed between the central magnetic poles 8A and 8B and is displaceably provided between the mover 5 and the center yokes 7A and 7B. The center yokes 7A and 7B are provided on both side surfaces of the mover 5. Permanent magnets 11 fixed to face each other
A, 11B and a center yoke 7 directly connected to the mover 5
And an output shaft 13 that movably penetrates through the inside of A and 7B. It is assumed that one end of the output shaft 13 is connected to a spool of a hydraulic / pneumatic valve (not shown) and the other end is inside a differential transformer 15 provided outside the yoke 3.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

Speed output from this position amplifier circuit 31
The command signal a0 is converted into the velocity field back signal b2 by the differentiator 33 from the displacement field back signal b, and then compared by the comparator 35 and amplified by the velocity amplifier circuit 37.

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (2)

[Claims] 1. A center yoke provided in the yoke so as to face each other, a coil wound around each of the center yokes, and a central magnetic pole provided orthogonally to the center yoke so as to face the inside of the yoke. A mover interposed between the central magnetic poles and displaceable between the central yoke and the center yoke;
Permanent magnets attached to both side surfaces of the mover facing the center yoke, and an output shaft provided at the mover and having one end penetrating through the center yoke and controlled by an exciting current to the coil. A linear actuator having, as a compensation current for compensating a detent force, which is a static thrust force at zero ampere of the excitation signal, when a displacement detection signal for detecting the displacement of the output shaft is added to the excitation signal as a feedback signal. A method of controlling a linear actuator, wherein the feedback signal is compensated. 2. A center yoke provided so as to face each other in the yoke, a coil wound around each of the center yokes, and a central magnetic pole provided so as to be orthogonal to the center yoke and face each other in the yoke. A mover interposed between the central magnetic poles and displaceable between the central yoke and the center yoke;
Permanent magnets attached to both side surfaces of the mover facing the center yoke, and an output shaft provided at the mover and having one end penetrating through the center yoke and controlled by an exciting current to the coil. A linear actuator having, as a compensation current for compensating a detent force, which is a static thrust force at zero ampere of the excitation signal, when a displacement detection signal for detecting the displacement of the output shaft is added to the excitation signal as a feedback signal. A linear actuator control device comprising a detent force compensating circuit for compensating the feedback signal.