JP2003195945A - Linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent vibration of a basic part at the stage of a cause of the vibration by eliminating inertial reaction force applied to the basic part from an mounting part of an actuator, and to prevent oscillation due to change in gravitational balance since the composite center of gravity of a movable part of the actuator remains unchanged. <P>SOLUTION: An upper actuator unit 8 and a bottom actuator unit 7 are operated in an opposite direction from each other so as to keep the position where the composite center of gravity of an object to be loaded 9 and the upper actuator unit 8 is horizontally projected unchanged. This eliminates the horizontal reaction force from the basic part due to acceleration and deceleration of the object to be loaded 9, thereby preventing generation of the oscillation. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] [0001] The present invention relates to a linear motion actuator.
About [0002] 2. Description of the Related Art Linear actuators are used for precision machinery,
Positioning in parts handling such as circuit assembly
Widely used in such as. In these operations, jigs etc.
High-speed and precise positioning of a large mass
Is required. [0003] In such applications, large mass
When the load is accelerated or decelerated with high acceleration,
Strong reaction force is generated in the opposite direction. Such reaction force
When transmitted to the base where the tutor is attached,
This causes vibration and hinders precise positioning. Conventionally, vibrations generated in this way are suppressed.
Attach the actuator to the anti-vibration table to
Vibration is passively absorbed by its characteristics and damping characteristics.
Furthermore, the vibration isolator itself is activated using another actuator.
Drive, measure vibration acceleration, etc.
Method to forcibly suppress vibration by
Had been. [0005] The conventional method as described above
Then, in order to suppress vibrations quickly and remove them promptly,
A large anti-vibration table or powerful anti-vibration actuator is required.
You. Also, the reaction force is transmitted to the floor through the vibration isolator,
The building where the equipment is installed is also required to be robust. Conventional techniques require extensive vibration isolation measures
The reason was to suppress the vibration after it had already occurred.
And the reaction force that causes vibration
This is because it is transmitted to the base of the actuator. So in the present invention
Has a structure in which the reaction force itself due to inertia is not transmitted to the base.
To eliminate the occurrence of vibration from the stage of its cause.
To provide a linear actuator that can be removed
Is the subject. [0007] The present invention solves the above-mentioned problems.
Lower actuator unit located on the base to
Knit and mounted on the lower actuator unit
Driven linearly by the lower actuator unit
Linear actuator having an upper actuator unit
The upper actuator unit is
With the load mounted and driven on a straight line parallel to the above straight line
The mounted object and the upper actuator
The projected position of the unit's composite center of gravity on the horizontal plane does not change.
The upper actuator unit and the lower
To drive the actuator units in opposite directions
Therefore, the horizontal reaction force due to the acceleration / deceleration of the load
Is isolated from the base to prevent generation of vibration.
And a linear motion actuator. [0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will now be described.
This will be described below with reference to the drawings. Specific of the present invention
Before explaining the general configuration, the general configuration of the conventional and the present invention
Will be described in comparison. FIG. 1 schematically shows a conventional linear motion actuator.
FIG. Actuator 1 installed on base 4
And the actuator 1
Configuration in which the object 2 mounted on 1 moves in the horizontal direction in the figure
It has become. Now, let the mass of the object 2 be M,
Let X be the displacement of the center of gravity of the object 2 from the point O. Object 2 accelerates
Degree d²X / dt²When driven by
A reaction force due to inertia is applied to the base 4 through the attachment 3.
The magnitude of the reaction force F is represented by the following equation (1). [0011] ## EQU1 ## F = -M (d²X / dt² ) FIG. 2 shows a linear motion actuator according to the present invention.
It is a figure explaining the outline of. Actuator on base 5
The lower actuator unit 7 is provided via the attachment 6
Have been. Further, the lower actuator unit 7
Means that the upper actuator unit 8 is
Mounted on the unit 7 so as to move in a straight line.
You. This upper actuator unit 8 carries an object 9
are doing. The mass of the object 9 (the upper actuator unit)
M including the movable part of₂, Upper actuator unit
The mass of the knit 8 is M₁And Also, is the origin O of the base 5
Let X be the displacement of the center of gravity of the object 9₂, Actuator 8 weight
X is the displacement of the heart₁And The object 9 has an acceleration d²X₂/ Dt
²Then, the upper actuator unit 8 has the acceleration d²X ₁
/ Dt²When moving with
The magnitude of the reaction force F applied to the base 5 through the attaching portion 6 is several
It is expressed by Equation 2. [0014] ## EQU2 ## F = -M₁(D²X₁/ Dt²) -M₂(D
²X₂/ Dt²) By the way, the upper actuator unit 8
Displacement X of the composite center of gravity of object and object 9₃Is represented by Expression 3. [0016] [Formula 3] X₃= (M₁X₁+ M₂X₂) / (M₁+ M
₂) As shown in Expression 4, X₃Is a constant value a
Lower actuator unit 7 and
The upper actuator unit 8 is driven. [0018] [Formula 4] X₃= (M₁X₁+ M₂X₂) / (M₁+ M
₂) = A For this purpose, the upper actuator unit
Relative displacement of the object 9 with respect to the lower actuator unit 8
Relative change of the upper actuator unit 8 with respect to the
Position (M₁+ M₂) / M₂Actuators to be doubled
It is only necessary to control the data units 7 and 8. At this time, Equation 4
When time-differentiated twice, Equation 5 is obtained.
Thus, the reaction force F = 0. That is, actuator mounting
Base through actuator mounting section 6 through section 6
The reaction force applied to 5 becomes zero. [0020] [Formula 5] d²X₃/ Dt²= (M₁d²X₁/ Dt²
+ M₂d²X₂/ Dt²) / (M₁+ M₂) = 0 (Embodiment) A linear motion actuator according to the present invention
Linear actuator
, Ball screw, rack and pinion, hydraulic cylinder, empty
Various linear drive elements such as pneumatic cylinders can be used.
Wear. However, to keep the relationship of Equation 4 always,
To control the actuator units 7 and 8 synchronously
Next, the displacement of each actuator unit 7, 8 is measured.
Displacement sensors such as potentiometers, encoders, and resolvers
Sensor is required. In general, the feed from these displacement sensors
To each actuator unit 7 and 8 by the feedback signal
And configure the position servo system.
Is given a position command signal that maintains the relationship of Equation 4.
You. Further, the change of the upper actuator unit 8 is performed.
A signal obtained by multiplying the position sensor signal by a certain coefficient
By giving a position command to the actuator unit 7,
However, the same control can be realized. FIG. 3 uses a ball screw and a servomotor.
An example will be described. This actuator is a lower actuator
Unit 7 and the upper actuator unit 8
You. Servo motors 10 and 11 each have a ball screw 1
2 and 13, and drive the sliders 14 and 15 in a straight line.
Move. The slider 14 is connected to the upper actuator unit 8
With. The slider 15 has the object 9 mounted thereon. The servo
The rotation angles of the motors 10 and 11 are measured by encoders 16 and 17.
And the sensor signals are fed to the controllers 18 and 19.
Will be played back. Controllers 18 and 19 are respectively
Calculate the deviation between the position command value and the feedback signal, and
The drive current of the motors 10 and 11 is output. The target displacement of the object 9 is X_2d(T)
And the controller 18 (lower actuator unit)
7) has-(M₂/ M₁) ・ X_2d(T), control
La (upper actuator unit 8) has (M₁+
M₂) / M₁・ X_2dContinuously apply the position command value of (t)
I can. The embodiment according to the present invention has been described above as an example.
However, the present invention is limited to such an embodiment.
It is not specified,
It goes without saying that there are various embodiments within the scope.
No. [0029] Since the present invention has the above configuration, the activator
The reaction force due to the inertia applied to the base from the
To prevent vibration of the base from the stage of the cause.
Can be. In addition, the composite center of gravity of the actuator
Oscillation due to change in gravity balance because the position does not change
Can also be prevented. In each actuator unit, the position
Open-loop systems for these
Vibration acceleration sensor, etc., which can be realized by position signal command
No additional sensor feedback signal is required
The result is simple.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic view of a conventional linear actuator. FIG. 2 is a diagram showing a schematic view of a linear motion actuator of the present invention. FIG. 3 is a diagram showing a configuration example using a ball screw and a servomotor of the present invention. [Description of Signs] 1 Actuator 2, 9 Object (mounting object) 3, 6 Actuator mounting part 4, 5 Base 7 Lower actuator unit 8 Upper actuator unit 10, 11 Servo motor 12, 13 Ball screw 14, 15 Slider 16, 17 Encoder 18, 19 Controller

Claims (1)

1. A direct actuator comprising: a lower actuator unit disposed on a base; and an upper actuator unit mounted on the lower actuator unit and driven linearly by the lower actuator unit. A dynamic actuator, wherein the upper actuator unit is mounted on and driven on a straight line parallel to the straight line, and projects a composite gravity center of the mounted object and the upper actuator unit onto a horizontal plane. By driving the upper actuator unit and the lower actuator unit in directions opposite to each other so that the position does not change, a horizontal reaction force due to acceleration / deceleration of the mounted object is cut off from the base to prevent generation of vibration. A linear motion actuator.