Strapdown Inertial Navigation Integration Algorithm Design Part 2: Velocity and Position Algorithms

This series of two papers (Parts 1 and 2) provides a rigorous comprehensive approach to the design of the principal software algorithmsutilized in modern-day strapdown inertial navigation systems: integration of angular rate into attitude, acceleration transformation/integration into velocity, and integration of velocity into position. The algorithmsare structured utilizing the two-speed updatingapproachoriginallydeveloped for attitudeupdating;an analyticallyexact equation is used at moderate speed to update the integration parameter (attitude, velocity, or position)with input provided from a high-speed algorithmmeasuring rectiŽ ed dynamicmotionwithin the parameter update time interval [coning for attitude updating, sculling for velocity updating, and scrolling (writer’s terminology) for high-resolutionpositionupdating].The algorithmdesign approachaccounts for angularrate/speciŽ c force acceleration inputs from the strapdown system inertial sensors, as well as rotation of the navigation frame used for attitude referencing and velocity integration. The Part 1 paper (Savage, P. G., “Strapdown Inertial Navigation Integration Algorithm Design Part 1: Attitude Algorithms,” Journal of Guidance, Control, and Dynamics, Vol. 21, No. 1, 1998, pp. 19–28) deŽ ned the overall design requirement for the strapdown inertial navigation integration function and developed the attitude updating algorithms. This paper, Part 2, deals with design of the acceleration transformation/velocity integration and position integration algorithms. Although Parts 1 and 2 often cover basic concepts, the material presented is intended for use by the practitioner who is already familiar with inertial navigation fundamentals.