IMU Performance Requirement Assessments for GPS/INS Missile Navigation Systems

Jan Wendel and Gert F. Trommer

Abstract:	GPS/INS systems are a proven and widely used means of navigation in military applications. However, in missile navigation systems the INS suffers from the vibration environment, especially in air carriage conditions. This paper presents final results of our investigations concerning the influence of the inertial sensor biases and noise on the performance of the missile GPS/INS system in a vibration environment. Flight test data of a medium range missile was used to obtain a representation of the vibration induced measurement noise in form of a noise process model. A Kalman filter was designed which was able to consider this time-correlated noise process correctly. The performance of a navigation system based on this Kalman filter was investigated by Monte Carlo simulation runs and covariance analysis. Starting from the characteristics of a typical tactical grade IMU, lower grade sensors were modeled by adding either white noise or increasing the assumed biases, or both. It turned out that during normal operation as well as during GPS outages lasting one minute constant accelerometer and gyroscope biases have no significant influence on position and attitude accuracy obtained by the navigation system. The reason for this is that despite the vibration induced noise, these biases can be estimated by the Kalman filter. Furthermore, an increased accelerometer inherent noise has little influence on the system performance, too, as the vibration induced noise levels sensed by the accelerometers are several times higher than the accelerometer inherent noise of a typical tactical grade IMU. However, a larger gyroscope inherent noise results in a reduced attitude accuracy. Thus, our findings showed that for typical medium-range missile applications, a tactical grade IMU is rather over- specified, giving the chance of significant cost reductions.
Published in:	Proceedings of the 58th Annual Meeting of The Institute of Navigation and CIGTF 21st Guidance Test Symposium (2002) June 24 - 26, 2002 Hyatt Regency Hotel Albuquerque, NM
Pages:	82 - 88
Cite this article:	Wendel, Jan, Trommer, Gert F., "IMU Performance Requirement Assessments for GPS/INS Missile Navigation Systems," Proceedings of the 58th Annual Meeting of The Institute of Navigation and CIGTF 21st Guidance Test Symposium (2002), Albuquerque, NM, June 2002, pp. 82-88.
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