«A DISSERTATION SUBMITTED TO THE DEPARTMENT OF AERONAUTICS AND ASTRONAUTICS AND THE COMMITTEE ON GRADUATE STUDIES OF STANFORD UNIVERSITY IN PARTIAL ...»
GPS/INS GENERALIZED EVALUATION TOOL (GIGET)
FOR THE DESIGN AND TESTING OF
INTEGRATED NAVIGATION SYSTEMS
SUBMITTED TO THE DEPARTMENT OF AERONAUTICS AND ASTRONAUTICS
AND THE COMMITTEE ON GRADUATE STUDIES
OF STANFORD UNIVERSITY
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF
DOCTOR OF PHILOSOPHYJennifer Denise Gautier June 2003 c Copyright 2003 by Jennifer Gautier All Rights Reserved ii I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy.
Professor Bradford W. Parkinson, Principal Advisor I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy.
Professor Per K. Enge I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy.
Professor Claire J. Tomlin Approved for the University Committee on Graduate Studies.
iii iv Abstract GIGET, the GPS/INS Generalized Evaluation Tool, experimentally tests, evaluates, and compares navigation systems that combine the Global Positioning System (GPS) with Inertial Navigation Systems (INS).
GPS is a precise and reliable navigation aid but can be susceptible to interference, multipath, or other outages. An INS is very accurate over short periods, but its errors drift unbounded over time. Blending GPS with INS can remedy the performance issues of both. However, there are many types of integration methods, and sensors vary greatly, from the complex and expensive, to the simple and inexpensive. It is difficult to determine the best combination for any desired application; most of the integrated systems built to date have been point designs for very specific applications. GIGET aids in the selection of sensor combinations for any general application or set of requirements; hence, GIGET is the generalized way to evaluate the performance of integrated systems.
GIGET is a combination of easily re-configurable hardware and analysis tools that can provide real-time comparisons of multiple integrated navigation systems. It includes a unique, five-antenna, forty-channel GPS receiver providing GPS attitude, position velocity, and timing. An embedded computer with modular real-time software blends the GPS v measurements with sensor information from a Honeywell HG1700 tactical grade inertial measurement unit. GIGET is quickly outfitted onto a variety of vehicle platforms to experimentally test and compare navigation performance.
In side-by-side experiments, GIGET compares loosely coupled and tightly coupled integrated navigation schemes blending navigation, tactical, or automotive grade inertial sensors with GPS. These results formulate a trade study to map previously uncharted territory of the GPS/INS space that trades accuracy and expense versus complexity of design. These GIGET results can be used to determine acceptable sensor quality in these integration methods for a variety of dynamic environments.
As a demonstration of its utility as a hardware evaluation tool, GIGET is used to design a navigation system on the DragonFly Unmanned Air Vehicle (UAV). The DragonFly UAV is a test-bed for autonomous control experiments. It is a small, lightweight, highly maneuverable aircraft that requires smooth, continuous navigation information. GIGET was flown on the DragonFly to evaluate different integrated navigation combinations in the UAV's dynamic environment. GIGET shows that a loosely coupled, single-antenna GPS system with a moderately priced inertial unit will provide the consistent navigation currently needed on the DragonFly.
encouragement throughout my graduate research here at Stanford University. I especially thank him for his leadership. I believe great leadership involves the ability to teach and instill confidence in other to lead themselves. Prof. Parkinson has helped me to develop my own leadership skills through mentoring and through the inspiration of his own great accomplishments.
The faculty and staff of Stanford University and the Department of Aeronautics and Astronautics have provided a wonderful environment for graduate study. I am also particularly grateful for the advice and guidance of Professors Claire Tomlin, Per Enge, and Dave Powell. Each has provided me with tremendous opportunities and inspiration.
It has been a privilege to work with the students of the GPS Lab and the Hybrid Systems Lab. I am sincerely grateful for all the many friends I have at Stanford. Special thanks go to: Sharon Houck, Demoz Gebre-Egziabher, Roger Hayward, Paul Montgomery, Jung Soon Jang, Rodney Teo, and Gokhan Inalhan.
support. In particular, I thank Scott Smith, Bruce Peetz, Brian Schipper, Larry Vallot, Scott Snyder.
I am also very grateful for my friends and communities of support: St. Mark’s Episcopal Church, and Women in Science and Engineering.
viii Table of Contents
1 Introduction 1
1.1.1 Global Positioning System
1.1.2 Inertial Navigation Systems
1.1.3 Integrated Navigation Systems
126.96.36.199 Levels of Integration
188.8.131.52 Prior Art
1.2 Purpose Statement
2 GIGET Components 17
2.1 GPS Receiver
2.1.1 Trimble Receiver Design
2.1.2 Unique GIGET Receiver Attributes
2.2 Inertial Measurement Unit
2.2.1 Honeywell HG1700
2.2.2 IMU Performance
2.3 Single Board Computer
2.3.1 Versalogic SBC
2.4 GIGET Avionics Box
2.5 Ground Systems
3 System Software Development 29
3.1 GIGET System View
3.1.1 Lab Development Systems
3.1.2 Operating System
3.2 Software Architecture
3.2.1 Client/Server Architecture
3.2.2 System Configuration
3.3 Software Modules
3.3.1 GPS Server
3.3.2 Inertial Measurement Unit (IMU) Server
3.3.3 High Resolution Timer (HRT) Server
3.3.4 DGPS Client
3.3.5 Attitude Client/Server
3.3.6 Navigation Client/Server
4 Navigation Algorithms and Applications 41
4.1 GPS Attitude Determination
4.1.1 Attitude Fundamentals
184.108.40.206 Attitude Determination.
220.127.116.11 GPS Measurements
18.104.22.168 GPS Attitude Receivers
4.1.2 GPS Attitude Algorithms
22.214.171.124 Attitude Solution
126.96.36.199 Line Bias Estimation
188.8.131.52 Integer Resolution
4.1.3 Testing and Evaluation
4.2 Inertial Navigation System
4.2.1 Reference Frames
184.108.40.206 Inertial Navigation Equations
220.127.116.11 Error Equations
4.2.3 GPS/INS Kalman Filter Formulation
18.104.22.168 Kalman Filter Basics
22.214.171.124 Transition Matrix
126.96.36.199 Kalman Filter Feedback Configuration
4.2.4 Loosely Coupled
4.2.5 Tightly Coupled
4.2.6 Testing and Evaluation
188.8.131.52 Roof-Top Testing
184.108.40.206 Ground Vehicle Testing
220.127.116.11 Simulation and Analysis
4.3 Inertial Aiding of GPS Receiver
18.104.22.168 Tracking Loop Example
4.3.2 GIGET Implementation
4.3.3 Aiding Conclusions
5 Trade Study Results 97
5.1 Test Scenario
5.2 Example Trades
5.2.1 Position Results
5.2.2 Velocity Results
5.2.3 Attitude Results
5.3 Summary and Conclusions
6 Case Study: DragonFly UAV 111
6.1 Project Motivation
6.2 Aircraft Description
6.3 DragonFly Project Requirements
6.3.1 Dynamic Performance
6.3.3 Availability, Continuity and Integrity.
6.4 DragonFly UAV Testing
6.4.1 Ground Systems
6.4.2 Flight Test Profile
6.5 Experimental Results
6.5.1 Attitude Results
6.5.2 Velocity Results
6.5.3 Position Results
6.6 DragonFly Conclusions and Recommendations
7 Future Work and Conclusions 131
7.1 Summary of Conclusions
7.1.1 The Evaluation Tool
7.1.2 DragonFly UAV
7.2 Future Work
7.2.1 Farm Tractor
References 139xi xii List of Tables Table 4.1. Sensor Quality in GIGET Simulation
Sensor Quality in GIGET Trade Study
xiii xiv List of Figures Figure 1.1.
Global Positioning System
Chart of Accuracy and Expense
Example of Inertial Navigation System--Honeywell SIGI
Loosely Coupled GPS/INS Integration
Tightly Coupled GPS/INS Integration
Ultra-Tightly Coupled or Deeply Integrated GPS/INS Integration..............7 Figure 1.7.
GPS/INS Trade Space
Three Tiers of GIGET
DragonFly Unmanned Air Vehicle
Trimble Navigation's GIGET Receiver
PC-104 Expansion Board
GIGET Avionics Box
Avionics Box Layout
Freewave Radio Modem
Ground System Suitcase and Laptop
GIGET System Configuration and Software Modules
Attitude Client/Server Process Flow
Navigation Client/Server Process Flow
Two-Dimensional View of GPS Measurements and Baseline Vectors.......44 Figure 4.2.
Queen Air Flight Test Results
Inertial Navigation Processing
Angle Error Vector Illustration
Closed Loop GPS/INS Kalman Filter Diagram
Loosely Coupled GPS/INS System
Tightly Coupled GPS/INS System
xv Figure 4.9.
Typical GIGET Roof-Top Testing Results
GIGET Ground Testing Set-Up
Typical GIGET Ground Test Trajectory
GPS Tracking Loops with External Aiding
Phase Error v. Signal Level for Various Bandwidths
GIGET Receiver Aiding State Transitions
GPS/INS Trade Space
GPS Outage Example
Tactical Grade v. Navigation Grade Position Results
Tactical Grade v. Navigation Grade Position Results--Zoomed-In View.102 Figure 5.5. Tactical Grade v. Automotive Grade Position Results
Tactical Grade v. Automotive Grade Position Results--Zoomed-In View104 Figure 5.7.
Tactical Grade v. Navigation Grade Velocity Results
Tactical Grade v. Navigation Grade Velocity Results--Zoomed-In View.105 Figure 5.9. Tactical Grade v. Automotive Grade Velocity Results
Tactical Grade v. Automotive Grade Velocity Results--Zoomed-In View106 Figure 5.11. Tactical Grade v. Navigation Grade Attitude Results
Tactical Grade v. Automotive Grade Attitude Results
Tactical Grade v. Automotive Grade Attitude Results--Zoomed-In View108 Figure 5.14.
GPS/INS Trade Space after GIGET Testing
DragonFly UAV Project
GIGET Avionics Box and DragonFly Fuselage
DragonFly Radio Frequency Equipment Locations
Actuator Control Computer