Spin-stabilized space craft with sloshing fluid stores are known to be a source of dynamic instability for certain spacecraft configurations. A time varying linear feedback control law was developed, using an equivalent spherical pendulum mechanical model of the fluid motion coupled to the main body dynamics, which stabilizes the highly nonlinear dynamic system within a large region of operation. The control law was also demonstrated to perform a pointing maneuver. A control design for a specific spacecraft is outlined and implemented by sensing only the main body angular rates and attitude

Control of spin-stabilized spacecraft with sloshing fluid stores

: Launching of several of the Star 48 Communications Satellites from the Space Shuttle have consistently resulted in a nutating motion of the spacecraft. Sloshing fluid stores have been suspected as a source of dynamic instability. A mathematical model of the sloshing fluid motion coupled with the satellite dynamics was developed and the launch phase simulated. The flight simulation similar behavior when compared to the telemetered flight data. Keywords: Coning motion; Communications satellites; Space launched.

Dynamic simulation of spin-stabilized spacecraft with sloshing fluid stores

Long-term precision pointing of the spin axis of a spinning satellite may be impossible because attitude control systems cannot counteract the effects of sensor-vehicle misalignments, the motion of the principle axes of inertia, and body-fixed disturbing torques. An automatic mass-trim system (AMTS) consisting of two pairs of movable trim masses is proposed as a means of providing control torques to eliminate errors resulting from these sources. An analysis of the equations of motion of a rigid spinning body with internal moving masses relates the dynamics of mass motion to the attitude motion of the spinning body. Specializing the geometry to a two-pair system allows calculation of the control torque available and the range through which the principal axis set may be moved relative to body-fixed coordinates. A control law for an automatic system used in conjunction with a previously developed spinning-vehicle attitude controller is presented and analyzed using root locus techniques. An analog simulation of the vehicle with trim system verifies the design.

An Automatic Mass-Trim System for Spinning Spacecraft

Hill, Daniel Eugene, "Dynamics and control of spin-stabilized spacecraft with sloshing fluid stores " (1985). Retrospective Theses and Dissertations. Paper 8702. This reproduction was made from a copy of a manuscript sent to us for publication and microfilming. While the most advanced technology has been used to pho­ tograph and reproduce this manuscript, the quality of the reproduction is heavily dependent upon the quality of the material submitted. Pages in any manuscript may have indistinct print. In all cases the best available copy has been filmed. The following explanation of techniques is provided to help clarify notations which may appear on this reproduction. 1. Manuscripts may not always be complete. When it is not possible to obtain missing pages, a note appears to indicate this. 2. When copyrighted materials are removed from the manuscript, a note ap­ pears to indicate this. 3. Oversize materials (maps, drawings, and charts) are photographed by sec­ tioning the original, beginning at the upper left hand comer and continu­ ing from left to right in equal sections with small overlaps. Each oversize page is also filmed as one exposure and is available, for an additional charge, as a standard 35mm slide or in black and white paper format. • In all cases this material has been filmed in the best possible way from the available copy. Problems encountered with this document have been identified here with a check mark V .

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=9701&context=rtd

R.C. Michelini

Papers

The Dynamics of a Non Rigid Spinning Satellite Containing Oscillating Liquids