SU1608625A1 - Method of controlling frequency of mechanical vibration of resonance object with electrodynamic exciter - Google Patents

Abstract

The invention can be used in a vibration technique operating in a resonance mode. The purpose of the invention is to increase the degree of frequency stabilization and tuning accuracy to resonance. The method is based on a physical criterion. By introducing a criterion determining the resonance conditions and equal to the ratio of the current integrals of the core of an electrodynamic vibration exciter, respectively, in the first and second quarters of each half-cycle of oscillations of a mechanical object, the accuracy and stability of the frequency of the excited oscillations is improved. The natural frequency of the mechanical object is measured, and the generator is tuned to this frequency, which sets the mode of forced oscillations in the future. The change of the natural frequency under the influence of external factors causes a disturbance of the resonance condition. This is recorded using the indicated criterion, and a signal is generated which acts on the parameters of the mechanical object in such a way that the resonant mode is restored. 9 il.

Description

The invention relates to the field of regulation of mechanical oscillations of resonant objects and can be used in vibration devices.

1KHNIKI.

The purpose of the invention is to increase the degree of frequency stabilization and tuning accuracy to resonance,

Figures 1 and 2 illustrate the essence of the physical criterion using the example of a seismic detector with an electrodynamic pathogen; and fig.Z - curves of some parameters; 4 shows the curves for the coefficient by which f is determined by the resonance at a given frequency; figure 5 is a block diagram of the device, I implements the proposed method; on (|| ig.6 - displacement and speed diagrams

platforms of a mechanical object, as well as currents and voltages in a device that implements the proposed method; 7 is an electrical block diagram of FIG. 8 is a frequency meter circuit; Fig. 9 is a block voltage ramp circuit diagram.

The proposed method is as follows.

In the free oscillation mode, the natural frequency of the mechanical object is measured.

The mechanical object is switched to the mode of forced oscillations with a frequency equal to the frequency of the measured natural oscillations. In the process of work, due to external factors there is a change in personal properties.

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about

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object frequency and violation of the resonance condition. Therefore, in order to maintain resonance, a constant adjustment of the natural frequency to the frequency of forced oscillations is required.

At each half-period of forced oscillations, the integrals of the core of the electrodynamic exciter Si and S2 are measured, respectively, for the time intervals 0 - T / 4 and T / 4 - T / 2, where T is the period of forced oscillations.

The ratio of the integrals is determined.

From the frequency of the forced oscillations, the Creuse value f (phase) is determined, which corresponds to the resonance condition.

The Kresz and K values are compared and, by the result of the comparison, they form a signal that changes the natural frequency of the mechanical object until equality is reached.

To Creuse.

The method is based on a physical criterion. The criterion is clarified by the example of a vibrator with an electrodynamic exciter, on which the rectangular alternating voltage pulses and (Fig. 1) are applied. In the operating mode, the seismic source platform and the measles of the pathogen undergo sinusoidal oscillations, while an emf is induced in the cortex, which determines the current of the cortex (t).

The mathematical model of the vibrator has the form

where 1 is the current core;

w 2 ng fsbiH - angular velocity;

y-turn angle;

Lfl, Р - inductance and active resistance of the core;

Cd is the engine constant;

Y is the stress on the cortex;

b is the dissipation coefficient;

с - stiffness of elastic elements (springs);

i is the moment of inertia.

The equations are written for an engine with a rotating rotor, which, through a lever mechanism, oscillates a platform with a linear velocity v (t) and a displacement x (t}. Between x and v, 9 and x is matched through the length of the lever arm.

The essence of the criterion is that to determine the resonance condition, the ratio of two integrals defined on the first and

0

five

0

second quarter x of each semi-period of oscillation.

tА / i «dt

about Si, PL

HERE:

J isdt

t / 4

those. the criterion is the ratio of the areas of Si and S2 obtained over a half period (Fig. 2).

On fig.Z are given curves К Si / S2 and т / 2 q J | 2 (j, depending on its own part

a hundred of a mechanical object.

The value of q, which is proportional to the heat loss in the crust, is minimal at resonance. And on the K () curve itself, the mode of operation of the vibrating mechanical object is unambiguously determined, namely, K Creuse-preresonant; K Creuse - resonance; By Croesus - resonant.

When the frequency of forced 5: fluctuations changes, the value of the cresis changes and the dependence of the cresis is shown in figure 4.

There are conditions under which the information properties of the criteria are limited. This happens when the right K Krez and the curve K (d) s) intersect at more than one point, which depends on the parameters of the oscillating system.

With fco6 fsbiH, these lines do not intersect and therefore, in the resonance mode, the information properties of the criterion are kept in an unlimited range of frequencies.

In the pre-resonance mode fco6, these lines can intersect at a certain frequency f and the information criteria properties are preserved from the frequency fnHx and higher. The value of the lower cut-off frequency fnizh depends on the quality factor of the mechanical loop, and the motor parameters 1 and K. The decrease in the Density can be accomplished by decreasing 1 or increasing H.

As follows from the research results, when the frequency of forced oscillations of Gwyn changes, the value of the Creuse coefficient, by which the resonance at this frequency is determined, is changed (Fig. 4). Therefore, in the device that implements this criterion, there must be a block that generates a nonlinear dependence Kpe3 (fBbiH). Before setting up a nonlinear block, the following calculation operations should be carried out.

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five

0

five

50

55

For a specific vibrator with parameters known as L, T, La, Re, the resonance modes are calculated using the equations for three values of the forced frequencies n 1, febiH 2, f exp 3, providing a resonance by selecting the stiffness coefficients of the spring S1,02, cz . For each frequency value

(2) Creuse 1, Creuse 2, Creuse 3, are determined

after that, using the Lagrange interpolation Muglocker, an analysis of the curve in the form of a Creusa (feHh) - P fsbiH + 9 pin + h is made,

Croesus1

(feuHl fBbiH2) (fsbiHl fBHH3)

MV 0)

sa

faM n

ti

where r

Croesus2

+

(fBbiH2 vy1

-fI (w2-fsuHS) ezZ

+

(febiHS fBbiH2)

(out of febiHl Pl + P2 + Pz.

The nonlinear block is adjusted according to the computed values of p, d, h.

In the process of regulation, according to the described criterion, a change in the dissipation coefficient b will cause a deviation of fUt. 1b from the cut - therefore, this device must be operated at constant values of b, or with a known law of variation of this coefficient. In the second case, this law must be taken into account when calculating the Kree Croz (fBbin).

A device for tuning in a resonance of mechanical objects contains plate 1 with an electrodynamic exciter 2 mounted on springs 3 with adjustable stiffness. The platform is connected to the platform 4 speed sensor.

The device also contains a comparator 5 | () Lok 6 linear voltage variation, one vibrator 7, frequency meter 8, generator 9, amplifier 10, current sensor 11. analysis block 12, frequency doubler 13, keys 14 and 15, comparator 16, single vibrators 17 and 18, integrators 19 and 20, keys 21 and 22, memory blocks 23 and 24, divider 25, amplifier 26, nonlinearity block 27.

Block Start (Fig.7) contains inverters 28 and 29; delay circuit 30; logical element AND-NOT 31; diodes 32 and 33. This unit performs the following functions - removes the platform from the locking device and the () live switch on the power amplifier 10 for a half-period of oscillation.

When the P button is pressed, the CTdnopHoe device is turned on and the platform is released from the stopper. Since in the first MO "leHT it is stationary, the voltage at the output of the sensor 4 is speed U4 O and at the output of the inverter 28 there is a logical 1. At the output of the circuit 30, the delay due to time, -.

ten

15

20

25

thirty

35

40

45

O, therefore, at the output of element 31, signal 1, and at the output of inverter 29, O. When the platform starts moving from the stopper, voltage U4 O appears on the speed sensor 4, which leads to the output of the inverter 28 of the signal O, which, however, does not change the state of the outputs of the element 31 - 1 and the inverter 29 - O. After a half-period of oscillation, the platform will be in the lower extreme position and again U4 O, and at the output of the inverter 28 will go to 1. K this time, the output of the delay circuit 30 is also equal to 1, since the time constant for the circuit 30 The supports are set so that after a half-period of oscillations a logical 1 appears at the output of the delay circuit 30. Thus, after a half-period of oscillation, after the start, 1 appears at both inputs of the element 31, and also 1, which is directly connected to the inverter 29, and 33 is applied to both inputs of the element 31, prohibiting further state changes of the element 31, and hence the inverter 29. The output signal of the inverter 29, having the value 1, will turn on the amplifier 10.

Meter 8 frequency, depicted in Fig, contains a two-input logic element And 34, the inverter 35, the analog key 36, the integrator 37, the divider 38 analog signals. This unit measures the natural frequency of oscillations of a mechanical object, stores and issues information about this frequency. The frequency measurement is carried out based on the integration of the function. In this case, the output

t integrator voltage U / Uidt Ui t,

about

and if the integration is carried out over a time interval (O - T / 2), then U UiT / 2 Ui / 2f, where f is the measured frequency. After the operation of dividing the constant voltage U2 by U at the output 8, the voltage is 2U2

Ubui

f a -f

50

55

The algorithm described in block 8 is as follows. During the measurement of the frequency at the input of the Stop, a logical O acts, and at the output of the inverter 35 there is 1, the closing switch 36. As a result, a constant voltage Ui is applied to the first input of the integrator 37. The beginning of the measurement is determined by the moment of occurrence of a short pulse 1 at the Start input, which causes 1 to appear at both inputs of element 34 and a short pulse 1 from the output of element 34 zeroes the integrator 37. The measurement is completed in

moment of occurrence at the input of the stop signal is H - and in this case, the output of the inverter do is O, which opens the switch 36, but does not change the output state of the element 34, since there the input O acts 8. integrator 37 maintains a constant voltage U8 Uit. To measure the frequency, the time interval is pulse 1 at the start-up input and 1 at the stop input must be equal to T / 2. To obtain high storage accuracy of voltage 7, electrometric amplifiers with input currents 10 ... 10 A can be used as operational amplifiers in block 8 YU.

DPSH. ....

Block 6 (Fig. 9) contains an odofactor 39 which is driven by a falling edge of the input signal, inverters .40 and 41, and a diode 42. This block responds only to the first rectangular voltage pulse received at the input, the falling edge of which changes state the output of the block 6 with O is 1 and is fixed after that. It works in a similar way. As long as a rectangular voltage pulse arrives at the input of the block, the output of the J9 single-shot oscillator is O, and the outputs of inverters 40 and 41 are 1 and O. When a rectangular 1puls appears on the input 6 of block 6, its state does not change, until the falling edge of this pulse passes, which will initiate the odiovibrator 39 and its output is 1. This 1 will change the state of the inverter 40 outputs to O, the inverter 41 will change to 1, From the output 41 the signal 1 to the directly connected diode 42 enters the input of the inverter 40 and thereby fixes the output state of block 6,

The device works as follows about & again.

Before starting, platform 1 is held in one of the extreme positions, for example in the upper. When the Start command is received, the locking device releases the platform 1 and it begins its downward motion; at the same time, during the first half-period of oscillation the engine does not turn on and the board-, form 1, makes a free oscillation

 the free oscillation time in the device measures the intrinsic frequency of a mechanical object. When platform 1 moves, the output of the speed sensor 4 causes a voltage U4, including

 comparator 5. On the leading edge of the signal U5 of the comparator 5, a single vibrator 7 is triggered and a pulse U7 turns on the meter 8 frequency. After half period

 when platform 1 is in the extreme low position (assumed t 0), the voltage

5 10

one

at the output of the speed sensor 4 is zero and the comparator 5 is closed; the rear front of the comparator output voltage. 5 will start block 6, which, by voltage U6, will stop the measurement in block 8, putting it into information storage mode. The output voltage of unit 8 will continuously exist at the input of generator 9, determine its frequency equal to the frequency of natural oscillations of a mechanical object at the time of its measurement.

At the moment of time t О mechanically / the object is transferred to the mode of forced oscillations by applying a sigial through the Start-up unit to turning on the power amplifier 10 and to the electrodynamic vibration exciter 2, the voltage Uio is applied through the current sensor 11. When voltage is applied to the core of exciter 2, a current flows, which is determined by the equation of motion of a mechanical object and the magnitude of the supply voltage Uio. The voltage frequency Uio is given by the generator 9. To obtain integrals of 5 tons / 4 tons / 2 for each half-period of oscillations

Si / "dt, Sa J, l" fit voltage with 0t / 4

Gnaron 9 arrives at frequency doubler 13, designed to highlight time moments 0 with T / 4 discreteness.

Consider the work of Lok 12 on a half-period of forced oscillations. The voltage Ui3 from the doubler 13 frequency is fed to the comparator 16, which forms right-angle pulses Ui6. On the leading edge of the pulse and 16, the one-shot 17 is triggered and the keys 21 are closed by the pulse Ui7 and the blocks 23 and 24 of the memory are switched to the Record mode. With the ego from the outputs of the integrators dp 19 and 20, the values of Si and S2 obtained in the previous half-period are recorded in memory blocks 23 and 24, respectively. After the disappearance of the pulse Ui, the keys 21 and 22 are open, and the blocks 23 and 24. will go into storage mode. On the leading edge of Ui7, a one-shot 18 is triggered and a pulse- Ui8 zeroes integrators 19 and 20. Thus, at the beginning of the current half-period of the oscillations, information Si and S2 is selected for the previous half-period and the channels are prepared for receiving this information on the current half-period. L. Memory blocks 23 and 24, which are in the Read mode, are voltage proportional to Si and S2./Open into divider 25, from the output of which UK bi / aa is fed to the direct input of the differential amplifier 26, to the inverting input of which receives the voltage Ukrez - Krez (Gvory) C of the nonlinearity block 27.

On the ekoA of block 27, the voltage comes from the measuring device 8 frequency.

The voltage from the output of the amplifier Uae Ui - Ok.ree affects the organs regulating the stiffness of the springs 3 so as to fulfill the condition Shk-rez. While the current half-period is adjusting the E resonance according to the values of Si and Sz of the previous half-period unit 12 calculates the new values of the integrals Si and S2. In the time interval O - T / 4, the voltage Ui3 is negative and the key 14 is closed, and the scrap 15 with the inverse input is open, the signal from the current sensor 11 enters the integrator 19 and the value Si is stored at its output. In the interval T / 4 - T / 2, the key is 14 times), the key is 15, the key 15 is closed and the signal from sensor 11 is fed to the integrator 20 and the value S2 is kept at its output. ; An aid for regulating the frequency of mechanical oscillations of a resonant object with

electrodynamic pathogen, at which the natural frequency of the object’s mechanical oscillations is measured, and then the object is put into

oscillations with a frequency equal to the natural frequency of oscillations, characterized in that, in order to increase the degree of frequency stabilization and tuning accuracy into resonance, at each half-period

oscillations measure the current integrals of the electrodynamic driver core Si and $ 2, respectively, for the time intervals O – T / 4 and T / 4 –T / 2, where T is the period of forced oscillations: the ratio

integrals K Si / S2, the value of Kresz corresponding to the resonance condition is determined from the frequency of forced oscillations; the values of Krez and K are compared and, with K Krez, the frequency of the natural mechanical oscillations of the object is changed by changing the stiffness of its elastic elements before establishing a resonance.

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S

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.. Her {{1H} stop locking device

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1608625

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Claims (1)

5g is stored at its exit. Fort. MULA INVENTIONS A method for controlling the frequency of mechanical vibrations of a resonant object with an electrodynamic pathogen, in which the natural frequency of the mechanical vibrations of the object is measured, and then the object is put into forced oscillation mode with a frequency equal to the natural frequency of vibrations, characterized in that, in order to increase the degree of frequency stabilization and accuracy settings in resonance, on each half-cycle of forced oscillations, the integrals of the armature current of the electrodynamic exciter Si and S2 are measured, respectively To time slots 0 - T / 4 and T / 4 - T / 2 where T - period of forced vibrations of: determining the ratio of the integrals K = S1 / S2, the frequency of forced vibration Krez determined value corresponding to a resonance condition; comparing the values of Croesus IK And when Croesus change the frequency of their own mechanical vibrations of the object by changing the stiffness of its elastic elements to establish resonance.