JPS6353617A - Active vibration insulating method - Google Patents

Abstract

PURPOSE:To execute the highly accurate vibration insulation in the combination of a structure by assembling a piezoelectric actuator to a vibration isolator to combine two vibration structures and expanding and damping this in accordance with the amplitude and the frequency of a rigid body at both sides. CONSTITUTION:Two vibration structures 1 and 2 are combined by vibration insulation device 3. For the device 3, a piezoelectric actuator 4 formed by a piezoelectric element disk is serially arranged to a load detect or 5, has rigid bodies 6 and both sides and on this, acceleration detectors 12 and 13 are provided. A control part 14 obtains the elongation quantity of the actuator 4 in accordance with the alternating force and the acceleration detected by detectors 5, 12 and 13 operates an impressing voltage control quantity to the actuator 4 necessary to generate this. When a voltage Va from a control part 14 is impressed to the actuator 4, the actuator 4 is elongated with the size equal to the difference in the displacement of the rigid bodies 6 and 7, the alternating force to propagate through the device 3 is suppressed and the structures 1 and 2 are independently oscillated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an active vibration I@edge method, and more specifically, the present invention relates to an active vibration I@edge method, and more specifically, two opposing vibrations each receiving an external excitation force. The present invention relates to an active vibration isolation method that connects two vibrating structures while suppressing alternating forces propagated through a connecting device, thereby completely separating the two structures vibrationally.

[Conventional technology and its problems]

Mechanical vibrations of structural members are caused by propagation of vibrations from an excitation source. Therefore, suppressing the propagation of vibrations from the vibration source has a great effect on damping the vibrations of structural members. Conventionally, as a method of suppressing the propagation of vibration from such a vibration source, a passive method of installing vibration-proof rubber at the supporting end of the vibration source has been generally used. Although anti-vibration rubber has a suppressing effect over a wide frequency band, it is known that the suppressing effect is insufficient for the propagation of periodic and large vibrations. For this reason, active vibration isolation, so-called active vibration isolation, has come to be considered.

This is a method that actively attempts to cancel vibrations based on signals obtained from the vibration source. The first is a method of vibration isolation by balancing forces, which involves applying a force in the opposite direction to the alternating force from the vibration source on the supporting end side, which is the object to be vibration-isolated. .

This method has the disadvantage that the device becomes bulky when the excitation force is large. The second method is to control the vibration of the vibration-isolated object by controlling the spring constant and changing the vibration system itself. This method is also disadvantageous in terms of cost because the device becomes large and the control is complicated.

Therefore, in order to solve the above-mentioned problems, the present inventor developed a vibration isolation system that suppresses the propagation of vibration to the vibration-isolated object by controlling the amount of extension of the piezoelectric actuator according to the mechanical vibration of the vibration source. Invented and previously proposed a support control method.

The outline of this method is as shown in FIGS. 6 and 7, in which a vibration source 101 is supported via a vibration isolator 103 attached to a support base 102 on the side of the vibration isolator, and the vibration isolator The device 103 is a piezoelectric actuator 104 (displacement generating section),
It is composed of a load detector 105 and a vibration isolator 106 arranged on the same axis as the piezoelectric actuator 104, and an acceleration detector 107 is provided to detect the acceleration of the vibration source 101. The varying load and acceleration during vibration of the piezoelectric actuator 101 are measured, the amount of elongation of the piezoelectric actuator 104 is calculated based on the measured values, and the amount of elongation is converted into a voltage, which is then applied to the piezoelectric actuator 104 and This is designed to suppress the propagation of vibrations to the body. In the figure, 108 is an arithmetic unit, 109 is an amplification unit, 110 is an adder, 111 is a second-order integrator, and 11
2 is an adder, Vf is a load signal detected by the load detector 105, Vc is an acceleration signal detected by the acceleration detection unit 107, and ■ is a voltage signal corresponding to the optimum amount of expansion of the piezoelectric actuator 104.

This anti-vibration support control method focuses on anti-vibration support for a single mass point system that receives external excitation force, and is designed to provide anti-vibration support that suppresses the propagation of vibration from the vibration source to the object to be isolated. In terms of control, it has the advantage of being able to perform highly accurate vibration isolation @ control and achieve vibration isolation suitable for the vibration source with a relatively simple configuration. It is said that it is not possible to perform vibration isolation control that connects two vibrating structures, suppresses the alternating force propagated through the coupling device, and completely separates the two structures vibrationally. There was a problem.

The present invention has been made to solve the above problems, and its purpose is to connect two vibrating structures that each receive an external excitation force while propagating the vibration through a connecting device. An object of the present invention is to provide a vibration isolation method that suppresses alternating forces.

Means for Solving Problem C] In order to achieve the above object, the active vibration isolation method of the present invention includes two vibrating structures that are attached to both ends of a piezoelectric actuator and a load detector arranged in series. The output signal of an acceleration detector attached to each rigid body of the device or the output signal of a displacement detector that measures the relative displacement between the two rigid bodies, and the load detection The alternating force acting on both ends of the device is measured from the output signal of the device, the amount of elongation of the piezoelectric actuator is calculated based on the measured value, and the amount of elongation is converted into a voltage, which is then applied to the piezoelectric actuator. It is configured as follows. Furthermore, the active vibration isolation method of the present invention preferably has a configuration in which each rigid body has approximately the same mass.

[Effect]

With this configuration, the piezoelectric actuator incorporated in the vibration isolating device that connects the two vibrating structures is controlled by voltage according to the amplitude and frequency of the rigid bodies of the device, thereby reducing the difference in displacement of each rigid body. The piezoelectric actuator extends by an amount equal to , and the alternating forces propagating through the device are suppressed.

Therefore, while the two vibrating structures are connected, they are completely vibrationally separated and each vibrates independently.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Two vibrating structures 1 and 2, each of which vibrates in response to an external excitation force, are connected by a vibration isolating device 3. In the vibration isolating device 3, a piezoelectric actuator 4 (displacement generating section) formed of a plurality of piezoelectric element disks made of piezoelectric ceramics such as zircon or lead titanate is arranged in series with a load detector 5, and a piezoelectric actuator 4 (displacement generating section) is arranged in series with a load detector 5. attached rigid body 6
, 7. Furthermore, the outside is made of anti-vibration rubber 8, 9.
Vibrating structure 1 with screws 10 and 11 via spring elements such as
, 2. The load detector 5 is constituted by a strain gauge, a piezoelectric load sensor, or the same piezoelectric element disk as the piezoelectric actuator 4. Further, acceleration detectors 12 and 13 are provided to detect the acceleration of the rigid bodies 6 and 7.

The control unit 14 includes a load detector 5 and an acceleration detector 12 .
The amount of expansion of the piezoelectric actuator 4 is determined according to the alternating force and acceleration detected by the piezoelectric actuator 13, and the amount of voltage control applied to the piezoelectric actuator 4 necessary to generate this amount of expansion is calculated.

Next, the operation of the above embodiment will be explained.

When the two vibrating structures 1 and 2 vibrate in the direction of arrow A in FIG. 1 due to external excitation force, an alternating force acts on the vibration isolating device 3. This alternating force is detected by the load detector 5 and input to the control unit 14 as a load signal Vf.

At the same time, the acceleration of the two rigid bodies 6.7 is detected by the acceleration detector 12.
．． 13, and the acceleration signals V C1, V c
2 is input to the control unit 14.

When the vibration system in Fig. 1 is solved using the equation of motion, the alternating force propagating through the vibration isolator 3 is: ...... (1) Here ...... (2 ) becomes. Here, the * mark is the value after Laplace transform, S represents the first differential, and S2 represents the second differential. kAykB is the spring constant of the vibration isolating rubbers 8 and 9, k is the sum of the spring constants of the piezoelectric actuator 4 and the load detector 5, Ml and M2 are the masses of the two rigid bodies 6 and 7, and PAtPB is the two vibration structures 1
, 2 is the excitation force applied from the outside. Also, CAy
DA is an influence coefficient that the external force P1 and the force applied to the vibrating structure 1 through the vibration isolating rubber 8 have on the boundary displacement between the vibrating structure 1 and the vibration isolating device 3, respectively. Similarly, CB and D are influence coefficients of the external force P2 and the force applied to the vibrating structure 2 through the vibration isolating rubber 9 on the boundary displacement between the vibrating structure 2 and the vibration isolating device 3. These values can be obtained by modeling the vibrating structure as a spring-mass system or by actually measuring the vibrating structure in question. From equation (1), set U so that the right side of equation (1) becomes O.
The force L propagating through the vibration isolating device 3 by driving *
* can be set to 0. This U* can be calculated by transforming the right side of equation (1) using the equation of motion as shown in (3). On the right side of equation (3), (X11
1-X%) is the relative displacement between the two rigid bodies in the vibration isolator 3, and is determined from the acceleration signals vC1 and vC2.

Further, L* is an alternating force propagating through the vibration isolating device 3, and is obtained from the load signal Vf. This L* also plays a role in stabilizing control when a filter is inserted to eliminate control of low frequency vibrations.

From the above, in the control unit 14, first, V cl, V C,
.

01 times and kc to each voltage-acceleration conversion coefficient
, multiplied and input to the subtracter 20. The output of the liquid calculator 20 is integrated twice by a double integrator 21.

On the other hand, Vf is also multiplied by the voltage-load conversion coefficient kf and input to the A/D converter 22. Then, on the computer 23, the formula (3
) is calculated by convolution or numerical integration. The result is then converted into an analog signal by the D/A converter 24 and input to the adder 25 together with the output of the double integrator 21 . This output voltage is further multiplied by (1/ka). Here, ka is a voltage-expansion amount conversion coefficient of the piezoelectric actuator. and,
A voltage obtained by adding a bias voltage required by the piezoelectric actuator 4 to the output voltage by an adder 26 becomes the voltage Va applied to the piezoelectric actuator 4. In addition, the double integrator 21
It is also possible to perform numerical integration digitally by replacing A/D converter + computer + D/A converter. Further, the computer 23 can be replaced with a commercially available convolver or digital filter.

When a voltage Va is applied to the piezoelectric actuator 4, for example, if the rigid body 6 is displaced upwardly more than the rigid body 7, the piezoelectric actuator 4 will extend by a magnitude equal to the difference, and an alternating force propagates through the vibration isolator 3. is suppressed, and the two upper and lower vibrating structures 1°2 vibrate independently.

FIG. 3 shows an example of a waveform when the vibrating structures 1 and 2 are vibrating by receiving excitation forces from the outside separately, and (1
) is the waveform when active control is not performed, (2
) shows the waveform when active control is performed. The piezoelectric actuator expands and contracts i in response to changes in the alternating forces P, P2 that act on the vibrating structures 1 and 2 from outside the system.
tu is controlled. As a result, the output of the load detector that was output when no active control was being performed becomes 0, and
The propagation of alternating forces is prevented. Therefore, as is clear from the figure, the interaction between the vibration displacements x1 and x2 disappears after the active control, and it can be seen that the vibration structures 1.2 vibrate independently.

- On the other hand, the two acceleration detectors 12 in the above embodiment.
13, the relative displacement between the two rigid bodies 6 and 7 (X, , -
It is also possible to use a displacement detector 16 that detects X2). FIG. 4 shows a configuration diagram at this time, and FIG. 5 shows a control section.

This control unit multiplies the output Vu of the displacement detector 16 by a voltage-displacement conversion coefficient ka and inputs the output voltage directly to the adder 25. is exactly the same.

In this way, by using a displacement detector instead of two acceleration detectors, it is possible to obtain the same control signal to the piezoelectric actuator as when using an acceleration detector, making active control possible.

Note that by selecting the masses M2M2 of the two rigid bodies 6 and 7 to be equal, the control system can be considerably simplified. Moreover, the piezoelectric actuator can also be used as another actuator, for example, an electrodynamic actuator. Furthermore, when considering the damping of the vibration system, kA→kA+ is expressed in equation (3).
cAs, kA-) to k 10 a) ys, to → k + cr3
An expression obtained by replacing s may be used. Here CA
+c3. Q is the damping coefficient of the anti-vibration rubber 8.9 and
This is the combination of the damping coefficients of the piezoelectric actuator 4 and the load detector 5.

〔Effect of the invention〕

- As mentioned above, according to the present invention, a piezoelectric actuator is incorporated in a vibration isolator that connects two vibrating structures,
This piezoelectric actuator is attached to both ends of the device and expands and contracts according to the amplitude and frequency of the nine rigid bodies to suppress vibration, so that two vibrating structures each receiving an external excitation force can be used. Alternating forces propagating through the device can be suppressed while connecting the bodies. Also, at that time,
By choosing the masses of the two rigid bodies to be approximately equal, the control system can be made considerably simpler.

In addition, while connecting two vibrating structures, it is possible to suppress the alternating force propagated through the coupling device and control the two structures to vibrationally separate them. Highly accurate vibration isolation is possible in connection.

[Brief explanation of the drawing]

Fig. 1 is a vibration isolation control configuration diagram for explaining an embodiment of the active vibration isolation method according to the present invention, Fig. 2 is a block diagram of its control section, Fig. 3 is a waveform diagram of a detection signal, and Fig. 4 is a vibration isolation configuration diagram for explaining another embodiment of the active vibration isolation method according to the present invention, FIG. 5 is a block diagram of its control section, and FIG. 6 is a conventional single mass point system active vibration isolation support control. FIG. 7 is a block diagram of the vibration isolation support control configuration for explaining the method, and is a block diagram of the calculation section. 1.2... Vibration structure, 3... Vibration isolator, 4.
...Piezoelectric actuator, 5...Load detector, 6.7
... Rigid body, 1.2.13 ... Acceleration detector, 16.
...Displacement detector.

Claims (2)

[Claims] (1) Two vibrating structures are connected by a coupling device having a piezoelectric actuator and a load detector arranged in series, and two rigid bodies attached to both ends, and
Acting on both ends of the device from the output signal of an acceleration detector attached to each rigid body of the device, or the output signal of a displacement detector that detects relative displacement between both rigid bodies, and the output signal of the load detector. An active vibration isolation method comprising: measuring an alternating force, calculating the amount of elongation of a piezoelectric actuator based on the measured value, converting the amount of elongation into a voltage, and then applying the voltage to the piezoelectric actuator. (2) The active vibration isolation method according to claim 1, wherein each rigid body has approximately the same mass.