Aerodynamic Modeling Using Flight Data

Patent metadata

Field	Value
Publication number	US-2016238481-A1
Application number	US-201414541732-A
Country	US
Kind code	A1
Filing date	Nov 14, 2014
Priority date	Nov 27, 2013
Publication date	Aug 18, 2016
Grant date	—

Abstract

Systems and methods are described for development of a nonlinear global aerodynamic model using fuzzy logic modeling as well as multivariate orthogonal function modeling with splines. The systems and methods described herein may be utilized to more quickly develop a global aerodynamic model of an aircraft, allowing for development of a global aerodynamic model of an aircraft in real-time, during a test flight, and reducing time and cost associated with the model development.

First claim

What is claimed is:

1 . A method of modeling aircraft aerodynamics, comprising:
receiving an indication of control inputs at a full-scale aircraft during a test flight; responsive to the control inputs, obtaining sensor data from one or more sensors on the aircraft during the test flight; selecting one or more explanatory variables from the sensor data; calculating one or more membership functions for each of the one or more explanatory variables; defining a plurality of fuzzy cell internal functions, wherein a fuzzy cell internal function from the plurality of fuzzy cell internal functions comprises a membership function, from the one or more membership functions; determining a model output as a weighted sum of the plurality of fuzzy cell internal functions; and predicting an aerodynamic performance characteristic of the aircraft using the model output.

2 . The method of claim 1 , further comprising:
determining a goodness of fit of the model output to the obtained sensor data; wherein if the goodness of fit is above a threshold value, outputting a final fuzzy model; and wherein if the goodness of fit is below a threshold value, calculating one or more additional membership functions to be added to the model output.

3 . The method of claim 1 , wherein the one or more explanatory variables comprise one or more of an angle of attack, a pitch rate and a control surface deflection of the aircraft.

4 . The method of claim 1 , wherein the model output is a global aerodynamics model comprising one or more nondimensional aerodynamic force and moment coefficients as a function of the one or more explanatory variables.

5 . The method of claim 1 , wherein the control inputs comprise one or more fuzzy inputs.

6 . The method of claim 5 , wherein a fuzzy input, from the one or more fuzzy inputs, comprises a quasi-random input with varying frequency content and amplitudes.

7 . The method of claim 1 , wherein the output model is determined in real-time while the aircraft is airborne.

8 . The method of claim 1 , wherein the method further comprises preprocessing of the sensor data to determine overall forces and moments acting on the aircraft.

9 . The method of claim 1 , wherein the calculating one or more membership functions for each of the one or more explanatory variables is carried out prior to the test flight.

10 . The method of claim 1 , wherein the control inputs alter one or more of a pitch, a roll, a yaw, or an engine thrust of the aircraft.

11 . A non-transitory computer-readable storage medium comprising computer-executable instructions that when executed by a processor are configured to cause a processor to perform at least:
receiving, responsive to control inputs to an aircraft during a test flight, sensor data from one or more sensors on the aircraft; selecting one or more explanatory variables from the sensor data; generating a plurality of multivariate functions using the one or more explanatory variables; generating a plurality of orthogonal modeling functions from the plurality of multivariate functions; generating an output model comprising one or more of the plurality of orthogonal modeling functions that minimize a predicted square error, and predicting a flight characteristic of the aircraft using the output model.

12 . The non-transitory computer-readable storage medium of claim 11 , wherein the computer-executable instructions are further configured to:
generate one or more spline functions to be added to the output model.

13 . The non-transitory computer-readable storage medium of claim 11 , wherein the computer-executable instructions are further configured to:
select a model complexity of the output model to be used to describe an aerodynamic behavior of the aircraft.

14 . The non-transitory computer-readable storage medium of claim 13 , wherein the plurality of multivariate functions have a maximum degree of complexity equal to a complexity of the selected model.

15 . The non-transitory computer-readable storage medium of claim 11 , wherein the generating a plurality of orthogonal modeling functions further comprises using a Gram-Schmidt orthogonalization procedure on the plurality of multivariate functions.

16 . The non-transitory computer-readable storage medium of claim 11 , wherein the output model is a global aerodynamic model of the aircraft comprising one or more nondimensional aerodynamic force and moment coefficients as a function of the one or more explanatory variables.

17 . The non-transitory computer-readable storage medium of claim 11 , wherein the output model is determined in real-time while the aircraft is airborne.

18 . A computer-implemented method for modeling aircraft aerodynamics, comprising:
applying control inputs to an aircraft during a test flight; receiving, responsive to the applied control inputs, sensor data from one or more sensors on the aircraft; selecting one or more explanatory variables from the sensor data; fitting a nonlinear model to the received sensor data as a function of the selected one or more explanatory variables; and generating an aerodynamics output model comprising the fitted nonlinear model.

19 . The computer-implemented method of claim 18 , further comprising:
determining a goodness of fit of the nonlinear model to the received sensor data; wherein if the goodness of fit is above a threshold value, generating the aerodynamics output model; and wherein if the goodness of fit is below a threshold value, adjusting the nonlinear model.

20 . The computer-implemented method of claim 18 , wherein the one or more explanatory variables comprise one or more of an angle of attack, a pitch rate and a control surface deflection of the aircraft.

Assignees

• Nasa

Inventors

• Brandon Jay
• Morelli Eugene A

Classifications

• G06F2111/10

  Numerical modelling · CPC title

• G06F30/20

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title

• G01M9/08 Primary

  Aerodynamic models · CPC title

• G06F30/15

  Vehicle, aircraft or watercraft design · CPC title

• G06N7/02

  using fuzzy logic (computing arrangements based on biological models G06N3/00; computing arrangements using knowledge-based models G06N5/00) · CPC title