Magnetic flux detector correction system

• US 4,680,866 A
• Filed: 12/19/1985
• Issued: 07/21/1987
• Est. Priority Date: 12/19/1985
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Johnson, James S., Albrecht, Gene A.
• Primary Examiner(s): Little, Willis
• Application Number:
  US06/811,066
• Time in Patent Office: 579 Days
• Field of Search: 33/356, 33/357, 33/363 Q, 33/361
• US Class Current: 33/356
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

An aircraft heading correction system utilizing the horizontal field strength of the earth'"'"'s magnetic field to determine the tangent of the dip angle generally associated with a given field strength. The tangent of the dip angle is then used to generate a signal which corrects the flux valve heading during accelerated flight.

Claims

1. An aircraft heading correction system of the type utilizing a magnetic flux detector to provide a signal as a function of magnetic heading of said aircraft, said correction system comprising:

a first means, configured to accept;

(a) a signal representative of north, east and down acceleration components of said aircraft,

(b) said signal as a function of magnetic heading of said aircraft, for providing a signal representative of horizontal field strength,

a second means, configured to accept said signal representative of horizontal field strength, for providing said signal representative of horizontal field strength and a signal representative of the tangent of a dip angle,

a third means, configured to accept said signal as a function of magnetic heading of said aircraft, for providing a magnetic heading signal,

a fourth means, configured to accept;

(a) said signal representative of horizontal field strength,

(b) said signal representative of the tangent of a dip angle,

(c) said signal representative of north, east and down acceleration components of said aircraft, for providing a magnetic heading correction signal, and

a fifth means, configured to accept said magnetic heading correction signal and said magnetic heading signal for providing a corrected magnetic heading signal.

2. An aircraft heading correction system according to claim 1 wherein said signal as a function of magnetic heading of said aircraft comprises a first and second signal having the relationship:

space="preserve" listing-type="equation">said first signal=X.sub.1 =horizontal field strength×

sine (magnetic heading)

space="preserve" listing-type="equation">said second signal=X.sub.2 =horizontal field strength×

cosine (magnetic heading).

3. A system according to claim 2 wherein said signal representative of horizontal field strength has the form

4. A system according to claim 2 wherein said third means provides a magnetic heading sigal having the form tan^-1 [X₁ /X₂ ].

5. A system according to claim 3 wherein said signal representative of the tangent of a dip angle is of the form

6. A system according to claim 5 wherein said magnetic heading correction signal is of the form:

##EQU1## where east component=[tan (dip angle)×

sin A_EM /A_DOWN)],

north component=[tan (dip angle×

sin (A_NM /A_DOWN)]+cos (A_NM /A_DOWN)],

A_EM =aircraft east acceleration,

A_NM =aircraft north acceleration,

A_DOWN =aircraft down acceleration.