Necessary Modifications to the Strap-Down Inertial Navigation System Model for Non-Earth-Based Users

Strap-down inertial navigation system (SDINS) is considered as a highly sophisticated dead reckoning system. The SDINS consists mainly of two triads the first is the three gyros triad, and the second is the three accelerometers triad. Modeling the SDINS has achieved a lot of importance in the literature, especially for surveying applications. However, using the SDINS for spacecraft applications imply some modifications to the SDINS deterministic models used for surveying applications. Traditional models of the SDINS include the effect of the earth rotational rate on the SDINS instruments (gyros, and accelerometers). This effect must be removed from the instrument model if the SDINS is to be used onboard of a spacecraft simply because the spacecraft doesn't rest on the earth, and thus doesn't sense the earth's rotational rate. Necessary modifications of the accompanying algorithms are derived analytically in the research at hand.