Adaptive method to control and optimize aircraft performance

• US 6,341,247 B1
• Filed: 12/17/1999
• Issued: 01/22/2002
• Est. Priority Date: 12/17/1999
• Status: Expired due to Term

• Current Assignee: Mcdonnell Douglas Corporation (The Boeing Co.), The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Inventors: Hreha, Mark A., Schkolnik, Gerard
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): MANCHO, RONNIE M
• Application Number:
  US09/465,897
• Time in Patent Office: 767 Days
• Field of Search: 701/1, 701/3, 701/4, 701/6, 701/7, 701/10, 244/45.R, 244/13, 244/35.R, 244/76.R, 244/36, 244/203, 244/184
• US Class Current: 701/3
• CPC Class Codes: G05D 1/0005 with arrangements to save energy
• CPC Class Codes: G05D 1/0825 using mathematical models

Abstract

A measurement-based method to control and optimize the performance of an airborne vehicle. The stability and control of the vehicle is modified to induce a response in the airborne vehicle as reflected by a plurality of response signals. Excitations signals having multi-term sinusoidal waveforms are generated and applied to control signals controlling one or more control effectors. A time domain response of each of the state variables, response signals, and control signals arising from the application of the excitation inputs to the control signals is then measured. These time domain responses are then transformed into frequency domain models. The effectiveness and vehicle stability and control derivatives may then be identified from the frequency domain models of the state variables, response signals, and control signals. These effectiveness derivatives represent the contribution that each of the one or more selected effectors has on a particular performance index of the airborne vehicle and are then used to derive a control effector setting for each of the one or more selected effectors. The selected performance index may then be modified by adjusting the one or more selected effectors to its derived control effector setting. The stability and control derivatives identified may be used to improve the control laws associated with the airborne vehicle.

Claims

1. A method to modify a performance index of an airborne vehicle having a plurality of control effectors, each control effector controlled by an associated control signal, the stability of the vehicle defined by a plurality of state variables, the method comprising the steps of:

(a) generating and applying excitation inputs to at least one control signal associated with at least one selected effector chosen from the plurality of control effectors to modify the plurality of state variables and induce a response in the airborne vehicle reflected by a plurality of response signals, wherein each of the excitation inputs comprises a multi-term sinusoidal waveform, each term uniquely associated with a particular system parameter and having a unique frequency selected such that each frequency is not a multiple of any other frequency;

(b) measuring a time domain response of each of the state variables, response signals, and control signals at a sampling rate, the time domain responses arising from the application of the excitation inputs to the control signals;

(c) transforming the measured time domain responses of the state variables, response signals, and control signals into frequency domain models;

(d) identifying effectiveness derivatives from the frequency domain models of the response signals and the control signals, the effectiveness derivatives representing the contribution that each of the one or more selected effectors has on a particular performance index;

(e) deriving a control effector setting for each of the one or more selected effectors based on the effectiveness derivatives; and

(f) modifying the performance index by adjusting the one or more selected effectors to its derived control effector setting.

2. The method of claim 1 wherein each unique frequency (ω

) is selected according to the equation;

3. The method of claim 1 further comprising the step of identifying vehicle stability and control derivatives from the frequency domain models of the state variables and control signals, the stability and control derivatives representing the static and dynamic control effects of the control effectors, wherein such vehicle stability and control derivatives may be used to improve control laws associated with the airborne vehicle.

4. The method of claim 3 wherein the step of measuring a time domain response of each of the state variables, response signals, and control signals comprises the step of measuring the time domain response for a time period sufficient to measure the state variables, response signals, and control signals of between three and five cycles of excitation.

5. The method of claim 3 wherein the step of transforming the measured time domain responses of the state variables, response signals, and control signals into frequency domain models comprises the step of using a Discrete Fourier Transform process.

6. The method of claim 1 wherein the performance index is selected from the group consisting of range factor, cruise factor, fuel efficiency, drag, and specific excess power.

7. The method of claim 1 wherein the plurality of state variables is selected from the group consisting of angle of attack, pitch attitude, roll attitude, pitch rate, roll rate, yaw rate, slid slip angle, speed, and mach number.

8. The method of claim 1 wherein the step of deriving a control effector setting comprises the step of applying linear programming techniques to the effectiveness derivatives.