Spacecraft attitude control using coupled thrusters

A three-axis stabilized spacecraft having at least three pairs of thrusters, each thruster producing force along a thruster axis, for controlling the spacecraft attitude with respect to three orthogonal spacecraft axes, wherein:

• at least some cross-coupling torque is produced by the thrusters, i.e., at least one pair of thrusters produces torque components about more than one spacecraft axis;
• said spacecraft further comprising:
• control means for generating torque requirement signals which are represented in terms of the spacecraft axes, said torque requirement signals specifying the amount of torque required to adjust the attitude of the spacecraft about each of the three spacecraft axes;
• and
• thruster command conditioning means interposed between the control means and the thruster pairs for converting the torque requirement signals into thruster actuating signals which are represented in terms of the thruster axes, said conditioning means taking the magnitude and direction of the cross-coupling into account, so that the spacecraft attitude is adjusted in a manner directed by the torque requirement signals despite the presence of the cross-coupling.