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

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.