Project Number: JAO-0701 EXPLORING INERTIAL NAVIGATION TECHNIQUES FOR PRECISION PERSONNEL LOCATION A Major Qualifying Project Report Submitted to the Faculty of the WORCESTER POLYTECHNIC INSTITUTE In Partial Fulfillment of the Requirements for the Degree of Bachelor of Science By ___________________________________ Tiffany Warrington And ___________________________________ Eric Wong Date: April 24, 2007 Approved: ___________________________ Professor John A. Orr, Major Advisor I Abstract This project aimed at characterizing both MEMs accelerometers and gyroscopes for use in a low cost inertial navigation unit. A hardware and software system, consisting of MEMs sensors, A/D converters, a 200 MHz processor, compact flash memory, and C++ coded software, was integrated into a test bed that calculates and outputs the unit’s final positioning after acceleration and/or rotation was applied. Testing of the unit proved that low cost sensors, performing at specifications are unable to provide accurate positioning with the current performance of MEMs technology. II Acknowledgements We would like to thank the following people for their help throughout this project: Professor John A. Orr Professor Cosme Furlong Irene Gouverneur Fred Hutson Brad A. Miller Worcester Polytechnic Institute 3 III Table of Contents I Abstract.............................................................................................................................2 II Acknowledgements .........................................................................................................3 III Table of Contents ...........................................................................................................4 IV List of Figures ................................................................................................................5 V List of Tables...................................................................................................................6 1 Introduction.................................................................................................................7 2 Problem Statement ......................................................................................................8 3 Project Goals and Requirements .................................................................................8 4 Technical Background.................................................................................................9 4.1 GPS......................................................................................................................9 4.2 Dead Reckoning................................................................................................11 4.3 Impulse Ultra-Wide Band ................................................................................. 11 4.4 Direction Finding ..............................................................................................13 4.5 Inertial Navigation.............................................................................................14 4.5.1 Accelerometers..........................................................................................15 4.5.2 Gyroscopes................................................................................................16 4.5.3 Sensor Error...............................................................................................20 4.5.4 Magnetometers and Compasses................................................................22 4.6 Potential System Block Diagram ...................................................................... 23 4.7 Processing Unit .................................................................................................23 4.8 Memory Storage................................................................................................24 5 Final Design ..............................................................................................................25 5.1 Physical Parameters...........................................................................................26 5.1.1 Sensors ......................................................................................................28 5.1.1.1 2-axis Accelerometer ADXL203 ..........................................................28 5.1.1.2 Yaw Rate Sensor Gyroscope ADXRS150 ............................................31 5.1.2 Processor ...................................................................................................33 5.2 Software ............................................................................................................35 5.2.1 Step 1.........................................................................................................36 5.2.2 Step 2.........................................................................................................37 5.2.3 Step 3.........................................................................................................37 5.2.4 Step 4.........................................................................................................38 5.2.5 Step 5.........................................................................................................38 5.2.6 Software Changes and Additions..............................................................39 5.2.7 Software Validation................................................................................... 40 5.3 System Functionality.........................................................................................42 5.4 Operational Modes............................................................................................45 6 Testing and Results ...................................................................................................45 6.1 Test Plan............................................................................................................46 6.2 Stationary ..........................................................................................................46 6.3 Rotary Stage Testing.........................................................................................53 6.4 One-Dimensional ..............................................................................................56 6.5 Two-Dimensional..............................................................................................59 4 6.6 Error Analysis ...................................................................................................63 6.7 Sensor Specification Testing............................................................................. 68 6.7.1 Accelerometer Zero g Bias Level..............................................................68 6.7.2 Accelerometer Temperature Variance ......................................................69 6.7.3 Accelerometer Sensitivity......................................................................... 70 6.7.4 Gyroscope Zero Rotation Null Value........................................................71 6.7.5 Gyroscope Sensitivity ............................................................................... 71 6.7.6 Gyroscope Temperature Variance.............................................................72 6.7.7 Gyroscope Self Test Response..................................................................73 7 Conclusions...............................................................................................................73 8 References.................................................................................................................76 IV List of Figures Figure 1: GPS Trilateralization Methods ..........................................................................10 Figure 2: Cell phone using GPS Navigation ..................................................................... 10 Figure 3 - Bandwidth of Signal Types ..............................................................................12 Figure 4: Solenoid and Directional Antenna.....................................................................13 Figure 5: Three dimensional axis......................................................................................14 Figure 6: A Spinning Mass Gyroscope .............................................................................17 Figure 7: Ring Laser Gyro ................................................................................................18 Figure 8: Diagram Explaining Coriolis Effect ..................................................................19 Figure 9: MEMs Gyro and the coriolis effect ...................................................................19 Figure 11: Potential System Block Diagram.....................................................................23 Figure 12: System Interconnect Diagram..........................................................................26 Figure 13: IMU Prototype.................................................................................................27 Figure 14: ADXL203 2-Axis Accelerometer Schematic ..................................................29 Figure 15: ADSL203 Evaluation Board Layout ............................................................... 30 Figure 16: ADXRS150 Gyro Schematic........................................................................... 32 Figure 17: ADXRS150 Evaluation Board Layout ............................................................ 33 Figure 18: Software Flowchart..........................................................................................36