Aircraft course correction for wind and fuzzy logic course intercept profile based upon accuracy and efficiency

• US 6,092,007 A
• Filed: 04/29/1998
• Issued: 07/18/2000
• Est. Priority Date: 04/29/1998
• Status: Expired due to Term

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Thornberg, Christopher A., Corning, Sherman III, Walsh, David M., Cotton, Bryan S.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US09/069,666
• Time in Patent Office: 811 Days
• Field of Search: 701/4, 701/1, 701/13, 701/14, 701/15, 701/16, 701/23, 701/202, 701/205, 701/206, 701/210, 701/224, 701/302, 244/76 R, 244/17.13, 244/96, 244/181, 244/158 R
• US Class Current: 701/4
• CPC Class Codes: G05D 1/0204 to counteract a sudden perturbation, e.g. cross-wind, gust

Abstract

An aircraft autopilot system provides a wind correction angle which is added to the desired course to provide commanded heading, the wind correction angle being generated as a proportional and integral function of ground track error. When the aircraft is off its desired course, it can be returned to the desired course by means of a course intercept angle, added to the desired course, to provide a corrected commanded course, the course intercept angle being a proportional function of the perpendicular error (the lateral distance of the aircraft from the original course) suitably limited to some angle within 90° of the desired course. The course correction angle may be generated as a proportion of the perpendicular course error determined by the degree of importance of accuracy, and may be switched over to a course directly toward a waypoint in dependence upon the importance of efficiency. The course intercept angle may be a variable proportion of the perpendicular error as a function of the importance of accuracy, and the limits on the intercept angle determined by the relative importance of efficiency.

Claims

1. An automatic flight control system for an aircraft, comprising:

means for providing a desired course signal indicative of a desired course which the aircraft may fly in order to reach a waypoint;

means for providing a ground track signal as a function of the arctangent of the ratio of the group speed in one direction in each coordinates divided by the groundspeed of the aircraft in a direction in each coordinates which is normal to said one direction, corrected for the quadrant of said ratio;

means for providing a ground track error signal as the difference between said desired course and said ground track; and

means for providing a commanded heading signal as a summation of said desired course signal with proportional and integral functions of said ground track error signal.

2. A system according to claim 1 further comprising:

means for providing a course intercept angle signal as a limited function of a proportion of the perpendicular distance of the aircraft from an original desired flight path to said way point; and

wherein

said means for providing a commanded heading signal provides it as the summation of said desired course signal, said proportional and integral functions of said track error signal, and said course intercept angle signal, whereby a smooth interception of the original desired flight path is made.

3. An automatic flight control system for an aircraft, comprising:

means for providing a desired course signal indicative of a desired course which the aircraft may fly in order to reach a waypoint;

means for providing a course intercept angle signal as a limited function of a proportion of the perpendicular distance of the aircraft from an original desired flight path to said waypoint; and

means for providing, as the summation of said desired course signal and said course intercept angle signal, a commanded heading signal indicative of a course the aircraft should fly to return to the original desired flight path to the waypoint, whereby a smooth interception to the original desired flight path is made.

4. A system according to claim 3 wherein the proportion of perpendicular error is determined by a selectable setting representative of the importance of accuracy in the manner in which the aircraft flies to the waypoint.

5. A system according to claim 4 wherein said commanded course is switched, when the aircraft reaches a particular perpendicular distance from the original flight path to the waypoint, from being (a) said limited function of a proportion of the perpendicular error to being (b) the bearing to the waypoint.

6. A system according to claim 5 wherein said particular distance is selected by a selectable setting representative of the importance of efficiency in the manner in which the aircraft flies to the waypoint.

7. A system according to claim 4 wherein said limited function has the limits thereof determined as a function of a selectable setting representative of the importance of efficiency in the manner in which the aircraft flies to the waypoint.