# Patent

## Title
Vibration control device

## Abstract

A vibration control device that can achieve the best vibration control effect within an allowable stroke range of a movable mass includes a controller that calculates at least one of a displacement deviation between a target displacement of a movable mass and a displacement of the movable mass detected by a mass displacement sensor and a velocity deviation between a target velocity of the movable mass and a velocity of the movable mass detected by a mass velocity sensor, and generates a control command for making a motor drive the movable mass on the basis of at least one of the displacement deviation and the velocity deviation. The target displacement and the target velocity are set in a manner that the amplitude of the movable mass becomes constant and that phases thereof are delayed 90 degrees with respect to the vibration of a building.

## Background
RELATED APPLICATIONS
The present application is a National Phase of International Application Number PCT/JP2013/004789, filed Aug. 8, 2013, which claims priority to Japanese Application Number 2013-033877, filed Feb. 22, 2013.
TECHNICAL FIELD
The present invention relates to a vibration control device that can reduce both a vibration due to winds and a vibration due to earthquakes by being installed on a top floor of a tall building, for example.
BACKGROUND ART
Conventionally, in order to address a wind-induced vibration of a tower-like structure such as a tall building, a vibration control device is installed on a top floor of the tall building. Such control device detects a vibration of the building (building velocity and displacement) and response quantities of a movable mass, such as a velocity and a displacement of the movable mass, by a velocity sensor installed on a floor surface of the top floor of the building, and calculates a control force (driving force) by multiplying the detected response quantities by a constant control gain preliminarily calculated in accordance with an optimum control theory or the like. The device then drives the movable mass with the control force and transmits the vibration of the movable mass to the structure to damp the vibration of the structure.
Patent Literature 1 proposes a method that improves a conventional vibration control device by performing variable gain control and limit control on the control force for the movable mass so that the movable mass is maintained within an allowable stroke range even when a large input occurs due to an earthquake, for example.
Also, Patent Literature 2 proposes a method of adjusting the control gain so that the displacement of the movable mass is maintained within an allowable stroke range by predicting the displacement of the movable mass.
Furthermore, Patent Literature 3 proposes a device including a vibration control mode for responding to winds and a vibration control mode for responding to earthquakes, and is capable of addressing a wind-induced vibration and an earthquake-induced vibration by switching between the control modes. In Patent Literature 3, the vibration control mode for responding to earthquakes is configured by multiplying a control force obtained in the vibration control mode for responding to winds by a gain.
CITATION LIST
Patent Literature
Patent Literature 1: Japanese Patent No. 4857829
Patent Literature 2: Japanese Patent Laid-Open No. 2010-255791
Patent Literature 3: Japanese Patent Laid-Open No. 2011-174509
SUMMARY OF INVENTION
Technical Problem
According to Patent Literature 1, however, because a control command for displacement is multiplied by an appropriately selected gain of not more than one, a stroke of the movable mass becomes considerably small in comparison with the allowable stroke range when the movable mass is actually driven. Therefore, according to Patent Literature 1, it is not possible to fully utilize the allowable stroke range within which the movable mass can move, causing it impossible to achieve the best vibration control effect. Also, because the limit control is performed, a value of the command for displacement is saturated under a large input so that enough vibration control effect cannot be achieved.
Also, according to Patent Literature 2, the displacement of the movable mass may exceed the allowable stroke range due to an error of the prediction or a sudden input.
Also, according to Patent Literature 3, because the allowable stroke range is exceeded under an excessive disturbance, a device is stopped in a brake mode. Thus, vibration control is not actively carried out under an earthquake.
It is thus an object of the present invention, which has been accomplished in view of these technical problems, to provide a vibration control device that can achieve the best vibration control effect within an allowable stroke range of a movable mass.
Solution to Problem
The present invention, which has been accomplished for the above-described object, relates to a vibration control device for damping a vibration of a structure to be vibration-controlled by driving a movable mass disposed on the structure via an actuator on the basis of the vibration of the structure. The vibration control device includes: first detection means for detecting at least one of a displacement of the structure, a velocity of the structure, and an acceleration of the structure; second detection means for detecting at least one of a displacement of the movable mass and a velocity of the movable mass; and a controller that calculates at least one of a displacement deviation between a target displacement of the movable mass and the displacement of the movable mass detected by the second detection means and a velocity deviation between a target velocity of the movable mass and the velocity of the movable mass detected by the second detection means, and generates a control command for making the actuator drive the movable mass on the basis of at least one of the displacement deviation and the velocity deviation, wherein the target displacement and the target velocity are set in a manner that an amplitude of the movable mass is constant and that phases thereof are adapted such that the target displacement and the target velocity work to damp the vibration of the structure.
In the present embodiment, there are at least first to fourth methods for setting the target displacement and the target velocity, as described below. Any of these methods includes arithmetic operation, and it is desirable to choose a method in a manner that the operation exerts a smaller influence.
In the first method, the target displacement and the target velocity are set on the basis of a result obtained by multiplying a damping term α, obtained by dividing a mass acceleration amplitude target value Aref for driving the movable mass at a constant amplitude within an allowable stroke range by an amplitude Ab of a velocity waveform of the structure, by a building velocity v1 of the structure detected by the first detection means.
In the second method, the target displacement and the target velocity are set on the basis of a result obtained by multiplying a damping term α, obtained by dividing a mass velocity amplitude target value Aref for driving the movable mass at a constant amplitude within an allowable stroke range by an amplitude Ab of a displacement waveform of the structure, by a building displacement x1 of the structure detected by the first detection means.
In the third method, the target displacement and the target velocity are set on the basis of a result obtained by multiplying a damping term α, obtained by dividing a mass displacement target value Aref for driving the movable mass at a constant amplitude within an allowable stroke range by an amplitude Ab of a velocity waveform of the structure, by a building velocity v1 of the structure detected by the first detection means.
In the fourth method, the target displacement and the target velocity are set on the basis of a result obtained by multiplying a damping term α, obtained by dividing a mass velocity target value Aref for driving the movable mass at a constant amplitude within an allowable stroke range by an amplitude Ab of a velocity waveform of the structure, by an acceleration a1 of the structure detected by the first detection means.
Advantageous Effects of Invention
According to the vibration control device of the present invention, because the target displacement and the target velocity are set in a manner that an amplitude of the movable mass is constant and that phases thereof are adapted such that the target displacement and the target velocity work to damp the vibration of the structure, it is possible to achieve the best vibration control effect within an allowable stroke range of the movable mass.



BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a diagram illustrating a modeled controlled object to which a control method of a vibration control device of the present embodiment is applied.
FIG. 2 is a diagram illustrating a control logic of the vibration control device of the present embodiment.
FIG. 3 is a diagram illustrating simulated vibration control effects of the vibration control device of the present embodiment and a comparison vibration control device.
FIG. 4 is a diagram illustrating a variation of the control logic of the present embodiment.
FIG. 5 is a diagram illustrating another variation of the control logic of the present embodiment.
FIG. 6 is a diagram illustrating yet another variation of the control logic of the present embodiment.



DESCRIPTION OF EMBODIMENTS
First Embodiment
The present invention will now be described on the basis of embodiments with reference to the accompanying drawings.
A vibration control device of the present embodiment is disposed on a modeled controlled object illustrated in FIG. 1, for example.
The controlled object includes a building 2 as a structure on a ground 1, and a movable mass (mass body) 3 constituting the vibration control device is disposed on the building 2. The controlled object is provided for damping a vibration of the building 2 by vibrating the movable mass 3 in a direction for counteracting the vibration of the building 2 and by transmitting the vibration of the movable mass 3 to the building 2.
In this model, a force acting between the ground 1 and the building 2 is approximated using a spring constant K1 and a damping constant (damper coefficient) C1. Here, the building 2 is considered as one rigid body, and it is supposed that the whole building 2 generates the force acting between the ground 1 and the building 2, causing a displacement. Also, the mass of the building 2 is represented as m1.
Also, a force acting between the building 2 and the movable mass 3 is approximated using a spring constant K2, a damping constant (damper constant) C2, and a control force f. Here, the control force is a force for driving the movable mass 3. Also, the mass of the movable mass 3 is represented as m2.
According to FIG. 1, a mathematical model of the controlled object can be represented with the following equations (1) and (2):

[Expression 1]

m1({umlaut over (x)}g+{umlaut over (x)}1)=−K1x1−C1{dot over (x)}1+K2x2+C2{dot over (x)}2−f  (1)

m2({umlaut over (x)}g+{umlaut over (x)}1+{umlaut over (x)}2)=−K2x2−C2{dot over (x)}2+f  (2)

Eliminating f (the control force for the movable mass 3) from equations (1) and (2) results equation (3):

[Expression 2]

(m1+m2){umlaut over (x)}1+K1x1+C1{dot over (x)}1=−(m1+m2){umlaut over (x)}g−m2{umlaut over (x)}2  (3)

If equation (4) holds in equation (3), then equation (5) can be obtained:

[Expression 3]

m2{umlaut over (x)}2=C′{dot over (x)}1  (4)

[Expression 4]

(m1+m2){umlaut over (x)}1+K1x1+(C1+C′){dot over (x)}1=−(m1+m2){umlaut over (x)}g  (5)

In equation (5), a viscosity coefficient of the building 2 is C1+C′, which means that the damping capacity acting for vibration control becomes larger.
Now, rewrite equation (4) as equation (6):




  
    
      
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In equation (6), a damping term α is determined by normalizing a building velocity (first-order differentiation of x1) and using equation (7) so that the movable mass is maintained within an allowable stroke range. Here, Aref is a mass acceleration amplitude target value for driving the movable mass with a constant amplitude within the allowable stroke range, and Ab is an amplitude of a velocity waveform (hereinafter referred to as velocity amplitude) of the building 2. In the present application, differentiation and integration mean time differentiation and time integration, respectively.




  
    
      
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In equation (7), α is a value that changes in accordance with the velocity amplitude of the building 2 that is sequentially detected. This means that the control method according to the present embodiment includes a variable gain control. Also, it is apparent from equations (6) and (7) that the displacement of the movable mass 3 can be made a constant value regardless of the vibration (amplitude) of the building. This constant value is of course within the allowable stroke range of the movable mass 3. Here, the displacement of the movable mass 3 is considered as a distance from a reference point, such as a center of a stroke.
This means that, by specifying equation (6) as a target acceleration of the movable mass 3, a value obtained by performing first-order integration of equation (6) as a target velocity of the movable mass 3, and a value obtained by performing second-order integration of equation (6) as a target displacement of the movable mass 3, it is possible to make the damping term of the building 2 to C1+C′. That is, according to the control method of the present embodiment, the damping performance can be enhanced. Also, the target velocity and the target displacement are meant to move the movable mass at a constant amplitude in a manner that phases of the target velocity and the target displacement are respectively delayed 90 degrees with respect to the velocity and the displacement of the vibration of the building 2.
Next, a vibration control device 10 of the present embodiment will be described with reference to FIG. 2. In the following description, it is assumed that the vibration control device 10 is applied to the modeled controlled object including the building 2 and the movable mass 3 illustrated in FIG. 1.
The vibration control device 10 includes a building displacement sensor 11 and a building velocity sensor 13 attached on the building 2. The building displacement sensor 11 detects the amount of a horizontal displacement of the building 2 (building displacement x1), and the building velocity sensor 13 detects a horizontal velocity of the building 2 (building velocity v1 (first-order differentiation of x1)).
The vibration control device 10 also includes a mass displacement sensor 15 and a mass velocity sensor 17 attached to a motor (actuator) 4 that drives the movable mass 3 disposed on a top portion of the building 2. The mass displacement sensor 15 detects the amount of a horizontal displacement of the movable mass 3 (mass displacement x2) from the behavior of the motor 4, and the mass velocity sensor 17 detects a horizontal velocity of the movable mass 3 (mass velocity v2 (first-order differentiation of x2)) from the behavior of the motor 4.
Because velocity can be obtained by performing time differentiation of displacement, the building velocity v1 and the mass velocity v2 can be calculated on the basis of a detection result of the displacement sensor instead of relying on the velocity sensor. Likewise, the building displacement x1 and the mass displacement x2 can be calculated on the basis of a detection result of the velocity sensor instead of relying on the displacement sensor. Thus, although an example of disposing a displacement sensor and a velocity sensor is described herein, the present embodiment can be achieved with either a displacement sensor or a velocity sensor.
The vibration control device 10 includes a controller 20. The controller 20 includes a first gain multiplier 21 that outputs a signal S1 obtained by multiplying the building displacement x1 by a control gain Kd1, a second gain multiplier 23 that outputs a signal S2 obtained by multiplying the building velocity v1 by a control gain Kd2, a third gain multiplier 25 that outputs a signal S3 obtained by multiplying a deviation D10 between the mass displacement x2 and a target displacement of the movable mass 3 by a control gain Kd3, and a fourth gain multiplier 27 that outputs a signal S4 obtained by multiplying a deviation D20 between the mass velocity v2 and a target velocity of the movable mass 3 by a control gain Kd4. As described above, the target velocity of the movable mass 3 is a value obtained by performing first-order integration of equation (6), and the target displacement of the movable mass 3 is a value obtained by performing second-order integration of equation (6). In the controller 20, the step corresponding to the above-described equation (7) is executed in the portion labeled as “variable gain”.
The control gains Kd1 to Kd4 are calculated in accordance with an optimum control theory, for example, and are meant to be constants that are arbitrarily set.
The controller 20 sums the signal S1 from the first gain multiplier 21, the signal S2 from the second gain multiplier 23, the signal S3 from the third gain multiplier 25, and the signal S4 from the fourth gain multiplier 27. The controller 20 gives the sum to the motor 4 as a control command for the control force f applied to the movable mass 3.
Here, another control logic (comparison logic) could be established in which a signal S3′ obtained by multiplying the mass displacement x2 by the control gain Kd3 and a signal S4′ obtained by multiplying the mass velocity v2 by the control gain Kd4 are summed to the above-described signals S1 and S2. This control logic is based on the assumption that the targets of the displacement and the velocity of the movable mass are made to zero. The control logic of the present embodiment, on the other hand, further includes the variable gain control, as described above. Thus, instead of making the targets of the displacement and the velocity of the movable mass 3 to zero, the movement that enhances the damping of the vibration of the building 2, which is a vibration-controlled structure, is adopted as target values.
As described above, according to the vibration control device 10, the target displacement and the target velocity are calculated using the variable control gain α such that the amplitude of the movable mass 3 becomes constant not only when the building 2 vibrates due to winds but also when the building 2 vibrates rapidly due to earthquakes. Thus, the best vibration control effect can be efficiently and reliably achieved within the allowable stroke range of the movable mass 3. Also, according to the present embodiment, the vibration control effect for earthquakes can be effectively obtained by simply changing control software without building a new device.
Simulations have been conducted for checking the vibration control effect for the building 2 under an earthquake by using the comparison logic and the logic of the present embodiment. FIG. 3 shows the results of the simulations. According to the present embodiment, while the comparison active logic permits the movable mass 3 to vibrate beyond the allowable stroke range, in the present invention the vibration of the movable mass 3 includes a constant portion and is maintained within the allowable stroke range.
Second to Fourth Embodiments
In the first embodiment, the variable control gain α is calculated by dividing the target acceleration of the movable mass 3 by the velocity amplitude of the building 2, as shown in equation (7). The variable control gain α is, however, not limited to the above calculation, as long as the phase relationship indicated in equation (4), or the condition that the mass displacement x2 is phase-delayed 90 degrees with respect to the building displacement x1, is satisfied. For example, the following (b), (c), and (d) are combinations that satisfy the phase relationship of equation (4). The (b), (c), and (d) correspond to equations (6) and (7). The (a) corresponds to the above-described first embodiment. FIGS. 4, 5 and 6 illustrate control logics based on the following (b), (c), and (d). In these figures, the same components as those of FIG. 2 are indicated with the same numerals. In the following description of FIGS. 4, 5, and 6, the differences from the first embodiment will be mainly described.

[Expression 7]

{umlaut over (x)}2=α{dot over (x)}1, α=mass target acceleration amplitude/building velocity amplitude (first embodiment)  (a)

{dot over (x)}2=αx1, α=mass target velocity amplitude/building displacement amplitude (second embodiment)  (b)

x2=−α{dot over (x)}1, α=mass target displacement amplitude/building velocity amplitude (third embodiment)  (c)

{dot over (x)}2=−α{umlaut over (x)}1, α=mass target velocity amplitude/building acceleration amplitude (fourth embodiment)  (d)

Second Embodiment
In a second embodiment, α is calculated by dividing the target velocity amplitude of the movable mass 3 by the amplitude of the displacement waveform (hereinafter referred to as displacement amplitude) of the building 2. Thus, α changes in accordance with the displacement amplitude of the building 2 that is sequentially detected. As with the first embodiment, the mass displacement can be maintained within a constant range regardless of the vibration of the building 2. This is also true of embodiments 3 and 4.
As illustrated in FIG. 4, in the second embodiment, a value obtained by performing first-order integration of the variable gain obtained with the above (b) (first-order differentiation of the displacement x2 of the movable mass 3) is used as a target displacement of the movable mass 3.
In the second embodiment, the third gain multiplier 25 outputs a signal S31 obtained by multiplying a deviation D11 between the mass displacement x2 and the target displacement of the movable mass 3 by a control gain Kd31, and the fourth gain multiplier 27 outputs a signal S41 obtained by multiplying a deviation D21 between the mass velocity v2 and the target velocity of the movable mass 3 by a control gain Kd41. The first gain multiplier 21 and the second gain multiplier 23 are the same as those of the first embodiment.
In the second embodiment, the signal S1 from the first gain multiplier 21, the signal S2 from the second gain multiplier 23, the signal S31 from the third gain multiplier 25, and the signal S41 from the fourth gain multiplier 27 are summed. The sum is given to the motor 4 as a control command for the control force f applied to the movable mass 3.
Third Embodiment
In the third embodiment, α is calculated by dividing the target displacement amplitude of the movable mass 3 by the velocity amplitude of the building 2. Thus, α changes in accordance with the velocity amplitude of the building 2 that is sequentially detected.
As illustrated in FIG. 5, in the third embodiment, a value obtained by performing first-order integration of the variable gain obtained with the above (c) (the mass displacement x2 of the movable mass 3) is used as a target velocity of the movable mass 3.
The (c) indicates that, if the relationship (equation (4)) in which the mass displacement x2 is phase-delayed 90 degrees with respect to the building displacement x1 is represented with the building velocity and the mass displacement, then the sign inversion of the building velocity has a phase which proceeds 90 degrees with respect to the mass displacement.
In the third embodiment, the third gain multiplier 25 outputs a signal S32 obtained by multiplying a deviation D12 between the mass displacement x2 and the target displacement of the movable mass 3 by a control gain Kd32, and the fourth gain multiplier 27 outputs a signal S42 obtained by multiplying a deviation D22 between the mass velocity v2 and the target velocity of the movable mass 3 by a control gain Kd42. The first gain multiplier 21 and the second gain multiplier 23 are the same as those of the first embodiment.
In the third embodiment, the signal S1 from the first gain multiplier 21, the signal S2 from the second gain multiplier 23, the signal S32 from the third gain multiplier 25, and the signal S42 from the fourth gain multiplier 27 are summed. The sum is given to the motor 4 as a control command S for the control force f applied to the movable mass 3.
Fourth Embodiment
The fourth embodiment includes a building acceleration sensor 14 for detecting a horizontal acceleration of the building 2.
Also, in the fourth embodiment, α is calculated by dividing a target velocity amplitude value of the movable mass 3 by the amplitude of the acceleration waveform (hereinafter referred to as acceleration amplitude) of the building 2. Thus, α changes in accordance with the acceleration amplitude of the building 2 that is sequentially detected.
As illustrated in FIG. 6, in the fourth embodiment, a value obtained by performing first-order integration of the variable gain obtained with the above (d) (first-order differentiation of the displacement x2 of the movable mass 3) is used as a target displacement of the movable mass 3.
In the fourth embodiment, the third gain multiplier 25 outputs a signal S33 obtained by multiplying a deviation D13 between the mass displacement x2 and the target displacement of the movable mass 3 by a control gain Kd33, and the fourth gain multiplier 27 outputs a signal S43 obtained by multiplying a deviation D23 between the mass velocity v2 and the target velocity of the movable mass 3 by a control gain Kd43. The first gain multiplier 21 and the second gain multiplier 23 are the same as those of the first embodiment.
The signal S1 from the first gain multiplier 21, the signal S2 from the second gain multiplier 23, the signal S33 from the third gain multiplier 25, and the signal S43 from the fourth gain multiplier 27 are summed. The sum is given to the motor 4 as the control command S for the control force f applied to the movable mass 3.
As described in the above description of the second to fourth embodiments, it is only necessary to specify a target value for either the displacement or the velocity of the movable mass 3. This means that the control method of the present invention can be utilized regardless of the type of sensors used, and it is possible to cut the cost of adding or re-installing sensors.
In order to obtain a vibration control effect more reliably, however, it is preferable to specify a target value for both the displacement and the velocity, as with the first embodiment.
In the first to fourth embodiments, if arithmetic operation such as differentiation and integration is used in an installed sensor, it is desirable to choose a combination in which the operation exerts a smaller influence.
Although the present invention has been described in accordance with the embodiments, it is possible to choose any of the configurations described in the above embodiments or arbitrarily change to another configuration, as long as they do not depart from the gist of the present invention.
For example, in the above embodiments, although an example is described in which the phase delay is 90 degrees, which is most preferable, the present invention is not limited to this. Because the phase delay larger than 0 degrees and less than 180 degrees contributes to damping, it is possible in the present invention to choose any angle of phase delay within this range. However, the further the phase delay gets away from the most preferable 90 degrees, the more the damping performance decreases. Therefore, the phase delay is preferably plus or minus 20 degrees, more preferably plus or minus 10 degrees, and still more preferably plus and minus 5 degrees from 90 degrees.
REFERENCE SIGNS LIST


    1 ground
    2 building
    3 movable mass
    4 motor
    10 vibration control device
    20 controller
    11 building displacement sensor
    13 building velocity sensor
    14 building acceleration sensor
    15 mass displacement sensor
    17 mass velocity sensor
    21 first gain multiplier
    23 second gain multiplier
    25 third gain multiplier
    27 fourth gain multiplier

## Claims

1. A vibration control device for damping a vibration of a structure to be vibration-controlled by driving a movable mass disposed on the structure via an actuator on the basis of the vibration of the structure, comprising:
first detection means for detecting at least one of a displacement of the structure, a velocity of the structure, and an acceleration of the structure;
second detection means for detecting at least one of a displacement of the movable mass and a velocity of the movable mass; and
a controller that calculates at least one of a displacement deviation between a target displacement of the movable mass and the displacement of the movable mass detected by the second detection means and a velocity deviation between a target velocity of the movable mass and the velocity of the movable mass detected by the second detection means, and generates a control command for making the actuator drive the movable mass on the basis of at least one of the displacement deviation and the velocity deviation, wherein
the target displacement and the target velocity are set in a manner that an amplitude of the movable mass is constant and that phases thereof are adapted such that the target displacement and the target velocity work to damp the vibration of the structure.

2. The vibration control device according to claim 1, wherein
the target displacement and the target velocity are set on the basis of a result obtained by multiplying a damping term α, obtained by dividing a mass acceleration amplitude target value Aref for driving the movable mass at a constant amplitude within an allowable stroke range by an amplitude Ab of a velocity waveform of the structure, by a building velocity v1 of the structure detected by the first detection means.

3. The vibration control device according to claim 2, wherein
the controller sets the target displacement and the target velocity such that phases of the target displacement and the target velocity are delayed 90 degrees with respect to the vibration of the structure.

4. The vibration control device according to claim 1, wherein
the target displacement and the target velocity are set on the basis of a result obtained by multiplying a damping term α, obtained by dividing a mass velocity amplitude target value Aref for driving the movable mass at a constant amplitude within an allowable stroke range by an amplitude Ab of a displacement waveform of the structure, by a building displacement x1 of the structure detected by the first detection means.

5. The vibration control device according to claim 4, wherein
the controller sets the target displacement and the target velocity such that phases of the target displacement and the target velocity are delayed 90 degrees with respect to the vibration of the structure.

6. The vibration control device according to claim 1, wherein
the target displacement and the target velocity are set on the basis of a result obtained by multiplying a damping term α, obtained by dividing a mass displacement target value Aref for driving the movable mass at a constant amplitude within an allowable stroke range by an amplitude Ab of a velocity waveform of the structure, by a building velocity v1 of the structure detected by the first detection means.

7. The vibration control device according to claim 6, wherein
the controller sets the target displacement and the target velocity such that phases of the target displacement and the target velocity are delayed 90 degrees with respect to the vibration of the structure.

8. The vibration control device according to claim 1, wherein
the target displacement and the target velocity are set on the basis of a result obtained by multiplying a damping term α, obtained by dividing a mass velocity target value Aref for driving the movable mass at a constant amplitude within an allowable stroke range by an amplitude Ab of an acceleration waveform of the structure, by an acceleration a1 of the structure detected by the first detection means.

9. The vibration control device according to claim 8, wherein
the controller sets the target displacement and the target velocity such that phases of the target displacement and the target velocity are delayed 90 degrees with respect to the vibration of the structure.

10. The vibration control device according to claim 1, wherein
the controller sets the target displacement and the target velocity such that phases of the target displacement and the target velocity are delayed 90 degrees with respect to the vibration of the structure.