Hi
@The Deterrent
i am uploading rate gyro and rate integrating gyro Just for the benefit of other members so that they too can get a feel of what we are discussing here.(Picture couresy:measurement systems -ernst doeblin and Dhanesh Manik)
Rate gyro as you know is the one that measures the absolute angular velocity(angular velocity is one half of the curl of linear velocity) and is widely used to generate stabilizing signal in an aerial vehicle.In the picture below one can see three rate gyros for three different axis!
View attachment 193696
A rate integrating gyro on the other hand (as the name suggests- integrates the angular velocity- hence it measures absolute angular displacement) is used to provide fixed reference(popularly known as set point in control systems engineering) in navigation and attitude control systems.As one can clearly see the bulky design of the honeywell's rate integrating gyros.
A FOG on the other hand works on the same principle as a LRG except that instead of carefully sealed,gas filled laser cavities and precision mirrors are replaced by long coil of optical fibre.Here in these "optical" gyros we are concerned with the phase shift(DS) between two light waves(one travelling in the direction of rotation and one opposite to that).
DS=((2*pi*L*D*W)/(c*l))
where L- length of coil
D-effective coil dia
W-angular velocity about the sensitive axis
c- velocity of light
l- mean optical wavelength.
The phase shift in actual application is very very feeble and hence require some serious signal processing
A more modern MEMS based gyros and accelerometers have been developed that utilize coriolis principle and quartz crystal to measure either the absolute angular displacement or absolute angular velocity.I will be posting the picture of MEMS based system pretty soon!
@The Deterrent
here is the cutting edge MEMS based gyro- available as gyro chip).Here in this case,a micro-machines quartz tuning crystal is used to implement a coriolis scheme.The reduction in weight from mechanical spinning wheel type gyros to MEMS based Coriolis scheme gyros is immense.Now imagine extensive application of MEMS from simple temperature sensor or accelerometer to actuators that will make big hydraulic systems redundant and obsolete!As in any other MEMS based system,micro machining along with packaging the quartz in an electronic circuit on an IC(along with all the amplifiers and filters) is a challenging task- one that a very very few countries can do