A Rate integrating gyroscope is a

rate gyro A rate gyro is a type of gyroscope, which rather than indicating direction, indicates the rate of change of angle with time. If a gyro has only one gimbal ring, with consequently only one plane of freedom, it can be adapted for use as a rate gyro t ...

with a built in integrator. It is usually a component of an Inertial Measurement Unit or a stabilization system.

Principle of operation

In a rate integrating gyroscope, the gyroscope is turned at a steady rate about its input axis and a torque is applied to the spin axis. This causes the gyroscope to

precess Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In othe ...

about the output axis. The rate indicating gyroscope consists of a

damping Damping is an influence within or upon an oscillatory system that has the effect of reducing or preventing its oscillation. In physical systems, damping is produced by processes that dissipate the energy stored in the oscillation. Examples in ...

fluid between the float assembly can and the outer casing. This

viscous The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...

fluid resists the motion of the

gimbal A gimbal is a pivoted support that permits rotation of an object about an axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow an object mounted on the innermost gimbal to remain independent of ...

precession. This causes the gimbal to accelerate initially in the fluid, until the damping effect is equal to the precessing force. The rate of precession, will hence be directly proportional to the rate of turn of the gyroscope about its input axis and the total angle of movement about the output axis will be proportional to the speed and length of time the input axis is turning. In a typical application (e.g. an aircraft), the output axis could have revolved 180 degrees clockwise in 20 seconds, then 80° anti-clockwise (say if the aircraft was changing direction again). This output would then be fed to a computer to calculate the total distance traveled ( Inertial Navigation Platform).
US Dynamics Rate Integrating Gyroscope Technical Brief

Key

* Spin Axis: Spin Axis is the axis of rotation of the rotor (rotating mass). * Input Axis: Input Axis is the Axis about which the torque is applied. * Output Axis: Output axis is the Axis perpendicular to the input axis and the spin axis.

Gimbal gain

Gimbal gain is the amount of precession that can be varied by varying the viscosity of the damping fluid. For (for example) increased sensitivity of a gyroscopic instrument.

External links

Spinning Mass Gyroscopes
Gyroscopes Navigational equipment