TABLE OF CONTENTS Chapter written by Andr MIGEON and Anne-Elisabeth LENEL.
The first practical experiment with a gyroscope was carried out in 1865, thanks to the provision of movement by an electric motor. The first gyrocompass was patented in 1904. Since acceleration and angular rate are measurable physical quantities without an external reference, they can be used for navigation of autonomous systems. These sensors are constantly improving because of their strategic importance. In the last 15 years in particular, thanks to optical and to micro-technologies, there has been enormous progress made in precision, linearity and stability as well as in the size and electric consumption of these sensors.
Inertial navigation has evolved continuously with the first combined accelerometer and gyroscope being produced in 1923, the first platform with three axes in 1924 and the first operational equipment being launched in 1940s on V2 rockets.
The gyrometers (= angular rate sensors) intended for inertial navigation must be able to detect revolution speeds varying from zero to 100 /s. In the standard case, a gyroscope has drifts of 10 -2 degree per hour where errors are incurred at 1 mile per hour. For a ship, whose navigation can last several weeks, errors can accumulate with time, and a periodic correction is required. This is not necessary for a plane whose flight lasts only a few hours, or a missile where the duration of flight is measured in minutes.
Let us consider a massive body in rotation with high initial...
