Flexible Software Implementation for a Miniature Integrated GPS/INS Tactical System

Douglas A. Macdonald, Thomas W. De Vries and Dwayne Mema

Abstract:	The algorithms, design and mechanization of the navigation software of the Rockwell C-MIGITS IITM integrated global positioning system/inertial navigation system (GPS/INS) system are presented. In addition, results of van and simulated-GPS testing of the C- MIGITS IITM are presented. The C-MIGITS IIrM is a member of the Miniature Integrated GPS/INS Tactical System (MIGITSTM) family of products developed by Rockwell. This low cost unit consists of a Rockwell-Autonetics Digital Quartz Inertial Measurement Unit (DQI) integrated with a Rockwell Semiconductor Systems MicroTrackerTM LP five channel C/A code GPS receiver. The software design allows the DQI to utilize a variety of GPS receivers, in either tightly or loosely coupled configurations. The C-MIGITS IITM navigation and Kalman filter software is hosted on the DQI’s CPU, which is a TMS32OC3 1 digital signal processor. The navigation algorithms employ a locally-level wander-angle mechanization implemented in fixed-point arithmetic, The attitude mechanization is done in terms of quaternions. A single 28-state Kalman filter is used during alignment and navigation. The filter estimates accelerometer and gyro biases and scale factors as well as navigation errors. A number of alignment modes and navigation modes are provided. Fine Alignment mode provides initial IMU estimates for a stationary system, while Air Alignment mode uses GPS measurements to provide initial estimates of heading, IMU parameters, and GPS antenna lever arms. Air Navigation mode provides continuous estimation of navigation errors and IMU parameters; Land Navigation mode adds the capability of utilizing measurements from an odometer, and estimating the odometer errors. Both navigation modes have the capability of using measurements from a heading reference such as a compass, or an altitude reference such as an altimeter, and of estimating errors in those reference instruments. The C-MIGITS IITM system has been tested in a variety of situations and configurations. Helicopter and van tests have been run, and simulations have been done using the Simulation and Evaluation System (SEVS) GPS simulation. Tests have been run with the MicroTrackerTM LP GPS receiver in tightly coupled mode, and with the Rockwell Precision Lightweight GPS Receiver (PLGR) in loosely coupled mode.
Published in:	Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996) September 17 - 20, 1996 Kansas City, MO
Pages:	1001 - 1008
Cite this article:	Macdonald, Douglas A., De Vries, Thomas W., Mema, Dwayne, "Flexible Software Implementation for a Miniature Integrated GPS/INS Tactical System," Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996), Kansas City, MO, September 1996, pp. 1001-1008.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In