Glide trajectory optimization for aerospace vehicles

Patent metadata

Field	Value
Publication number	US-12092432-B2
Application number	US-202017061787-A
Country	US
Kind code	B2
Filing date	Oct 2, 2020
Priority date	Oct 2, 2020
Publication date	Sep 17, 2024
Grant date	Sep 17, 2024

Abstract

A computer implemented method is provided for in-flight trajectory steering a vehicle by an optimal path to a destination. This includes incorporating physical constants; setting initial angle of attack (AoA) and initial AoA rate; incrementing flight AoA; measuring operation parameters; establishing a flight trajectory; calculating an optimal trajectory; comparing flight trajectories; and commanding flight control. The physical constants include gravity and atmospheric conditions. The flight AoA increments from the initial AoA and any prior increments. The operation parameters of the vehicle include pressure, velocity and flight path angle. The flight trajectory denotes the vehicle's path to its destination based on the operation parameters using the physical constants. The optimal trajectory is based on with altitude and velocity of the vehicle. The flight trajectory is compared to the optimal trajectory as a steering correction by altering the flight AoA. The vehicle's flight control executes the steering correction at the flight AoA.

First claim

What is claimed is:

1. A computer-implemented method for in-flight trajectory steering a vehicle to a target destination, said method comprising:
incorporating a plurality of physical constants for gravitational acceleration and atmospheric conditions;
setting initial angle of attack (AoA) and initial AoA rate for the vehicle along an initial trajectory as respective flight AoA and flight AoA rate;
incrementing said flight AoA from said initial AoA and prior increments;
measuring a plurality of operation parameters of the vehicle, including measured dynamic pressure, measured altitude, measured velocity and measured flight path angle;
establishing an operational glide trajectory to the target destination based on said operation parameters using said physical constants from said initial trajectory;
calculating an optimal trajectory with estimated altitude and estimated velocity by setting a control state as

p
γ

=

⌊

∂

D

/

∂

α

∂

L

/

∂

α

⌋

⁢

p
V

⁢
V

,

 such that α is said AoA as control variable, p i is an adjoint variable with subscript i being γ for flight angle and V for velocity, D is drag and L is lift;
comparing said operational glide trajectory to said optimal trajectory as a steering correction for altering said flight AoA and said flight AoA rate; and
commanding flight control of the vehicle to execute said steering correction of said flight AoA and said flight AoA rate.

2. The method according to claim 1 , wherein said measuring operation includes determining measured velocity from said measured dynamic pressure and deriving air density from said measured altitude.

3. The method according to claim 1 , wherein said measuring operation is performed by onboard sensors.

4. The method according to claim 1 , wherein said incrementing operation establishes an increment limit for terminating said measuring operation.

5. The method according to claim 1 , wherein said establishing operation includes replacing said steering correction for the target destination with an alternate steering correction to an alternate destination via the comparing operation.

6. The method according to claim 1 , wherein said setting and establishing operations include receiving global positioning system (GPS) signals for establishing vehicle position in said operational glide trajectory to adjust said steering correction.

7. The method according to claim 1 , wherein said calculating operation further includes incorporating said flight path angle.

8. The method according to claim 1 , wherein said comparing operation further includes setting said flight AoA to be not less than a test AoA based on drag coefficients while in a glide path for said operational glide trajectory.

9. The method according to claim 1 , wherein said establishing operation further includes calculating lift and drag forces on the vehicle from said operation parameters.

10. The method according to claim 1 , wherein said physical constants and said operation parameters are stored in random access memory (RAM).

11. The method according to claim 1 , wherein said physical constants further include an interpolative selection of atmospheric tables based said measured altitude and season.

12. The method according to claim 1 , wherein said calculating operation employs Pontryagin principle and Chebyshev polynomial interpolation.

13. The method according to claim 1 , wherein said measuring operation further includes establishing vehicle position.

14. The method according to claim 1 , wherein said measuring operation further includes subtracting an absolute velocity difference between said estimated and said measured velocities determining whether said absolute difference exceeds a set tolerance.

15. The method according to claim 1 , wherein said calculating operation further includes revising said flight AoA and said flight AoA rate.

16. The method according to claim 1 , wherein said incorporating operation further includes adjusting said gravitational acceleration based on earth's geometry.

Assignees

• Cerasuolo Ed Frank
• Us Navy

Inventors

• Cerasuolo Ed Frank

Classifications

• B64G1/244

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• B64G1/62

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• G05D1/683

  Intercepting moving targets (docking at a base station G05D1/661) · CPC title

• G05D1/686

  Maintaining a relative position with respect to moving targets, e.g. following animals or humans (for pointing payloads towards targets G05D1/689; involving controlling the position or course of two or more vehicles G05D1/69) · CPC title

• G05D1/689

  Pointing payloads towards fixed or moving targets (positioning towed, pushed or suspended implements G05D1/672) · CPC title