Strapdown inertial navigation technology

Transcription

1 Strapdown inertial navigation technology D. H. Titterton and J. L. Weston Peter Peregrinus Ltd. on behalf of the Institution of Electrical Engineers

2 Contents Preface Page xiii 1 Introduction Navigation Inertial navigation Strapdown technology Layout of book 4 2 Fundamental principles and historical development of inertial navigation Basic concepts Historical developments The modern day inertial navigation system 16 3 Basic principles of strapdown inertial navigation systems Introduction A simple 2-D strapdown navigation system Reference frames D strapdown navigation system general analysis Navigation with respect to a fixed frame Navigation with respect to a rotating frame The choice of reference frame Resolution of accelerometer measurements System example Strapdown system mechanisations Inertial frame mechanisation Earth frame mechanisation Navigation frame mechanisation 35

3 vi Contents Wander azimuth mechanisation Summary of strapdown system mechanisations Strapdown attitude representations Introductory remarks Direction cosine matrix Euler angles Quaternions Relationships between direction cosines, Euler angles and quaternions Detailed navigation equations Navigation equations expressed in component form The shape of the Earth Variation of gravitational attraction over the Earth 54 Gyroscope technology Introduction Conventional sensors Introduction Fundamental principles Components of a mechanical gyroscope Sensor errors Rate integrating gyroscope Dynamically tuned gyroscope Flex gyroscope Rate sensors Dual-axis rate transducer (DART) Magneto-hydrodynamic sensor Vibratory gyroscopes Introduction Vibrating wine glass sensor Vibrating disc sensor Tuning fork sensor Quartz rate sensor Silicon sensor Vibrating wire rate sensor General characteristics of vibratory sensors Cryogenic devices Nuclear magnetic resonance gyroscope SARDIN Electrostatically suspended gyroscope Other devices for sensing angular motion 109

4 Contents vii Fluidic (flueric) sensors Fluxgate magnetometers The transmission line gyroscope 116 Gyroscope technology Optical sensors Introduction Fundamental principles Ring laser gyroscope Three-axis RLG configuration Fibre optic gyroscope Fibre optic ring resonator gyroscope Ring resonator gyroscope Summary of gyroscope technology 148 Accelerometer and multi-sensor technology Introduction The measurement of translational motion Mechanical sensors Introduction Principles of operation Sensor errors Force feedback pendulous accelerometer Pendulous accelerometer hinge elements Two-axis force feedback accelerometer Open loop accelerometers Solid state accelerometers Vibratory devices Surface acoustic wave accelerometer Silicon sensors Fibre optic accelerometer Other acceleration sensors Multi-sensors Introduction Rotating devices Vibratory multi-sensor Mass unbalanced gyroscope Angular accelerometers 185 '6.6.1 Liquid rotor angular accelerometer Gas rotor angular accelerometer Inclinometers Summary of accelerometer and multi-sensor technology 189

5 Contents Testing, calibration and compensation Introduction Testing philosophy Test equipment Data logging equipment Gyroscope testing Stability tests multi-position tests Rate transfer tests Thermal tests Oscillating rate table tests Magnetic sensitivity tests Centrifuge tests Shock tests Vibration tests Combination tests Ageing and storage tests Accelerometer testing Multi-position tests Long-term stability Thermal tests Magnetic sensitivity tests Centrifuge tests Shock tests Vibration tests Combination tests Ageing and storage tests Calibration and error compensation Introduction Gyroscope error compensation Accelerometer error compensation Further comments on error compensation Testing of inertial navigation systems Hardware in the loop tests 239 Strapdown system technology Introduction The components of a strapdown navigation system The instrument cluster Orthogonal sensor configurations Skewed-sensor configurations A skewed-sensor configuration using dual-axis gyroscopes Redundant sensor configurations 249

6 Contents ix 8.4 Instrument electronics The attitude computer The navigation computer Power conditioning Anti-vibration mounts Concluding remarks 256 Inertial navigation system alignment Introduction Basic principles Alignment on a fixed platform Alignment on a moving platform Alignment on the ground Introduction Ground alignment methods Northfinding techniques In-flight alignment Introduction Sources of error In-flight alignment methods Alignment at sea Introduction Sources of error Shipboard alignment methods 285 Strapdown navigation system computation Introduction Attitude computation Direction cosine algorithms Rotation angle computation Rotation vector compensation Body and navigation frame rotations Quaternion algorithms Orthogonalisation and normalisation algorithms The choice of attitude representation Acceleration vector transformation algorithm Acceleration vector transformation using direction cosines Rotation correction Dynamic correction Acceleration vector transformation using quaternions 315

7 x Contents 10.4 Navigation algorithm Summary Generalised system performance analysis Introduction Propagation of errors in a 2-D strapdown navigation system Navigation in a non-rotating reference frame Navigation in a rotating reference frame The Schüler pendulum Propagation of errors in a Schüler tuned system Discussion of results General error equations Derivation of error equations Discussion Analytical assessment Single-channel error model Derivation of single-channel error propagation equations Single-channel error propagation examples Assessment by simulation Introductory remarks Error modelling Simulation techniques Motion dependency of strapdown system performance Manoeuvre dependent error terms Vibration dependent error terms Summary Integrated navigation systems Introduction Basic principles External navigation aids Radio navigation aids Satellite navigation aids GPS Star trackers Surface radar trackers Onboard measurements Doppler radar Magnetic measurements Altimeters Terrain referenced navigation Scene matching 382

8 Contents xi 12.5 System integration Application of Kaiman filtering to aided inertial navigation systems Introduction Design example of aiding Summary Design example Introduction Background to the requirement The navigation system requirement Why choose strapdown inertial navigation? Navigation system design and analysis process Introduction Choice of system mechanisation Error budget calculations System alignment Choice of inertial instruments Computational requirements Electrical and mechanical interfaces Testing, calibration and compensation requirements Performance enhancement by aiding Concluding remarks 416 Glossary of principal terms 417 Appendix A: Kaiman filtering 429 Appendix B: Inertial navigation system error budgets 439 List of symbols 443 Index 446