Aircraft ground collision avoidance and autorecovery systems device

• US 4,924,401 A
• Filed: 10/30/1987
• Issued: 05/08/1990
• Est. Priority Date: 10/30/1987
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Howard, John D., Bice, Gregory W., Skoog, Mark A.
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): Lee, Benny T.
• Application Number:
  US07/120,567
• Time in Patent Office: 921 Days
• Field of Search: 364/428, 364/433, 364/434, 364/460, 364/461, 342/29, 342/65, 318/584, 340/970, 73/178 T, 244/76 R, 244/180, 244/181
• US Class Current: 701/6
• CPC Class Codes: G05D 1/0646 to follow the profile of undulating ground
• CPC Class Codes: G09B 9/006 for locating or ranging of objects

Abstract

The invention comprises an aircraft ground collision avoidance system which utilizes a flight control computer for monitoring aircraft flight states and calculating preferred aircraft flyup altitudes at which automatic aircraft flyups should be initiated. The flyup altitude is determined by calculating aircraft altitude to be lost during a recovery maneuver from a current aircraft flight state. The invention also comprises an aircraft autopilot for monitoring aircraft flight states and initiating an automatic aircraft flyup when so directed by the flight control computer. The monitored aircraft states include aircraft airspeed, angle of attack, bank angle and velocity. Sensor lag, aircraft load factor and engine throttle position are also considered in determining when to conduct an automatic aircraft flyup.

Claims

1. An aircraft ground collision avoidance system comprising:

(a) means for computing a flyup, said flyup computing means receiving sensor signals which represent aircraft flight states and calculating preferred aircraft flyup altitudes at which an automatic aircraft flyup should be initiated, wherein each aircraft flyup altitude of said preferred aircraft flyup altitudes is calculated by determining the aircraft altitude which is lost (Δ

Z) during a recovery maneuver due to a current aircraft flight state; and

(b) means for automatically controlling an aircraft, said automatic aircraft controlling means receiving aircraft flight data and implementing an automatic aircraft flyup when said preferred aircraft flyup altitude is achieved, wherein said aircraft flight states and data include aircraft angle of attack and bank angle, said preferred aircraft flyup altitude is provided to said automatic aircraft controlling means by said flyup computing means.

2. The aircraft ground collision avoidance system of claim 1 wherein the flyup computing means utilizes aircraft speed and angle of attack to determine flyup altitudes.

3. The aircraft ground collision avoidance system of claim 2 wherein the flyup computing means also utilizes aircraft bank angle to determine flyup altitudes.

4. The aircraft ground collision avoidance system of claim 3 wherein the flyup computing means also utilizes aircraft roll rate to determine flyup altitudes.

5. The aircraft ground collision avoidance system of claim 2 wherein the flyup computing means also considers aircraft sensor lag to determine flyup altitudes, wherein aircraft sensor lag is characterized by the time which elapses between a change in an aircraft flight state and a sensor response to that change.

6. The aircraft ground collision avoidance system of claim 1 wherein the flyup computing means compensates for non-idle aircraft engine power settings when determining aircraft flyup altitudes.

7. The aircraft ground collision avoidance system of claim 1 wherein said automatic aircraft controlling means further comprises angle of attack and roll rate limiters for preventing overloading of aircraft structures during an automatic aircraft flyup.

8. The aircraft ground collision avoidance system of claim 1 wherein said automatic aircraft controlling means includes an autopilot, said automatic aircraft controlling means also monitors aircraft load factors and further includes means for limiting load, said load limiting means prevents overloading of the aircraft structures during autorecovery which limits operation of said autopilot so as to prevent said autopilot from implementing an automatic flyup in a manner which would exceed predetermined aircraft load limit, said predetermined aircraft load limit being stored in said flyup computing means.

9. The aircraft ground collision avoidance system of claim 1 wherein the aircraft altitude calculated to be lost (Δ

Z) is equal to the sum of;

space="preserve" listing-type="equation">Δ

z.sub.1 +Δ

z.sub.2 +Δ

z.sub.3

and is used by the flyup computing means to determine when to initiate a flyup and wherein;

Δ

z₁ accounts for altitude lost during a wings level dive to level flight while maintaining a constant load factor;

Δ

z₂ accounts for the amount of time required for an aircraft to attain a desired pullup load factor; and

Δ

z₃ accounts for correcting initial bank angle during a flyup.

10. The aircraft ground collision avoidance system of claim 9 wherein Δ

Z further is equal to the sum including Δ

z₄ which accounts for aircraft roll rate at flyup initiation.

11. The aircraft ground collision avoidance system of claim 9 wherein Δ

Z further is equal to the sum including Δ

z₅ which accounts for sensor lags in determining a flyup initiation, wherein aircraft sensor lag is characterized by the time which elapses between a change in an aircraft flight state and a sensor response to that change.

12. The aircraft ground collision avoidance system of claim 9 wherein Δ

Z further is equal to the sum including Δ

z₆ which adjusts for aircraft non-idle power settings.

13. The aircraft ground collision avoidance system of claim 9 further comprising an autothrottle for adjusting airspeed to provide aircraft flyup with a minimum turn radius when the flyup computing means initiate an automatic flyup.

14. The aircraft ground collision avoidance system of claim 1 wherein the aircraft altitude calculated to be lost (Δ

Z) is equal to the sum of;

space="preserve" listing-type="equation">Δ

z.sub.1 +Δ

z.sub.2 +Δ

z.sub.3 +Δ

z.sub.4 +Δ

z.sub.5

and is used by the flyup computing means to determine when to initiate a flyup and wherein;

Δ

z₁ accounts for altitude lost during a wings level dive to level flight while maintaining a constant load factor;

Δ

z₂ accounts for the amount of time required for an aircraft to attain a desired pullup load factor;

Δ

z₃ accounts for correcting initial bank angle during a flyup;

Δ

z₄ accounts for aircraft roll rate at flyup initiation; and

Δ

z₅ accounts for sensor lags in determining a flyup initiation, wherein aircraft sensor lag is characterized by the time which elapses between a change in an aircraft flight state and a sensor response to that change.

15. The aircraft ground collision avoidance system of claim 14 wherein Δ

Z further is equal to the sum including Δ

z₆ which adjusts for aircraft non-idle power settings.

16. The aircraft ground collision avoidance system of claim 13 further comprising an autothrottle for adjusting airspeed to provide aircraft flyup with a minimum turn radius when the flyup computing means initiate an automatic flyup.

17. A method of automatically avoiding aircraft ground collision comprising the steps of:

entering a preselected aircraft flight floor altitude in an aircraft flight computer;

monitoring aircraft flight states with said flight computer, said flight states including air speed, altitude and flight path angles;

calculating by said flight computer the amount of altitude to be lost during recovery maneuver if the monitored flight states, when extrapolated would indicate a loss of altitude;

adding by said flight computer the amount of altitude to be lost as indicated by the monitored flight states during the recovery maneuver to the preselected floor altitude to determine a flyup altitude;

comparing by said flight computer the flyup altitude to aircraft altitude; and

sending a command via said flight computer to an autopilot to commence initiation of an automatic flyup maneuver if aircraft altitude is less than the preselected aircraft flight floor altitude.

18. The method of automatically avoiding aircraft ground collisions of claim 17 further comprising the steps of:

monitoring aircraft bank angle in order to control aircraft elevator deflection during the automatic aircraft flyup; and

monitoring aircraft pitch attitude in order to control aircraft aileron deflection during the automatic aircraft flyup.

19. The method of automatically avoiding aircraft ground collisions of claim 17 further comprising the step of:

selectively combining pilot flight commands with the automatic flyup.

20. The method of automatically avoiding aircraft ground collisions of claim 17 wherein said step cf calculating the amount of aircraft altitude to be lost during a recovery maneuver is performed by said flight computer by calculating Δ

Z, which is equal to the sum of;

space="preserve" listing-type="equation">Δ

z.sub.1 +Δ

z.sub.2 +Δ

z.sub.3

wherein;

Δ

z₁ accounts for altitude lost during a wings level dive to level flight while maintaining a constant load factor;

Δ

z₂ accounts for the amount of time required for an aircraft to attain a desired pullup load factor; and

Δ

z₃ accounts for correcting initial bank angle during a flyup.

21. The method of automatically avoiding aircraft ground collisions of claim 17 wherein the step of calculating the amount of aircraft altitude to be lost during a recovery maneuver is performed by said flight computer by calculating Δ

Z, which is equal to the sum of;

space="preserve" listing-type="equation">Δ

z.sub.1 +Δ

z.sub.2 +Δ

z.sub.3 +Δ

z.sub.4 +Δ

z.sub.5

wherein;

Δ

z₁ accounts for altitude lost during a wings level dive to level flight while maintaining a constant load factor;

Δ

z₂ accounts for the amount of time required for an aircraft to attain a desired pullup load factor;

Δ

z₃ accounts for correcting initial bank angle during a flyup;

Δ

z₄ accounts for aircraft roll rate at flyup initiation; and

Δ

z₅ accounts for sensor lags in determining a flyup initiation, wherein aircraft sensor lag is characterized by the time which elapses between a change in an aircraft flight state and a sensor response to that change.

22. The method of automatically avoiding aircraft ground collisions of claim 21 wherein Δ

Z further is equal to the sum includes Δ

z₆ which adjusts for aircraft non-idle power settings.

23. An autopilot for automatically performing an aircraft altitude recovery comprising:

(a) an angle of attack limiter including an angle of attack detector, for producing an angle of attack signal that limits aircraft angle of attack to within an aircraft stall margin during aircraft altitude recovery;

(b) a g-force limiter including a g-force detector for producing a signal that prevents overloading of aircraft structures during aircraft altitude recovery;

(c) a bank angle recovery signal generating means including a bank angle detector, generating a signal for controlling aircraft elevators to promote aircraft altitude recovery;

(d) an elevator summing junction for combining signals from said angle of attack limiter, said g-force limiter and said bank angle recovery generating means to provide a sum signal to control aircraft elevators to achieve aircraft recovery without exceeding aircraft flight capabilities;

(e) a roll rate limiter including a roll rate detector, for providing a signal to eliminate excessive aircraft roll; and

(f) an aileron summing junction for combining signals from said roll rate limiter and the bank angle detector to provide a sum signal to control aircraft ailerons to achieve level flight and aircraft altitude recovery.

24. The autopilot for automatically performing an aircraft recovery maneuver of claim 23 further comprising pitch angle signal generating means for preventing an automatic bank angle adjustment by the aircraft ailerons at very high aircraft pitch angles.

25. The autopilot for automatically performing an aircraft altitude recovery maneuver of claim 23 further comprising manual control summing junctions for combining pilot commands with automatic control of the aircraft elevators and ailerons.

26. The autopilot for automatically performing an aircraft altitude recovery maneuver of claim 25 further comprising pilot command stick-force breakout limiters for preventing inadvertent pilot commands from influencing the autopilot during an autorecovery.