Adaptive ground collision avoidance system

• US 5,892,462 A
• Filed: 06/20/1997
• Issued: 04/06/1999
• Est. Priority Date: 06/20/1995
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Tran, My
• Primary Examiner(s): SWARTHOUT, BRENT
• Application Number:
  US08/880,062
• Time in Patent Office: 655 Days
• Field of Search: 340/945, 340/961, 340/988, 340/968, 340/980, 340/963, 340/970, 340/995, 364/424.06, 364/429, 364/439, 364/441, 364/461, 364/462, 364/449.1, 364/460, 364/454, 342/29, 342/36, 342/453, 342/65, 701/3, 701/4, 701/9, 701/14, 701/18, 701/301
• US Class Current: 340/961
• CPC Class Codes: G01C 5/005 altimeters for aircraft G01C5/02, G01C5/06 take precedence
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 13/935 for terrain-avoidance
• CPC Class Codes: G05D 1/0646 to follow the profile of undulating ground
• CPC Class Codes: G08G 5/0086 for monitoring terrain radar or analogous systems specially adapted for terrain avoidance G01S13/935
• CPC Class Codes: G08G 5/045 Navigation or guidance aids, e.g. determination of anti-collision manoeuvers radar or analogous systems specially adapted for anti-collision between aircraft G01S13/933

Abstract

A ground collision avoidance system that exhibits improved accuracy and performance by integrating with all other aircraft systems including guidance systems, navigation systems, digital terrain elevation databases, mission computers, and radar altimeters. The ground collision avoidance system fully utilizes active onboard sensors in combination with the knowledge of terrain and obstacle data contained in databases. Furthermore, the ground collision avoidance system provides a multiple processing path to determine numerous predicted flight paths based on a number of reasonable assumptions regarding the aircraft flight during a predetermined amount of time. By using predictive flight path schemes a realistic estimate of the predicted flight path envelope can be determined and then this information can be used in conjunction with accurate terrain elevation databases to determine whether a ground collision condition exists. On the basis of these calculations, appropriate warnings can be provided to the air crew as well as suggested maneuvers to avoid ground collision.

Claims

1. A ground collision avoidance system for use by a pilot in an aircraft that has a mission control system, a navigation system, a digital terrain elevation database, active terrain sensors and a radar altimeter, the ground collision avoidance system comprising:

a local terrain awareness system that fuses inputs from the mission control system, the navigation system, the active terrain sensors, and the radar altimeter with terrain information in the digital terrain elevation database to generate a current profile of the elevation and character of the terrain over which the aircraft is operating;

a flight envelope prediction system attached to the mission control system for providing first and second flight path envelopes, wherein the first flight path envelope is a first prediction of the aircraft'"'"'s flight path based on a current flight path and the second flight path envelope is a second prediction of the aircraft'"'"'s flight path based on the first path envelope and a flight path angle that is necessary to avoid the terrain which may exist in the first path envelope, the second flight path envelope being determined by iteratively and simultaneously determining a ground collision point and a ground avoidance point, the ground collision point being a predicted point of collision with the terrain and the ground avoidance point being a predicted point with respect to the ground collision point at which the aircraft'"'"'s path should be modified to avoid the terrain;

a ground correlation system attached to the local terrain awareness system and the flight envelope prediction system for correlating terrain elevation data with the first and second flight path envelopes for providing pathway elevation data indicative of specific ground elevation data over which the aircraft travels;

a collision control and guidance system attached to the ground correlation system and the flight envelope prediction system which determines that a ground collision condition exists when the generation of the second flight path envelope by the flight envelope prediction system is no longer possible, and then uses the terrain information to calculate at least one standard replanning maneuver to avoid collision with the terrain; and

a collision warning system attached to the collision control and guidance system for producing an alarm if the ground collision condition exists as determined by the collision control and guidance system.

2. The ground collision system of claim 1 wherein the alarm is indicative of the response required of the pilot to avoid the ground avoidance point or an imminent ground collision condition.

3. The ground collision system of claim 1 further comprising a display system attached to the collision warning system for providing a visual depiction of the ground collision point and the ground avoidance point along with guidance controls to the pilot of the aircraft.

4. The ground collision system of claim 3 wherein, in response to the alarm produced by the collision warning system, the collision control and guidance system determines a calculated evasive maneuver which, if carried out, will avoid the ground collision condition.

5. The ground collision system of claim 4 wherein the calculated evasive maneuver includes a pitch control command, a roll control command and a thrust control command.

6. The ground collision system of claim 1 further comprising an aircraft dynamics model indicative of the operating dynamics of the aircraft, the aircraft dynamics model accessible by the flight prediction envelope system, the collision control and guidance system, and the collision warning system.

7. The ground collision system of claim 6 wherein the aircraft dynamics model includes a plurality of information regarding pilot and aircraft dynamic performance characteristics to accurately predict possible maneuvering capabilities of the aircraft.

8. The ground collision system of claim 2, wherein the warning buzzer is a variable frequency and distinctive voice advisory and warning for various ground collision and ground avoidance situations.

9. The ground collision system of claim 6, wherein the aircraft dynamics model is a reduced order and high fidelity model.

10. The ground collision system of claim 1 further comprising means for continuously monitoring the location of the ground avoidance point in response to the aircraft following the recommended flight path.

11. The ground collision system of claim 1, further comprising scanning means, in communication with said ground correlation system, for calculating the at least one standard replanning maneuver, said scanning means operable to provide a multi-directional scan of the terrain whereby any deviations from the current flight path are minimized.

12. The ground collision system of claim 1, further comprising means, cooperating with the ground correlation system, for advising the pilot when the ground collision condition no longer exists.

13. The ground collision system of claim 1, further comprising display means, communicating with said flight envelope prediction system, for displaying the second flight path envelope to the pilot.

14. The ground collision system of claim 1, wherein the ground collision point is determined by a minimum clearance altitude delta, the minimum clearance altitude delta being a minimum acceptable distance between the ground impact point and the current flight path that will allow the aircraft to avoid collision with the terrain.

15. The ground collision system of claim 1, wherein the ground collision point is determined by calculating forward in time a plurality of instantaneous positions and an inertial vector status with respect to the digital terrain elevation database.

16. A method for avoiding collision between an aircraft and the ground, the aircraft having a mission control system, an inertial navigation system, a digital terrain elevation database, active terrain sensors and a radar altimeter, the method comprising the steps of:

determining the aircraft altitude and a first predicted flight envelope where the first predicted flight envelope is the aircraft'"'"'s current flight path;

generating a vertical profile which includes terrain elevations over which the aircraft is currently positioned, and the terrain elevations corresponding to the terrain over which the first predicted flight envelope passes, where the terrain elevations are generated from a fusion of the digital terrain elevation database and inputs from the active terrain sensors, the inertial navigation system, and the radar altimeter;

continually determining a second predicted flight envelope, where the second predicted flight path is a recommended flight path that is based on the first predicted flight envelope and a flight path angle, in which the aircraft travels out of the first predicted flight envelope to avoid any collisions with the terrain, the second predicted flight envelope being determined by iteratively and simultaneously locating a ground collision point and a ground avoidance point, the ground collision point being a predicted point of collision with the terrain and the ground avoidance point being a Predicted point with respect to the ground collision point at which the pilot should follow the recommended flight path to avoid the terrain;

determining that a collision condition exists when the aircraft is traveling within the first predicted flight envelope and exceeds the second predicted flight envelope;

warning the pilot when the collision condition exists and accessing the digital terrain elevation database to generate at least one evasive maneuver which will avoid the collision condition; and

presenting the at least one evasive maneuver to the pilot via a display means.

17. The method of claim 16 wherein the vertical profile comprises a plurality of phase of flight information, the phase of flight information being indicative of a certain phase of flight of the aircraft at any particular point in time, and the step of determining that a collision condition exists includes consideration of the phase of flight in which the aircraft is currently operating.

18. The ground collision system of claim 16 further comprising the step of providing a flight envelope prediction system and a flight phase monitor apparatus, the flight phase monitor apparatus being adapted to monitor a plurality of phase of flight information, the phase of flight information being indicative of a certain phase of flight of the aircraft at any particular point in time, the flight phase monitor apparatus being adapted to provide the phase of flight information to the flight envelope prediction system.

19. The method of claim 16 further comprising the step of providing scanning means operable to provide a multi-directional scan of the terrain whereby any deviations from the current flight path are minimized.

20. The method of claim 16 further comprising the step of continuously monitoring the ground avoidance point at any particular point in time for determining the second predicted flight envelope.

21. The method of claim 20, further comprising the steps of capturing a plurality of complete simulated aircraft inertial states, and of storing the plurality of complete simulated aircraft inertial states for use in said step of continually determining a second predicted flight envelope.

22. The method of claim 16 further comprising the step of continuously monitoring the mission control system for avoiding nuisance warnings related to deliberate ground approach conditions.