AN EXTENDED KALMAN SMOOTHER FOR THE DICE MISSION ATTITUDE DETERMINATION POST PROCESSING WITH DOUBLE ELECTRICAL FIELD PROBE INCLUSION

摘要

This paper describes implementation and verification of a post-processing attitudedetermination tool for the DICE spacecraft. The DICE mission represents a constellationof two spin-stabilized cubesats used for probing the native electrical fieldof the Earth. The DICE mission is scheduled for launch in September 2011. EachDICE spacecraft is equipped with a GPS receiver, a Sun Sensor and a Magnetometer.The data from the Double Electrical Field Probe is to be included in theattitude solution. The attitude post-processing determination tool is based on twooptimal quaternion-based Kalman filters. Those filters are combined together inone fixed-interval Extended Kalman Smoother. Simulated results showed that theExtended Kalman Smoother can effectively reduce the covariance of the estimationby 40%. This paper also extents previous research into incorporating datafrom the Double Electrical Field Probe science sensors into the attitude solution.It shows that using Double Electrical Field Probes combined with aMagnetometercan improve the attitude accuracy about 3 times in the eclipse. Hence, the combinationof a Magnetometer and Double Electrical Field Probes improves attitudesolution for low cost missions when in eclipse, when the sun is not in the Field ofView or when the spacecraft is spin stabilized and, consequently, cannot use a startracker. The simulated results also show that the improvement in the estimation isnot constant but it depends on the spacecraft position on the orbit.