10.1 Fundamental principles

Gyroscopes are used in various applications to sense either the angle turned through by a body (displacement gyroscopes) or, more commonly, its angular rate of turn about some defined axis (rate gyroscopes).

The most basic and the original form of gyroscopes make use of the inertial properties of a wheel or rotor spinning at high speed. Many people are familiar with the child’s toy which has a heavy metal rotor supported by a pair of gimbals. When the rotor is spun at high speed, the rotor axis continues to point in the same direction despite the gimbals being rotated. This is a crude example of a mechanical, or conventional, displacement gyroscope.

The operation of a conventional spinning mass gyroscopes depend the following phenomena:

• gyroscopic inertia
• angular momentum
• precession.