Inertial Guidance System
Definition - What does Inertial Guidance System mean?
The inertial guidance system is a type of measurement while drilling (MWD) system that is used for drilling head guidance in trenchless construction methods of vertical drilling and horizontal directional drilling (HDD). It is also used for geotechnical surveys and is very accurate.
The system uses a set of gyros to orient the system due North and can measure movement using gyros and gravity accelerometers in the x, y, and z axes of the wellbore.
Trenchlesspedia explains Inertial Guidance System
The inertial guidance electronic system monitors the position and orientation of the drill bit on a continuous basis, enabling navigational control over the drilling operation. It relies on knowing the initial position, velocity, and attitude, after which it measures the attitude rates and accelerations.
It does not rely on external references. To compensate for errors, two redundant accelerometers fixed at two different planes are used.
The results from the two accelerometers are used to arrive at the final calculation. It can take measurements of azimuth, pitch, and roll simultaneously.