Purpose: The purpose of this knowledge base article is to explain the method of integration known as Coning and Sculling used by Inertial Labs.

Updated: March, 2020

For strap-down based inertial sensors, the method of integration known as sculling (for linear accelerations) and coning (for angular rates) has been implemented for all Inertial Labs sensing components to reduce the erroneous build up of seemingly valid measurements of accelerations and angular rates. These errors, if left unaccounted for then produce further errors in calculations for velocity and attitude in inertial based navigation systems and attitude and heading reference units.

Coning is the name given for errors seen in gyroscopes especially when moving in a sweeping motion around the gyroscopes vertical axis at a high rate that approaches the rate of integration. Similarly, sculling is the error seen in accelerometers when the carrier object experiences high rates of cyclic linear accelerations that approach the rate of integration of accelerations on the IMU.

The Inertial Labs units (INS/MRU/WS/IMU/DTS) all use Coning and Sculling methods of integrations to account for these errors. This integration method in its simplest form integrates angular rates and acceleration values at high frequencies such that the Inertial Labs Kalman Filter is not saturated by the effects of coning and sculling errors.