Inertial corrections by dynamic estimation

Abstract

The highlights are presented of an Engineering Memorandum, Dynamic Estimation for Floated Gradiometers. The original impetus for the work was that gradiometers, in principle, measure components of the gravity gradient tensor, plus rotation effects, similar to centrifugal and Coriolis effects in accelerometers. The problem is that the rotation effects are often quite large, compared to the gradient, and that available inertial instruments can't measure them to adequate accuracy. The paper advances the idea that, if the instruments can be floated in a package subject to very low disturbances, a dynamic estimation, based on the Euler and translational equations of motion, plus models of all the instruments, can be used to greatly strengthen the estimates of the gradient and the rotation parameters. Moreover, symmetry constraints can be imposed directly in the filter, further strengthening the solution.