초록 ▼

Disclosed is a method and apparatus estimating yaw error and roll and yaw disturbance torques from measured roll error and yaw momentum on a continuous on-orbit basis in an orbiting satellite. The information thus obtained can be used to continuously correct for the yaw error by means of, for exampl

Disclosed is a method and apparatus estimating yaw error and roll and yaw disturbance torques from measured roll error and yaw momentum on a continuous on-orbit basis in an orbiting satellite. The information thus obtained can be used to continuously correct for the yaw error by means of, for example, activating a magnetic torquer. Two control loops are used in this invention, a fast loop to damp nutations by changing momentum wheel speed, and a slow loop of the Luenberger observer variety. The latter is a yaw error correction loop which also serves to unload yaw momentum. The satellite in which the invention was first incorporated is of the type having three momentum wheels, all situated in the plane orthogonal to the roll axis. In normal operation, two wheels, each having major momentum component along the pitch axis and minor momentum component along the yaw axis, are operable. A third backup wheel aligned along the yaw axis becomes operable only in the eventuality that one of the primary wheels suffers a breakdown during the life of the satellite. The slow speed yaw loop is used to adjust a magnetic coil torquer. It can be implemented in a number of forms including a hard-wired analog form or a digital computer with certain constant scaling factors programmed into the memory of the computer.

대표청구항 ▼

In an orbiting satellite having a stored momentum system for stabilizing the attitude of the satellite about orthogonal roll, pitch, and yaw axes, apparatus for estimating and directly correcting yaw error, said apparatus comprising: at least one momentum wheel having a component of momentum about t

In an orbiting satellite having a stored momentum system for stabilizing the attitude of the satellite about orthogonal roll, pitch, and yaw axes, apparatus for estimating and directly correcting yaw error, said apparatus comprising: at least one momentum wheel having a component of momentum about the yaw axis; means situated on board the satellite for measuring the angular error of the satellite body with respect to the roll axis, said means generating a signal corresponding to said roll error; coupled to said roll error measuring means and to said momentum wheel, means comprising solely electronic components for estimating the angular error of the satellite body with respect to the yaw axis from the roll error signal and from a measured component of momentum about the yaw axis; and coupled to an output of said yaw error estimating means, means for continuously and directly correcting said yaw error during the satellite\s orbit.