JP2007107722A - Vibration isolating method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration isolating method and its device, which provide not only passive vibration isolation for the purpose of insulation of ground motion disturbance, but also active vibration isolation coping with spring disturbance, being applied to various devices such as an NC machine, a machine tool in a machining center and the like, and a stepper in an IC business field, and achieves machining of high accuracy by insulating a machining table and the like from disturbance. <P>SOLUTION: This vibration insulating method is constituted to insulate vibration conducting from a floor 6 to a first member 1 by mounting a spring 5 having prescribed positive spring characteristic between the floor 6 and the first member 1. Here, a negative spring characteristic is applied between the first member 1 and a second member 2 on which load is placed, by a supporting mechanism composed of an actuator 25 and a control device 26, to insulate the vibration conducting from the first member 1 to the second member 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

 TECHNICAL FIELD The present invention relates to vibration isolation of equipment, and to a vibration isolation method and apparatus capable of active vibration isolation that can cope with disturbance on a spring as well as passive vibration isolation for the purpose of isolating ground disturbance. Therefore, it is used for machine tools such as NC machines and machining centers, as well as various devices typified by steppers in the IC industry, to insulate processing tables from disturbances and achieve high-precision machining.

 At present, semiconductor device manufacturing systems and ultra-small area measurement systems are rapidly increasing in accuracy and performance, and in these systems, the importance of vibration isolation and vibration isolation devices that remove disturbances such as vibrations is important. It is increasing. Vibration disturbances to be removed by the vibration isolation device can be broadly classified into ground disturbances caused by vibrations from the installation floor and linear motion disturbances that are input on the springs of the device. For the latter, a highly rigid mechanism is suitable. FIG. 11 shows a conventional passive vibration isolation system that insulates and isolates ground disturbance, and in order to reduce the vibration transmissibility from the floor 36, if the spring constant k is decreased and the spring rigidity is decreased, It becomes weak against disturbance on the spring such as mass change Δm on the vibration isolation table 32 (mass m) and load change acting on the vibration isolation table 32. On the contrary, it is necessary to increase the spring rigidity to some extent against disturbance on the spring. The contradictory characteristics of such a low-rigidity mechanism for absorbing disturbance and a high-rigidity mechanism for maintaining position and posture are required.

Generally, when two vibration springs 35-1 and 35-2 having positive spring constants k1 and k2 are connected in series to constitute one vibration isolation mechanism, the spring constant is obtained by the following equation.
kc = k1 k2 / (k1 + k2) (1)
That is, when a spring having a normal positive spring constant is coupled in series, the spring constant formed by the coupling is necessarily smaller than the spring constant before the coupling. Therefore, with these conventional vibration isolation devices that use only springs, it is extremely difficult to ensure high rigidity against disturbances on the spring, such as mass changes and vibrations, so an active vibration isolation control device is proposed. It was done.

FIG. 12 shows the principle of a general active vibration isolation control device. The controller 115 suppresses the vibration of the vibration isolation table 110 based on a detection signal from the acceleration sensor 114 installed on the vibration isolation table 110. The control input is calculated, and the vibration isolation control is performed by operating the actuator 113 installed in parallel with the spring 111 and the attenuator 112 according to the obtained control input.

However, this approach is based on the premise that vibrations from the vibration isolation table and floor are accurately detected. To realize this approach, it is necessary to use a servo-type acceleration sensor that can detect even low-frequency vibrations with high sensitivity. Therefore, depending on the servo type acceleration sensor employed, the rigidity against the direct acting disturbance is still not sufficient, and it is insufficient to ensure complete vibration insulation performance.

Therefore, the present invention solves the problems of the conventional vibration isolation method and the device thereof, secures high rigidity against linear motion disturbance without damaging the vibration insulation performance against ground motion disturbance, and exhibits a high vibration isolation function. It is an object of the present invention to provide a vibration isolation method and apparatus that enable precision machining and the like.

Therefore, the technical solution adopted by the present invention is:
A spring having a predetermined positive spring characteristic is disposed between the floor and the first member to insulate vibration transmitted from the floor to the first member, and the first member and the second member for placing a load thereon In the vibration isolation method, a negative spring characteristic is imparted by a support mechanism including an actuator and a control device, and vibration transmitted from the first member to the second member is insulated.
In addition, while insulating a vibration transmitted from the support column to the first member by providing a negative spring characteristic by a support mechanism constituted by an actuator and a control device between the support column and the first member erected from the floor, Vibration transmitted from the first member to the second member by disposing a spring having a predetermined positive spring characteristic between the second member disposed opposite to the first member and the first member. Is a vibration isolation method characterized by insulating
The first member is an intermediate member, and the second member is a vibration isolation table.
A floor; a spring having a predetermined positive spring constant; a first member supported on the floor by the spring; and a first member disposed opposite to the first member for mounting a load. The vibration isolator includes two members, and a support mechanism having a negative spring characteristic composed of an actuator and a control device is disposed between the first member and the second member.
A first support member disposed on the floor; a first member disposed opposite to the first support member; a second member disposed opposite to the first member for placing a load; and the first member. A support mechanism having a negative spring characteristic, which includes a spring having a positive spring constant disposed between the member and the second member, and includes an actuator and a control device between the support column and the first member. This is a vibration isolator characterized by the arrangement.
The first member is an intermediate member, and the second member is a vibration isolation table.
Further, the vibration isolator is provided with an attenuator having a predetermined attenuation factor in combination with the spring.
In addition, the vibration isolator is provided with a spring having a predetermined spring constant and an attenuation device having a predetermined attenuation rate in combination with the actuator.
Further, the vibration isolator is configured to increase or decrease the elongation of the actuator according to the increase or decrease of the load.
The actuator is a linear actuator such as a voice coil motor, a linear motor, a pneumatic actuator, or a hydraulic actuator, and the control device includes a displacement sensor, a control circuit, and a power amplifier. .

As described above in detail, in the present invention, a spring is provided between the floor and the first member to insulate vibration transmitted from the floor to the first member, and the first member and the second member By providing a negative spring characteristic between the first member and the second member by providing a negative spring characteristic between the first member and the second member, the vibration is transmitted from the first member to the second member. Of course, it is not possible to insulate vibration and ensure high rigidity against linear motion disturbance without damaging the vibration isolation performance against vibration disturbance of the vibration isolation table, and to realize high vibration isolation function and enable precision machining, etc. In other words, various actuators can be employed to obtain negative spring characteristics, and the degree of freedom in design is improved.

In addition, when a damping device having a predetermined damping rate is installed between the floor and the intermediate platform in combination with the spring, it is possible to suppress the occurrence of resonance and exhibit a higher vibration isolation function as a whole. it can. Furthermore, when it is configured to increase or decrease the attractive force of the electromagnet provided on the intermediate table in accordance with the increase or decrease of the load acting on the vibration isolation table provided with the permanent magnet, or the actuator provided on the intermediate table In the case where the elongation is increased or decreased according to the increase or decrease of the load acting on the vibration isolation table, wiring to the vibration isolation table can be avoided, so that the control equipment is simplified.

Further, the attraction force of the composite magnet composed of the electromagnet and the permanent magnet provided on the intermediate table to the vibration isolation table provided with the ferromagnetic material is increased or decreased according to the increase or decrease of the load acting on the vibration isolation table. In this case, wiring to the vibration isolation table can be avoided, and at the same time, it becomes easy to manufacture the vibration isolation table in which only the ferromagnetic material is installed. Furthermore, when the electromagnet provided on the vibration isolation table is configured to increase / decrease the attraction force with respect to the intermediate table provided with the permanent magnet according to the increase / decrease of the load acting on the vibration isolation table, only the permanent magnet is provided. It is possible to simplify the configuration of the intermediate platform on which is installed. Further, the attraction force of the composite magnet composed of the electromagnet and the permanent magnet provided on the vibration isolation table to the intermediate base provided with the ferromagnetic material is increased or decreased according to the increase or decrease of the load acting on the vibration isolation table. In this case, it becomes easy to manufacture an intermediate stand on which only a ferromagnetic material is installed.

Further, when a magnetic levitation mechanism having zero power characteristics is disposed between the floor and the first member, or supported by a support mechanism having a predetermined negative spring characteristic that is configured of an actuator and a control device for the floor. And a vibration isolation table supported by a spring having a predetermined positive spring constant on the intermediate table, the magnetic force control of the magnetic levitation mechanism or the control of the actuator is on the stationary side. Since it can be performed between floors, wiring and the like are simplified. Further, when a spring having a predetermined spring constant and a damping device having a predetermined damping rate are installed between the intermediate platform and the vibration isolation table in combination with the actuator, the weight of the vibration isolation table is supported by the spring. As a result, the energy consumption of the actuator can be reduced, and the damping characteristics can be improved by avoiding resonance of the vibration isolation system. Thus, according to the present invention, a vibration isolation method that ensures high rigidity against linear motion disturbance without damaging the vibration insulation performance against ground motion disturbance, exhibits high vibration isolation function and enables precision machining, and the like. An apparatus is provided.

According to the present invention, a spring having a predetermined positive spring characteristic is disposed between the floor and the first member to insulate vibration transmitted from the floor to the first member, and the first member and the load are mounted. A negative spring characteristic is provided between the second member and the second member by a support mechanism including an actuator and a control device, and vibration transmitted from the first member to the second member is insulated from the first member. Insulates vibration transmitted to the two members, ensures high rigidity against linear motion disturbance without impairing vibration isolation performance against vibration disturbance of the vibration isolation table, enables high vibration isolation function and enables precision machining, etc. Of course, various actuators can be used to obtain negative spring characteristics, and the degree of freedom in design is improved.

Embodiments of the vibration isolation method and apparatus of the present invention will be described below with reference to the drawings. In the present invention, a support mechanism having a positive spring characteristic and a support mechanism having a negative spring characteristic are connected in series, thereby providing almost infinite rigidity against a linear motion disturbance generated on the apparatus. In addition, an embodiment using a magnetic levitation mechanism having zero power characteristics as a support mechanism having negative spring characteristics will be described first. FIG. 1 shows a first embodiment of a vibration isolation method and apparatus according to the present invention. In the present invention, a spring 5 is disposed between a floor 6 and a first member 1 which is an intermediate platform. 6 which insulates the vibration transmitted from the first member 1 to the first member 1 and has a zero power characteristic composed of a permanent magnet 3 and an electromagnet 4 between the first member 1 and the second member 2 which is a vibration isolation table. By providing a levitation mechanism, the vibration transmitted from the first member 1 to the second member 2 is insulated. In the present embodiment, the intermediate base 1 supported by a spring 5 having a predetermined positive spring constant kP with respect to the floor 6, and the permanent base 3 and the electromagnet 4 with respect to the intermediate base 1 are provided. And a vibration isolation table 2 supported by a magnetic levitation mechanism having a zero power characteristic with a negative spring constant ks. In the illustrated example, the permanent magnet 3 provides the attractive force of the electromagnet 4 provided on the intermediate stand 1. The vibration isolation table 2 is configured to be controlled by an appropriate control device (not shown) so as to increase / decrease according to the increase / decrease of the load caused by the increase in mass or the like of the vibration isolation table 2.

As shown in FIG. 2A, the ferromagnetic material 7 may be arranged on the vibration isolation table 2 side in combination with the permanent magnet 3 in order to increase the attractive force by the magnet. Alternatively, as shown in FIG. 2B, the permanent magnet 3 may be embedded in the iron core of the electromagnet 4 to form a composite magnet, and only the ferromagnetic material 7 may be installed on the vibration isolation table 2 side. Further, the arrangement of the electromagnet and the permanent magnet is reversed, that is, the electromagnet 4 is provided on the vibration isolation table 2 side, the permanent magnet 3 is provided on the intermediate stand 1 side, and the load applied to the vibration isolation table 2 is increased or decreased. You may comprise so that it may increase / decrease according to. Also in this case, as shown in FIG. 2C, the ferromagnetic material 7 may be installed on the intermediate table 1 side in combination with the permanent magnet 3. Alternatively, as shown in FIG. 2D, the permanent magnet 3 may be embedded in the iron core of the electromagnet 4 to form a composite magnet, and only the ferromagnetic body 7 may be installed on the intermediate platform 1 side.

Next, a zero power magnetic levitation control system employed between the intermediate platform and the vibration isolation table in the present invention will be described with reference to FIGS. Zero power control is an attraction type magnetic levitation system configured by combining an electromagnet and a permanent magnet. As shown in FIG. 3, the weight of the vibration isolation table 12 that is a levitating object is determined only by the attraction force of the permanent magnet 13. This is a control method in which the coil current of the electromagnet 14 on the support fixing side 11 is constantly maintained at zero while being supported. In the stationary state “a”, the vibration isolation table 12 stays at the stationary position in a state where the forces are balanced. However, as shown in the load “b”, the vibration isolation table 12 has a constant downward external force (mass increase Δm, etc.). ) Is applied, a current is applied to the coil of the electromagnet 14 to generate an attraction force for pulling up the vibration isolation table 12, and the attraction force by the permanent magnet 13 and the downward force are controlled to be balanced, as shown in c As described above, the current flowing through the electromagnet 14 becomes zero at a position where the gap becomes narrow, and the stationary state is established. Although the control system that performs the above operation is omitted in FIG. 1, as shown in d, the position relative to the support and fixing side of the vibration isolation table 12 that is a floating object (the intermediate platform in the apparatus of FIG. 1). A control circuit 22 for generating a control signal for levitating and holding the vibration isolation table 12 while constantly holding the coil current of the electromagnet 14 at zero based on an output signal of the sensor 21; This is realized by using a control device 20 including a power amplifier 23 and the like for supplying a predetermined current to the coil of the electromagnet 14 according to the output of the control circuit 22.

FIG. 4 illustrates a comparison with a normal spring system. As shown on the left side of the drawing, in the normal spring system, a mass m22 supported by a spring having a predetermined positive spring constant causes a mass increase Δm. In other words, so-called passive vibration isolation control that moves in the direction of mass increase (load) is performed. On the other hand, in the zero power control, as shown on the right side of the drawing, when the mass increase Δm occurs, the electromagnet 14 is controlled so that the mass m12 moves upward in the opposite direction to the spring system to narrow the gap. Is done. Therefore, it behaves as if it has a negative spring constant. By utilizing the property of the negative spring constant realized by this zero power control, in the present invention, even if the mass change on the spring occurs by combining with the passive vibration isolation control by the normal positive spring constant, the mass m, that is, the vibration isolation table or the like is configured so as not to be displaced.

That is, as shown in FIG. 1B, when a constant downward external force F0 (= Δmg) is applied to the vibration isolation table 2 due to a mass increase Δm or the like, the electromagnet installed on the intermediate stand 1 by the action of zero power control. The distance between 4 and the vibration isolation table is shortened by F0 / ks (ks is a negative spring constant realized by zero power control). Therefore, if the vibration isolation device is designed so as to satisfy the relationship ks = kP, the vibration isolation table will not be displaced at all. Describing using the equation (1) kc = k1 k2 / (k1 + k2) When a negative spring constant satisfying the relationship k1 = -k2 can be realized by zero power control,
| Kc | = + ∞ (2)
A spring constant is obtained. That is, by combining a positive spring and a negative spring having the same spring constant, a spring having an infinite spring constant can be obtained. This means zero compliance.

ここで、ｘ1 、ｘ2 ：中間台、除振テーブルの平衡点からの変位
ｘ0 ：床の振動変位
ｋP ：床から中間台を支持するばねのばね定数
ｆc ：磁石の吸引力の動作点からの変動分
ｆd ：除振テーブルに作用する直動外乱
また、ｃP は、図１には示されていないが、ばね５と並列に設置された減衰装置の減衰係数である。減衰装置がない場合はｃP ＝０とすればよい。磁石の吸引力の変動分は、近似的に次のように表される。
ｆc ＝ｋs （ｘ2 −ｘ1 ）＋ｋi ｉ （６）
ここで、ｋs ：磁石の変位・吸引力係数
ｋi ：磁石の電流・吸引力係数
ｉ：制御電流 Hereinafter, a theoretical analysis is performed on the vibration isolation control system of the present invention shown in FIG.
<Basic equation> In this analysis, only the vertical displacement of each mass and floor is handled. The equation of motion of this system is obtained as follows:

Where x1, x2: intermediate platform, displacement from the equilibrium point of the vibration isolation table x0: vibration displacement of the floor kP: spring constant of the spring supporting the intermediate platform from the floor fc: fluctuation of the magnetic attraction force from the operating point Minute fd: Linear motion disturbance acting on the vibration isolation table Further, cP is a damping coefficient of a damping device that is not shown in FIG. If there is no attenuator, cP = 0. The fluctuation of the magnet attractive force is approximately expressed as follows.
fc = ks (x2-x1) + kii (6)
Where ks: displacement / attraction force coefficient of magnet ki: current / attraction force coefficient of magnet
i: Control current

<Zero power control system> Here, the control input is constituted by the relative displacement between the intermediate platform and the vibration isolation table. In this case, the control input to achieve zero power control can generally be expressed as:
I (s) =-c2 (s) s (X2 (s) -X1 (s)) (7)
Here, c2 (s) is a strong proper transfer function having no zero and is selected so that the control system becomes stable. If the dynamics of the intermediate stage can be ignored, stabilization can be achieved by a controller having an order of 2 or more.

<Analysis of basic characteristics> For simplicity, assuming that the initial condition is zero and performing Laplace transform, the following formula is obtained from formulas (4) to (7).
X1 (s) = (cP s + kP) t2 (s) X0 (s) / tc (s) + (ki c2 (s) s-ks) Fd (s) / tc (s) (8)
X2 (s) = (cPs + kP) (kic2 (s) s-ks) X0 (s) / tc (s) + (m1s2 + (cP + kic2 (s)) s + kP-ks) Fd (s) / tc (S) (9)
Where t1 (s) = m1 s2 + cP s + kP (10)
t2 (s) = m2 s2 + ki c2 (s) s-ks (11)
t3 (s) = t1 (s) t2 (s) + m2 s2 (ki c2 (s) s-ks)
(12)

The Laplace transform of each variable is represented by the corresponding capital letter. Fd = F0 / s (F0: const) (13)
And If the influence of floor vibration is ignored (x0 = 0), the steady displacement x2 (∞) of the vibration isolation table is obtained as follows.
x2 (∞) / F0 = lim (m1 s2-(cP + k1 c2 (s)) s + kP
s → 0
-Ks) / lc (s) = (kP-ks) / kP (-ks) = 1 / kP-1 / ks (14)
Therefore, kP = ks (15)
If the vibration isolation device is designed to satisfy
x2 (∞) / F0 = 0 (16)
It becomes. This means that the compliance is zero, that is, the stiffness is infinite. Further, the displacement x1 (∞) of the intermediate platform and the amount of change in the gap between the electromagnet and the vibration isolation table (x1 (∞) −x2 (∞)) are obtained as follows.
x1 (∞) / F0 = 1 / kP (17)
(X1 (∞) −x2 (∞)) / F0 = 1 / ks (18)
Therefore, it was confirmed that when the downward force (F0 <0) acts on the vibration isolation table, the intermediate table is displaced downward, while the vibration isolation table is displaced upward so as to approach the intermediate table. As described above, in the vibration isolator using the zero power magnetic levitation mechanism, the spring constant of the mechanical spring supporting the intermediate base and the magnitude of the displacement / attraction force coefficient of the magnet are set to be equal to each other to prevent direct acting disturbance. It has been theoretically shown that the stiffness is infinite.

FIG. 5 shows a vibration isolation method and a basic experimental apparatus for the apparatus of the present invention. FIG. 5 (A) is a front view of the experimental apparatus, and FIG. 5 (B) is a side view thereof. An intermediate platform 1 is installed via springs 5a and 5b fitted and inserted into linear shafts 9a and 9b standing from a base 10 fixed to the floor, and the linear shafts 9a and 9b are fitted into the intermediate platform. The linear bushes 8a and 8b installed at 1 restrain the motion of the intermediate platform 1 to translational motion with one degree of freedom in the vertical direction. On the other hand, the guide blocks 15a and 15b installed on both sides of the lower part of the vibration isolation table 2 engage with the guide rails 16a and 16b provided upright on the base 10, and the motion of the vibration isolation table 2 is one degree of freedom in the vertical direction. Restrained to translational movement. Permanent magnets 3, 3 facing upward are installed at the lower end of the vibration isolation table 2, and an electromagnet 4 is installed at the lower part of the facing intermediate platform 1. The sensor 17 detects the relative displacement of the vibration isolation table 2 with respect to the intermediate base 1, and the sensor 18 detects the relative displacement of the intermediate base 1 with respect to the base 10.

Next, with reference to FIG. 6 and FIG. 7, the results of experiments conducted using the prototype basic experimental apparatus will be described. FIG. 6 is a result of an experiment on the negative spring characteristic of the zero power magnetic levitation system. In the case where the intermediate stand 1 is fixed and the mass of the vibration isolation table is increased to 1700 g, 1310 g, and 700 g, the additional mass Δm is increased. The displacement of the table was measured, and the table displacement increased linearly at any mass, and it was found that zero power control was operating as a linear negative spring. It can also be seen that the spring constant of zero power control can be set to various values by manipulating the mass of the vibration isolation table.

Fig. 7 shows the experimental results of the displacement of the vibration isolation table against the floor with the intermediate stand supported by the spring. The positive spring constant is 6.825 (kN / m), and the positive and negative spring constants are almost the same. It can be estimated that the table mass is in the range of 1280 g to 1400 g based on the vicinity of 1300 g. Incidentally, the negative spring constant at 1310 g is about 7 kN / m. According to the figure, it can be seen that when the table mass is 1380 g, the vibration isolation table displacement amount is 20 μm, and the table position is operating well while maintaining the initial position. This value of 1380 g is a value within the range estimated before the experiment, and it can also be seen that the operating performance decreases as the difference between the positive and negative spring constants increases.

From these relationships, the effectiveness of the theoretical analysis shown above was confirmed. The zero-compliance mechanism, which combines the zero-power magnetic levitation mechanism and the spring mechanism, makes the displacement of the vibration isolation table relative to the floor zero and allows infinite table rigidity against linear motion disturbance. In the actually measured range, the maximum rigidity of the table with respect to the floor is about 490 kN / m. At this time, the displacement of the vibration isolation table with respect to the floor also shows the minimum value. It was confirmed that by combining the zero power magnetic levitation mechanism and the spring, the compliance can be made almost zero, and thereby the rigidity against the direct acting disturbance can be extremely increased.

FIG. 8 shows a second embodiment of the vibration isolation method and apparatus according to the present invention, which is composed of a permanent magnet 203 and an electromagnet 204 with respect to a column 207 installed on a floor 206, and a predetermined negative spring. An intermediate table 201 supported by a magnetic levitation mechanism having a zero power characteristic having a constant KS, and a vibration isolation table 202 supported by the intermediate table 201 by a spring 205 having a predetermined positive spring constant Kp, In this example, the electromagnet 204 is controlled by an appropriate control device (not shown) so as to increase / decrease the attractive force of the electromagnet 204 provided on the support 207 according to the increase / decrease of the load applied to the intermediate table 201 provided with the permanent magnet 203. And the intermediate table 201 are controlled to be controlled.

With such a configuration, when a downward constant external force F0 (= Δmg) is applied to the vibration isolation table 202 due to a mass increase Δm or the like, the spring 205 supporting the vibration isolation table 202 is compressed by F0 / KP and shortened. At the same time, a downward external force F0 is also applied to the intermediate table 201 by the reaction force of the spring 205, and the distance between the electromagnet 204 and the intermediate table 201 is shortened by F0 / KS due to the action of zero power control. Will be displaced upward by this amount. Therefore, if the vibration isolation device is designed so as to satisfy the relationship KS = KP, the vibration isolation table 202 will not be displaced at all. This means that the compliance is zero, that is, the stiffness is infinite. That is, it is understood that the vibration isolation device shown in FIG. 8 has the same vibration isolation performance as the vibration isolation device shown in FIG.

FIG. 9 shows a third embodiment of the vibration isolation method and apparatus according to the present invention. An intermediate platform 303 supported on a floor 300 by a spring 301 having a predetermined positive spring constant KP and a damping device 302; A magnetic levitation mechanism having a zero power characteristic, which is composed of a permanent magnet 304 and an electromagnet 305 with respect to the intermediate base 303 and has a predetermined negative spring constant KS, and a spring 311 having a predetermined positive spring constant KP ′ on the floor 300 and Supported by an intermediate platform 313 supported by the damping device 312 and a magnetic levitation mechanism having a zero power characteristic, which is composed of a permanent magnet 314 and an electromagnet 315 with respect to the intermediate platform 313 and has a predetermined negative spring constant KS ′. The anti-vibration table 320 is configured.

In such a configuration, if the vibration isolator is designed so as to satisfy the relationship of KS = KP and KS '= KP', the left side (intermediate base 303 side) and right side (intermediate base 313 side) of the vibration isolation table 320 ), The compliance is zero, that is, the rigidity is infinite. Therefore, the vibration isolation table 320 is not displaced at all regardless of the position on the vibration isolation table 320 where a constant external force is applied in the vertical direction. From such characteristics, when the movable stage 321 is installed on the vibration isolation table 320, the vibration isolation table 320 is not displaced regardless of the position of the moving load 322, and the posture can be kept horizontal.

FIG. 10 shows a fourth embodiment of the vibration isolation method and apparatus according to the present invention. In the floor 400, a spring 401 and a damping device 402 having a predetermined positive spring constant KP 1 in the vertical direction and in the horizontal direction are shown. Is an intermediate base 405 supported by a spring 403 having a predetermined positive spring constant KP 2 and a damping device 404, and a predetermined magnet configured by a permanent magnet 406 and an electromagnet 407 in a direction perpendicular to the intermediate base 405. A magnetic levitation mechanism having a zero power characteristic having a negative spring constant KS 1 and a magnetic levitation mechanism having a zero power characteristic having a predetermined negative spring constant KS 2 composed of a permanent magnet 408 and an electromagnet 409 in the horizontal direction. Furthermore, a spring 411 and a damping device 412 having a predetermined positive spring constant KP 3 in the vertical direction and a spring 413 having a predetermined positive spring constant KP 4 in the horizontal direction are supported on the floor 400. And a zero power characteristic having a predetermined negative spring constant KS 3 composed of a permanent magnet 416 and an electromagnet 417 in the vertical direction with respect to the intermediate table 415 supported by the damping device 414 and the intermediate table 415. And a vibration isolation table 420 supported by a magnetic levitation mechanism having a zero power characteristic having a predetermined negative spring constant KS 4 composed of a permanent magnet 418 and an electromagnet 419 in the horizontal direction. It is a thing.

In such a configuration, if the vibration isolator is designed so as to satisfy the relations KS 1 = KP 1, KS 2 = KP 2, KS 3 = KP 3 and KS 4 = KP 4, On the left side (intermediate base 405 side) and on the right side (intermediate base 415 side), the compliance is zero, that is, the rigidity is infinite, and the horizontal compliance on the vibration isolation table 420 is also zero. Even if a constant external force in the vertical and horizontal directions is applied to the vibration isolation table 420, the vibration isolation table 420 is not displaced at all.

Next, with reference to FIG. 13 to FIG. 27, a vibration isolation method using a support mechanism composed of an actuator and a control device as a support mechanism having a negative spring characteristic, and a theoretical analysis and embodiment of the device will be described. . FIG. 13 shows an intermediate platform 1 supported on a floor 6 by a spring 5 having a predetermined positive spring constant, and an actuator 25 and a control device 26 for the intermediate platform 1 to form a predetermined negative load. The vibration isolation table 2 is supported by a support mechanism having a spring constant of, and as the actuator 25, a linear actuator such as a voice coil motor, a linear motor, a pneumatic actuator, or a hydraulic actuator is employed. The control device 26 includes a displacement sensor 27 that detects the displacement of the vibration isolation table 2 with respect to the intermediate platform 1, a control circuit 28, and a power amplifier 29.

In the configuration shown in FIG. 14, an attenuation device 19 having a predetermined attenuation rate is installed between the floor 6 and the intermediate platform 1 along with the spring 5, so that the damping characteristics can be avoided while avoiding resonance of the vibration isolation system. It is an improvement. FIG. 15 shows a structure in which a spring 30 having a predetermined spring constant and a damping device 31 having a predetermined damping rate are installed between the intermediate platform 1 and the vibration isolation table 2 along with the actuator 25. By supporting the weight of the vibration isolation table 2 at 30, the energy consumption of the actuator 25 can be reduced, and further, the damping characteristic can be improved by avoiding resonance of the vibration isolation system. FIG. 16 shows a combination of those shown in FIG. 14 and FIG. In other words, a damping device 19 having a predetermined damping rate is installed between the floor 6 and the intermediate table 1 along with the spring 5, and an actuator 25 is installed between the intermediate table 1 and the vibration isolation table 2. A spring 30 having a predetermined spring constant and a damping device 31 having a predetermined damping rate are installed.

The negative spring characteristics will be described with reference to FIGS.
<Normal Spring Characteristic (Positive Spring Characteristic)> As shown in FIG. 17A, on a table 24 of mass m supported by a normal spring having a predetermined positive spring constant (k), If a new mass Δm is generated as shown in FIG. 17B and a downward external force Δm is applied, the spring is contracted by Δmg / k, and the table 24 is displaced by Δmg / k in the same direction as the external force. The distance to is L-Δmg / k.
<Negative Spring Characteristics> In FIG. 18A, the gravity mg acting on the mass m table 24 and the force generated in the actuator 25 are balanced, and the distance between the floor 6 and the mass m is kept at L. Suppose that As shown in FIG. 18B, when a mass increase Δm is newly generated on the table 24 and a downward external force Δmg is applied, the actuator 25 extends and the distance of the mass m from the floor 6 increases to L + ΔL. Suppose that At this time, the table 24 is displaced by ΔL in the direction opposite to the external force. It can be said that this system has a negative spring characteristic. The magnitude of the negative spring constant ks is given by ks = Δmg / ΔL.

19 shows the behavior when a system in which a spring 30 and a damping device 31 are provided in parallel with the actuator 25 has a negative spring characteristic like the vibration isolator shown in FIGS. 15 and 16. In FIG. 19A, the gravity mg acting on the table 24 of mass m, the force generated in the actuator 25, and the spring force of the spring 30 are balanced, and the distance between the floor 6 and the mass m is L. Suppose that As shown in FIG. 19 (b), when a mass increase Δm is newly generated on the table 24 and a downward external force Δmg is applied, the actuator 25 extends, and the distance of the mass m from the floor 6 becomes smaller. Suppose that it has a characteristic of increasing to L + ΔL. At this time, similarly to the case shown in FIG. 18, the table 24 is displaced by ΔL in the direction opposite to the external force, so it can be said that this system has a negative spring characteristic. The magnitude of the negative spring constant is given by ks = Δmg / ΔL.

<Response to the linear motion disturbance of the vibration isolation device> Here, the response to the linear motion disturbance of the vibration isolation device shown in FIG. 13 will be described with reference to FIG. If a downward constant force F0 (= Δmg) is applied to the vibration isolation table 2 due to a mass increase Δm or the like, a negative spring characteristic is realized. Therefore, the distance between the vibration isolation table 2 and the intermediate table 1 is Δmg / ks. Only increase. On the other hand, if the spring constant is k1, the spring 5 contracts by Δmg / k1, so the distance between the intermediate platform 1 and the floor 6 decreases by Δmg / k1. Therefore, if the vibration isolation device is designed so as to satisfy the relationship kS = k1, the vibration isolation table 2 is not displaced at all. That is, a spring having an infinite spring constant is realized by connecting a positive spring and a negative spring having the same spring constant in series.

<First Control Method for Realizing Negative Spring Characteristics> A method for realizing negative spring characteristics in the system shown in FIG. 19 will be described with reference to FIG. A control device 28 including a displacement sensor 27, a control circuit 28, and a power amplifier 29 is added to the system shown in FIG. These elements correspond to the displacement sensor 27, the control circuit 28, and the power amplifier 29 in FIGS. The control circuit 28 is configured by the following mechanism. The external force estimation mechanism 28A estimates an external force fd (corresponding to -Δmg in the example shown in FIG. 19) acting on the table 24 based on information from the displacement sensor 27. When the estimated value is expressed as f ^ d, the target displacement generation mechanism 28B calculates a target displacement determined from the negative spring characteristic to be realized based on the output from the external force estimation mechanism 28A. If the negative spring constant to be set is ks, the target displacement xref is obtained from the following equation.
xref = -f ^ d / kS (19)
However, the case where the sign of the displacement is the same as the direction of the external force is positive. The position control mechanism 28C controls the displacement of the table 24 so as to coincide with the target displacement. Specifically, a control signal for expanding and contracting the actuator 25 by the target displacement obtained by Expression 19 is generated and output to the power amplifier circuit 29. The power amplifier circuit 29 drives the actuator 25 according to the control signal.

ここで、
ｍ2 ：テーブル２４の質量
ｘ ：テーブル２４の平衡点からの変位
ｋa ：アクチュエータ２５と並列に挿入されたばね３０のばね定数
ｃa ：アクチュエータ２５と並列に挿入された減衰装置３１の減衰係数
ｆa ：アクチュエータ２５の発生力
ｆd ：テーブル２４に作用する直動外乱
アクチュエータ２５に発生する力は、コイル電流に比例するので、次のように表される。ｆa ＝ｋi ｉ, （２１）
ここで、
ｋi ：ボイスコイルモータの推力定数
ｉ ：制御電流 <Theoretical Analysis> Here, a case where a voice coil motor is used as the actuator 25 will be described. Similarly, when using other actuators, a negative spring characteristic can be realized. FIG. 22 shows a mechanical model. The equation of motion of this system is obtained as follows:

here,
m2: Mass of the table 24 x: Displacement from the equilibrium point of the table 24 ka: Spring constant ca of the spring 30 inserted in parallel with the actuator 25: Damping coefficient fa of the damping device 31 inserted in parallel with the actuator 25: Actuator 25 Generated force fd: The force generated in the direct acting disturbance actuator 25 acting on the table 24 is proportional to the coil current, and is expressed as follows. fa = ki i, (21)
here,
ki: thrust constant i of voice coil motor: control current

制御系を設計するときには、直動外乱ｆd は一定であるとする。すなわち、

式（２２）（２３）をまとめて状態空間表示すると、次式が得られる。

ここで、

ｕ＝ｉ，ａ0 ＝ｋa ／ｍ2 ，ａ1 ＝ｃa ／ｍ2 ，ｂ0 ＝ｋi ／ｍ2 ，ｄ0 ＝１／ｍ2オブザーバ理論を適用することによって、センサ２７によって検出されるテーブル２４の変位ｘから、テーブル２４に作用する外力を推定することができる。 Substituting equation (21) into equation (20) yields:

When designing the control system, the linear motion disturbance fd is assumed to be constant. That is,

When the expressions (22) and (23) are collectively displayed in the state space, the following expression is obtained.

here,

u = i, a0 = ka / m2, a1 = ca / m2, b0 = ki / m2, d0 = 1 / m2 From the displacement x of the table 24 detected by the sensor 27 by applying the observer theory, the table 24 It is possible to estimate the external force acting on the.

ここで、

行列Ｅは、オブザーバのゲインと呼ばれる行列で、これを定める手順を以下に述べる。実際の状態ベクトルｘ（ｔ）とその推定値ｘ＾（ｔ）との間の誤差ベクトル

は次式を満足する。

したがって、行列（Ａ−ＥＣ）の固有値がすべて負の実部を持てば、

となる。 When using the same dimensional observer, the dynamic characteristic of the observer is expressed by the following equation.

here,

The matrix E is a matrix called an observer gain, and the procedure for determining it will be described below. Error vector between actual state vector x (t) and its estimated value x ^ (t)

Satisfies the following equation.

Therefore, if all eigenvalues of the matrix (A-EC) have negative real parts,

It becomes.

The eigenvalue of the matrix (A-EC) is called the observer pole, which is the characteristic polynomial of the matrix (A-EC) det [sI- (A-EC)] = s3 + (a1 + e1) s2 + (a0 + a1 e1 + E2) s + d0 e3 (29)
It is requested from. Here, the poles of the observer
Λ = {− λ1, −λ2, −λ3} (30)
The observer gain E is determined so that Where λ1 is
Re [λ1]> 0 (i = 1, 2, 3) (31)
It is assumed that it is selected to satisfy A characteristic polynomial determined from the pole to be arranged is obtained as follows.
td (s) = (s + λ1) (s + λ2) (s + λ3) = s3 + (λ1 + λ2 + λ3) s2 + (λ1λ2 + λ2λ3 + λ3λ1) s + λ1λ2λ3 (32)
By comparing the equations (29) and (32), the observer gain E is determined as the following equation.
e1 = λ1 + λ2 + λ3 -a1 (33)
e2 = λ1 λ2 + λ2 λ3 + λ3 λ1 -a0 -a1 e1 (34)
e3 = λ1 λ2 λ3 / d0 (35)

が成立する。設定する負のばね定数の大きさをｋs とすると、目標変位ｘref は次式から求められる。

オブザーバ（２５）によって求められるｆd の推定値である。位置制御には、Ｉ−ＰＤ制御を適用する。すなわち、制御入力を次式のように定める。

When the observer gain E is determined as described above, if f ^ d is an estimated value of fd, the following relationship is established.
f ^ d = fd + c1exp (-[lambda] 1t) + c2exp (-[lambda] 2t) + c3exp (-[lambda] 3t) (36)
Here, c1, c2, and c3 are constants determined from the initial conditions of the controlled object and the observer. From the condition of Equation 31,

Is established. Assuming that the negative spring constant to be set is ks, the target displacement xref can be obtained from the following equation.

This is an estimated value of fd obtained by the observer (25). For position control, I-PD control is applied. That is, the control input is determined as follows:

ここで、ラプラス変換された変数は、対応する大文字で示している。フィードバックゲインｐI 、ｐd 、ｐV が閉ループ系の極が安定になるように選定さているとき、式（３６）（４０）から、式（２３）を満たすｆd に対して、

が成立する。したがって、ばね定数の大きさｋs の負のばね特性が実現される。 By substituting equation (35) into equation (21) and rearranging the Laplace transformed equation, the following equation is obtained.

Here, the Laplace-transformed variable is indicated by a corresponding capital letter. When the feedback gains pI, pd, and pV are selected so that the poles of the closed loop system are stable, from the equations (36) and (40), fd satisfying the equation (23)

Is established. Therefore, a negative spring characteristic with a spring constant magnitude ks is realized.

<Second Control Method for Realizing Negative Spring Characteristics> Here, a method for directly configuring a control input for realizing negative spring characteristics without explicitly using an observer or a position control system will be described. A transfer function expression method is used for derivation on the control side. For simplicity, when the Laplace transform is performed with the initial condition set to zero, the following equation is obtained from equations (20) and (21).
X (s) = (b0 I (s) + d0 Fd (s)) / (s2 + a1 s + a0)
(42)
The control input i (t) (I (s)) is determined based on the signal of the displacement sensor. When linear control of time-invariant gain is performed, the control law is generally expressed as follows: be able to.
I (s) =-p (s) X (s) (43)
When a controller having a proper transfer function is used, it can be generally expressed as the following equation.
p (s) = h (s) / g (s) = (hn sn + hn-1 sn-1 +... + h1 s + h0) / (sn + gn-1 sn-1 +... + g1 s + g0) (44)
When using a controller with a strictly proper transfer function, hn = 0 (45)
It becomes.

Substituting equation (43) into equation (42) and rearranging results in the following equation.
X (s) = (g (s) / ((s 2 + a 1 s + a 0) g (s) + b 0 h (s)
)) D0 Fd (s) (46)
To evaluate the stiffness against linear motion disturbance,
Fd (s) = F0 / s (F0 is constant) (47)
And Assuming that the control law is selected so that the closed-loop system is stable, the steady displacement x (∞) is obtained as follows.
x2 (∞) / F0 = lim ((g (s) / ((s2 + a1 s + a0) g (s
t → 0
) + B0 h (s))) d0 = d0 g0 / (a0 g0 + b0 h0) (48)
From equation (48), it can be seen that g (s) and h (s) should be selected so as to satisfy the following equation in order for this system to have a negative spring stiffness of size ks.
d0 g0 / (a0 g0 + b0 h0) =-1 / ks (49)
∴ka + ki h0 / g0 = -ks (50)
When a controller having a proper transfer function is used, it is necessary to have an order of n = 2 or more in order to satisfy the equation (49) and to stabilize the closed loop system. Conversely, if this condition is satisfied, the poles of the closed loop system can be arbitrarily arranged. In the case of n = 2, the characteristic polynomial tc (s) of the closed loop system is obtained from the equation (46) as follows:
tc (s) = s4 + (a1 + g1) s3 + (a0 + g0 + a1 g1 + b0 h2) s2 + (a0 g1 + a1 g0 + b0 h1) s + (a0 g0 + b0 h0) (51)

とすると、コントローラの係数が次のように求められる。
ｇ0 ＝−ｃ0 ／ｄ0 ｋn ＝−ｃ0 ｍ／ｋs （５９）
ｇ2 ＝ｃ4 −ａ1 （６０）
ｇ1 ＝ｃ3 −ａ0 −ａ1 ｇ2 （６１）
ｈ0 ＝ｃ0 （ａ0 ／ｄ0 ｋs ＋１）／ｂ0 ＝ｃ0 （ｋ／ｋs ＋１）／ｂ0 （６２）
ｈ1 ＝（ｃ1 −ａ0 ｇ1 −ａ1 ｇ0 ）／ｂ0 （６３）
ｈ2 ＝（ｃ2 −ａ0 ｇ2 −ａ1 ｇ1 −ｇ0 ）／ｂ0 （６４） Assume that the characteristic polynomial determined from the pole to be arranged is given by the following equation. td (s) = s4 + c3 s3 + c2 s2 + c1 s + c0 (52)
From the equations (50), (51), and (52), the coefficient of the controller that realizes a closed loop system having a negative spring stiffness of a set magnitude and having a desirable pole is obtained as follows.
g0 = -c0 / d0 ks = -c0 m / ks (53)
g1 = c3 -a1 (54)
h0 = (c0 -a0 g0) / b0 (55)
h1 = (c1-a0 g1-a1 g0) / b0 (56)
h2 = (c2-a0-g0-a1 g1) / b0 (57)
When a controller having a strictly proper transfer function is used, a controller having three or more orders is required in order to satisfy Equation (50) and arbitrarily arrange poles of the closed loop system. In the case of n = 3, the characteristic polynomial determined from the pole to be arranged is

Then, the coefficient of the controller is obtained as follows.
g0 = -c0 / d0 kn = -c0 m / ks (59)
g2 = c4 -a1 (60)
g1 = c3 -a0 -a1 g2 (61)
h0 = c0 (a0 / d0 ks +1) / b0 = c0 (k / ks +1) / b0 (62)
h1 = (c1-a0 g1-a1 g0) / b0 (63)
h2 = (c2-a0 g2-a1 g1-g0) / b0 (64)

ここでｘ1 ：中間台１の平衡点からの変位
ｘ2 ：除振テーブル２の平衡点からの変位
ｘ0 ：床６の振動変位
ｋ1 ：ばね５のばね定数
ｃ1 ：減衰装置１９の減衰係数
ｋa ：アクチュエータ２５と併設されたばね３０のばね定数
ｃa ：アクチュエータ２５と併設された減衰装置３１の減衰係数
ｆd ：除振テーブル２に作用する直動外乱
ｆa ：アクチュエータ２５（ボイスコイルモータ）の推力アクチュエータの発生する力は、コイル電流に比例するもで、次のように表される。
ｆa ＝ｋi ｉ （６７）
ここで、
ｋi ：ボイスコイルモータの推力定数
ｉ ：制御電流 <Operation Analysis of Vibration Isolator> Theoretical analysis is performed on the vibration isolator shown in FIG. FIG. 23 shows the dynamic model. It is assumed that a voice coil motor is used as the actuator, as in the above-described theoretical analysis of the control method for realizing the negative spring characteristic. <Basic Equation> It is assumed that the masses 1 and 2 and the floor 6 in FIG. 23 translate in the vertical direction. The equation of motion of this system is obtained as follows:

Where x1: displacement from the equilibrium point of the intermediate stand 1 x2: displacement from the equilibrium point of the vibration isolation table 2 x0: vibration displacement of the floor 6 k1: spring constant of the spring 5 c1: damping coefficient of the damping device 19 ka: actuator 25: Spring constant of the spring 30 attached to the actuator 25 ca: Damping coefficient of the damping device 31 attached to the actuator 25 fd: Linear motion disturbance acting on the vibration isolation table 2 fa: Generation of a thrust actuator of the actuator 25 (voice coil motor) The force is proportional to the coil current and is expressed as follows.
fa = ki i (67)
here,
ki: thrust constant i of voice coil motor: control current

<Control System Realizing Negative Rigidity (Control Method 2)> Here, the second control method is applied. If the control input is configured from the relative displacement between the intermediate platform and the vibration isolation table, the control input can be generally expressed as follows.
I (s) =-p (s) (X2 (s) -X1 (s)) = ((hn sn + hn-1 sn-1 +... + H1 s + h0) / (sn + gn-1 sn-1 + .multidot. .. + g1 s + g0)) (X2 (s) -X1 (s)) (68)
Here, it is assumed that p (s) is selected so as to stabilize the closed loop system and satisfy the following equation (see equation (50)).
k0 + ki h0 / g0 = -ks (69)
When the dynamics of the intermediate platform 1 can be ignored, the closed loop can be stabilized and the expression (69) can be satisfied at the same time by using a controller having an order of n = 2 or more.

<Analysis of basic characteristics> For simplicity, assuming that the initial condition is zero and performing Laplace transform, the following formula is obtained from formulas (65) to (68).
X1 (s) = (c1 s + k1) (m2 s2 + ca s + ka + ki p (s))
X0 (s) / tc (s) + (cas + ka + kip (s)) Fd (s) / tc (s)
(70)
X2 (s) = (c1 s + k1) (ca s + ka + ki p (s)) X0 (s)
/ Tc (s) + (m1 s2 + c1 s + k1 + ca s + ka + ki p (s)) Fd (s) / tc (s)
(71)
Tc (s) = (m1 s2 + c1 s + k1) (m2 s2 + ca s + ka + ki p (s)) + m2 s2 (ca s + ka + ki p (s)) (72)

To evaluate the stiffness against linear motion disturbance,
Fd = F0 / s (F0: constant) (73)
And If the influence of the vibration of the floor 6 is ignored (x0 = 0), the steady displacement x2 (∞) of the vibration isolation table 2 is obtained as follows.
x2 (∞) / F0 = lim (m1 s2 + c1 s + k1 + cas s + ka + ki
t → 0
p (s)) / tc (s) = (k1 + ka + ki h0 / g0) / k1 (ka + ki h0 / g0) (74)
From equation (69), x2 (∞) / F0 =-(k1 -ks) / k1 ks (75)
Therefore, k1 = ks (76)
If the vibration isolation device is designed to satisfy
x2 (∞) / F0 = 0 (77)
It becomes. This means that the compliance is zero, that is, the stiffness is infinite. In the above analysis, if c1 = 0, ka = 0, ca = 0, the analysis result relating to the vibration isolator shown in FIG. 13 is obtained, and if ka = 0, ca = 0, FIG. The analysis result regarding the vibration isolator shown in FIG. 15 is obtained. When c1 = 0 is set, the analysis result regarding the vibration isolator shown in FIG. 15 is obtained immediately.

FIG. 24 shows a vibration isolation method of the present invention and a basic experimental apparatus of the apparatus, and a voice coil motor 104 is provided on an intermediate stage 103 coupled to a base 100 via a pair of parallel leaf springs 101 and 102. Is attached. The movement of the intermediate stage 103 is constrained to a translational movement with one degree of freedom in the vertical direction by the parallel leaf springs 101 and 102. On the other hand, a vibration isolation table 106 is attached to the movable part 105 of the voice coil motor, and is driven so as to translate in the vertical direction by the voice coil motor. The sensor 107 detects the relative displacement of the vibration isolation table 106 with respect to the intermediate table 103, and the sensor 108 detects the relative displacement of the intermediate table 103 with respect to the base 100.

Next, with reference to FIG. 25 and FIG. 26, the results of experiments conducted using the prototype basic experimental device will be described. FIG. 25 is an experimental result regarding the negative spring characteristic realized by using the second control method (paragraph 0039 to paragraph 0041) that realizes the negative spring characteristic. When the intermediate stand 103 is fixed and the control system is designed. Measure the table displacement when the negative spring constant is set to (a) 15 kN / m, (b) 20 kN / m, (c) 25 kN / m, and the added mass Δm to the table is increased. It is a thing. In the figure, the vertical axis represents the load (= Δmg) [N] due to the additional mass Δm, and the horizontal axis represents the upward displacement [mm] of the table. From FIG. 25, it was found that in any of the cases (a) to (c), the table displacement increased linearly and a negative spring characteristic was realized. The measured negative spring constants are (a) 14.9 kN / m, (b) 19.7 kN / m, and (c) 25.1 kN / m. When designing the control system, It was found that it was almost the same as the set value. From this result, it can also be seen that the magnitude of the negative spring constant can be freely set by the value of k3 set in the festival for designing the control system.

FIG. 26 shows the experimental results of the displacement of the vibration isolation table with respect to the base and the displacement of the intermediate table with respect to the base with the intermediate table supported by the parallel leaf springs. The value of the positive spring constant by the parallel leaf spring is 16.4 kN / m, and the magnitude of the negative spring constant set at the festival for designing the control system is also 16.4 kN / m. From the figure, it can be seen that when the load on the table is increased, the intermediate table descends linearly, while the displacement of the table hardly occurs. When the load on the table is 5N, the displacement of the table is about 5 μm, and the rigidity with respect to the base is about 1000 kN / m, which is about 61 times the size of the positive spring constant or the set negative spring constant. Yes.

From these relationships, the effectiveness of the theoretical analysis shown above was confirmed. The zero-compliance mechanism that combines a spring mechanism with a negative spring characteristic support mechanism composed of a voice coil motor (actuator) and a control device theoretically makes the displacement of the vibration isolation table relative to the base (floor) zero. It is possible to have infinite rigidity against linear motion disturbance. In the actually measured range, the rigidity of the table base (floor) is about 1000 kN / m, and the displacement of the vibration isolation table relative to the floor at this time is 5 μm with respect to 5 N linear motion disturbance. By combining a support mechanism having a negative spring characteristic composed of a voice coil motor (actuator) and a control device and a spring mechanism, the compliance can be made almost zero. It was confirmed that the rigidity can be extremely increased.

27 to 30 show another embodiment. Although the basic structure is the same as that shown in FIGS. 13 to 16, the structure shown in FIGS. 13 to 16 is the spring 5 between the intermediate platform 1 and the floor 6, or the spring 5 and the damping device. 19 and the actuator 25 or the actuator 25 and the spring 30 and the damping device 31 are disposed between the intermediate table 1 and the vibration isolation table 2. In this case, a configuration is adopted in which the mechanism for supporting the intermediate table 1 and the mechanism for supporting the vibration isolation table 2 are exchanged. That is, in the one shown in FIGS. 27 to 30, a negative spring characteristic composed of an actuator and a control device is provided between the floor 6 and the intermediate platform 1 to insulate vibration transmitted from the floor to the intermediate platform 1. It is configured as follows. With this configuration, the control device 26 including the displacement sensor 27, the control circuit 28, the power amplifier 29, and the actuator 25 can be controlled with the floor 6 on the stationary side. Simplified.

The embodiments of the vibration isolation method and apparatus of the present invention have been described above. However, within the scope of the present invention, the shape and type of the intermediate platform and the vibration isolation table, the shape and type of the electromagnet and the permanent magnet, and Arrangement of them (electromagnets are installed on an intermediate stand or vibration isolation table, permanent magnets are installed on a vibration isolation table or intermediate stand, a ferromagnetic material is added to the permanent magnets, or permanent magnets are It may be configured to be incorporated in the iron core of the electromagnet and installed only on one of the vibration isolation table or the intermediate stand, and the other may be configured to install a ferromagnetic material), and the shape, type, and type of actuator, spring and damping device Arrangement on the intermediate platform (an appropriate damping device may be provided in addition to the spring between the floor and the intermediate platform), zero power control means, actuator control means (displacement sensor Type, control circuit type, power amplification form and actuator control form thereof), direction of vibration isolation (in each of the above-described embodiments, vibration isolation in the vertical direction has mainly been described. Needless to say, it can be configured so that the vertical direction and the horizontal direction are simultaneously vibration-isolated.

  The present invention can be used for an acceleration sensor for a vehicle. Further, the present invention is not limited to automobiles, and can be widely used in places where it is necessary to detect industrial acceleration.

It is explanatory drawing which shows 1st Embodiment using the magnetic levitation mechanism which has the zero power characteristic of the vibration isolating method of this invention, and its apparatus. It is a figure which shows the modification of 1st Embodiment. It is explanatory drawing of the characteristic of the zero power control system used by this invention. It is an operation | movement comparison figure of a spring system and a zero power control system. It is a figure which shows the vibration isolation method of this invention, and the basic experiment apparatus of the apparatus. It is an experimental result figure of the negative spring characteristic of a zero power magnetic levitation system. It is an experimental result figure of the displacement to the floor of a vibration isolation table. It is explanatory drawing which shows 2nd Embodiment of the vibration isolating method and its apparatus of this invention. It is explanatory drawing which shows 3rd Embodiment of the vibration isolating method and its apparatus of this invention. It is explanatory drawing which shows 4th Embodiment of the vibration isolating method and its apparatus of this invention. It is a conventional vibration isolation system for a spring system. It is explanatory drawing of the conventional active vibration isolator. It is explanatory drawing which shows 5th Embodiment using the support mechanism which has the negative spring characteristic using the vibration isolating method of this invention, the actuator of the apparatus, and a control apparatus. It is explanatory drawing which shows 6th Embodiment of the vibration isolating method and its apparatus of this invention. It is explanatory drawing which shows 7th Embodiment of the vibration isolating method and its apparatus of this invention. It is explanatory drawing which shows 8th Embodiment of the vibration isolating method and its apparatus of this invention. It is explanatory drawing of a positive spring characteristic. It is explanatory drawing of a negative spring characteristic. It is a negative spring characteristic behavior diagram by an actuator provided with a spring and a damping device. It is a response figure with respect to the linear motion disturbance of a vibration isolator. It is explanatory drawing of the control method which implement | achieves the negative spring characteristic using an actuator. It is a dynamic model figure using a voice coil motor as an actuator. It is a mechanical model figure of the vibration isolator of FIG. It is a basic experimental apparatus figure of the support mechanism which has a negative spring characteristic. It is a related figure of a load and the displacement of a table. It is a displacement figure of a table and an intermediate stand. It is explanatory drawing which shows 9th Embodiment of the vibration isolating method and its apparatus of this invention. It is explanatory drawing which shows 10th Embodiment of the vibration isolating method and its apparatus of this invention. It is explanatory drawing which shows 11th Embodiment of the vibration isolating method and its apparatus of this invention. It is explanatory drawing which shows 12th Embodiment of the vibration isolating method and its apparatus of this invention.

Explanation of symbols

1 Intermediate stand (first member)
2 Vibration isolation table (second member)
3 Permanent magnet 4 Electromagnet 5 Spring 6 Floor 7 Ferromagnetic material 19 Attenuator 25 Actuator 26 Controller 27 Displacement sensor 28 Control circuit 29 Power amplifier 30 Spring 31 Attenuator

Claims (10)

A spring having a predetermined positive spring characteristic is disposed between the floor and the first member to insulate vibration transmitted from the floor to the first member, and the first member and the second member for placing a load thereon A vibration isolation method comprising: providing a negative spring characteristic by a support mechanism including an actuator and a control device between the first member and the second member to insulate vibration transmitted from the first member to the second member. A negative spring characteristic is imparted between the support and the first member standing from the floor by a support mechanism including an actuator and a control device to insulate vibration transmitted from the support to the first member. Insulating vibration transmitted from the first member to the second member by disposing a spring having a predetermined positive spring characteristic between the first member and the second member disposed facing the one member An anti-vibration method characterized by: 3. The vibration isolation method according to claim 1, wherein the first member is an intermediate member, and the second member is a vibration isolation table. A floor, a spring having a predetermined positive spring constant, a first member supported on the floor by the spring, and a second member disposed opposite to the first member for mounting a load And a support mechanism having a negative spring characteristic composed of an actuator and a control device is disposed between the first member and the second member. A column erected on the floor; a first member disposed opposite to the column; a second member disposed opposite to the first member for placing a load; and the first member; And a spring having a positive spring constant disposed between the second member, and a support mechanism having a negative spring characteristic composed of an actuator and a control device is disposed between the column and the first member. An anti-vibration device characterized by that. The vibration isolator according to claim 4 or 5, wherein the first member is an intermediate member, and the second member is a vibration isolation table. The vibration isolator according to any one of claims 4 to 6, wherein an attenuator having a predetermined attenuation rate is installed along with the spring. The vibration isolation device according to any one of claims 4 to 7, wherein a spring having a predetermined spring constant and a damping device having a predetermined damping rate are installed in parallel with the actuator. The vibration isolation device according to any one of claims 4 to 8, wherein the actuator is configured to increase or decrease the elongation of the actuator according to an increase or decrease of a load. 10. The actuator according to claim 4, wherein the actuator is a linear actuator such as a voice coil motor, a linear motor, a pneumatic actuator, or a hydraulic actuator, and the control device includes a displacement sensor, a control circuit, and a power amplifier. The anti-vibration device according to the above.

Images