Relative position and attitude estimation of feature point deviating from center of mass

For satellite formation flight, the relative translational dynamics of an arbitrary point on a satellite body is coupled with rotational motion due to its bias from the center of mass. A coupled translational dynamics is derived to represent orbital motion, and the relative attitude motion is formulated by a rotational dynamics for no-gyro satellite. Based on the coupled dynamics of feature point and the traditional dynamics of center of mass, two strategies are proposed to estimate the relative attitude of the satellite and relative position of the feature point. The line-of-sight measurements from a PSD sensor are coupled with dynamical models both in an EKF and an UKF for each strategy, and simulations are carried out to test their performance and computation and load. Results indicate that all approaches can provide accurate relative position and attitude estimation.