JPH0114525B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for controlling the rotation of a shaking table in a drive testing machine.

[Conventional technology]

Conventional vibration testing machines include one-dimensional types that vibrate a shaking table on which a specimen to be earthquake resistant is mounted in only one direction, two-dimensional types that vibrate in two intersecting directions, and 2 orthogonal in one plane
There is a three-dimensional type that vibrates both in the vertical direction and in the vertical direction. Particularly in recent years, there has been a demand for vibration testing machines that can accurately examine the earthquake resistance of large specimens. A three-dimensional type vibration tester is effective as a vibration tester that satisfies this requirement. For this reason, various large three-dimensional vibration testing machines have been developed. In this type of three-dimensional vibration testing machine, the vibration table is large, so it is common to have multiple vibrators forming a hydraulic servo system in each driving direction of the vibration table. . If the specimen is placed unbalanced on the vibration table, the operation of the vibrator in each axis direction will not be synchronized, and the vibration table will rotate around one axis in the plane, i.e. rolling R. This produces rotational movements such as rotation about one axis, or pitching P, and rotation or yawing O, about an axis perpendicular to said axis. For this reason, it is not possible to accurately perform an earthquake resistance test on the specimen. Therefore, conventionally, as disclosed in Japanese Patent Application Laid-Open No. 127652/1983, an input signal generator is connected to each servo valve via an amplifier, and an acceleration detector to detect the acceleration and a speed to the actuator are respectively connected. A speed detector is provided to detect the displacement, and a displacement detector is provided to detect the displacement.
An adder that connects the acceleration detector, speed detector, and displacement detector of each actuator to each servo amplifier in a feedback manner and detects the difference in acceleration from the acceleration detector between one actuator and the other actuator, and a speed detector. There is one in which an adder for detecting the speed difference from the actuator and an adder for detecting the displacement difference from the displacement detector are connected in feedback to the servo amplifier of the actuator.

[Problem to be solved by the invention]

The rotation control means described above uses an average value of actually measured acceleration as a reference value for obtaining a signal for rotation control, and therefore cannot sufficiently suppress the rotational motion of the vibration table. Specifically, the first reason is that if the accelerations of the vibrators 2a and 2b detected by the accelerometers are a ₁ and a ₂ , then the average value of the accelerations is = a ₁ + a ₂ /2. Also, the deviations Δa ₁ and Δa ₂ are respectively Δa ₁ = −a ₁ Δa ₂ = −a _{2 ,} and the sum values a+Δa ₁ and +Δa 2 of each average value and the deviations Δa ₁ and Δa ₂ are sent to the respective adders. Because of the feedback, the adder connected to the vibrator 2a receives the above-mentioned added value of + _Δa1 , that is, the detected acceleration _a2 on the vibrator 2b side, and the acceleration connected to the vibrator 2b. The added value of +Δa ₂ , that is, the detected acceleration a ₁ on the vibrator 2a side is added to the vibration exciter 2a.
As a result, simply change the acceleration a ₂ or a ₁ to the vibration exciter 2
It merely feeds back to the a and 2b sides. This is simply a measure to control mutual interference.

The second reason is that the acceleration at the corner of the shaking table, which is affected by expansion and contraction due to the excitation of the shaking table, is detected by a detector and used as the reference value, which is regarded as the acceleration at the center of the shaking table. This is different from the acceleration experienced by a specimen placed in the center of the For these reasons, the rotation of the shaking table cannot be sufficiently suppressed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotation control device for a vibration table that can accurately control a rotating body of a vibration table.

[Means to solve the problem]

The above purpose is to provide a plurality of vibrators constituting a hydraulic servo system in one driving direction of one vibration table, and to connect an input circuit that generates an input signal to each of these servo systems via an adder. , in a vibration table in which each of the vibration exciters is provided with a displacement detector for detecting displacement, and the displacement detector of each vibration exciter is connected to an adder for feedback, the center of the vibration table and the At the corner of the vibration table where the extension lines of the drive directions for the Y-axis excitation, which are orthogonal to the X-axis of the vibration machine, intersect, An accelerometer is installed to detect acceleration in each direction of the Z-axis direction perpendicular to the plane, and the deviation between the acceleration signal from the accelerometer at the center of the shaking table and the acceleration signal from the accelerometer at the corner of the shaking table is determined. This is achieved by feeding back the deviations to the respective inputs of the servo systems driving the exciters.

[Effect]

By setting the reference value of the acceleration of the shaking table to the acceleration detected at the center of the shaking table, it is possible to eliminate the influence of the shaking table when it is vibrated from the side, that is, the influence of the shaking table expanding and contracting. Therefore, the reference value is stable, and since the reference value is the value detected at the center of the shaking table, it is equal to the acceleration applied to the specimen, and the acceleration at the center of the shaking table and the acceleration at the corner The deviation from the vibration table is fed back to the adder, and the adder adds this deviation amount to the servo system, so that the deviation in the acceleration of the vibration table is eliminated, and therefore rotation control is suppressed.

〔Example〕

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

Figure 1 is an external view of the shaking table, and Figure 2 is an explanatory diagram of its operation.
When exciting in three directions: the axial direction), the direction perpendicular to one direction in the horizontal plane (hereinafter referred to as the Y-axis direction), and the vertical direction (hereinafter referred to as the Z-axis direction), two vibrator 2a,
2b, two vibration exciters 3a and 3b for vibration in the Y-axis direction, and four vibration exciters 4a to 4d for vibration in the Z-axis direction are connected to the vibration table 1 by joints 5, respectively. ing. An accelerometer 6 is provided inside the center of the shaking table 1 to detect accelerations A _XO , A _YO , and A _ZO occurring in the X-axis, Y-axis, and Z-axis directions at the center of the shaking table. This accelerometer 6 is
Axial, Y-axis and Z-axis acceleration A _XO ,
It consists of three accelerometers that detect A _YO and A _ZO , respectively, or an addendometer that detects the three components of X, Y, and Z. Vibrator 2a, 2 for vibration in the X-axis direction
Driving direction extension line of b and vibration exciter 3 for vibration in the Y-axis direction
Accelerometers 7 to 10 are installed in the corners of the vibration table 1 corresponding to the intersections of a and 3b with the driving direction extension lines, respectively.
is provided. Like the accelerometer 6 described above, the accelerometer 8 detects accelerations A _X2 , A _Y1 , and A _Z3 in the three axis directions of X, Y, and Z at its installation position. The accelerometer 7 detects accelerations A _X1 and A _Z4 in two axis directions, X and Z. Further, the accelerometer 10 detects accelerations A _Y2 and A _Z2 in two axis directions, Y and Z. Furthermore, accelerometer 9
detects the acceleration A _Z1 in the Z-axis direction. The acceleration values in the X, Y, and Z axis directions detected by these accelerations 7 to 10 are compared with the acceleration values in the X, Y, and Z axis directions detected by the accelerometer 6. The deviation generated by this comparison is used as a rotational motion control signal to suppress rotational motion around each X, Y, and Z axis.
-4d is fed back to the input side of each servo system. That is, the vibration exciters 2a, 2b, 3a, 3
Each feedback amount to b, 4a to 4d is F _X1 ,
Assuming F _X2 , _{F Y1} , _{F Y2} , F _{Z1 ~ F Z4, F X1 = K} (2) F _Y1 =K _Y (A _Y0 −A _Y1 ) ………(3) F _Y2 =K _Y (A _Y0 −A _Y2 ) ………(4) F _Z1 =K _Z (A _Z0 −A _Z1 ) ………(5) F _Z2 = K _Z (A _Z0 −A _Z2 ) ………(6) F _Z3 = K _Z (A _Z0 −A _Z3 ) ………(7) F _Z4 =K _Z (A _Z0 −A _Z4 ) ………(8) However, K _X , K _Y , K _Z are constants. The feedback amount F _X1 of the above equations (1) to (8),
F _X2 , F _Y1 , F _Y2 , F _Z1 to F _Z4 are
By providing feedback to the input side of each of the servo systems b, 3a, 3b, and 4a to 4d, rotational movement of the vibration table 1 around the X, Y, and Z axes can be suppressed.

A configuration for suppressing the movement around the Z axis, which is one of the three rotational movements of the vibration table 1 described above, that is, the yawing O caused by the unsynchronization of the vibration exciters 2a and 2b, will be described with reference to FIG. In the figure, the same reference numerals as in FIG. 2 are the same parts. Vibrator 2
a and 2b are driven by pressure oil from servo valves 11a and 11b, respectively. Servo valve 11a, 1
1b controls the direction and flow rate of pressure oil supplied from the hydraulic source 12 to the vibrators 2a and 2b. The signals that control the servo valves 11a and 11b are input to the input circuit 1.
Output from 3. This input circuit 13 transmits the displacement signal d, velocity signal v, and acceleration signal a to the vibrators 2a and 2b.
are added to each adder 14a, 14b. Adder 14
a and 14b compare displacement feedback signals from displacement detectors 15a and 15b that detect the displacement of the vibrators 2a and 2b with the input displacement signal d, and output the deviation signals between the two to servo amplifiers 16a and 16b, respectively.
The acceleration feedback signals from the accelerometers 7 and 8 are compared with the input acceleration signal a, and the deviation signals between the two are applied to the servo valves 11a and 11b via the servo amplifiers 16a and 16b, respectively. Add to. Also, a velocity feedback signal, which is the output of the integrator 17a, 17b which performs one-time integration of the previous acceleration feedback signal, is similarly applied to the adders 14a, 14b. This speed feedback signal is used to improve control characteristics. Further, rotation control signals Oa and Ob for suppressing yawing O of the vibration table 1 are applied to each adder 14a and 14b, respectively. This rotation control signal Oa, Ob
are comparators 18a, 18b and coefficient unit 1, respectively.
9a, 19b. That is, the comparator 18a on the vibrator 2a side compares the acceleration A _X0 at the center of the shaking table from the accelerometer 6 with _the acceleration _A
−A _X1 ). This deviation signal (A _X0 −A _X1 )
is multiplied by the coefficient _KX by the coefficient unit 19a and added to the adder 14a as the rotation control signal Oa.
Further, the comparator 18b on the vibrator 2b side compares the acceleration A _X0 from the accelerometer 6 and the acceleration A _X2 from the accelerometer 8, and outputs a deviation signal (A _X0 - _{A X2} ) between the two. This bias signal (A _X0 −A _X2 ) is
b is multiplied by a coefficient _KX and added to the adder 14b as a rotation control signal Ob.

With this configuration, for example, if the specimen is placed on the vibration table 1 in an unbalanced state, the vibration table 1 will yawing around the Z axis, which is the center of the specimen. . When the shaking table 1 yaws in this way, the comparators 18a and 18b calculate the acceleration A _X0 at the center of the shaking table from the accelerometer 6 and the acceleration _A , A _X2 are compared, and their deviation signals A _X0 −A _X1 and A _X0 −A _X2 are calculated.
These deviation signals A _X0 -A _X1 and _{A X0} -A
a, 14b. For this reason, the adder 14
a and 14b apply signals corresponding to the aforementioned deviation signals to the servo valves 11a and 11b via the servo amplifiers 16a and 16b, respectively, so that the servo valve 11
a and 11b vibrate the vibration table 1 so as to reduce the above-mentioned deviation. As a result, yawing of the vibration table 1 can be suppressed.

In addition, although the above-mentioned embodiment explained the case where the vibration table 1 is vibrated in the The pitching P and rolling R that occur when exciting in the direction are also controlled by feeding back the deviation between the acceleration at the center of the vibration table 1 and the acceleration on each vibrator side to the input side of the servo system, as described above. It can be suppressed.

〔Effect of the invention〕

As described in detail above, the present invention uses the actually measured acceleration at the center of the shaking table, which is the center point of rotational motion such as yawing, pitching, and rolling of the shaking table, as a reference, and calculates the difference between this acceleration and the acceleration on each shaker side. The deviation is used as a rotation control signal and is fed back to the input side of each vibrator, making it possible to eliminate the effects of expansion and contraction of the vibration table. Rotation of the table can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a three-dimensional vibration tester implementing the apparatus of the present invention, FIG. 2 is an explanatory diagram of the operation of a three-dimensional vibration tester equipped with an example of the apparatus of the present invention, and FIG. 3 is an apparatus of the present invention. FIG. 2 is a plan view showing the configuration of an example. 1... Vibration table, 2a, 2b... Vibrator for vibration in the X-axis direction, 3a, 3b... Vibrator for vibration in the Y-axis direction, 4a to 4d... Vibration machine for vibration in the Z-axis direction Vibrator, 6
~10... Accelerometer, 18a, 18b... Comparator, 19a, 19b... Coefficient unit.

Claims (1)

[Claims] 1 A plurality of vibration exciters forming a hydraulic servo system are provided in one drive direction of one vibration table, and an input circuit that generates an input signal is connected to each of these servo systems via an adder. In a vibration table in which each vibration machine is provided with a displacement detector for detecting displacement, and the displacement detector of each vibration machine is connected to an adder for feedback, the center of the vibration table and the vibration exciter for X-axis vibration, At the corner of the vibration table where the extension lines of the respective drive directions of the vibration exciters for Y-axis vibration perpendicular to the X-axis intersect, An accelerometer is provided to detect acceleration in each direction of the Z-axis direction perpendicular to the plane of the vibration table, and the deviation between the acceleration signal from the accelerometer at the center of the shaking table and the acceleration signal from the accelerometer at the corner of the shaking table is determined. A vibration table rotation control device characterized in that this deviation is fed back to the input side of a servo system that drives a vibrator.