MEMS-based Inertial Navigation Systems onboard Balloons

Performances of low-cost inertial navigation sensors, usually poor, can often match different mission requirements by means of a careful signal and data processing and/or an augmentation by means of different observables. The paper presents the LOWCOINS navigation experiment, intended to fly onboard BEXUS balloon mission in late 2008. LOWCOINS has as the main component a low-cost three-axes inertial unit, integrating three accelerometers and three gyros. The slow dynamic typical of a balloon flight is deemed as an ideal test to verify the performances of the unit and to improve the knowledge on the data processing needed to obtain an accurate final navigation solution. In order to enlarge the set of available data, a cluster of magnetometers and a pressure sensor, always belonging to low-cost instrumentation range, are hosted on board. Measurements are both stored on board and downlinked to a ground station. Position and velocity components (both the onboard computed first guess and the post-flight calibrated solution) will be compared with the data gathered by a GPS receiver, which is a standard component of BEXUS balloon avionics. Substantial attention to thermal aspects has been requested in order to cope with environmental conditions prior of and all along the flight. The requested navigation unit case design is shortly reported.