TABLE OF CONTENTS In integrated navigation systems analysis, inertial sensors are described by their performance characteristics and error models. In most integrated navigation system implementations the gyro's characteristics are of primary importance. This presentation of navigation sensor models includes the following:
gyro performance characterizations.
sensor error models.
Inertial sensors commonly used in navigation units are rate/rate integrating gyros, dynamically tuned rotor gyros, ring laser gyros (RLG), fiber-optic gyros (FOG), and various types of accelerometers. The most recent developments are in RLG and FOG gyro technologies.
Both RLG and FOG sensors employ the Sagnac effect. This effect is described at a simplified level in this chapter. These sensors are presented to illustrate how the gyro's design, i.e., RLG path length, influences its performance.
A vital part of the design and evaluation of integrated navigation systems is the ability to model and simulate errors associated with gyros and accelerometers. Models allow computer-based evaluations prior to fabricating hardware, thus saving time and money. General mathematical models representing gyro and accelerometer errors are presented. Terms included within these representations are long-term stable errors, which can be described as random constants, and short-term random errors, represented as time-correlated and random walk errors. Dynamic models for time-correlated and random walk errors are developed, with examples from simulations illustrating the model's time characteristics.
Problems are included that expand upon the material presented.
The RLG has recently seen increased usage in strap-down navigation system mechanizations. Most current RLG sensors are single degree-of-freedom sensors...
