A cost-effective inertial motion sensor for short-duration autonomous navigation

The need for systems, capable of continuously monitoring the inertial position and orientation of vehicles, has motivated the fields of inertial guidance and autonomous navigation. These systems typically employ suites of sophisticated motion sensors for obtaining measurements of motion occurring in all six axes of the Cartesian coordinate system. Through appropriate arithmetic manipulation of sensor output signals, the position and orientation of aircraft, satellites, submarines, and a host of other vehicles can be derived with respect to inertial space. While a wide variety of inertial sensor technologies have been demonstrated in these applications, there are still advances to be made. For example, gyroscopes are typically used to generate measurements of inertial angular position and inertial angular velocity. Requirements imposed on gyroscope drift rates drive up the cost of these instruments and force them to be fragile and complicated. Although there are applications in which gyroscopes remain the only proven solution, there are a growing number of applications in which conventional gyroscopes do not meet technical or cost requirements. This paper addresses the use of magnetohydrodynamic angular rate sensors (MHD ARS) as an alternative to gyroscopes in applications in which measurements are takers over short time durations. In such applications, drift rates, which exceed those exhibited by typical gyroscopes, can be tolerated in exchange for drastic reductions in sensor costs. The drift performance of the MHD ARS can be predicted based on the spectral description of the noise in the measurements provided by the instrument. A complete discussion of this analysis is presented in this paper