SKIPPING FILTER FOR INERTIALLY AUGMENTED LANDING SYSTEM

• US 20030083792A1
• Filed: 10/31/2001
• Published: 05/01/2003
• Est. Priority Date: 10/31/2001
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: McIntyre, Melville D., Murphy, Thimothy, Anderson, Leonard R., Krogh, Steven B.
• Granted Patent: US 6,549,829 B1
• Time in Patent Office: Days
• US Class Current: 701/16
• CPC Class Codes: G01S 19/15 Aircraft landing systems
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled
• CPC Class Codes: G01S 19/52 Determining velocity

Abstract

The present method and apparatus consists of storing past values of estimated IRU error and using these past values to update the coasting filter when switching from GPS to inertial mode. Through the storage of past IRU error estimates, it is possible to avoid misdirected guidance from an erroneous GPS signal. The MMR and ground station can require up to 6 seconds to identify a failed GLS signal.

Claims

1. In combination in an inertially augmented GPS landing system:

means for continuously storing a moving time period window of data representative of an aircraft GPS and inertial state for the last time period; and

means for reconstructing the estimate of the inertial state errors in the event of a GPS signal failure.

2. The invention according to claim 1 wherein said moving time period window is 6 seconds.

3. A method for correcting the corruption of an inertial guidance signal caused by a faulty GPS signal comprising the steps of:

recognizing a GPS signal failure; and

,

reconstructing in non-real time the prior 6 seconds of blended GPS inertial filtering; and

replacing the 6 seconds of corrupted filter output data with an uncorrupted set of data representing said 6 seconds.

4. In combination in an inertially augmented landing system:

a coasting filter; and

a skipping filter; and

,

said skipping filter comprising a complementary filter including two integrators for separating an inertial guidance signal from a GPS guidance signal thereby avoiding corruption for the delayed detection of a GLS signal loss.

5. A method for utilizing a skipping filter comprising the steps of:

storing past values of estimated IRU error; and

, then

utilizing said stored past values of estimated IRU error to update a coasting filter when switching from GPS to inertial mode.