Maximizing agility envelopes for reaction wheel spacecraft
King, Jeffery T.
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Spacecraft agility is limited by the maximum torque that reaction wheels can provide. Therefore, a reaction wheel array is typically configured to maximize the inscribed sphere of the reaction wheel torque envelope. Agility is then determined by dividing the spherical torque by the maximum principal inertia. This industry standard approach can severely underestimate the true capability of an attitude control system. An agility envelope considers the reaction wheel torque envelope along with the spacecraft inertia tensor. The agility envelope can therefore be used as a means to quantify the conservatism associated with the standard approach in order to improve slew performance of a conventional attitude control system without the need for larger, more costly hardware or new control algorithms. This paper, presents a simple approach for constructing the agility envelope of a reaction wheel attitude control system. The agility envelope is applied to determine design curves for limits on angular acceleration and rate for maneuver design and for finding the reaction wheel skew angles that maximize agility for a given spacecraft configuration. A surprising result is the observation that maximizing the inscribed sphere of the reaction wheel torque envelope does not, in general, optimize agility.
The article of record as published may be found at http://dx.doi.org/10.1177/0954410018787866
RightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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Karpenko, Mark; King, Jeffrey T.; Dennehy, Cornelius J.; Ross, I. Michael (AIAA, 2019-04);The agility of a rigid-body spacecraft can be expressed in terms of a geometric, three-dimensional, solid called the agilitoid. Originally developed as a means for explaining the concept of “hidden agility” made visible ...
King, Jeffery T.; Karpenko, Mark (American Astronomical Society, 2017);Rigid-body agility is limited by the maximum torque and orientation of the reaction wheels. Maximizing the inscribed sphere of the torque envelope can underestimate the true capability of the system because spacecraft ...
Crews, Steven R.,II (Monterey, California: Naval Postgraduate School, 2013-09);This thesis explores the physical and mathematical limitations of two common attitude control systems: one based on reaction wheels and another based on control moment gyroscopes (CMGs). The dynamics are derived from first ...