Air data attitude reference system

Patent metadata

Field	Value
Publication number	US-2018299293-A1
Application number	US-201715489148-A
Country	US
Kind code	A1
Filing date	Apr 17, 2017
Priority date	Apr 17, 2017
Publication date	Oct 18, 2018
Grant date	—

Abstract

An air data computer senses acceleration and rotational rate of an aircraft with an inertial sensor assembly of the air data computer. The air data computer determines first attitude information of the aircraft based on the acceleration and rotational rate sensed with the inertial sensor assembly. The air data computer receives second attitude information of the aircraft from a source external to the air data computer, and determines attitude correction values based on the first attitude information and the second attitude information. The air data computer applies the attitude correction values to the first attitude information to produce error-corrected attitude information that is output from the air data computer.

First claim

1 . A system comprising:
a first air data computer that includes a first inertial sensor assembly, the first air data computer configured to:
sense, with the first inertial sensor assembly, acceleration and rotational rate of an aircraft;
determine first attitude information of the aircraft based on the acceleration and rotational rate sensed with the first inertial sensor assembly;
receive second attitude information of the aircraft from a source external to the first air data computer;
determine first attitude correction values based on the first attitude information and the second attitude information;
apply the first attitude correction values to the first attitude information to produce first error-corrected attitude information of the aircraft; and
output the first error-corrected attitude information.

2 . The system of claim 1 , further comprising:
a second air data computer that includes a second inertial sensor assembly, the second air data computer configured to produce the second attitude information of the aircraft.

3 . The system of claim 2 ,
wherein the second air data computer is configured to:
determine the second attitude information of the aircraft based on acceleration and rotational rate sensed by the second inertial sensor assembly;
receive the first error-corrected attitude information from the first air data computer;
determine second attitude correction values based on the second attitude information and the first error-corrected attitude information;
apply the second attitude correction values to the second attitude information to produce second error-corrected attitude information of the aircraft; and
output the second error-corrected attitude information.

4 . The system of claim 1 ,
wherein the first attitude information comprises:
a first aircraft pitch angle;
a first aircraft roll angle;
a covariance estimate of an error of the first aircraft pitch angle; and
a covariance estimate of an error of the first aircraft roll angle;
wherein the second attitude information received from the source external to the first air data computer comprises:
a second aircraft pitch angle;
a second aircraft roll angle;
a covariance estimate of an error of the second aircraft pitch angle; and
a covariance estimate of an error of the second aircraft roll angle; and
wherein the first air data computer is configured to determine the first set of error correction values based on the first aircraft pitch angle, the first aircraft roll angle, the covariance estimate of the error of the first aircraft pitch angle, the covariance estimate of the error of the first roll angle, the second aircraft pitch angle, the second aircraft roll angle, the covariance estimate of the error of the second aircraft pitch angle, and the covariance estimate of the error of the second aircraft roll angle.

5 . The system of claim 4 ,
wherein the first air data computer is configured to determine the first attitude correction values via an extended Kalman filter that utilizes the first aircraft pitch angle, the first aircraft roll angle, the covariance estimate of the error of the first pitch angle, the covariance estimate of the error of the first roll angle, the second aircraft pitch angle, the second aircraft roll angle, the covariance estimate of the error of the second pitch angle, and the covariance estimate of the error of the second roll angle.

6 . The system of claim 1 ,
wherein the first air data computer is further configured to:
determine a set of sensor error correction values based on the first attitude information and the second attitude information;
apply the set of sensor error correction values to each of the acceleration and the rotational rate sensed with the first inertial sensor assembly to produce error-corrected acceleration and error-corrected rotational rate of the aircraft; and
determine the first attitude information based on the first error-corrected acceleration and the first error-corrected rotational rate.

7 . The system of claim 6 ,
wherein the first air data computer is configured to receive acceleration information from the source external to the first air data computer; and wherein the first air data computer is configured to determine the first attitude information based on the error-corrected acceleration and the error-corrected rotational rate by being configured to:
determine aircraft angular acceleration based on the error-corrected acceleration and the acceleration information received from the source external to the first air data computer,
blend the aircraft angular acceleration and the error-corrected rotational rate using a complementary filter to produce a blended rotational rate; and
determine the first error-corrected attitude information based on the blended rotational rate.

8 . The system of claim 7 ,
wherein the complementary filter is configured to:
integrate the aircraft angular acceleration to produce an accelerometer-based rotational rate of the aircraft;
filter the accelerometer-based rotational rate to remove low frequency signal and noise to produce a high-pass filtered accelerometer-based rotational rate;
filter the error-corrected rotational rate to remove high frequency signal and noise to produce a low-pass filtered error-corrected rotational rate; and
blend the high-pass filtered accelerometer-based rotational rate and the low-pass filtered error-corrected rotational rate to produce the blended rotational rate of the aircraft.

9 . The system of claim 7 ,
wherein the complementary filter is a multi-input single-output (MISO) filter that takes the aircraft angular acceleration and the first error-corrected rotational rate as inputs and produces the blended rotational rate of the aircraft as an output.

10 . The system of claim 1 ,
wherein the source external to the first air data computer comprises a second air data computer including a second inertial sensor assembly; wherein the aircraft has a first side and a second side separated by a centerline extending from a nose of the aircraft to a tail of the aircraft; wherein the first air data computer is disposed at the first side of the aircraft; and wherein the second air data computer is disposed at the second side of the aircraft.

11 . The system of claim 1 ,
wherein the source external to the first air data computer comprises a first external source; wherein the first air data computer is configured to receive third attitude information of the aircraft from a second external source that is separate from both the first air data computer and the first external source; and wherein the first air data computer is configured to determine the first attitude correction values based on the first attitude information, the second attitude information, and the third attitude information.

12 . The system of claim 11 ,
wherein the first air data computer is configured to compare the first attitude information, the second attitude information, and the third attitude information to determine a validity status of one or more of the first attitude information, the second attitude information, and the third attitude information.

13 . An air data computer comprising:
an inertial sensor assembly comprising:
a plurality of accelerometers, each of the plurality of accelerometers configured to sense acceleration along one of a plurality of axes;
a plurality of rate gyroscopes, each of the plurality of rate gyroscopes configured to sense rotational rate along one of the plurality of axes;
a Kalman estimator module configured to determine a set of attitude correction values based on attitude

Assignees

• Rosemount Aerospace Inc

Inventors

• Ell Todd Anthony

Classifications

• G01C25/00

  Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass (testing, calibrating or compensating compasses G01C17/38) · CPC title

• B64D43/00

  Arrangements or adaptations of instruments · CPC title

• G01C23/00 Primary

  Combined instruments indicating more than one navigational value, e.g. for aircraft; Combined measuring devices for measuring two or more variables of movement, e.g. distance, speed or acceleration · CPC title

• G01C21/183 Primary

  Compensation of inertial measurements, e.g. for temperature effects · CPC title