Redundant system for the indication of heading and attitude in an aircraft

• US 6,782,742 B1
• Filed: 08/31/2001
• Issued: 08/31/2004
• Est. Priority Date: 01/18/1999
• Status: Expired due to Fees

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Nordlund, Per-Johan, Carlsson, Carl-Olof, Adebjörk, Peter
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): ALLEN, ANDRE J
• Application Number:
  US09/889,311
• Time in Patent Office: 1,096 Days
• Field of Search: 356/350, 356/484, 701/3, 731/700.2, 731/700.1
• US Class Current: 73/170.01
• CPC Class Codes: G01C 21/16 by integrating acceleration or speed, i.e. inertial navigation
• CPC Class Codes: G05D 1/0077 using redundant signals or controls

Abstract

A method and an arrangement for synthetically calculating redundant attitude and redundant heading by means of existing data in an aircraft. In one embodiment the heading of the aircraft is available and in another embodiment the heading is calculated from a magnetic heading sensor. When the heading is available (redundant heading) attitude is calculated by weighting together the signals from and angular rate gyros (2) in the aircraft'"'"'s flight control system, information from air data (altitude, speed, angle of attack) as well as information about heading (redundant heading). When the heading is not available, attitude and heading are calculated in one embodiment with the aid of Kalman filters (11, 22) by weighting together the signals from the angular rate gyros in the aircraft'"'"'s control system, information from air data (altitude, speed, angle of attack and sideslip angle) as well as information from a magnetic heading detector existing in the aircraft.

Claims

1. Method for synthetically calculating redundant attitude for an aircraft when a heading of the aircraft is known, using data existing in the aircraft, including angular rates p, q, r around x-, y- and z-coordinates of an aircraft-fixed (body frame) coordinate system, air data information including speed, altitude and angle of attack of the aircraft, and the heading information, wherein the method includes the steps:

calculating the attitude based on the aircraft-fixed angular rates p, q, r; and

correcting the calculated attitude using the air data and the heading information.

2. Method according to claim 1, wherein the heading information is obtained from a heading gyro.

3. Method according to claim 1, wherein the step of calculating the attitude comprises the step of integrating out the attitude via information about the body-frame angular rates (p, q and r) obtained from the aircraft-fixed angular rate gyros of the aircraft.

4. Method according to claim 3, wherein correction of the integrated-out attitude takes place with the aid of attitude calculated on the basis of air data information and heading information.

5. Arrangement for synthetically calculating redundant attitude for an aircraft when a heading of the aircraft is known, using data existing in the aircraft, including body-frame angular rates (p, q and r) of the aircraft, air data including at least speed, altitude and angle of attack of the aircraft, and the heading information, wherein the arrangement includes an integration routine operable to integrate out the attitude of the aircraft from information about the body-frame angular rates (p, q and r) of the aircraft;

and a correction routine operable to correct the calculated attitude using a reference attitude determined from air data and redundant heading information.

6. Arrangement according to claim 5, wherein the heading information is obtained from a heading gyro.

7. Arrangement according to claim 5, wherein the integration routine is further operable to integrate out the attitude of the aircraft from the body-frame angular rates (p, q and r) of the aircraft obtained from body-frame angular rate gyros of the aircraft.

8. Arrangement according to claim 7, wherein the integration routine receives a zero-error-compensated body-frame angular rate gyro signal.

9. Arrangement according to claim 5, wherein the correction routine if further operable to calculate a reference attitude using air data information and the redundant heading information.

10. Arrangement according to claim 5, further comprising a routine operable to obtain a synthetically-generated corrected attitude by generating a difference between the attitude obtained from the integration routine and an error signal that represents an error between the integrated attitude and the reference attitude.