RU2557999C1 - Measuring method of very low flight altitude of plane, mainly hydroplane above water surface and sea disturbance parameters - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: invention relates to noncontact oceanographic measurements and can be used for determination of statistical characteristics of sea disturbance from the board of the moving airborne vehicle. A measuring method of very low flight altitude of a plane, mainly a hydroplane, above water surface and sea disturbance parameters, which is based on recording of physical parameters depending on an electromagnetic field created by an antenna installed on the plane, as per which the following is estimated: plane flight altitude, sea wave height, sea wave length in the flight direction and the place that is flown over by the plane, in which the antenna for creation of an electromagnetic field is made in the form of five independent antennas installed on the plane body in the plane centre of gravity, in the front and rear parts of the plane, and in end parts of plane wings.

EFFECT: improvement of reliability and informativity of measurement of sea wave height from the board of the airborne vehicle to provide landing on sea surface.

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Description

The invention relates to the field of aviation instrumentation and can be used to create systems for automated control of flight parameters, depending on its current altitude and sea waves, in particular for automation of landing (splashdown) of a seaplane on a smooth and excited surface.

There are various methods for determining the flight altitude of an airplane (seaplane), for example, barometric, and methods for determining the altitude using isotopic and laser altimeters. The known barometric method for determining the flight altitude of an aircraft by taking into account the static pressure near the aircraft and the parameters of the state of the atmosphere near the ground (air pressure and density) (Flight tests of aircraft MG Kotik et al., Mechanical Engineering, 1968 [1]). The disadvantage of this method is that when flying at subsonic speed in front of the fuselage, wing and other parts of the aircraft (seaplane), an increased pressure zone is formed. This zone is so large that it is practically impossible to remove the LDPE (air pressure receiver) beyond it. Therefore, local static pressure is supplied to the LDPE static chamber, which is greater in magnitude than the atmospheric static air pressure. When the aircraft is flying at altitudes lower than the wing span, significant errors in determining the barometric altitude are introduced by the aerodynamic effect of the screen (water or earth surface) on the velocity and pressure field near the aircraft. For accurate measurement of small flight heights, isotopic altimeters are used. To do this, sensors containing a radioactive element are placed along the runway (runway), and equipment is installed on the plane that allows you to determine the exact height of the aircraft above the runway but the radiation intensity. However, with the help of such altimeters they do not solve the problem of determining the flight altitude of a seaplane when landing in an unprepared water area. Closest to the claimed one is the well-known and widely used radar method of measuring flight altitude, based on the registration of radiation fields (far field fields) generated and received by an antenna mounted on an airplane (seaplane). The class of devices using this principle includes radio altimeters (Flight operation of radio navigation equipment of aircraft. IE Bondarchuk, Transport, 1978, pp. 112-152 [2]). A feature of this method is that there is an increase in measurement error with a decrease in flight height. Error reduction is achieved by significantly complicating the equipment.

Contact method of measurement (copyright certificate SU No. 1584513 [3]) can serve as analogues of the method of measuring the parameters of sea waves. However, the measurement in this case can be made when the seaplane is afloat, i.e. after landing on water.

A device is also known for measuring the parameters of sea waves by means of the radar method of sensing the sea surface (see "Radar location of the sea surface", A. A. Garnakeryan, A. S. Sosunov, University of Rostov, 1978 [4], copyright certificate SU No. 805745 [5]). However, this device allows you to get the characteristics of the excitement when flying at high altitude.

It is also known a device for measuring the parameters of sea waves (patent RU No. 1788484 A1, 12/15/1989 [6]), containing a series-connected antenna, antenna switch, receiver, first envelope detector, first low-pass filter, second voltage divider, second quadrator, third a multiplier and a second indicator, the second input of the antenna switch through the transmitter is connected to the output of the synchronizer, the output of the first low-pass filter through the automatic gain control unit is connected to the second input of the receiver, the second input the second voltage divider through the fifth low-pass filter is connected to the output of the second envelope detector, the output of the first envelope detector through a centering unit, a zero level comparator, a voltage period converter and a second low-pass filter is connected to the first input of the first multiplier, the second input of which is connected to the output of the speed meter flight, and the output is with the input of the first indicator, the output of the centering unit through the first quadrator, the third low-pass filter, a functional converter and an adder nen with the second input of the third multiplier, the second adder input through the first voltage divider, the fourth low-pass filter and the second multiplier connected to the output of the centering unit, the output of the first quadrator connected to the second input of the second multiplier, and the output of the third low-pass filter to the second input of the first divider voltage, characterized in that in order to improve accuracy and simplify the design, it is equipped with a series-connected radio altimeter, a selective pulse generator and a selector, synchronous output mash is connected to the second input of the selective pulse generator and the receiver output - to a second selector input, whose output is connected to the input of second envelope detector. This device also allows you to obtain the characteristics of the waves during flight at high altitude. In the known method for measuring the ultra-low altitude of the aircraft, mainly a seaplane, and sea waves parameters, it is proposed to use near-field fields created by the antenna to eliminate such a disadvantage. These fields are quasistatic in nature, which means that it is permissible to use the language and concepts of the theory of electrical circuits to describe the properties of the antenna due to them. The fields of the near zone increase much faster than the fields of the far zone with a decrease in the distance to their source (to the antenna). This gives reason to believe that the measurement error will decrease with decreasing flight altitude. When moving away from its source, the near field fields decrease much faster than the far field fields, therefore, a method of measuring the altitude and sea waves parameters, based on recording the near field fields, can be used, unlike radar meters, only at very low altitudes: less wing span of a seaplane (patent RU No. 2183010, 05.27.2002 [7]).

At the same time, to increase the safety of landing an airplane, mainly a seaplane, by automatically maintaining the vertical speed set for a given type of aircraft, in a known method for measuring the ultra-low altitude of an airplane, mainly a seaplane, and sea waves based on recording physical quantities that depend on electromagnetic of the field created by the antenna mounted on the aircraft, a sequential LC circuit is created with the antenna formed in the near field of the antenna to nensator, one of the plates of which is the antenna, and the other is the aircraft body, include this LC circuit in one of the arms of the bridge circuit, a harmonic voltage stabilized in amplitude and frequency is applied to the input of the bridge circuit, and the amplitude of the aircraft’s flight above the water mirror is judged by amplitude the harmonic signal removed from the bridge circuit, and when the water surface is excited, the signal removed from the bridge circuit is detected, extracted from the detected signal, and the constant and variable components are measured, while m the altitude of the aircraft is judged by the constant component, the height of the sea wave - by the amplitude of the low-frequency variable component, and the length of the sea wave in the direction of flight and in the place over which the plane flies - by the quotient of dividing the horizontal speed of the aircraft by the frequency of the low-frequency variable component. In this case, the inductance of the serial LC circuit is selected from the condition that the resonant frequency of the LC circuit falls when the aircraft’s flight altitude is above 50-100 m in the range of 1.5-6 MHz. The value of capacity C depends on the flight altitude. At a very high flight altitude, it is equal to C ₀ , where C ₀ is the capacitance of the LC circuit at high altitude, while the resonant frequency of the LC ₀ circuit is f ₀ . With decreasing flight altitude, the value of capacity C increases and becomes equal to: C = C ₀ + ΔС, where ΔС - additional capacity - increases with decreasing altitude and tends to zero with an unlimited increase in flight altitude. Thus, δf — the departure of the resonant frequency of the LC circuit with a decrease in the flight altitude of an airplane (seaplane) sharply increases with a decrease in flight altitude. However, in a very wide range of capacitance variations, ΔCδf - the resonance frequency drift - is almost proportional to the harmonic signal amplitude U _c (t), where U _c (t) is the signal taken from the midpoints of the bridge circuit, to the input of which the harmonic voltage U (t) stabilized frequency f ₀ and amplitude U _m . In this case, the resistance r in the lower part of the bridge circuit contains a series resonant L (C ₀ + ΔC) circuit, and L and (C ₀ + Δ C) are ideal (i.e., lossless) inductance and capacitance, and the resistance r in the upper part of the shoulder of the bridge circuit containing the resonant serial L (C ₀ + ΔC) -contour, is the equivalent active resistance of a real inductor, calculated through its inductance L and quality factor. If the flight takes place over an agitated sea surface, the signal U _c (t) must be additionally detected with the subsequent separation of the constant and variable (low-frequency) components, since during a strictly horizontal flight, the value of the additional capacitance ΔС periodically changes, reaching a maximum value above the crest of the sea wave and a minimum value above the depression, and the signal U _c (t) can be considered an amplitude-modulated radio signal.

When it is detected, the amplitude of the constant component will be proportional to the average flight height above the excited sea surface, the amplitude of the variable (low-frequency) component will be the height of the sea wave with a proportionality coefficient depending on the average flight height, and the frequency of the low-frequency variable component (i.e., the envelope frequency of the signal) allows you to find the wavelength in the direction of flight by dividing the known horizontal speed of the aircraft by the value of this frequency. Thus, due to the fact that at very low altitudes, the horizontal speed of the aircraft is much greater than its vertical speed, you can continuously monitor the altitude and parameters of sea waves in the place over which the aircraft is currently located. However, this method at very low altitudes: less than the wing span of a seaplane, is operational only under ideal hydrometeorological conditions. In addition, the known method of measuring the ultra-low altitude of an airplane, mainly a seaplane, above the water surface and sea waves parameters does not provide a determination of the angle of the wave, which is crucial to ensure a safe landing on an excited water surface.

The objective of the proposed method for measuring the ultra-low altitude of an airplane, mainly a seaplane, above the water surface and the parameters of sea waves is to expand the functionality and increase the reliability of determining the parameters of sea waves.

(где h_в - высота волны, Т - период волны), период волнения определяют в зависимости от соотношения амплитуды волны и амплитуды ускорения.The problem is solved due to the fact that in the method of measuring the ultra-low altitude of an airplane, mainly a seaplane, above the surface of the sea and the parameters of sea waves, based on the registration of physical quantities that depend on the electromagnetic field generated by the antenna installed on the airplane, which is used to judge the flight altitude aircraft, about the height of the sea wave, about the length of the sea wave in the direction of flight and in the place over which the plane flies, the antenna for creating an electromagnetic field is made in the form of five dependent antennas mounted on the aircraft body, respectively, in the center of gravity of the aircraft, in the nose and tail parts of the aircraft, and in the terminal parts of the wings of the aircraft, the height of the sea wave is judged by the difference between the maximum and minimum values of the amplitudes of the electromagnetic signal (average wave height from the sole to the top ), the length of the sea wave in the direction of flight and in the place over which the plane flies is judged depending on the ratio of the wave height to the steepness of the wave, which is determined in accordance with the dependence $$\xi =2\pi h_{\mathrm{at}}g\stackrel{2}{T}$$

(where h _in - wave height, T - wave period), the wave period is determined depending on the ratio of the wave amplitude and acceleration amplitude.

The inventive method allows to measure the parameters of sea waves immediately before landing the seaplane on water. In addition, this method will allow you to combine in one device as an altimeter of very low altitudes, and a meter of sea waves and a speed meter. In addition, unlike the prototype [7], the phase velocity of the sea wave is determined, which allows us to determine the direction of the waves, which allows us to choose more favorable heading angles for landing the seaplane.

The well-known non-contact methods for determining waves are integral in nature and require measuring a wide range of signals reflected from a large area or a set of data on wave profiles along several directions (Zagorodnikov A.A. Radar survey of sea waves from aircraft. L .: Gidrometeoizdat, 1978. Ustylenko NS, Lesnaya LL Use of microprocessor modules in problems of assessing the state of the sea surface // Signal Processing in Location Systems of Inhomogeneous Media. SK: Ed. UPI, 1987, issue 1), which excludes the possibility of prompt information. The wave parameters can be determined on-line from the aircraft using the output data of at least two single-beam radio-Doppler speed meters and two wave profile meters.

The method of measuring the ultra-low altitude of an airplane, mainly a seaplane, above the water surface and sea waves parameters is illustrated by the drawings (Fig. 1 ÷ 3).

FIG. 1. The projection of the first and second radio beams on a horizontal plane. 1 - front of the wave, 2 - diametrical plane of the seaplane, V - flight speed, v _f - phase velocity of the sea wave, τ - time interval of passage of the sea wave by the radio beam, determined by its apex, α - angle between the general directions of wave propagation and the diametrical plane of the seaplane (counted from the direction of the longitudinal axis of the seaplane counterclockwise is considered positive, and clockwise - negative, L is the base (the distance between the intersection points of the radio beam and the sea surface).

FIG. 2. Determination of the horizontal component of the orbital velocity. V _zo is the vertical component of the orbital movement, γ _o is the angle of deviation of the radio beam from the vertical, V _th is the horizontal component of the orbital velocity at the intersection of the radio beam with the sea surface, H _o is the antenna mounting height, R _o is the distance along the radio beam, G _o and G _∑ - the angles between the plane OZ _o R _{o the} direction of movement of the seaplane and the X axis, respectively.

FIG. 3. A block diagram of a device for implementing the method. Antenna 3, transceiver 4, height measuring unit 5, Doppler frequency meter 6, motion speed measuring unit 7, calculator 8 for determining wave heights and phase wave velocity, block 9 for determining the direction of wave arrival, block 10 for determining the fluctuation component of velocity, block 11 for determining the angle of encounter with the wave, block 12 for measuring the vertical movements of the aircraft, block 13 for evaluating measurement errors.

For a two-beam meter, the necessary formula dependencies can be obtained from FIG. one:

where V is the flight speed, v _f is the phase velocity of the sea wave, τ is the time interval of the sea wave passing by the radio beam, determined by its top, α is the angle between the general directions of wave propagation and the diametrical plane of the seaplane (counted counterclockwise from the longitudinal axis of the seaplane is considered positive, and clockwise - negative, L is the base (the distance between the points of intersection of the radio beam and the sea surface).

In the formula (1), the sign “+” is placed in front of v _f / cosα, if the waves move towards the aircraft, and if the direction of the waves coincides with the direction of movement of the aircraft, then the sign “-” is placed.

.Formula (1) can be simplified by bringing it to the form

.

Knowing the profiles of the excited sea surface at the points of intersection of the radio beam with it and determining the time interval t of the sea wave passing successively the points of intersection of two radio beams with the sea surface, we can calculate the angle of encounter with the wave in accordance with formula (2).

To determine the direction of the wave (towards or in the direction of travel), you can use the effect of modulating the Doppler frequency in each beam of the orbital velocity meter. The Doppler frequency (Fig. 2) can be written:

where k is the wave number, V _zo is the vertical component of the orbital motion, γ _o is the angle of deviation of the radio beam from the vertical, V _th is the horizontal component of the orbital velocity at the intersection of the radio beam with the sea surface, H _o is the antenna installation height, R _o is the distance along the radio beam, G _o and G _∑ - the angles between the plane OZ _o R _{o the} direction of movement of the seaplane and the X axis, respectively.

и

And also we have (Fig. 2):

and

where Г _о and Г _∑ are the angles between the plane OZ _o R _{o the} direction of movement of the seaplane and the X axis, respectively.

Further, approximating, on a scale of the radio emission spot on the surface, a two-dimensional sine wave wave, we have that the components of the orbital velocity of such a wave and the relief of its surface h (x, y, t) can be represented by the following formulas:

where h _в - wave height, φ (x, y, t) - its phase.

Substituting formulas (6) and (7) into formula (3) taking into account relation (4) we obtain:

where ω _mode (x, y, t) is the modulation function.

From formulas (9) and (10) it can be seen that the phase of the modulation function ω _modes (x, y, t) of the Doppler frequency differs from the relief phase h (x, y, t) by - {90 deg + arctg [cos (Г _о -α) tgγ _o ]}, depending on the given angles γ _o and Г _о, only on the direction of wave propagation α.

In determining the wave parameters, an important property of the modulation function ω _modes (x, y, t) is that its phase component arctg [cos (Г _о -α) tgγ _o ] changes sign depending on the wave arrival with respect to the projection of the radio beam onto the horizontal plane. So for -90 degrees <(Г _о -α) <90 degrees, it is positive, and for

90 degrees <(Г _о -α) <180 degrees - it is negative.

From the theory of sea gravitational waves it is known that between the value of the phase velocity of the wave and its length λ _in there is a relationship v _f = √ gλ _in / 2π (where g is the acceleration of gravity). Moreover, the value of λ _in is associated with the height of the wave h _{in a} ratio depending on the type of approximation. According to the Register, λ _in = 2.44 (h _in +1) ² .

In turn, the height of the waves can be determined from the fluctuation component of the readings of height meters, which, due to the normality of elevations of the sea surface, is also normal. In this case, the wave height is 3% of the coverage h _в3% = 5.3σ _в , where σ _в is the standard deviation of the measured elevations of the sea surface.

Antenna 3 is a slotted waveguide antenna with a working aperture of 325 × 310 mm, formed by the 29th radiating aluminum waveguides with inclined slots on a narrow wall. The emitting waveguides are powered by two transverse waveguides with slots and provides two radiation beams from a single aperture with a beam width of 4 °, 5. The antenna also includes a waveguide path with a circulator, and load elements.

The transceiver 4 consists of an ultra-high frequency generator, a filter resonator, a diode mixer, an amplifier, a block for automatically adjusting the generator zone, a modulator, and a synchronous detector.

The height measurement unit 5 consists of a circuit for setting the initial height, an integrator and a voltage-code converter.

The Doppler frequency meter 6 consists of a block of Doppler frequency filters, a block of formers, a controversial frequency circuit, a switching circuit, an electronic adder of Doppler frequencies, a block of output dividers.

The unit for measuring the speed of movement 7 consists of an inverter, a differentiating circuit, a shaper, two triggers, an adder, an amplifier.

The calculator of the height of the waves and phase velocity of the waves 8 consists of a circuit for isolating the fluctuation component, a rectification circuit, an amplifier-limiter, an integrator, a voltage-code converter designed to process signals when determining the height of the waves, and to determine the phase velocity of the waves, the circuit consists of an integrator including circuit AND, integrator, threshold device, character extraction schemes, including adder, threshold device and angle converter, including a scheme for entering a character in a code and a calculation scheme naka.

Block 9 for determining the direction of arrival of the waves consists of an AND circuit, an adder, an analog-to-digital converter, a divider, a multiplier, and a functional calculator.

Block 10 for determining the fluctuation component of speed consists of a frequency-voltage converter, a circuit for isolating the fluctuation component, an amplifier-limiter.

Block 11 for determining the angle of encounter with the wave consists of a sign inverter, switching circuit, adder, subtracting device.

Block 12 for measuring the vertical movements of an aircraft consists of a newmeter and an analog-to-digital converter (V.D. Andreev. Inertial Navigation Theory. M., Nauka, 1966, 580 pp., Pp. 16-21).

Block 13 for estimating measurement errors consists of a switch, an electronic adder, a microprocessor, a frequency-to-code converter, a voltage-to-code converter, a comparison circuit, and an output unit.

The device operates as follows. The microwave oscillator through the circulator in the antenna 3 in the valve mode is loaded on the filter resonator, which serves to automatically adjust the generator zone and temperature stabilization.

The frequency modulation of the generator is carried out by the block APZG. The signal emitted by antenna 3 is reflected from the underlying sea surface and, after reception by the same antenna, is sent through a circulator to a diode mixer, which uses a detector section based on a Schottky diode with low noise.

After conversion with a part of the emitted signal, the value of which is regulated by a special screw, the received signal (first harmonic) is filtered and amplified in the amplifier of the transceiver 4, the tuning frequency of which is equal to the modulation frequency, the band is the doubled band of the spectrum at the maximum speed of the vessel. The signal from the output of the amplifier of the transceiver enters the synchronous detector. After synchronous detection with a modulating signal, an alternating voltage is emitted by the Doppler frequency.

The transceiver 4 uses the frequency manipulation mode described in the book. Varkatapyan A.G., Korshunov G.I., Nadelyaev M.A. and others. Automation of control of parameters of the aquatic environment. - L .: Shipbuilding, 1988, 232 p.

From the transceiver 4, the signals are fed to the height measuring unit 5 and the Doppler frequency meter 6, in block 6 the following functions are provided:

- filtering Doppler signals;

- amplification of Doppler signals;

- transformation of the shape of the Doppler signals from a sinusoidal shape to a rectangular one.

Low-pass filters are analog active filters that pass iron signals in the frequency range from 0 to 6500 Hz. The main interference is at a frequency of 20 kHz, at which the supply voltage converter operates, 75 and 100 kHz - at frequencies of modulation of the microwave signal.

Shapes of the waveform convert Doppler signals of a sinusoidal shape, varying in amplitude and frequency, and signals of a rectangular shape with a constant amplitude and a constant pulse duration equal to the minimum period of the useful signal. During a long pulse, the shaper is not sensitive to input signals. Thus, additional filtering of the useful signal from interference caused by vibration of the transceiver housing occurs. These interferences are critical for small amplitudes of the Doppler signal, for a weak reflected microwave energy signal, i.e. with a small signal to noise ratio. Since during the reference period the Doppler signals pass two transitions through the zero state, the frequency of the rectangular pulses at the output of the driver is twice as high as the input Doppler signal.

The reference frequency circuit contains a 200 kHz crystal oscillator, a reference pulse signal distributor, and a frequency divider. A reference time interval of 0.25 s is formed on the frequency divider. The reference pulse signal distributor comprises synchronization devices in an amount corresponding to the number of rays generated by the antenna. Each synchronization device, which is a logical trigger ring, designed to synchronize the reference frequency of the pulse sequences of the Doppler signal. For each synchronization device, the reference frequency obtained at the reference signal distributor is applied, the pulses of which are spaced in time. Thus, the time diversity of the Doppler pulse signals from each beam occurs.

The signals from the Doppler frequency meter 6 are fed to the speed measuring unit 7, where pulse sequences are formed with frequencies proportional to the longitudinal and transverse components of the speed of movement. The Doppler signal coming from the transceiver 4 to determine the sign of motion is also used as input information. Since two identical Doppler signals with a phase shift between them are received for each beam after demodulation, taking one of them as a reference signal, we determine the phase sign of the other signal, which characterizes the sign of the direction of movement of the vessel.

The differential frequency signal F _p (t) = f ₁ (t) -f ₂ (t) (instantaneous frequency of the converted signal) is transmitted to the Doppler frequency meter 6 from the transceiver 4, which carries information on the shift τ of the laws of change in the frequency of the studied f ₁ and received f ₂ signals

,

,

where Δf is the frequency deviation;

T _Δf is the modulation period.

When measuring the height of movement from the antenna to the underlying surface, the Doppler frequency meter 6 uses its proportional relationship with the difference frequency H = ΔtF _p ,

- коэффициент пропорциональности.Where

- coefficient of proportionality.

The determination of the value of F _p in the height measuring unit 5 is reduced to counting the number of pulses (for example, positive half-waves of the difference frequency signal) for the modulation period. When the radiation is alternately with the frequency by the manipulation of two signals f _1,2 (t) = E _m1,2 cos (ω _1,2 + φ _1,2 ),

where E _m1,2 , ω _1,2 + φ _1,2 - amplitude, frequency and phase, respectively, the received signals have the form:

.

.

where Ω _1,2 (t) are the Doppler frequencies;

K _1,2 - wave numbers;

R is the slant range.

The phase difference is more convenient to measure for voltages having a low frequency, such as Doppler. Such signals are formed by shifting the received signal with part of the emitted:

f _1,2 (t) = E _mcm · 2cos (Ω _1,2 (t) ± 2K _1,2 R).

In this case, the phase difference for K ₁ <K ₂ is

пропорционален высоте волны, т.е. для выделения высоты волны необходимо измерить разность фаз с выделением из результата флюктуационной составляющей, что производится в вычислителе высоты волн и фазовой скорости волн 8, а также производится измерение х. В блоке 10 для определения флюктуационной составляющей скорости производится преобразование напряжения доплеровской частоты в последовательность импульсов с частотой следования, равной частоте Доплера, и согласование этой последовательности, но с переменной постоянной времени, что необходимо для более эффективного согласованния флюктуации частоты Доплера, вызванных случайным характером принятого сигнала, и выделения флюктуации, вызванных волнением.The constant component (Δφ) is proportional to the average distance to the surface, and the variable is its profile, and the magnitude of the variable component $$\left|\Delta \varphi \right|$$

proportional to the height of the wave, i.e. to select the wave height, it is necessary to measure the phase difference with the separation of the fluctuation component from the result, which is performed in the calculator of the wave height and phase wave velocity of 8, and x is also measured. In block 10, to determine the fluctuation component of the velocity, the voltage of the Doppler frequency is converted into a pulse train with a repetition rate equal to the Doppler frequency, and this sequence is matched, but with a variable time constant, which is necessary for more efficient matching of the fluctuation of the Doppler frequency caused by the random nature of the received signal , and the allocation of fluctuations caused by agitation.

The speed and altitude signals are fed to block 9 to determine the direction of arrival of the waves, where the angle of arrival of the wave is determined for each pair of beams with algorithms (1 ÷ 10).

The signals from the computer 8 to determine the height of the waves and the phase velocity of the waves and block 9 to determine the direction of arrival of the waves are sent to block 11 to determine the angle of the wave, where the angles are reduced to the diametrical plane of the vessel.

Block 12 for measuring the vertical movements of the aircraft provides a measurement of their own vertical movements of the object, the signals of which are digitally supplied to block 13 to evaluate measurement errors.

Since the measurement channels are not narrow-band and contain spectral components distorted by the measurement noise, in order to clear these signals from interference, a block 13 has been introduced for estimating measurement errors, which provides a solution to the transfer functions of the form:

;

;

;

;

.

.

Antenna 3 for creating an electromagnetic field is made in the form of five independent antennas mounted on the aircraft body, respectively, in the center of gravity of the aircraft, in the nose and tail parts of the aircraft and in the terminal parts of the wings of the aircraft.

The height of the sea wave is judged by the difference between the maximum and minimum values of the amplitudes of the electromagnetic signal (the average wave height from the sole to the top), the length of the sea wave in the direction of flight and in the place over which the plane flies is judged depending on the ratio of wave height to steepness wave, which is determined in accordance with the dependence

(где h_в - высота волны, Т - период волны), период волнения определяют в зависимости от соотношения амплитуды волны и амплитуды ускорения. $$\xi =2\pi h_{\mathrm{at}}g\stackrel{2}{T}$$

(where h _in - wave height, T - wave period), the wave period is determined depending on the ratio of the wave amplitude and acceleration amplitude.

The proposed method for measuring the ultra-low altitude of an airplane, mainly a seaplane, above the water surface and sea waves parameters, based on the registration of physical quantities that depend on the electromagnetic field, unlike analogs and prototypes, provides a complete set of spectral components of the measured parameters in the form most cleared of interference, which provides high accuracy and inertialess measurements. An assessment of the accuracy of measurement by the proposed device showed that at h _3% = 4 m (incomplete six-wave excitement), φ = 45 °, Δf = 0.01 Hz and the characteristic speed of aircraft in the landing area, for example, at V = 150 m / s, the rms value of the measurement error will be:

which is significantly higher than that of analogues and prototype: 0.031 <0.2 m with a sea wave of about 6 points on the Gugmo scale.

Sea waves are the most significant disturbing factor for the vast majority of ships and non-displacement marine vehicles (hydrofoils or air cushions, ekranoplanes; seaplanes and sea helicopters during takeoff and landing) as control objects. Its influence leads to the appearance of undesirable oscillatory movements, worsening the functional efficiency, safety and comfort of using such devices in comparison with the case of a calm sea. Using the proposed method will allow the adaptation of the control loop and the characteristics of sea waves.

Information sources

1. Flight tests of aircraft. M.G. Kotik et al., Mechanical Engineering, 1968

2. Flight operation of radio navigation equipment of aircraft. I.E. Bondarchuk, Transport, 1978, pp. 112-152.

3. Copyright certificate SU No. 1584513.

4. Radar location of the sea surface ", A. A. Garnakeryan, A. S. Sosunov, University of Rostov, 1978.

5. Copyright certificate SU No. 805745.

6. Patent RU No. 1788484 A1, 12/15/1989

7. Patent RU No. 2183010, 05.27.2002.

Claims (1)

A method of measuring the ultra-low altitude of an airplane, mainly a seaplane, above the water surface and sea waves parameters, based on recording physical quantities that depend on the electromagnetic field generated by the antenna installed on the airplane, which are used to judge the altitude of the airplane, the height of the sea wave, and the length sea wave in the direction of flight and in the place over which the plane flies, characterized in that the antenna for creating an electromagnetic field is made in the form of five independent antennas, setting data on the aircraft body, respectively, in the center of gravity of the aircraft, in the nose and tail parts of the aircraft, and in the terminal parts of the wings of the aircraft, the height of the sea wave is judged by the difference between the maximum and minimum values of the amplitudes of the electromagnetic signal (average wave height from the sole to the top), o the length of the sea wave in the direction of flight and in the place over which the plane flies, is judged depending on the ratio of wave height to the steepness of the wave, which is determined in accordance with the dependence

(where h _in - wave height, T - wave period), the wave period is determined depending on the ratio of the wave amplitude and acceleration amplitude.

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