A merging of system technologies: all-accelerometer inertial navigation and gravity gradiometry

Abstract

Significant research has been conducted in recent decades on developing a practical all-accelerometer inertial navigation system and on developing a practical moving-base gravity gradiometer. The former strives to measure kinematic motion in the presence of unwanted variations in gravity; the latter endeavors to measure variations in gravity in the presence of unwanted motion. Thus, goes the adage, one person's signal is another person's noise. In this paper, a mathematical relationship is derived that links the two concepts together. It is demonstrated that a complete solution to real-time navigation and gravity gradient determination can be performed simultaneously and unambiguously using all-accelerometer inertial measurements only. Although the separation of gravity from kinematic motion appears to violate Einstein's principle of equivalence, this is not the case. Nonetheless, accelerometer technology is not yet of sufficient maturity to allow a practical implementation of this concept, but advances certainly are being made that could result in a practical implementation perhaps within a decade.