JP2005195330A - Magnetic force support type vibration measuring method and instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration measuring method and instrument capable of measuring directly three-dimensional vibration itself of a deformation, an inclination or the like, without measuring separately vertical-directional and horizontal-directional vibrations by component resolution, by applying a principle of a magnetic force support balance device to a magnetic force support type vibration measuring instrument. <P>SOLUTION: An object 10 mounted with a magnet, and levitation-supported by magnetic interaction with magnetic force generated by electrification to magnetic coils 21-30 provided in a magnetic force support mechanism 20 is moved related to a vibration characteristic and a support characteristic of the magnetic force support mechanism 20, for example, such as acting as a steady point, when the magnetic force support mechanism 20 is exposed, for example, to an earthquake to be vibrated. The three-dimensional vibration itself acting on the magnetic force support mechanism 20 is directly measured without conducting the component resolution, by measuring a relative displacement to the magnetic force support mechanism 20 of the object 10 and by considering the support characteristic of the magnetic force support mechanism. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention applies the principle of a magnetic force support balance device that magnetically supports an object, and makes it possible to measure the displacement, velocity, and acceleration of the position, posture, and position of the magnetic force support mechanism itself that magnetically supports the object. The present invention relates to a vibration measurement method and apparatus.

  Conventionally, as a form of vibrometer that measures the vibration of an object such as a machine or a structure, a fixed point is formed by a weight supported by a spring, and the relative displacement between the fixed point and the surrounding movement is measured. And a displacement meter for measuring the displacement of the object. The displacement meter is suitable for measurement when the object vibrates at a frequency larger than the natural frequency of the device determined by the weight and the spring, and by configuring the spring with a soft spring by increasing the mass of the weight, It is possible to set the natural frequency of the device small. The seismometer that measures the shaking of the crust is this type of vibrometer (Seismo type). An object with large inertia is supported in a pendulum form on a support via a spring, and the seismic wave has propagated to the support. Sometimes the support body is displaced by the vibration of the earthquake, but by measuring the vibration due to the earthquake as the relative displacement between the support body and the inertial fixed point by forming the inertial fixed point by minimizing the displacement of the object. doing. Considering the vibration frequency of the earthquake, the spring constant of the spring that supports the object is reduced (a soft spring), thereby blocking the transmission of the earthquake vibration to the object through the support. On the other hand, as another form of the vibrometer, there is a type in which the natural frequency of the device is set larger than the frequency of the object by reducing the weight mass and configuring the spring with a hard spring. In this case, the relative displacement with the surroundings of the weight becomes an amount proportional to the acceleration of the vibration of the object, and a vibrometer as an accelerometer is obtained. The velocity can be calculated by integrating the acceleration, and the displacement can be calculated by further integrating the acceleration.

As a seismometer capable of detecting a long-period vertical or horizontal movement, an apocalyptic rotation type vibration detector using a pendulum having a permanent magnet arranged in a parallel magnetic field has been proposed (see Patent Document 1). According to this non-rotating rotational vibration detector, a permanent magnet is rotatably arranged in a parallel magnetic field, and the rotational moment due to gravity acting on the permanent magnet is canceled by the rotational moment due to the magnetic force acting on the permanent magnet by the parallel magnetic field. Yes. By configuring in this way, it is intended to cancel the rotational moment of the pendulum due to gravity without using a spring, to widen the range in which the rotational moment can be made indeterminate without acting on the pendulum, and to increase the natural period. .
JP 2002-357665 A (paragraphs [0015], [0026] to [0028], FIGS. 1 to 3)

  However, conventional seismometers measure vibrations in the vertical and horizontal directions separately, and in the analysis of measurement data, seismic waves capture these individually measured vibration waves as a simple composition. Interference (duplicate measurement, measurement defect, phase difference, etc.) of individual measuring devices is ignored, so it is difficult to say that the measurement of seismic waves as vectors is sufficient and complete. At present, there are no seismometers that can directly measure the three-dimensional vibrations of the ground surface caused by earthquakes without decomposing them. In addition, the seismometer has a configuration in which an inertial object is supported by a spring, and the characteristics of the spring may change over time or in the surrounding environment, so it is necessary to adjust the spring setting frequently. .

  As a device that supports an object in a movable manner, there is a model magnetic support balance device used for a wind tunnel test. Supporting the model with the support in the measurement section to obtain the aerodynamic characteristics of the aircraft with the model has been generally performed, but the support itself affects the air flow on the model surface, so the test results Cannot be used as the aerodynamic characteristics of the model. Therefore, in the wind tunnel test, a magnetic support balance device that supports the model with magnetic force has been devised. Since the support is not required by magnetically supporting the model, an aerodynamic influence on the model due to the presence of the support is removed, and an ideal wind tunnel test can be performed.

  With the magnetic support balance device, it is possible to accurately know the dynamic characteristics that change with time as the effects of airflow on the fuselage are indispensable for the development and design of space reciprocators such as aircraft and space shuttles. . When dynamic characteristics are required, for example, when the flow of airflow changes, such as gusts or turbulence of the airflow, when the characteristics of the airflow, such as density or temperature change, or by steering, There are cases where the attitude of the aircraft is changed. By knowing dynamically changing forces such as lift, drag, and moment acting on the model in response to such changes in the situation, it is possible to know the dynamic characteristics according to the position and attitude angle of the actual machine. The dynamic characteristics of the actual aircraft can contribute to the development and design of the outer shape, structural strength, engine characteristics, steering device, etc. of the wings and fuselage of the aircraft.

  The magnetic support balance device for the wind tunnel model is equipped with a coil to generate a magnetic force that interacts with the magnet provided inside the model, and the lift force that the airflow around the model acts on the model in the wind tunnel test The static or dynamic aerodynamic characteristics such as drag, pitching (pitch) moment, etc. are replaced with the magnitude of the current flowing through the coil. By investigating the relationship between the aerodynamic force and the magnitude of the coil current and preparing correspondences such as maps, functions, and tables in advance, the aerodynamic characteristics acting on the model can be known by measuring the coil current. .

  By the way, when the magnetic force support balance apparatus vibrates due to an external event such as an earthquake, the model may behave according to the characteristics of the model due to the influence of the vibration. Therefore, focusing on the fact that the object is supported separately from the surroundings by the magnetic support balance device in the wind tunnel test, it is possible to directly measure vibrations in any direction due to earthquakes etc. There are issues to be solved.

  The object of the present invention is to apply the principle of the magnetic force support balance device to the magnetic force support type vibration measuring device by utilizing this property, and the three-dimensional vibration itself such as displacement and inclination is horizontally and vertically separated by component decomposition. It is to provide a vibration measuring method and apparatus that can be directly measured without separately measuring the vibration in the direction.

  In order to solve the above problems, a magnetic force support type vibration measuring method according to the present invention levitates and supports an object mounted with a magnet by a magnetic force generated by energizing a magnetic coil provided in a magnetic force support mechanism. It consists of measuring the vibration generated in the magnetic support mechanism by measuring the relative displacement of the object with respect to the mechanism or the change in the control amount related to the magnetic coil.

  Further, the magnetic force support type vibration measuring apparatus according to the present invention includes an object mounted with a magnet, a magnetic force support mechanism having a magnetic coil that generates a magnetic force by energizing the object to float and support the object, and the magnetic force support of the object. Detection means for detecting a relative displacement with respect to the mechanism or a change in the control amount related to the magnetic coil is provided, and the vibration generated in the magnetic force support mechanism is measured by measuring the relative displacement or the change in the control amount of the object by the detection means. It consists of that.

  According to the magnetic force support type vibration measuring method and the magnetic force support type vibration measuring device, the object on which the magnet is mounted is levitated and supported by the magnetic interaction with the magnetic force generated by energizing the magnetic coil provided in the magnetic force support mechanism. The In this state, when the magnetic support mechanism vibrates due to, for example, earthquake vibration, the object that is levitated and supported acts as a fixed point, or vibrates by an amount proportional to the acceleration of vibration. Since the movement is related to the support characteristics of the support mechanism, it measures the relative displacement of the object as seen from the magnetic support mechanism or the change in the control amount related to the magnetic coil (by the detection means in the apparatus), and the support characteristics of the magnetic support mechanism. By taking into account, vibrations acting on the magnetic force support mechanism can be measured. In this case, since the vibration generated in the magnetic support mechanism is measured by measuring the relative displacement of the object with respect to the magnetic support mechanism or the change in the control amount related to the magnetic coil, the three-dimensional vibration itself is divided into vertical and horizontal directions by component decomposition. It can be measured directly without separately measuring as vibration.

  In the magnetic force support type vibration measuring method and the magnetic force support type vibration measuring device, the mass of the object is increased to reduce the magnetic force restraint of the object by the magnetic force support mechanism other than levitation support of the object. An object can act as a fixed point. When the mass of the object is sufficiently large and the displacement of vibration is sufficiently small, the object acts as a fixed point regardless of the vibration of the magnetic support mechanism, and the change in the magnetic field around the object due to the vibration of the magnetic support mechanism is reduced. . As a result, the relative vibration of the object measured from the magnetic support mechanism is a vibration in which the sign of the vibration of the magnetic support mechanism is reversed.

  In this magnetic force support type vibration measurement method and magnetic force support type vibration measurement device, by reducing the mass of the object and increasing the magnetic force restraint of the object by the magnetic force support mechanism other than levitation support of the object, The acceleration of the vibration generated in the magnetic force support mechanism can be measured based on the fluctuation amount of the magnetic force acting on the object. When reducing the mass of the object and increasing the spring restraint by the magnetic force support to the magnetic support mechanism, the relative acceleration of the object to the magnetic support mechanism is set to the acceleration equivalent obtained from the mass of the object and the fluctuation amount of the magnetic force. Since it can be ignored, the acceleration equivalent amount can be directly measured as the acceleration with respect to the inertial system of the magnetic support mechanism. The magnetic force supported vibration measurement for measuring the magnetic force fluctuation amount corresponds to the use as an accelerometer for measuring an amount proportional to the acceleration of the external vibration.

  In this magnetic force support type vibration measurement method and magnetic force support type vibration measurement device, the magnetic coil is passed through the magnetic coil so as to eliminate the change of the magnetic field around the model due to the relative displacement of the model with respect to the magnetic force support mechanism. The current can be controlled (the device is equipped with such a control device). Since the magnetic support mechanism is inherently an unstable system, the motion of the model is detected by the detection means, and feedback control is performed so that the model does not exhibit unstable behavior. Interference is also reduced. However, when the magnetic support mechanism is used to measure the vibrations acting on it, when the model is displaced with respect to the magnetic support mechanism, the magnetic field around the model at a new location has changed. There is a possibility that a new magnetic force acts on the model due to the magnetic field, and additional motion occurs in the model. If additional movement occurs in the model, the relative displacement due to vibration cannot be measured accurately, resulting in erroneous measurement results. Therefore, even if the model causes a relative displacement with respect to the magnetic support mechanism due to the vibration acting on the magnetic support mechanism, the magnetic field around the model does not change as in the case where the vibration does not act on the magnetic support mechanism. Controls the current flowing through the magnetic coil. With such current control, true external fluctuations can be measured with high accuracy in real time.

  In the magnetic force support type vibration measuring method and the magnetic force support type vibration measuring device, the vibration generated in the magnetic force support mechanism includes a three-axis translational displacement and a two-axis rotational displacement constituting an orthogonal coordinate system with respect to the inertial space. Dimensional displacement. When the magnetic support mechanism is exposed to, for example, earthquake vibration and displaced in the inertial space, the relative position and angle between the model that is completely levitated and the magnetic support mechanism change. The relative displacement is a three-axis translational displacement consisting of x, y, and z of inertial coordinates and a rotational displacement about three axes (pitch axis, yaw axis, and roll axis). Any displacement can be measured in the form of an electrical signal as a relative displacement between the model and the magnetic force support mechanism or a change in control amount.

  The magnetic force support type vibration measuring apparatus can be applied as an inclinometer that measures a static or dynamic inclination generated in the magnetic force support mechanism by attaching the magnetic force support mechanism to an object that vibrates and vibrates. Since the magnetic support type vibration measuring device can also measure rotational displacement, by attaching the magnetic force support type vibration measuring device to the object to be rotated and vibrated, static or dynamic inclination generated in the magnetic support mechanism as an inclinometer can be obtained. It can be measured.

  The magnetic support vibration measurement method or apparatus according to the present invention is configured as described above, and the inertial object is magnetically levitated and supported without depending on the support. It is possible to directly measure the three-dimensional displacement itself such as tilt and inclination without decomposing components. For example, when applied as a seismometer, seismic waves can be captured as a three-dimensional wavefront, and can be used as a measuring instrument that contributes to the progress of research and research in various fields such as fault measurement and crust research.

  Embodiments of a magnetic force support type vibration measuring method and apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing an outline of a magnetic force support type vibration measuring apparatus according to the present invention, and FIG. 2 is a block diagram showing an example of a control block that can be used in the magnetic force support type vibration measuring apparatus. A magnetic force support type vibration measuring apparatus 1 shown in FIG. 1 is configured by applying the principle of a model magnetic force support balance device used for a wind tunnel test, and the position and orientation of the magnetic force support mechanism 20 itself supporting the object 10 as a magnetic force. It is possible to measure the vibration (displacement, inclination, velocity or acceleration) of the lens.

  With reference to FIG. 1, the outline | summary of a magnetic force support type | formula vibration measuring apparatus is demonstrated. FIG. 1 is a perspective view showing an outline of a magnetic support type vibration measuring apparatus provided with a magnetic support mechanism, and a measurement system and a control system attached to the magnetic support mechanism. A magnetic force support type vibration measuring apparatus 1 shown in FIG. 1 includes a magnetic force support mechanism 20 for levitating and supporting an object 10 formed of a nonmagnetic material such as aluminum in a desired shape by a magnetic force. Inside the object 10 is mounted a magnetized material, a coil that continues to pass a current such as a superconducting coil, or a strong cylindrical magnet body made of a permanent magnet or the like. A magnetic force is generated in the magnet body of the object 10 by a magnetic action with an external magnetic field generated by energizing a coil disposed around the object. When no vibration is applied to the magnetic force support type vibration measuring apparatus 1, the object 10 can be magnetically levitated and supported against gravity by this magnetic force.

  The magnetic support mechanism 20 has a configuration in which a magnetic coil and a magnetic circuit of a magnetic support balance device used for a wind tunnel test are directly converted. The magnetic field for applying a force to the object 10 includes two magnetic circuits composed of coils 22 to 25 and coils 26 to 29 as magnetic support coils, and a coil 21 as a magnetic support coil disposed on the outside thereof. 30. By adjusting the currents flowing through the coils 22 to 29 of the magnetic circuit, it is possible to continuously change the strength and direction of the magnetic field in the yz plane and the rate of change in the x-axis direction in the magnetic circuit. it can. Further, the rate of change of the strength of the magnetic field in the x-axis direction as viewed in the x-axis direction can be controlled by adjusting the current flowing through the coils 21 and 30, so that six-axis control is possible. That is, the coils 22 to 29 of the magnetic circuit function as a lift coil and a lateral force coil that apply a magnetic force against the lifting force, lateral force and pitching moment, yawing moment, and rolling moment acting on the object 10. The coils 21 and 30 function as a drag coil that applies a magnetic force against the drag acting on the object 10 when the object 10 has a fluid flow in the x-axis direction. The coils 21 and 30 are in the form of air-core coils that allow the flow of airflow because they are diverted from those for wind tunnel testing, but they may be ordinary electromagnets that are not air-core for measuring vibration displacement. .

  In addition to the object 10 and the coils 21 to 30, the magnetic force support type vibration measuring apparatus 1 includes a power supply system that drives each coil, a measurement system that measures the position and orientation of the object 10 with respect to the magnetic force support mechanism 20, and the object 10. A control system for controlling the position and posture of the robot is incorporated. As shown in FIG. 1, measurement data regarding the relative position and orientation displacement of the object 10 relative to the magnetic force support mechanism 20 detected by a sensor (camera) 33 that is a measurement system is transmitted to a computer 34 such as a personal computer. Is amplified by the amplifier 35, and then supplied to each of the coils 21 to 30 as a controlled command current necessary for eliminating the relative displacement. By measuring this command current, the magnetic force acting on the object 10 can also be estimated.

  Since the magnetic support mechanism 20 is an essentially unstable system, feedback control is always performed. That is, a magnetic force acts on the object 10 by the command current, and as a result, a change appears in the position / posture angle that is a state variable of the object 10 as an output. The position / orientation angle of the object 10 is detected by a sensor 33 that is a measurement system, and a computer 34 that is a control device outputs a command current in accordance with the detected value, whereby feedback control is performed.

As shown in FIG. 1, the coordinate system used in the conventional control is based on the center of the wind tunnel measuring unit, the upstream direction of the flow is the x-axis (reverse drag direction), and the vertically upward direction (lift direction) is the z-axis. The axis that forms the axis and the right-handed system is defined as the y-axis, and the roll angle around the x-axis, the pitch angle around the y-axis, and the yaw angle around the z-axis are φ, θ, and ψ, respectively. In order to apply these axial magnetic forces and axial moments, coils are combined as shown in Table 1. The coil numbers shown in Table 1 correspond to the numbers given to the coils shown in FIG.

物体１０運動方程式は、次の式（２）で表される。

式（２）の十分に長い期間で平均を取れば、重力の変化はないとすることができるので、次の式（３）が得られる。ここで、上部の横棒は平均操作を施した結果を示す。

式（１）〜（３）から、次の式（４）が得られる。

ここで、ｒｃとＦｍ等は、計測又は評価可能な量であるから、地震を計測する場合、結局、式（４）の左辺である慣性系に対する磁力支持機構２０の位置ｒａの変化として、地震の振動を測定することができる。 The position of the magnetic support mechanism 20 in the inertial system is ra (vector quantity), the position of the floating object 10 in the inertial system is rb (vector quantity), and the position of the floating object 10 measured by the sensor 33 provided in the magnetic support mechanism 20 (sensor 33 ), The mass of the object 10 is m, the magnetic force acting on the object 10 is Fm, and the gravity acting on the object 10 is Fg.
The positional relationship between the object 10 and the magnetic force support mechanism 20 is expressed by the following formula (1).

The equation of motion of the object 10 is expressed by the following equation (2).

If the average is taken over a sufficiently long period of equation (2), it can be assumed that there is no change in gravity, and therefore the following equation (3) is obtained. Here, the upper horizontal bar shows the result of the average operation.

From the equations (1) to (3), the following equation (4) is obtained.

Here, since rc, Fm, and the like are quantities that can be measured or evaluated, when measuring an earthquake, as a change in the position ra of the magnetic force support mechanism 20 with respect to the inertial system that is the left side of Equation (4), the earthquake Can be measured.

  In the above formula (4), when the mass m of the object 10 is very large with respect to the magnetic force fluctuation amount, the second term on the right side can be ignored with respect to the first term. The change in the position of the magnetic force support mechanism 20 in the inertial system shown on the left side is vibration due to an earthquake. At this time, the vibration displacement is the amount remaining as the first term on the right side, that is, the object 10 measured by the sensor 33. It can be obtained as the opposite sign of the position change. This state corresponds to the fact that the inertia of the object 10 is very large and substantially forms a fixed point. If the object 10 forms a fixed point, the movement of the object 10 viewed from the vibrating magnetic support mechanism 20 directly observes the vibration of the magnetic support mechanism 20 (however, the sign is inverted with respect to the vibration direction). The signatures match. In a magnetic support balance device in a wind tunnel test, the weight of the model is heavy and the spring constant of a virtual spring that magnetically fixes the model in space is often small. Advantageously, the upper spring constant is small.

  On the other hand, in the above formula (4), when the mass m of the object 10 is very small with respect to the magnetic force fluctuation amount, the first term on the right side may be negligible with respect to the second term. At this time, the amount represented by the second term on the right side is the second derivative of the position of the magnetic force support mechanism 20 in the inertial system indicated by the left side, and thus represents the acceleration of the earthquake. The acceleration of the earthquake can be measured as the amount of change from the average value of the magnetic force that can be measured.

  In order to obtain the function of a normal seismometer in the magnetic force supported vibration measuring apparatus 1, the extremes of the mass m of the object 10 and the magnetic force fluctuation amount for continuing to support the object 10 are as described above. Will set the condition. Furthermore, since both the output of the sensor 33 and the magnetic force can be measured in the magnetic force support type vibration measuring apparatus 1, the seismic wave can be accurately measured even in the intermediate condition between the two extreme conditions.

  In order to measure external vibration such as an earthquake with high accuracy, it is necessary to consider a change in the magnetic field around the object 10 due to the relative displacement between the object 10 and the magnetic support mechanism 20 due to the external vibration. The change in the magnetic field causes a new magnetic force to act on the object 10 and induces an additional motion in the object 10. In order to remove such a change in the magnetic field, the model is lifted and supported by a magnetic force in a wind tunnel device or the like invented by the present inventors and previously filed as a patent application. The technology of “Control Method and Device (Japanese Patent Application No. 2003-149969)” is applicable. That is, for two axes (including the rotation axis) that interfere with each other, the interference amount relating to the displacement in the other axial direction caused by the displacement in the other axial direction is evaluated in advance, and the command current for the other axis is determined. Is applied with a correction current determined based on the evaluation of the displacement in one axial direction and the amount of interference.

  FIG. 2 shows an example of a control block diagram that can be used in the magnetic force support type vibration measuring apparatus shown in FIG. Since the control system of the magnetic support mechanism 20 is inherently unstable, feedback control is performed on the position / posture angle of the object 10 by the control system shown in FIG. That is, a signal based on the position / posture angle Y (x, y, z, φ, θ, ψ) as the current value (state variable) and each target value R of the position / posture angle in the target value setter 2 The deviation E is input to a PI controller (proportional integration controller) 3 having a transfer function K, and a control amount is calculated. The calculated control amount is further subjected to D / A conversion and amplifier amplification after the bias current B from the bias applier 4 is added, and then, as a command signal U, the coils 21 to 30 ( 1) and is supplied to a coil system (magnetic force support mechanism 20) having a transfer function Gc. The bias current B is a current value necessary for the object 10 to balance with gravity. The magnetic field generated by the magnetic support mechanism 20 acts on the object 10 as a coil magnetic force due to the interaction with the magnet body. When an external vibration such as an earthquake acts on the system, a seismic wave (excitation force) d acts on the object 10 relative to the magnetic force support mechanism 20, but the seismic wave is a noise source 5 in the control system. Captured and processed.

  The optical sensor 33 (see FIG. 1) detects the position / posture angle Y as the current value of the object 10. Since the detected position / posture angle Y contains noise, it has an appropriate cutoff frequency of about 60 Hz for noise removal and is applied to the noise cut filter 11 represented by the transfer function Hn. Since the sensor 33 has a delay time (dead time) L of about 6 milliseconds from detection to output as the time required for charge accumulation as in the CCD sensor (transfer function Hs), the position of the detected object 10 is detected.・ The posture angle information is actually different from the instantaneous position and posture angle. Further, since the computer 34 requires time to calculate the command current U to be supplied to the coils 21 to 30 such as the coil current and the coil voltage, the position / posture angle of the object 10 further fluctuates at the moment of applying the force. Yes. Therefore, a double phase advancer 12 represented by the transfer function Hp (s) is used to compensate for these time delays. The phase double advance through the double phase advance element 12 plays an important role in the stability of the system. The deviation E is calculated by the difference between the compensated position / posture angle signal and the target value R. Thus, the magnetic force support mechanism 20 performs feedback control on the position / posture angle of the object 10 based on the detected position / posture angle Y of the object 10. In order to perform further high-accuracy measurement of vibration, an auxiliary control system 13 having a transfer function K as a circuit element for magnetic field correction is disposed at the illustrated position in order to perform feedback control of the magnetic field.

  In the magnetic force support mechanism 20 that is a coil system, the relative position based on the vibration of the object 10 is detected by the sensor 33, but it can also be measured as a change in the control amount of the magnetic force. The control amount of the magnetic force is specifically the magnetic force Fm in the equation (4), and the coil current that determines the magnetic force Fm can be measured based on FIG. 1 and Table 1 above. In the control block diagram of FIG. 2, the control amount of the magnetic force is determined based on the command signal U immediately before the magnetic force support mechanism 20. The evaluation of the seismic wave can be performed based on Expression (4). Whereas existing seismometers have been measured by component decomposition in the horizontal and vertical directions, the magnetic force supported vibration measuring apparatus 1 can capture vibration as one spatial vibration. In addition, it is possible to avoid intrusion of uncertain errors due to mechanical separation in two directions, horizontal and vertical. Angular changes such as changes in the inclination of the ground surface and changes in the horizontal inward direction are also observed, for example, by crustal movements caused by volcanic activity. According to the magnetic support type vibration measuring apparatus 1, such changes in inclination and angle are also observed. It can be measured as a change in posture angle of the object 10. In this case, for the object 10, the moment of inertia is used instead of the mass m, and the equation of motion is an equation in which the moment of inertia multiplied by the angular acceleration is balanced with the moment of the magnetic force. The same as in the case of magnetic force.

  Whether the vibrometer is used as a vibrometer that forms a fixed point or an accelerometer depends on the hardness of the spring that supports the weight (mass point). The hardness of the spring corresponds to the proportional constant portion Kp that appears in the transfer function of the PI controller 3 in the magnetic force supported vibration measuring apparatus 1. The proportionality constant portion Kp is a coefficient for controlling to return the displacement position of the object 10 by generating a magnetic force (finally a coil current) proportional to the amount of deviation from the set position of the object 10. By adjusting the proportional constant portion Kp, the operation mode of the magnetic force supported vibration measuring apparatus 1 can be changed. In the case of an accelerometer, this corresponds to increasing Fm in Equation (4), and therefore corresponds to increasing the proportionality constant. In this way, if the balance technique for aerodynamic evaluation is applied, the virtual motion of the object 10 when no magnetic force (moment due to magnetic force) is applied, that is, the true external displacement can be accurately detected in real time. Can be estimated.

  Based on FIGS. 3 to 5, measurement results when vibration is applied to the magnetic support mechanism are shown. A magnetic support balance device used for a wind tunnel test is used as it is for a magnetic support mechanism of a magnetic support type displacement measuring device. Since the measurement was performed during the wind tunnel test, the measurement result includes the influence of the air flow on the object 10. 3 to 5, the magnetic support mechanism 20 is disposed in a low temperature wind tunnel that actually creates an air flow, the object 10 is placed inside the magnetic support mechanism 20, and three-dimensional vibration is applied to the magnetic support mechanism 20. The detected data is shown.

  FIG. 3 is a graph in which the horizontal axis indicates the frequency and the vertical axis indicates the logarithm, and in this example, an example is shown when vibration in the X-axis direction having a sharp peak at a frequency of 40 Hz is detected. . FIG. 4 similarly shows an example when vibration in the Y-axis direction is detected. The vibration detection sensitivity in the Y-axis direction is a value close to about 10,000 times. A normal seismometer has a sensitivity in the Y-axis direction of 100,000 to 1,000,000 times, which is lower than that, but in practice it does not matter. FIG. 5 similarly shows an example when vibration in the Z-axis direction is detected.

  If the vibration in the Y-axis direction is 1, it can be estimated that the vibration in the X-axis direction is 1/10 and the vibration in the Z-axis direction is about 1/100. The low temperature wind tunnel is restrained from top to bottom, so vibration is suppressed. Moreover, it is estimated that the vibration in the low frequency region commonly seen is due to the effect of the airflow and the interference between the control and the aerodynamic force.

  6 and 7 show an example of the seismic vibration actually measured by the magnetic force support type vibration measuring apparatus. 6 (a), 6 (b) and 6 (c) are graphs showing examples of measurement results obtained by actually measuring the seismic vibration with respect to the three axes x, y and z by the magnetic force support type vibration measuring apparatus according to the present invention. . The x-axis indicates the east-west direction, the y-axis indicates the north-south direction, and the z-axis indicates the vertical direction. In the figure, (a) shows data at the time of an earthquake, and (b) shows data at the time of no earthquake. From this measurement result, it can be seen that this seismic vibration was an earthquake whose vibration in the x-axis direction was stronger than that in the other axial directions. FIG. 7 is a graph showing the spectrum analysis result of the seismic vibration component in the y-axis (north-south) direction in this seismic vibration. Also in FIG. 7, (a) shows data at the time of an earthquake, and (b) shows data at the time of not an earthquake. From FIG. 7, it can be seen that the vibration frequency of 1 to 10 Hz was the main frequency. FIG. 8 is an example of a measurement result obtained by measuring a seismometer of the vibration shown in FIG. 6 measured by the magnetic force support type vibration measuring apparatus with a dedicated seismometer. This earthquake occurred at 16:30 on October 15, 2003 at a magnitude of 5.0 with an epicenter of 35.6 degrees north latitude, 140.1 degrees east longitude, and a depth of 80 km. The upper seismic waveform represents the north-south vibration, the middle seismic waveform represents the east-west vibration, and the lower seismic waveform represents the vertical vibration. In both cases, the horizontal axis represents time (seconds), and the vertical axis represents acceleration (unit, gal) in the corresponding direction.

  Although the present invention has been described by taking the seismometer as an example as described above, the displacement meter according to the present invention is not limited to this, and measures the displacement of the position and angle of an accelerometer, a vibrometer, an inclinometer, and the like. Obviously, it can be applied to any application.

It is a perspective view which shows the outline | summary of the magnetic support type displacement measuring apparatus by this invention. It is a block diagram which shows an example of the control block diagram which can be used for the magnetic force support type | formula vibration measuring apparatus shown in FIG. It is a graph which shows the measurement result of a X-axis direction when adding a vibration to the magnetic support mechanism of the magnetic support type measuring apparatus by this invention. It is a graph which shows the measurement result of the Y-axis direction corresponding to FIG. It is a graph which shows the measurement result of the Z-axis direction corresponding to FIG. It is a graph which shows an example of the measurement result which the magnetic support type | formula vibration measuring apparatus by this invention actually measured the seismic vibration about three orthogonal axes. It is a graph which shows the spectrum analysis result of the seismic vibration component of the north-south direction in this seismic vibration. It is an example of the measurement result which the dedicated seismometer measured the vibration of the earthquake shown in FIG. 6 measured by the magnetic support type vibration measuring device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic support type vibration measuring device 2 Target setting device 3 PI controller 4 Bias applying device 10 Object 11 Noise cut filter 12 Double phase advancer 13 Auxiliary control system 20 Magnetic support mechanism 22-25, 26-29 coil 21,30 Air core coil 33 Sensor 34 Computer 35 Amplifier x, y, z Orthogonal position coordinate φ Roll angle θ Pitch angle ψ Yaw angle ra (vector quantity) Position of magnetic support mechanism 20 in inertial system rb (vector quantity) Levitated object in inertial system 10 position rc Position of the floating object 10 measured by the sensor 33 m Mass of the object 10 Fm Magnetic force acting on the object Fg Gravity acting on the object 10 Y Position / attitude angle R Target value E Deviation B Bias Current U Command signal d Seismic wave (Excitation force) Gc Transfer function of magnetic support mechanism 20 (coil system) Hn Noise cut The transfer function of the transfer function Hs sensor 33 of motor
Hp Transfer Function of Double Phase Leader 12 K Transfer Function of Auxiliary Control System 13

Claims (11)

  Levitating and supporting an object carrying a magnet by a magnetic force generated by energizing a magnetic coil provided in the magnetic force support mechanism, and measuring a relative displacement of the object with respect to the magnetic force support mechanism or a change in a control amount related to the magnetic coil. A magnetic force support type vibration measuring method comprising measuring vibration generated in the magnetic force support mechanism by the method.   2. The method according to claim 1, further comprising causing the object to act as a fixed point by increasing a mass of the object and reducing a magnetic force restraint of the object by the magnetic force support mechanism other than levitating and supporting the object. Magnetic support type vibration measurement method.   The magnetic force based on the amount of variation of the magnetic force acting on the object is reduced by reducing the mass of the object and increasing the magnetic force restraint of the object by the magnetic force support mechanism other than the levitating support of the object. The magnetic support vibration measurement method according to claim 1, further comprising measuring acceleration of the vibration generated in the support mechanism.   2. A magnetic support system according to claim 1, comprising controlling a current passed through the magnetic coil so as to eliminate a change in the magnetic field around the object due to the relative displacement of the object with respect to the magnetic support mechanism. Vibration measurement method.   The vibration generated in the magnetic force support mechanism is a three-dimensional displacement including a three-axis translational displacement and a two-axis rotational displacement constituting an orthogonal coordinate system with respect to the inertial space. The magnetic force support type vibration measuring method according to item.   An object on which a magnet is mounted, a magnetic force support mechanism having a magnetic coil that generates a magnetic force by energizing to support the object, and a relative displacement of the object with respect to the magnetic force support mechanism or a control amount change with respect to the magnetic coil. A magnetic force support type vibration measuring apparatus comprising a detecting means for detecting, and measuring vibration generated in the magnetic force supporting mechanism by measuring the relative displacement or the change in the control amount of the object by the detecting means.   The mass of the object is increased and the object is caused to act as a fixed point by reducing a magnetic force restraint of the object by the magnetic support mechanism other than levitation support of the object. Magnetic support type vibration measurement device.   The magnetic force based on the amount of variation of the magnetic force acting on the object is reduced by reducing the mass of the object and increasing the magnetic force restraint of the object by the magnetic force support mechanism other than the levitating support of the object. The magnetic force support type vibration measuring device according to claim 6, comprising measuring acceleration of the vibration generated in the support mechanism.   7. A control device for controlling a current passed through the magnetic coil so as to eliminate a change in a magnetic field around the object due to the relative displacement of the object with respect to the magnetic support mechanism. The magnetic force support type vibration measuring device described in 1.   The vibration generated in the magnetic force support mechanism is a three-dimensional displacement including a three-axis translational displacement and a two-axis rotational displacement constituting an orthogonal coordinate system with respect to the inertial space. The magnetic force support type vibration measuring device according to item.   10. The magnetic support mechanism according to claim 6, wherein the magnetic support mechanism is applied as a static or dynamic inclinometer generated in the magnetic support mechanism by attaching the magnetic support mechanism to an object that vibrates and vibrates. Magnetic support type vibration measuring device.

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