AU2019201015B2

AU2019201015B2 - Method and apparatus for compensating air data using inertial navigation data

Info

Publication number: AU2019201015B2
Application number: AU2019201015A
Authority: AU
Inventors: Su Kweon Hwang; Tae Seok Ki; Ik Soo Park; Jung Woo Park
Original assignee: Agency for Defence Development
Current assignee: Agency for Defence Development
Priority date: 2018-08-30
Filing date: 2019-02-14
Publication date: 2020-10-22
Anticipated expiration: 2039-02-14
Also published as: PH12019000095B1; PH12019000095A1; AU2019201015A1; KR101982181B1

Abstract

A method of compensating flight information includes estimating first flight information from an air data system (ADS) having a plurality of sensors provided on a flight vehicle, estimating second flight information by using sensor data output from at least one of the plurality of sensors and navigation data output from an inertial navigation device provided on the flight vehicle, and outputting compensated flight information by using the estimated first flight information and the estimated second flight information. When flight information is acquired by using the ADS, the reliability and accuracy of the acquired flight information may be improved. 15 2/4 C co, -*~0 Iccn 0 7I 4- 10 I ZC C I 0 as Cl) -0 ca 0 CCj, EE

Description

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Australian Patents Act 1990

ORI GI NAL COMPLETE SPECI F1 CATI ON STANDARD PATENT

Invention Title Method and apparatus for compensating air data using inertial navigation data

The following statement is a full description of this invention, including the best method of performing it known to me/us:-

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2018 0103038, filed on August 30, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

1. Field

[0001] One or more embodiments relate to methods and apparatuses for compensating air data using inertial navigation data when flight information is acquired by employing an air data system (ADS), thereby improving the reliability and accuracy of the acquired flight information. 2. Description of the Related Art

[0002] A flight information measurement system of a flight vehicle which provides airspeed-based information is more useful when measuring and estimating actual aerodynamic environment experienced by the flight vehicle, rather than using position and speed information based on a geographic coordinate system such as the local tangent plane coordinates (LTP). The airspeed-based information may be measured through a flight information acquisition system that is generally referred to as an ADS.

[0003] The flight information measurement system has been deveoloped as ADS's in various forms according to flight envelope and its flight objectives, in addition to a conventional method using a pitot-tube configuration. The ADS acquires flight information such as a flight Mach number, aerodynamic parameters, and pressure altitude by using static or total pressure information obtained through probes and pressure holes on the surface of a flight vehicle.

[0004] The flight information measurement system has been developed as ADS's in various forms according to flight areas and missions, in addition to a conventional method using a pitot-tube shape. The ADS acquires flight information such as a flight

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Mach number, aerodynamic parameters, and pressure altitude by using static pressure or total pressure information obtained through probes and pressure holes in a surface of a flight vehicle.

[0005] In order to acquire accurate and precise flight information, it is advantageous to acquire a plurality of pieces of pressure information at proper locations where high quality data may be obtained. In this regard, however, the need to maintain reliability also increases, which can be achieved by considering additional fault isolation and compensation algorithms for the measurement system. As an effort to improve the reliability of ADS information to estimate flight information, a compensation technique using additional independent information acquired through a global positioning system(GPS) or/and an inertial navigation system(INS) mounted on the flight vehicle has been generalized. And, to ensure the reliability of ADS itself, various methods to exclude defective signals of fault sensors or sensors group and regenerate alternative signals from relevant measurement information have been developed.

[0006] As described above, flight information measurement technologies have been variously developed to acquire high precision flight information. On the other hand, these kind of technologies with various sources of sensors are only possible when considering complementary algorithms for measurement information compensation and fault control to ensure the reliability of the measurement system, which increases complexity and uncertainty. As the complexity and uncertainty of the system are higher, it is more difficult to address the effect from undetected measurement errors. Here, the undetected measurement error signifies unknown measurement characteristics with its own dynamic and biased nature of sensing device(s) and unpredictable measurement characteristics such as sudden local flow field change. For this reason, it has been also emphasized to make the measurement system robust to the undetected measurement error when designing the system with highly accurate performance.

[0007] [Prior Art Document No.]

[0008] Prior art document 1: Korean Patent Publication No, 2017-0067138

[0009] Prior art document 2: Korean Patent Publication No. 2016-0127734

[0010] Prior art document 3: Korean Patent No. 10-1665375

SUMMARY

[0011] One or more embodiments include methods and apparatuses for compensating air data using inertial navigation data when flight information is acquired by employing an air data system (ADS), thereby improving the reliability and accuracy of the acquired flight information.

[0012] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

[0013]According to one or more embodiments, a method of compensating flight information includes estimating first flight information from an air data system (ADS) having a plurality of sensors provided on a flight vehicle, estimating second flight information by using both sensor data output from at least one of the plurality of sensors in the ADS and navigation data output from an inertial navigation device provided on the flight vehicle, and outputting compensated flight information by using the estimated first flight information and the estimated second flight information. The second flight information includes a flight Mach number acquired by using an atmospheric static pressure estimated value using altitude information of the inertial navigation device and total pressure information acquired at a position of at least one of the plurality of sensors in the ADS, and an aerodynamic angle output from the inertial navigation device. The compensated flight information is calculated based on a difference value between a first flight Mach number that is part of the estimated first flight information and a second flight Mach number that is part of the estimated second flight information. The compensated flight information is calculated as a weighted function according to the difference value is determined, and the estimated first flight information and the estimated second flight information are mixed based on the determined weighted function.

[0014]According to one or more embodiments, a flight information compensation apparatus includes a first flight information estimator configured to estimate first flight information from an air data system (ADS) having a plurality of sensors provided on a flight vehicle, a second flight information estimator configured to estimate second flight information by using both sensor data output from at least one of the plurality of sensors in the ADS and navigation data output from an inertial navigation device provided on the flight vehicle, and a flight information compensator configured to output compensated flight information by using the estimated first flight information and the estimated second flight information. The second flight information includes a flight Mach number acquired by using an atmospheric static pressure estimated value using altitude information of the inertial navigation device and total pressure information acquired at a position of at least one of the plurality of sensors in the ADS, and an aerodynamic angle output from the inertial navigation device. The flight information compensator calculates the compensated flight information based on a difference value between a first flight Mach number that is part of the estimated first flight information and a second flight Mach number that is part of the estimated second flight information. The flight information compensator determines a weighted function according to the difference value, and mixes the estimated first flight information and the estimated second flight information based on the determined weighted function.

[0015] According to one or more embodiments, a flight vehicle includes an air data system (ADS) having a plurality of sensors, an inertial navigation device, and a processor configured to control the ADS and the inertial navigation device, wherein the processor estimates first flight information from the ADS, estimates second flight information by using both sensor data output from at least one of the plurality of sensors in the ADS and navigation data output from the inertial navigation device, and outputs compensated flight information by using the estimated first flight information and the estimated second flight information. The second flight information includes a flight Mach number acquired by using an atmospheric static pressure estimated value using altitude information of the inertial navigation device and total pressure information acquired at a position of at least one of the plurality of sensors in the ADS, and an aerodynamic angle output from the inertial navigation device. The compensated flight information is calculated based on a difference value between a first flight Mach number that is part of the estimated first flight information and a second flight Mach number that is part of the estimated second flight information. The processor determines a weighted function according to the difference value, and mixes the estimated first flight information and the estimated second flight information based on the determined weighted function.

[0016]According to one or more embodiments, a non-transitory computer-readable recording medium having recorded thereon a program, which when executed by a computer, performs the method of compensating flight information which includes estimating first flight information from an air data system (ADS) having a plurality of sensors provided on a flight vehicle, estimating second flight information by using sensor data output from at least one of the plurality of sensors and navigation data output from an inertial navigation device provided on the flight vehicle, and outputting compensated flight information by using the estimated first flight information and the estimated second flight information.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which:

[0018] FIG. 1 is a conceptual diagram showing measurement of flight information, according to an embodiment;

[0019] FIG. 2 is a schematic block diagram of a flight information compensation apparatus according to another embodiment;

[0020] FIG. 3 is a detailed block diagram of the flight information compensation apparatus of FIG. 2; and

[0021] FIGS. 4 and 5 are graphs showing results of flight information compensation, according to an embodiment.

DETAILED DESCRIPTION

[0022] The terms used in the present disclosure have been selected from currently widely used general terms in consideration of the functions in the present disclosure.

4A

However, the terms may vary according to the intention of one of ordinary skill in the art, case precedents, and the advent of new technologies. Also, for special cases, meanings of the terms selected by the applicant are described in detail in the description section. Accordingly, the terms used in the present disclosure are defined based on their meanings in relation to the contents discussed throughout the specification, not by their simple meanings.

[0023] In the present specification, when a constituent element "connects" or is "connected" to another constituent element, the constituent element contacts or is connected to the other constituent element directly or through at least one of other constituent elements. Conversely, when a constituent element is described to "directly connect" or to be "directly connected" to another constituent element, the constituent element should be construed to be directly connected to another constituent element without any other constituent element interposed therebetween. Terms such as "~ portion", "- unit", "- module", and "- block" stated in the specification may signify a unit to process at least one function or operation and the unit may be embodied by hardware, software, or a combination of hardware and software.

[0024] Also, terms such as "include" or "comprise" may be construed to denote a certain characteristic, number, step, operation, constituent element, or a combination thereof, but may not be construed to exclude the existence of or a possibility of addition of one or more other characteristics, numbers, steps, operations, constituent elements, or combinations thereof.

[0025] The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the disclosure to those of ordinary skill in the art. Hereinafter, the present disclosure will be described in detail by explaining preferred embodiments of the disclosure with reference to the attached drawings.

[0026] An algorithm for improving the reliability and accuracy of flight information acquired by employing an air data system (ADS) is proposed. Flight information is finally obtained by a method of independently calculating second flight information by sharing sensor measurement information constituting the ADS considering ADS estimated flight information as first flight information, and by a method of mixing the calculated two estimated flight information.

[0027] FIG. 1 is a conceptual diagram showing measurement of flight information, according to an embodiment.

[0028] In FIG. 1, a left diagram is a front view illustrating positions of ADS sensors 1 to 5 provided in a flight vehicle, and a right diagram is a side view illustrating positions of the ADS sensors 1 to 5.

[0029] In the embodiment, sensor measurement characteristics of a simple ADS system of a supersonic flight vehicle capable of estimating flight speed, angle of attack, and side slip angle are taken into consideration. In other words, when it is not a sensor failure situation, there is a high possibility of occurrence of an undetected measurement error of other sensor group except the measurement physical quantity of a first sensor that is insensitive to dynamic flow characteristic, which includes a case in which a change of a local flow field is generated due to flight dynamic characteristic and an effect of a boundary layer generated when a flow flows along an inclined surface of a cone nose.

[0030] A flight vehicle according to an embodiment may include an ADS having a plurality of sensors illustrated in FIG. 1, an inertial navigation device, and a processor for controlling the ADS and the inertial navigation device. The processor estimates first flight information from the ADS and second flight information by using sensor data output from at least one of the sensors and navigation data output from an inertial navigation device. For example, the second flight information may be estimated by using the measurement physical quantity of the first sensor illustrated in FIG. 1 and the navigation data output from the inertial navigation device. The processor outputs compensated flight information by using estimated first flight information and estimated second flight information.

[0031] FIG. 2 is a schematic block diagram of a flight information compensation apparatus 100 according to another embodiment.

[0032] Referring to FIG. 2, the flight information compensation apparatus 100 may include a first flight information estimator 110, a second flight information estimator 120, and a flight information compensator 130.

[0033] The first flight information estimator 110 estimates first flight information from an ADS having a plurality of sensors provided on a flight vehicle.

[0034] The second flight information estimator 120 estimates second flight information by using sensor data output from at least one of a plurality of sensors, for example, the first sensor of the ADS sensors illustrated in FIG. 1, and the navigation data output from the inertial navigation device provided in the flight vehicle.

[0035] The flight information compensator 130 outputs compensated flight information by using the estimated first flight information from the first flight information estimator 110 and the estimated second flight information from the second flight information estimator 120.

[0036] FIG. 3 is a detailed block diagram of the flight information compensation apparatus 100 of FIG. 2.

[0037] In an embodiment, in the above-described flow environment, a flight information compensation algorithm using first estimated flight information using an ADS algorithm, for example, a flight Mach number and an aerodynamic angle, and second estimated flight information based on flight vehicle inertial navigation system (INS) flight information, for example, a flight Mach number and an aerodynamic angle, is considered. The first estimated flight information may be obtained through a flight Mach number and aerodynamic angle calculation algorithm based on measurement pressure information. A related algorithm may include a data processing method similar to a generally well-known technique. However, since the algorithm is not within the scope of the claims, a detailed description thereof is omitted. The second estimated flight information may include a flight Mach number acquired by using an atmospheric static pressure estimated value using altitude information of the INS and total pressure information acquired at a position of the sensor 1 of FIG. 1, and an aerodynamic angle output from the INS. The flight Mach number of the second estimated flight information is acquired by a calculation method that shares part of information measured by a sensor constituting the ADS, which is distinguished from a related-art method of calculating the flight Mach number directly using flight navigation information through INS or GPS. Finally, compensated flight information is acquired by using the first estimated flight information and the second estimated flight information.

[0038] The flight Mach number of the second estimated flight information may be calculated by using Equation 1 below.

[Equation 1]

P, PIQP,

(Y 1 +1 Jl( I+YyMA4 SCjMZ + C2M+ C,

[0039] The flight information compensation method using two pieces of estimated flight information includes the following items. Compensated output flight information calculates a difference (=AM) between the flight Mach number of the first estimated flight information and the flight Mach number of the second estimated flight information. Then, compensated flight information calculated by using a weighted function output according to the AM is suggested as a mixing result of the two different pieces of flight information. The weighted function has a value between 0 and 1 in the form of a polynomial structure having a difference between two flight Mach numbers as an input or a look-up table based on a sectional scheduling technique and may be set to have a value close to 0 as the AM decreases. When the weighted function value is 0, the first flight information is the output, and when it is 1, it signifies that the second flight information becomes more reliable. Selectively, for the AM, a range thereof may be determined considering a flight vehicle operation condition and uncertainty of measurement values.

[0040] In the embodiment, an optimal weighted function acquired according to a considered flight area, for example, a Mach number-altitude plane, and an expected range of undetected measurement error may be applied. Weighted function optimization may include the following items.

[0041] An undetected error of the measurement information and uncertainty of the estimation information considered for optimization may be modeled to probabilistically have uniform distribution characteristics within minimum and maximum expected ranges.

The optimization is performed by receiving a feedback of a result of a Monte Carlo (MC) simulation (hereinafter, referred to as the MC simulation) in various flight areas to be considered. The MC simulation is performed on probabilistic environment factors of an object to be tested, and may be performed by generating accidental results by random sampling according to probability distributions of probability elements. Finally, a weighted function determined through the result of optimization may serve as an output filter for compensating a flight information output according to a difference between different flight information. The final compensated flight information is shown in Equation 2 below.

[Equation 2] Flight info(gxa4 -(1 - f( M))x Fjghtinfo()+ A-M}x F ght info(2)

[0042] In Equation 2, " A" is a function of a flight Mach number difference between two flight information groups as mentioned above as the optimized weighted function.

[0043] The optimization cost function and constraint are as follows. The cost function for optimization is set to be an optimization performance index to decrease a difference between actual flight information and the compensated flight information, and the constraint may be provided as an item which makes an error of the compensated flight information is less than an error of the first estimated flight information. The constraint for optimization is shown as Equation 3 below.

[Equation 3] min J==( True FEght info- Fligt info(nal)? subject to ( Tme Fukt info- F&ht info(fina)). ( Tme F&kht info - Fiht info( D0

[0044] FIGS. 4 and 5 are graphs showing results of flight information compensation, according to an embodiment. Atmospheric static pressure uncertainty according to the altitude, and measurement uncertainty of sensor groups are probabilistically modeled, and are applied to a plurality of flight operation condition, for example, Predetermined

Mach number-altitude design points. The results of FIGS. 4 and 5 show a flight information estimation error performance bound for each operation Mach number. It may be seen from the results that a flight Mach number estimation error and an angle of attack estimation error are improved in the flight information compensation algorithm according to an embodiment, rather than by being singularly applied for ADS.

[0045] Since the flight information compensation algorithm according to the present embodiment adopts an intuitive compensation method of ADS estimation information without including an additional complicated compensation algorithm, it may easily analyze an algorithm. Furthermore, convenience in a mixing method of different flight information is advantageous in the manufacture and implementation of an algorithm.

[0046] The flight information compensation algorithm according to the present embodiment may be applied regardless of the size of an undetected measurement error in the sensor measurement information other than the sensor 1 of FIG. 1, and has solid performance because the algorithm may be solely applied without any sensor fault isolation and alternative signal generation algorithms under corresponding conditions.

[0047] According to the flight information compensation algorithm according to the present embodiment, flight information estimation algorithm redundancy can be secured under the use of two different flight information estimators, and the reliability of ADS of a similar concept using a plurality of sensor groups may be improved through the application of the methodology.

[0048] The flight information compensation algorithm according to the present embodiment is a multiple information combined estimation technique, and the improvement of estimation performance compared to the ADS single application may be seen from the results of FIGS. 4 and 5.

[0049] An embodiment of the present disclosure may be embodied in the form of a recording medium including computer executable command languages such as a program module executed by a computer. A computer-readable storage medium may be a useable medium that is accessible by a computer and may include all of volatile and non-volatile media or a separable and inseparable media. Also, the computer readable storage medium may include all of computer storage media and communication media. The computer-readable storage medium may include all of volatile and non-volatile media or separable and inseparable media embodied by a certain method or technology for storing information such as computer-readable command languages, data structures, program modules, or other data. The communication medium may typically include computer-readable command languages, data structures, program modules, or other data of a modulated data signal, or other transmission mechanism, and may also include a certain information forwarding medium.

[0050] The above descriptions of the present disclosure are exemplary, and it will be understood that one of ordinary skill in the art to which the present disclosure pertains can easily modify the present disclosure into other detailed form without changing the technical concept or essential features of the present disclosure. Thus, the above described embodiments are exemplary in all aspects and should not be for purposes of limitation. For example, each constituent element described to be a single type may be embodied in a distributive manner. Likewise, the constituent elements described to be distributed may be embodied in a combined form.

[0051] The scope of the present disclosure is defined not by the detailed description of the disclosure but by the appended claims, and all changes and modifications introduced from the concept and scope of the claims and the equivalent concept thereof will be construed as being included in the present disclosure.

[0052] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0053] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavor to which this specification relates.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A method of compensating flight information, the method comprising: estimating first flight information from an air data system (ADS) having a plurality of sensors provided on a flight vehicle; estimating second flight information by using both sensor data output from at least one of the plurality of sensors in the ADS and navigation data output from an inertial navigation device provided on the flight vehicle, wherein the second flight information includes a flight Mach number acquired by using an atmospheric static pressure estimated value using altitude information of the inertial navigation device and total pressure information acquired at a position of at least one of the plurality of sensors in the ADS, and an aerodynamic angle output from the inertial navigation device; and outputting compensated flight information by using the estimated first flight information and the estimated second flight information; wherein the compensated flight information is calculated based on a difference value between a first flight Mach number that is part of the estimated first flight information and a second flight Mach number that is part of the estimated second flight information, wherein the compensated flight information is calculated as a weighted function according to the difference value is determined, and the estimated first flight information and the estimated second flight information are mixed based on the determined weighted function.

2. The method of claim 1, wherein the compensated flight information is determined according to an equation below,

Flight info (final) = (1 - f(AM)) x Flight info (1) + f(AM) x Flight info (2)

wherein f(AM) is an optimized weighted function that is a function according to the difference value.

3. The method of claim 2, wherein a constraint for optimization of the weighted function is that an error value of the compensated flight information is less than an error value of the estimated first flight information.

4. A non-transitory computer-readable recording medium having recorded thereon a program, which, when executed by a computer, performs the compensation method defined in any one of claims 1 to 3.

5. A flight information compensation apparatus comprising: a first flight information estimator configured to estimate first flight information from an air data system (ADS) having a plurality of sensors provided on a flight vehicle; a second flight information estimator configured to estimate second flight information by using both sensor data output from at least one of the plurality of sensors in the ADS and navigation data output from an inertial navigation device provided on the flight vehicle, wherein the second flight information includes a flight Mach number acquired by using an atmospheric static pressure estimated value using altitude information of the inertial navigation device and total pressure information acquired at a position of at least one of the plurality of sensors in the ADS, and an aerodynamic angle output from the inertial navigation device; and a flight information compensator configured to output compensated flight information by using the estimated first flight information and the estimated second flight information, wherein the flight information compensator calculates the compensated flight information based on a difference value between a first flight Mach number that is part of the estimated first flight information and a second flight Mach number that is part of the estimated second flight information, wherein the flight information compensator determines a weighted function according to the difference value, and mixes the estimated first flight information and the estimated second flight information based on the determined weighted function.

6. A flight vehicle comprising: an air data system (ADS) having a plurality of sensors; an inertial navigation device; and a processor configured to control the ADS and the inertial navigation device, wherein the processor estimates first flight information from the ADS, estimates second flight information by using both sensor data output from at least one of the plurality of sensors in the ADS and navigation data output from the inertial navigation device, and outputs compensated flight information by using the estimated first flight information and the estimated second flight information, wherein the second flight information includes a flight Mach number acquired by using an atmospheric static pressure estimated value using altitude information of the inertial navigation device and total pressure information acquired at a position of at least one of the plurality of sensors in the ADS, and an aerodynamic angle output from the inertial navigation device, wherein the compensated flight information is calculated based on a difference value between a first flight Mach number that is part of the estimated first flight information and a second flight Mach number that is part of the estimated second flight information, wherein the processor determines a weighted function according to the difference value, and mixes the estimated first flight information and the estimated second flight information based on the determined weighted function.