Satellite spin axis stabilization using a single degree of freedom transverse momentum storage device

A method of stabilizing the spin of a spinning satellite about an intermediate inertia axis, the method comprising the steps of:

• sensing a first component of the angular velocity of the satellite about a first axis transverse to the intermediate inertia axis;
• sensing a second component of the angular velocity of the satellite about a second axis transverse to the intermediate inertia axis, wherein the second axis is transverse to the first axis;
• sensing the angular velocity of not more than one single degree of freedom momentum wheel, wherein the momentum wheel has a fixed transverse orientation with respect to the intermediate inertia axis, wherein the fixed transverse orientation of the momentum wheel is offset from a principal axis of the satellite by an angle between 0 and 90 degrees;
• computing a commanded angular velocity for the momentum wheel in dependence upon the first component and the second component, wherein the commanded angular velocity is proportional to a transverse component of the angular velocity of the satellite, wherein the transverse component is in a direction based upon an eigenvector associated with an unstable eigenvalue of a linear dynamic model of the satellite;
• forming a control signal representative of a control torque to be applied to the momentum wheel, wherein the control torque is proportional to a difference between the angular velocity of the momentum wheel and the commanded angular velocity;
• and
• applying the control signal to the momentum wheel.

A system for stabilizing the spin of a spinning satellite about an intermediate inertia axis, the system comprising:

• at least one gyro for sensing a component of the angular velocity of the satellite about a sensing axis transverse to the intermediate inertia axis;
• not more than one single degree of freedom momentum storage device having a fixed transverse orientation with respect to the intermediate inertia axis;
• and
• a processor, coupled to the at least one gyro and the momentum storage device, which forms a control signal in dependence upon the component of the angular velocity, and applies the control signal to the momentum storage device, wherein the fixed transverse orientation of the momentum storage device is offset from the sensing axis by less than 90 degrees.