The design and implementation of a low cost GPS-MEMS/INS precision approach algorithm with health monitoring

Keywords

Navigation (Aeronautics)

Abstract

An algorithm for precision approach guidance using GPS and a MicroElectroMechanical Systems/Inertial Navigation System (MEMS/INS) has been developed to meet the Required Navigational Performance (RNP) at a cost that is suitable for General Aviation (GA) applications. This scheme allows for accurate approach guidance (Category I) using Wide Area Augmentation System (WAAS) at locations not served by ILS, MLS or other types of precision landing guidance, thereby greatly expanding the number of useable airports in poor weather. At locations served by a Local Area Augmentation System (LAAS), Category ill-like navigation is possible with the novel idea of a Missed Approach Time (MAT) that is similar to a Missed Approach Point (MAP) but not fixed m space. Though certain augmented types of GPS have sufficient precision for approach navigation, its use alone is insufficient to meet RNP due to an inability to monitor loss, degradation or intentional spoofing and meaconing of the GPS signal. A redundant navigation system and a health monitoring system must be added to acquire sufficient reliability, safety and time-to-alert as stated by required navigation performance. An inertial navigation system is the best choice, as it requires no external radio signals and its errors are complementary to GPS. An aiding Kalman filter is used to derive parameters

that monitor the correlation b~tween the GPS and MEMS/INS. These approach guidance parameters determines the MAT for a given RNP and provide the pilot or autopilot with proceed/do-not-proceed decision in real time. Thus, when the GPS system is working well, the approach minimums will be low and when the GPS navigation solution is poor, the approach minimums will be high. The enabling technology used to derive the guidance program is a MEMS gyroscope and accelerometer package in conjunction with a single-antenna pseudo-attitude algorithm. To be viable for most GA applications, the hardware must be reasonably priced. The MEMS gyros allows for the first cost-effective INS package to be developed. With lower cost, however, comes higher drift rates and a more dependence on GPS aiding. In this novel application, the GPS single-antenna pseudo-attitudes are determined and changed to a real aircraft attitude solution via an angle of attack transformation. This aircraft attitude solution is then used for in-flight INS alignment and update.

Notes

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Graduation Date

2003

Advisor

Johnson, Roger

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering

Department

Mechanical, Materials, and Aerospace Engineering

Format

PDF

Pages

222 p.

Language

English

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

Identifier

DP0029120

Subjects

Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic

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