EE 570 Location and Navigation Theory Practice Navigation

EE 570: Location and Navigation: Theory & Practice Navigation Sensors and INS Mechanization Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 1 of 14

Navigation Sensors and INS Mechanization Navigation Equations – The Fundamental Problem • Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 2 of 14

Navigation Sensors and INS Mechanization Navigation Equations – Inertial Navigation • Inertial Navigation § The process of “integrating” angular velocity & acceleration to determine one’s position, velocity, and attitude (PVA) o Effectively “dead reckoning” § To measure the acceleration and angular velocity vectors we need at least 3 -gyros and 3 -accels o Typically configured in an orthogonal triad § The “mechanization” can be performed wrt: o o o The ECI frame, The ECEF frame, or The Nav frame. Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 3 of 14

Navigation Sensors and INS Mechanization Navigation Equations – ISA, IMU, & INS • An Inertial Navigation System (INS) § ISA – Inertial Sensor Assembly o Typically, 3 -gyros + 3 -accels + basic electronics (power, …) § IMU – Inertial Measurement Unit o ISA + Compensation algorithms (i. e. basic processing) § INS – Inertial Navigation System o IMU + gravity model + “mechanization” algorithms Initialization INS IMU ISA Raw sensor outputs Comp Algs Mechanization Equations Position, Velocity, and Attitude (PVA) - Basic Processing Gravity Model Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 4 of 14

Navigation Sensors and INS Mechanization Navigation Equations – Mechanization Process IMU Measurements Prior PVA Attitude Prior Velocity Mechanization Equations Gravity / Gravitational Model Prior Position Updated Attitude Velocity Position Updated PVA Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 5 of 14

Navigation Sensors and INS Mechanization Navigation Equations – A Four Step Mechanization • Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 6 of 14

Navigation Sensors and INS Mechanization Navigation Equations – A Four Step Mechanization IMU Measurements Prior PVA Attitude 1. Attitude Update 2. SF Transform 3. Velocity Update Prior Velocity Prior Grav Model 3. Position Updated Attitude Velocity Position Updated PVA Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 7 of 14

Navigation Sensors and INS Mechanization Navigation Equations – Case 1: ECI Mechanization • Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 8 of 14

Navigation Sensors and INS Mechanization Navigation Equations – Case 1: ECI Mechanization 1. Attitude Update: Method A § Body orientation frame at time “k” wrt time “k-1” o t = Timek – Timek-1 Body Frame at time “k-1” Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Body Frame at time “k” Slide 9 of 14

Navigation Sensors and INS Mechanization Navigation Equations – Case 1: ECI Mechanization 1. Attitude Update: Method B § Body orientation frame at time “k” wrt time “k-1” o t = Timek – Timek-1 Body Frame at time “k-1” Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Body Frame at time “k” Slide 10 of 14

Navigation Sensors and INS Mechanization Navigation Equations – Case 1: ECI Mechanization 1. Attitude Update: § High Fidelity § Lower Fidelity Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 11 of 14

Navigation Sensors and INS Mechanization Navigation Equations – Case 1: ECI Mechanization 2. Specific Force Transformation § Simply coordinatize the specific force 3. Velocity Update § Assuming that we are in space (i. e. no centrifugal component) § Thus, by simple numerical integration 4. Position Update § By simple numerical integration Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 12 of 14

Navigation Sensors and INS Mechanization Navigation Equations – Case 1: ECI Mechanization 1. Attitude Update 2. SF Transform 3. Velocity Update Grav Model 3. Position Update Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 13 of 14

Navigation Sensors and INS Mechanization Navigation Equations – Case 1: ECI Mechanization • Tuesday 26 Feb 2013 NMT EE 570: Location and Navigation: Theory & Practice Slide 14 of 14