Pre-bias scheme for roll momentum unloads on pitch momentum bias/yaw reaction wheel spacecraft
AssigneeSpace Systems/Loral, Inc.
InventorsJohn S. Higham, Rhys Kevin Adsit
Life of this patent
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Abstract
An automatic, on-board system for orbiting spacecraft that controls and reduces short-term transients caused by roll momentum unloads by manipulating the states of the nutation damper through resetting one of the states in the polynomial transfer function to a value in proportion to the magnitude of the expected roll momentum unload and creating a transient equal and opposite in magnitude to that expected by the roll unload. The compensator will, of its own accord, automatically damp out the resulting transient. Thus the short-term transient is reduced without biasing the spacecraft in roll. No angle bias need be changed or removed.
Claims7
Apparatus for reducing short-term transients, such as due to roll momentum unloads, in a spacecraft having a nutation compensator with a polynomial transfer function, a n - 1 s n - 1 + a n - 2 s n - 2 + ⋯ + a 0 s n + d n - 1 s n - 1 + d n - 2 s n - 2 + ⋯ + d 0 ,
- comprising:
- means for resetting one of the states of the polynomial in proportion to the expected roll momentum unload and producing a signal indicative thereof;
- and
- means, responsive to said indicative signal, for producing an equal and opposite transient to damp out the transient due to roll unload.
A method for reducing short-term transients in the motion of a spacecraft, due to disturbances such as roll momentum unloads, which spacecraft has a nutation compensator with a polynomial transfer function, a n - 1 s n - 1 + a n - 2 s n - 2 + ⋯ + a 0 s n + d n - 1 s n - 1 + d n - 2 s n - 2 + ⋯ + d 0 ,
- comprising the steps of:
- resetting one of the states of said polynomial transfer function in proportion to the expected roll momentum unload;
- and
- allowing the equal and opposite resulting transient to damp out the transient due to roll unload.
A method for reducing short-term transients in the motion of a spacecraft, due to roll momentum unloads, which spacecraft has a nutation compensator with a polynomial transfer function, a n - 1 s n - 1 + a n - 2 s n - 2 + ⋯ + a 0 s n + d n - 1 s n - 1 + d n - 2 s n - 2 + ⋯ + d 0 ,
- comprising the steps of:
- disturbing the state of the nutation compensator by changing the value of one of the “s'” in said polynomial transfer function;
- and
- selecting said “s” to be changed in proportion to the expected roll momentum unload to produce a transient that is equal and opposite in magnitude to that expected by the roll unload.
Dependencies are inferred from the claim text.