Techniques for providing singularity escape and avoidance are disclosed.
In one embodiment, a method for providing control moment gyroscope (CMG)
attitude control singularity escape includes calculating a Jacobian A of
a set of control equations, calculating a measure of closeness to a
singularity, and comparing the calculated closeness to a threshold value,
when the calculated closeness is less than or equal to the threshold
value, recalculating the Jacobian A. Recalculating may include
determining a new direction of virtual misalignment of .beta. and
.gamma., recalculating the Jacobian inputting the new direction of the
virtual misalignment, recalculating the measure of closeness to a
singularity, and comparing the measure of closeness to the threshold
value. Further, the method may include calculating a gimbal rate command
if the of closeness is greater than the threshold value and generating a
torque from the gimbal rate command to control the attitude of a
satellite.