Landing area obstacle detection radar system

• US 6,219,594 B1
• Filed: 10/18/1999
• Issued: 04/17/2001
• Est. Priority Date: 05/31/1994
• Status: Expired due to Fees

• Current Assignee: Winged Systems Corporation
• Original Assignee: Winged Systems Corporation
• Inventors: Nicosia, Joseph M., Loss, Keith R., Taylor, Gordon A.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US09/419,767
• Time in Patent Office: 547 Days
• Field of Search: 701/4, 701/5, 701/16, 701/17, 701/207, 701/208, 701/213, 701/214, 701/216, 701/223, 342/26, 342/33, 342/34, 342/63, 342/64, 342/118, 340/972, 340/988, 340/990, 340/995
• US Class Current: 701/16
• CPC Class Codes: G01C 21/1652 with ranging devices, e.g. LIDAR or RADAR
• CPC Class Codes: G01C 23/005 Flight directors indicating arrangements specially adapted for rotary gyroscopes G01C19/32
• CPC Class Codes: G01S 13/286 frequency shift keyed
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 13/90 using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques
• CPC Class Codes: G01S 13/913 for landing purposes
• CPC Class Codes: G01S 13/953 mounted on aircraft
• CPC Class Codes: G01S 19/15 Aircraft landing systems
• CPC Class Codes: G01S 19/52 Determining velocity
• CPC Class Codes: G01S 7/412 based on a comparison between measured values and known or stored values
• CPC Class Codes: G05D 1/0676 specially adapted for landing
• CPC Class Codes: G08G 5/0021 located in the aircraft
• CPC Class Codes: G08G 5/0065 for taking-off
• CPC Class Codes: G08G 5/0086 for monitoring terrain radar or analogous systems specially adapted for terrain avoidance G01S13/935
• CPC Class Codes: G08G 5/0091 for monitoring atmospheric conditions radar or analogous systems specially adapted for meteorological use G01S13/95; meteorology G01W
• CPC Class Codes: G08G 5/025 Navigation or guidance aids radar or analogous systems specially adapted for landing purposes G01S13/913
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

An aircraft including an approach and landing system, including a navigation unit for providing navigation information, a weather radar unit for providing radar information, a processor which receives navigation information from the navigation unit and information from the weather radar unit, the processor unit providing an output representing information concerning the aircraft in accordance with the provided navigation information and radar information, a memory for storing information representing a scene, the processor unit correlating the stored scene information with the output representing information concerning the aircraft to provide a mapped scene, a display unit for displaying the output of said processor and the mapped scene, and a steppable frequency oscillator for providing a signal which is stepped in frequency to the weather radar unit, thereby providing an increased range resolution.

Claims

1. A method of detecting ground obstacles on or near the runway area of an arriving or departing aircraft, the method comprising:

storing radar signature and map position information of cultural or natural ground features in the vicinity of a landing area;

transmitting radar signals from an airborne radar unit that reflect off of objects, said reflected radar signals being received by said radar unit;

processing said received signals in real-time to compensate for a state vector of said aircraft relative to said landing area,

comparing information of said received radar signals with a portion of said stored ground feature information; and

detecting obstacles which are additional to said stored radar feature and map position information.

2. The method according to claim 1, wherein:

said stored map position information is represented in rectilinear coordinates, and real-time radar information is in range, range-rate coordinates for each antenna pointing angle, and

said real-time radar information is adjusted for said aircraft'"'"'s state vector relative to said landing area in real-time, resulting in rectilinear coordinate data compatible with said stored radar signature and map position information, and

where said obstacles are detected by determining if said real-time radar information contains returns which are additional to said stored information.

3. The method according to claim 2, wherein:

range resolution is increased by the use of a pseudo-ran dom, frequency hopped radar signal, and

processing of said radar returns utilizes knowledge of an aircraft state vector relative to the landing area.

4. The method according to claim 3, wherein the comparison of said stored data to said adjusted real-time radar data is performed using rectilinear pixel mapping techniques.

5. The method according to claim 4, wherein said ground feature information is represented by a plurality of pixels such that each pixel represents a particular section of said ground feature information, said resolution of said radar being sufficient to resolve information of said obstacles into more than one pixel per obstacle.

6. The method according to claim 1, wherein said obstacles include at least one of an aircraft, ground vehicle, or other radar reflecting object.

7. An system for detecting ground obstacles on or near the runway area of an arriving or departing aircraft, comprising:

a memory for storing radar signature and map position information of cultural or natural ground features in the vicinity of a landing area;

a radar system having a transmitter and a receiver, said radar system operable to transmit radar signals from said aircraft that reflect off of objects, said radar system also operable to receive said reflected radar signals; and

a processing system programmed to process received signals in real-time and compensate for a state vector of said aircraft relative to said landing area, said processing system also programmed to compare information of said received radar signals with a portion of said stored ground feature information and thereby identify obstacles on or near said ground by detecting information which is additional to said stored radar feature and map position information.

8. The system according to claim 7, wherein:

said stored map position information is represented in rectilinear coordinates, and real-time radar information is in range, range-rate coordinates for each antenna pointing angle, and

said real-time radar information is adjusted for said aircraft'"'"'s state vector relative to said landing area in real-time, resulting in rectilinear coordinate data compatible with said stored radar signature and map position information, and

where said obstacles are detected by determining if said real-time radar information contains returns which are additional to said stored information.

9. The system according to claim 8, wherein:

range resolution is increased by the use of a pseudo-random, frequency hopped radar signal, and

processing of said radar returns utilizes knowledge of an aircraft state vector relative to the landing area.

10. The system according to claim 9, wherein the comparison of said stored data to said adjusted real-time radar data is performed using rectilinear pixel mapping techniques.

11. The system according to claim 10, wherein said ground feature information is represented by a plurality of pixels such that each pixel represents a particular section of said ground feature information, said resolution of said radar being sufficient to resolve information of said obstacles into more than one pixel per obstacle.

12. The system according to claim 7, wherein said obstacles include at least one of an aircraft, ground vehicle, or other radar reflecting object.

13. A method of improving airborne navigation using stored information about a radar signature of natural and cultural ground objects in combination with airborne radar measurements of said natural and cultural ground objects, such method comprising:

selection of groups of radar reflective targets in a small geographic area which can be illuminated by a single radar emission, such groups having sufficient numbers and geometries of said radar reflective targets so as to make an aggregate radar signature of a group unlikely to occur again within the area of navigation;

storing the details of the radar signature of each group of targets along with a precise map location of at least one radar reflective target in each said group;

while in-flight, using current position estimates and data from said stored group of targets to select the optimum geometry target groups on the ground, and making radar measurements of a geographical area containing those groups;

correcting the received radar data to account for effects of an aircraft state vector;

matching said corrected radar data with said stored radar signatures;

utilizing real-time radar data to determine the position of the aircraft relative to at least one said map referenced target point within the matched group; and

utilizing said stored geographical position of said target point to determine the aircraft'"'"'s position in the stored map coordinate system.

14. The method of claim 13 whereby the stored data of said group'"'"'s radar signature is contained in a coordinate system which is non-linearly related to the coordinate system used in the radar measurements.

15. The method of claim 13 whereby multiple measurements are made of geometrically separated groups to determine a position of the aircraft in the stored data coordinate system.

16. The method of claim 13 whereby multiple, successive measurements are made of groups along and to the sides of the aircraft'"'"'s flight path, each measurement updating and refining the determined position of the aircraft in the stored data coordinate system.

17. The method of claim 16 whereby the magnitude of each measurement update to the aircraft'"'"'s position is monitored as a indication of navigation quality.