RU2178147C1 - Complex navigation system - Google Patents

Abstract

FIELD: navigation equipment. SUBSTANCE: proposed system is designed for use in mix of complexes of navigation equipment of aircraft. System comprising autonomous navigation system, satellite navigation system, two integrators, two correction filters and four adders is supplemented with two amplifiers, two adders, two integrators, delay line and differential element which ensures increase of precision of determination of coordinates of position and speed of aircraft. EFFECT: increased precision of complex navigation system. 2 cl, 5 dwg

Description

 The invention relates to the field of aviation instrumentation.

 Coordinate and speed measurement systems are one of the main navigational aids on board aircraft and helicopters. The quality and reliability of their work largely determines the effectiveness of the use of these aircraft (LA).

 On board modern aircraft (LA), autonomous navigation systems (ANS) are widely used. A description of some of them is given in the book of I. Pomykaev, V. P. Seleznev, L. A. Dmitrochenko, “Navigation Instruments and Systems”. M.: Mechanical Engineering, 1983.

 ANSs, as a rule, combine in their composition sensors of course, vertical, acceleration and speed and are used to measure and issue to consumers the coordinates and speed of the aircraft.

 For autonomous measurement of heading, roll and pitch aboard modern aircraft, systems based on gyroscopic and magnetic devices - course systems (CS), gyroverticals (GV), course verticals (KB) and inertial navigation systems (INS) are widely used. Some of them are described in the aforementioned book "Navigation Instruments and Systems" (chapter 4) and the book "Instruments for Heading and Vertical Measurement on Civil Aircraft". M.: Mechanical Engineering, 1989.

 For autonomous measurement of speed on board modern aircraft, systems based on gyroscopic, aerometric and Doppler devices — ANNs, airborne signal systems (SHS) and Doppler speed meters (DIS) —was widely used. A description of some of them is given in the aforementioned book "Navigation Instruments and Systems" (chapters 2, 3, 7).

 As part of the airborne equipment, aircraft are always present, in any combination of a system for simultaneously measuring heading, roll, pitch, acceleration and speed. For example, it can be simultaneously KS + GV + DIS, or KB + SHS, or ANN. As part of the ANS, other combinations of autonomous sensors are also possible to measure heading, roll, pitch, acceleration and speed.

 In addition, for backup purposes, as part of the aircraft’s onboard equipment, several sensors are simultaneously used to measure the same parameters. So, the following combinations of autonomous sensors for measuring heading, roll, pitch, acceleration and speed — INS + KB + SHS and INS + INS + KB + SHS + DIS are very typical for the equipment of modern aircraft. The following combinations of autonomous sensors for measuring heading, roll, pitch, acceleration and speed are typical for the equipment of modern helicopters - ANN + KB + DISS + SHS and KS + GV + GV + SHS + DIS.

 Based on the data on the heading, roll, pitch, acceleration and speed, the ANS determines the values of the components of the ground speed vector in the earth (geographical and / or orthodromic) coordinate system and calculates the coordinates of the location of the aircraft.

 Gyroscopic sensors for heading, roll and pitch from the composition of KS, GV, KB and ANN, as a rule, are not accurate enough and have an error that increases with time.

 Acceleration and velocity sensors also, as a rule, have sufficiently large errors and the coordinates obtained by calculating the speed will not be accurate enough and will also contain an error that increases with time.

 Thus, the main disadvantage of the ANS is the lack of accuracy in determining the speed and location coordinates of the aircraft. As part of the aircraft's onboard equipment, this ANS deficiency is eliminated by periodically correcting data for speed and coordinates from other high-precision, but non-autonomous systems.

 As follows from the aforementioned book "Navigation Instruments and Systems" (chapter 8, 9), as well as the book by M. Yarlykov, "The Statistical Theory of Radio Navigation." M.: Radio and communications, 1985, for these purposes, data from radio systems of long and short range navigation, extreme correlation-extreme navigation systems for various geophysical fields of the Earth, astrosystems, etc. can be used.

 Currently, as part of the aircraft's onboard equipment, satellite navigation systems (SNA) are increasingly used. Based on the signals received from artificial Earth satellites, the SSS provide high-precision measurements of location coordinates and components of the aircraft velocity vector in the geographical coordinate system. A description of the principles of construction and the features of the functioning of the SNA is given in the aforementioned book "The Statistical Theory of Radio Navigation" (Chapter 12).

 An analysis of the development trends of the onboard equipment of modern aircraft shows that the use of signals from the SNA in the foreseeable future will be the main way to improve the accuracy of determining the speed and location coordinates on board the aircraft.

 For the proposed integrated navigation system, the closest in technical essence of the known analogues is the inertial-radio navigation system, the structural diagrams of which are shown in Fig. 9.4 in the aforementioned book, “Navigation Devices and Systems” (p. 394).

 At the same time, we mean that since the SNA provides the simultaneous measurement of speed and location coordinates, the SNA is used instead of the “Navigation corrector” and “DISS”.

 We assume that this integrated navigation system (SPS), taking into account only the features essential for the present invention, and also for the purpose of greater functional commonality, contains an autonomous navigation system (ANS), a satellite navigation system (SNA), two integrators (I1, I2 ), two corrective filters (F1, F2) and four adders (C1, C2, C3, C4).

 The main disadvantage of this SNA is the potentially insufficient accuracy of the correction of the coordinates of the location and flight speed of the aircraft according to the data from the SNA.

 As you know, for the SNA, both domestic and foreign, the update rate of speed and location coordinates is 1 second. This means that for one second the output signals of the SNA despite the movement and various maneuvers of the aircraft are constant.

Moreover, they are assigned with a high degree of accuracy to a specific point in time. For consumers of SNA signals, this moment of time is indicated by a special short-term signal such as a one-time command issued from a separate SNA output. At the same time, the beginning of the output of the SNS output signals in speed and coordinates can be shifted in time relative to this one-time command by a strictly fixed time interval (hereinafter ΔT _E ). As practice shows, the value of this interval for various types of SNA can be in the range of 0.1-0.3 seconds.

 Onboard equipment of modern aircraft, as a rule, is based on elements of digital technology, therefore, corrected signals in speed and coordinates also have a discrete character. However, their update cycle, as a rule, does not exceed 0.1 second, which is an order of magnitude less than the update cycle of signals from the SNA, and therefore, during further analysis, the discreteness of the properties of their signals can be neglected.

 The neglect of the discrete properties of signals from the SNA can lead to errors in the correction of coordinates and aircraft speed.

 As a theoretical and experimental analysis of the nature of the manifestation of errors shows, they are random in nature, and their characteristics correspond to a uniform law of probability distribution.

The mathematical expectations of errors in the coordinates M _ΔX and speed M _{ΔV are} directly proportional to the data update cycle in the SNA T _CHC and, accordingly, the current ground speed V and the current relative acceleration a.

M _ΔX = V • T _СНС / 2;
M _ΔV = a • T _СНС / 2.
The standard deviations of the errors in the coordinates σ _ΔX and velocity σ _{ΔV are} also directly proportional to the data update cycle in the SNA T _CHC and, accordingly, the current ground speed of the aircraft V and the current relative acceleration of the aircraft a:
σ _ΔX = V • T _СНС / 3,464;
σ _ΔV = a • T _СНС / 3,464.
The proposed integrated navigation system allows to increase the accuracy of determining the speed and location coordinates of the aircraft.

 The technical result in terms of increasing the accuracy of determining the coordinates of the location of the aircraft is provided by introducing into the integrated navigation system an additional first amplifier (U1), a third integrator (I3), a fifth adder (C5) and a delay line (LZ).

 The technical result in terms of increasing the accuracy of determining the flight speed of an aircraft is provided by introducing an additional second amplifier (U2), a fourth integrator (I4) and a sixth adder (C6) into the integrated navigation system.

 In addition, given that in some ANSs, especially from the composition of previous generations of aviation equipment, a way to accelerate aircraft is not always available, in order to expand functional capabilities, a differential link (DZ) is additionally introduced into the structure of the ANS.

 In FIG. 1 shows a structural block diagram of the SPS prototype.

 In FIG. 2, 3 and 4 are block diagrams of the proposed SSC.

 In FIG. 5 is a drawing illustrating the discrete properties of the output signals of the SNA.

 The proposed SPS contains: 1 - ANS, 2 - SNA, 3 - I1, 4 - I2, 5 - F1, 6 - F2, 7 - C1, 8 - C2, 9 - C3, 10 - C4, 11 - I3, 12 - U1, 13 - C5, 14 - LZ, 15 - I4, 16 - U2, 17 - C6, 18 - DZ.

Using ANS determine the acceleration vector of LA a _LA .

 As part of the KNS, the ANS is associated with C1, U2 and I4.

Using the SNA determine the velocity vector V _SNA and the coordinate vector of the location of the aircraft LA X _SNA . SNA also generates and issues with a period of one second a short-term signal such as a one-time command "MV" (timestamp).

 As part of the CNS, the SNS is associated with LZ, C3 or C5, C4 or C6.

With the help of C1, a correction signal from Ф2 ΔК ₂ is introduced into the vector acceleration signal of the aircraft LA a _LA in accordance with the ratio:
a $\genfrac{}{}{0ex}{}{\text{TO}}{\text{LA}}$ = a _LA -ΔK ₂ .
If necessary, in the acceleration signal a of the _aircraft using the correction signal ΔK ₂ compensate for the acceleration vector of gravity g.

 As part of the CNS, C1 is associated with ANS, I1 and F2.

Using I1 determine the velocity vector V _LA in accordance with the ratio:
V _LA = ∫a $\genfrac{}{}{0ex}{}{\text{TO}}{\text{LA}}$ dt.
The zero initial state of the integrator is set at the moment the system is turned on.

 As part of the KNS, I1 is associated with C1, C2, C4, U1, I3 and DZ.

Using C2, a correction signal from F1 ΔK ₁ is introduced into the vector acceleration signal of the aircraft V V _LA in accordance with the ratio:
V $\genfrac{}{}{0ex}{}{\text{TO}}{\text{LA}}$ = V _LA -ΔK ₁ .
As part of the SSC, C2 is associated with I1, I2 and F1.

Using I2 determine the coordinate vector of the location of X _LA in accordance with the ratio:
X _LA = ∫V $\genfrac{}{}{0ex}{}{\text{TO}}{\text{LA}}$ dt.
The initial state of the integrator is set at the time the system is turned on.

 As part of the KNS, I2 is associated with C2 and C3.

Using C3, the error is measured in the vector signal of the coordinates of the location X of the _aircraft according to the data on the vector of coordinates of the location X of the _SNA , obtained from the data from the SNA or calculated in the third integrator:
ΔX _LA = X _LA -X _SNA .
As part of the SSC, C3 is associated with I2, F1, SNA or I3.

Using C4, the error is measured in the vector signal of the speed V _LA according to the data on the velocity vector V _SNA , obtained from the data from the SNA or calculated in the fourth integrator:
ΔV _LA = V _LA -V _SNA .
As part of the SSS, C4 is associated with I1, F2, SNA or I4.

Using the corrective filter F1 and F2 form the correcting signals ΔK ₁ and ΔK ₂ supplied through C1 and C2 to the inputs I1 and I2.

 The formation of corrective signals that provide an estimate of the errors of the SSC by speed and location coordinates can be carried out using any of the known methods for estimating random signals.

 For example, when describing a prototype device, the aforementioned book "Navigation Devices" on pages 394-395 says that "... correction channels provide acceptable dynamic properties of an integrated system with the simplest transfer functions of correction filters in the form of amplifying links ...".

 The best dynamic properties are provided by the application of optimal integration methods. For example, in F1 and F2, the Kalman optimal filtering method can be used. A description of the construction principles and construction features of correction filters based on the Kalman optimal filtering method is given in the aforementioned book "Statistical Theory of Radio Navigation" (Chapter 5).

 As part of the KNS, F1 is associated with C3 and C2.

 As part of the KNS, F2 is associated with C4 and C1.

Х^В _СНС - выходной сигнал СНС по координатам.Using I3, U1, C5 and LZ synchronize substantially discrete signals from the SNA in coordinates with similar signals received from the ANS in accordance with the ratio:

X ^In _SNA - the output signal of the SNA in coordinates.

Using U1, extrapolation (forecasting) of the increment of the coordinate vector from the SNA for a fixed time interval ΔT _{E is} carried out.

ΔX _E = ΔT _E • V _LA .

 As part of the KNS, U1 is associated with I1 and C5.

Using C5, the coordinate vector is extrapolated from the SNA for a fixed point in time T ₀ + ΔT _E (T ₀ is the moment of issuing a one-time command "MB":
X ^VE _CHC = X ^V _CHC + ΔX _e
As part of the SNA, C5 is associated with the SNA, I3 and U1.

Начальное состояние интегратора, равное Х^ВЭ _СНС, задается в момент поступления в интегратор из СНС и задержанной в ЛЗ на время ΔТ_Э разовой команды "МВ".Using I3, the value of the coordinate vector from the SNA is extrapolated at the current time by calculating the aircraft velocity vector in the time interval from 0 to 1 second:

The initial state of the integrator is equal to x ^VE _SNA is set at the time of admission to the integrator of the SNA and detained in the LZ at the time? T _e single "MV" command.

 As part of the KNS, I3 is associated with I1, LZ, C5 and C3.

Using LZ, a one-time “MB” command is delayed from the SNA for a fixed time interval ΔТ _Э.

 As part of the SPS, LZ is associated with the SNA, I3 and I4.

С помощью У2 осуществляют экстраполяцию приращения вектора скорости от СНС на фиксированный интервал времени ΔТ_Э:
ΔV_Э= ΔT_Э•a_ЛА.
В составе КНС У2 связан с С6 и АНС или ДЗ.Using I4, U2 and C6 synchronize substantially discrete signals from the SNA in speed with similar signals received according to the data from the ANS in accordance with the ratio:

Using U2, the increment of the velocity vector from the SNA is extrapolated for a fixed time interval ΔT _E :
ΔV _E = ΔT _E • a _LA .
As part of the KNS, U2 is associated with C6 and ANS or DZ.

Using C6 extrapolates the velocity vector from the SNA for a fixed point in time T ₀ + ΔT _E :
V _SNA ^VE = V ^B + ΔV _{e SHS.}

 As part of the SSS, C6 is associated with the SNA, I4 and U2.

Начальное состояние интегратора, равное V^ВЭ _СНС, задается в момент поступления в интегратор из СНС и задержанной в ЛЗ разовой команды "МВ".Using I4, the velocity vector value is extrapolated from the SNA at the current time by calculating the aircraft acceleration vector in the time interval from 0 to 1 second:

The initial state of the integrator, equal to V ^VE _SNA , is set at the moment of arrival to the integrator from the SNA and the one-time command “MV” delayed in the LZ.

 As part of the KNS, I4 is associated with ANS or DZ, LZ, C4 and C6.

 DZ is intended to determine the acceleration vector of an aircraft, if the ANS does not provide for the possibility of using the acceleration signal in other devices, in addition to using it to obtain the velocity vector of an aircraft.

 As part of the KNS, DZ is associated with I1, U2 and I4.

 Thus, the implementation examples show the achievement of technical results.

Claims (3)

 1. An integrated navigation system of an aircraft, comprising a series-connected autonomous navigation system, a first adder, a first integrator, a second adder, a second integrator, a third adder and a first correction filter, the output of which is connected to the subtracting input of the second adder, as well as a satellite navigation system connected in series , the fourth adder and the second correction filter, the output of which is connected to the subtracting input of the first adder, the output of the first integrator over is also given to the summing input of the fourth adder, characterized in that it additionally includes a series-connected amplifier, a fifth adder and a third integrator, the output of which is fed to the subtracting input of the third adder, and the second input is connected to the output of the first integrator, as well as a delay line, connected between the third input of the third integrator and the third output of the satellite navigation system, the second output of which is fed to the second input of the fifth adder, and the input of the amplifier is connected to the output of the first inte Gratra.  2. The integrated navigation system according to claim 1, characterized in that the second amplifier, the sixth adder and the fourth integrator are additionally connected to the output of the autonomous navigation system, the first output of the satellite navigation system being connected to the first input of the fourth adder through the sixth adder connected in series and a fourth integrator, the second and third inputs of which are connected respectively to the output of the autonomous navigation system and the output of the delay line.  3. The integrated navigation system according to claim 1, characterized in that the output of the first integrator is additionally connected in series with a differential link, a second amplifier, a sixth adder and a fourth integrator, while the first output of the satellite navigation system is connected to the first input of the fourth adder through series-connected the sixth adder and the fourth integrator, the second and third inputs of which are connected respectively to the output of the differential link and the output of the delay line.

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