RU2086934C1 - Method for measuring movement characteristics and device which implements said method - Google Patents

Abstract

FIELD: instruments. SUBSTANCE: device has ferromagnetic rod inertia member 4 which is located in stable equilibrium position in magnetic field of magnetic system which has solenoid 2 and nonmagnetic support 3. In order to measure movement characteristics of object, method involves periodic variation of intensity of magnetic field with frequency which is greater than frequency of signal to be measured, measurement of mechanic oscillations of inertia member, which follow frequency of magnetic filed and judging movement characteristics by variation of amplitude of these oscillations. EFFECT: increased frequency range. 3 cl, 2 dwg

Description

 The invention relates to measuring technique and can be used to record vibration parameters of objects and structures in the infra-low-frequency range of frequencies, in geophysics to register infra-low-frequency seismic vibrations, tilts of the earth's surface, tidal moon-solar oscillations of the earth's surface for the purposes of modern geodynamics and earthquake prediction.

 The aim of the invention is to increase the noise immunity and the expansion of the frequency range by providing the ability to register infra-low-frequency movements of the controlled object.

 In FIG. 1 shows a functional diagram of a device; figure 2 plot voltage at the output of the blocks of the device.

 The method of measuring the object’s motion parameters is that an inertial element mounted in a stable equilibrium position in a magnetic field is fixed on the object, the magnetic field strength is changed with a frequency much higher than the object’s oscillation frequency, mechanical vibrations of the inertial element are recorded and the object’s motion parameters are determined from changes in the amplitude of oscillations. The frequency of the magnetic field is selected multiple or fractional natural resonant frequency of the inertial element.

 A device for implementing the method comprises a housing 1, rigidly connected with a controlled object, a magnetic system made in the form of a solenoid 2 and a non-magnetic support 3, mounted on the latter in the state of stable equilibrium, a ferromagnetic inertial element 4, connected to a direct current source 5 and a modulator 6, the output of which connected to a solenoid coil 2, a capacitive sensor 7, a converter 8, a capacitance-voltage, a synchronous detector 9 and a recorder 10, and a reference frequency generator 11, the outputs of which are connected in series oedineny to a second input of the modulator 6 and the control input of the synchronous detector 9.

 The ferromagnetic inertial element 4 can be made in the form of a rod with a sharp end, which is installed on a ruby or sapphire glide to reduce dry friction. Capacitive sensor 7 can be made in the form of two plates 12 and 13 connected to the inputs of the Converter 8 capacitance-voltage.

 The device implements the method as follows.

Through the DC source 5, a direct current I _{post is} supplied to the solenoid coil _. creating a constant magnetic field in the area of the ferromagnetic inertial element 4. The value of I _post. choose a value so as to ensure the retention of the latter on non-magnetic support 3, i.e. constant magnetic field with intensity H _post. created due to the current I _post. , provides attraction of the ferromagnetic inertial element 4 to the non-magnetic support 3, compensating for the gravitational forces, due to which the ferromagnetic inertial element 4 tends to fall down. In addition, the value of I _post. is selected from the condition of providing a minimum clamp to the non-magnetic support 3 to create a sufficiently small amount of dry friction.

In the position of stable equilibrium of the ferromagnetic inertial element 4, the considered oscillatory system will have its own resonant frequency F _res. , which is determined by the size of the element 4, its mass, as well as the equivalent stiffness of the "spring", which returns the ferromagnetic inertial element 4 to the position of stable equilibrium when it deviates from the vertical. The equivalent rigidity of the indicated "spring" is determined mainly by the Earth's gravitational field and, to some extent, by the magnetic field of the magnetic system.

Using the generator 11 of the reference frequency, the frequency F _mod. which choose a much higher oscillation frequency of the controlled object, and modulator 6, for direct current I _post. feeding the coil of the solenoid 2, impose an alternating current component. Since in this case the configuration of the magnetic field does not change, then with a strict orientation of the ferromagnetic inertial element 4 in the vertical direction / i.e. when the condition is met when the direction of the gravity vector and the direction of the magnetic lines of force of the magnetic system coincide / and in the absence of an external disturbing force acting on the housing 1, the oscillation amplitude of the ferromagnetic inertial element 4 will be zero at the modulation frequency of the magnetic field strength. When exposed to a disturbing force F _pos. onto the housing 1, the latter changes its position, while the direction of the magnetic field lines vector changes, as a result of which a force component appears, which will try to install the ferromagnetic inertial element 4 along the magnetic field lines. With increasing magnetic field /, the change in the magnetic field strength is due to its modulation with a frequency F _mod. equal to the frequency of the reference frequency generator 11 / element 4 tends to occupy a position along the direction of the magnetic field lines vector, and when the magnetic field decreases, the inertial ferromagnetic element 4 leaves its previous position and tends to take an orientation along the gravity vector. With zero disorientation, i.e. when the direction of the vector of magnetic field lines and the direction of the vector of gravity coincide, the force acting on element 4 does not occur. Thus, during the movement of the controlled object, and, consequently, the body 1 of the device, mechanical vibrations of the ferromagnetic inertial element 4 occur with a frequency of modulation of the magnetic field of the magnetic system, while the amplitude of the oscillations will change in accordance with the vibration parameters of the controlled object.

 Mechanical vibrations of the ferromagnetic inertial element 4 are converted into an electrical signal using a capacitive sensor 7 and a capacitance-voltage converter 8, detected by a synchronous detector 9 and recorded by a recorder 10, which records an electrical signal corresponding to the vibrations of the controlled object.

To increase the sensitivity of measurements, the frequency F _mod. changes in the magnetic field, you can choose multiple or fractional natural resonance frequency F _res. ferromagnetic inertial element 4. With the dimensions of the last order of units cm and its mass of the order of fractions and units of grams, F _res. will be of the order of units and tens of Hz, and the frequency F _mod. You can choose 2-3 times higher or lower than the frequency F _res. . In this case, the condition for selecting the frequency F _mod will be satisfied _. much higher than the oscillation frequency of the controlled object, for example, infra-low-frequency vibrations of structures, nodes, mechanisms, tidal lunar-solar vibrations of the earth's crust, infra-low-frequency seismic vibrations, tilts of the earth's surface, etc.

The proposed solution allows to increase the information content of measurements by expanding the measurement range towards infralow frequencies. Indeed, by modulating the magnetic field, it is possible to obtain mechanical vibrations of the inertial element, the amplitude of which varies in accordance with the change in the motion parameters of the controlled object. In this case, the modulation frequency F _mod. magnetic field strength, you can choose a sufficiently large / F _mod. units, tens and hundreds of Hz / in comparison with the frequency F _counter. fluctuations of the controlled object / F _counter. about tenths of a second, units, tens, hundreds and thousands of seconds, days, weeks and months. Carrying out synchronous detection of the amplitude of the mechanical vibrations of the inertial element with the reference frequency F _mod. , you can register infra-low-frequency oscillations of the controlled object with a stable zero-point device.

The proposed solution has a higher noise immunity, since the registration of the motion parameters of the controlled object is carried out using synchronous detection with a reference frequency of F _mod. set by the reference frequency generator.

 Since the proposed device has small overall dimensions / all devices are of the order of several tens of grams /, it does not impose special requirements for installation on a controlled object and can be placed in a wide variety of conditions / on various structures, components, mechanisms, deep-sea and aircraft, deep and superdeep wells, etc. /.

 The proposed device provides a higher measurement sensitivity and a stable zero point in comparison with the known pendulum vibration sensors and seismometers. The high sensitivity of the measurements is due to the very small dry friction of the inertial element in the support, as well as the fact that the pressure force of the inertial element on the support can be minimized by choosing the magnetic field strength. The high stability of the zero point of the proposed device is due to the absence of uncontrolled temporary movements of the inertial element / pendulum / relative to its support, for example, due to the pulling of the pendulum system from the seal, the phenomena of secondary elasticity in materials, especially the phenomena of elastic aftereffect and creep, the type of fastening of the pendulum and t .d. occurring in known vibration sensors and seismometers.

Claims (3)

 1. The method of measuring the motion parameters of an object, which consists in registering mechanical vibrations of an inertial element set in a stable equilibrium position in a magnetic field, characterized in that, in order to increase noise immunity and expand the measurement frequency range, a change in the magnetic field intensity with a frequency , a greater frequency of the object’s vibrations, and the object’s motion parameters are determined by changes in the amplitude of the inertial element’s vibrations.  2. The method according to claim 1, characterized in that the frequency of change of the magnetic field is selected multiple or fractional natural resonant frequency of the inertial element.  3. A device for measuring the parameters of the movement of an object, comprising a housing designed for rigid connection with the object, a ferromagnetic inertial element, a magnetic system made in the form of a solenoid, a non-magnetic support on which a ferromagnetic inertial element is mounted in a state of stable equilibrium, and a constant current source, the recorder and the connected capacitive sensor and transducer capacitance n voltage, characterized in that, in order to increase noise immunity and expand the frequency range, it is equipped with a modulator, the first input of which is connected to the output of a direct current source, and the output with a solenoid coil, a synchronous detector, the signal input of which is connected to the output of the converter, the capacitance is voltage, and the output with the recorder input, and a reference frequency generator, the outputs of which are connected to the second input of the modulator and control input of a synchronous detector.

Images