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The interest for an integrated autonomous guidance and navigation control package, satisfying to different mission requirements with a common architecture, is becoming very attractive in the perspective to reduce cost mission and to provide significant benefits when measurements noise conditions may change during the mission and safety critical spacecraft operations are involved. In this paper Laben and Honeywell present an interesting approach to integrate an attitude GPS space receiver and a miniaturized inertial measurement unit (MIMU), to enhance the performances of both sensor systems. In traditional G&NC systems, based on Inertial Navigation Sensor (INS) Measurements, long term drift, affecting zero point stability of gyroscope and accelerometer, are integrated over time during the measurement process, resulting in an increasing attitude and navigation error. These errors can be reduced by periodic reset, shifting the problem to the need of on board accurate and precise absolute position and attitude references. A convenient way to overcome such limitation is here discussed making profit of Laben experience, matured as a company leader in on board data handling and space qualified GPS receiver systems, and by Honeywell as a world leader manufacturer of guidance and navigation packages. The approach would be a guideline for a novel scheme of G&NC architecture where a GPS receiver, performing both attitude and orbit determination, and a MIMU that includes three ring laser gyro and three accelerometers, are integrated in a common unit. In such a system, the measurements performed by the sensors are numerically filtered, removing high side frequency bandwidth noise components, to provide accurate and reliable input data for the attitude and navigation algorithms that will be executed by the embedded guidance computer. The results of such elaboration will be directly the actuation values to drive the space vehicle under both operative and non operative conditions, according to control laws established for the specific mission. With respect to other papers on the subject, the present introduces the characterization of the noise performances of the GPS tensor receiver, the first space qualified GPS receiver performing attitude and orbit determination -- designed and manufactured by Laben, and the analysis of the error model of the MIMU designed and manufactured by Honeywell. From the discussion of such error models a scheme for the sensors data fusion based on an extended Kalman filter is then proposed.
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