Communications: directive radio wave systems and devices (e.g. – Return signal controls radar system – Receiver
Patent
1994-02-07
1995-03-21
Sotomayor, John B.
Communications: directive radio wave systems and devices (e.g.,
Return signal controls radar system
Receiver
342 96, 342 77, 342 81, 342357, 342 76, 342 62, 342 97, G01S 1372
Patent
active
054000335
ABSTRACT:
This invention comprises the use of integral pulse frequency modulation (IPFM) reaction jet controllers for multi-axis precision tracking of moving objects with flexible spacecraft, and vibration suppression. Two sets of position, rate and accelertion command profiles for multi-axis tracking are disclosed: one for a payload initially facing the zenith and the commands based on a pitch-roll sequence; the other for a payload facing the nadir and the commands based on a roll-pitch sequence. The procedure for designing an IPFM controller for tracking a given, inertial acceleration command profile is disclosed. Important elastic modes of a spacecraft are identified according to their spontaneous attitude and rate response to the minimum impulse bit of the thrusters. The stability of the control-structure interaction is shown to be governed by the ratio of the moments of inertia of the flexible to the rigid portions of the spacecraft. If this ratio is below unity for any axis, the spacecraft is stable; otherwise, not. The stability inequality for symmetric elastic modes, when they induce attitude motion because of a moment arm from the vehicle mass center, is formulated.
REFERENCES:
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patent: 5341142 (1994-08-01), Reis et al.
patent: 5341143 (1994-08-01), Reis et al.
patent: 5351056 (1994-09-01), Sawyer
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"Design of a Payload Pointing Control System for Tracking Moving Objects", by Hari B. Hablani (J. Guidance, vol. 12, No. 3, May-Jun. 1989).
"Satellite Attitude Control by Reaction Jet Frequency Modulation" by J. Bernussou (J. Spacecraft, vol. 10, No. 1, 1972).
"Target Acquisition, Tracking, Spacecraft Attitude Control, and Vibration Suppression With IPFM Reaction Jet Controllers", H. Hablani (Aug. 1992 pp. 1118-1137).
"Basic Relations for Control of Flexible Vehicles", W. B. Gevarter (AIAA Journal, vol. 8, No. 4, Apr. 1970, pp. 666-672).
"Attitude Stabilization of Flexible Spacecraft During Stationkeeping Maneuvers" by B. Wie and C. Plescia (J. Guidance, vol. 7, No. 4, 1983, pp. 430-436).
"The Effects of Structural Stability on the Nonlinear Attitude Control of Spacecraft" by T. M. Abdel-Rahman (UTIAS Report No. 222, CN ISSN 0082-5255 Dec. 1977).
Ginsberg Lawrence N.
Rockwell International Corporation
Silberberg Charles T.
Sotomayor John B.
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