meetings - Space Flight Mechanics Committee

while using only limited sensing. This filter enables nano satellites to perform onboard
attitude determination even when no dedicated attitude sensors are installed, instead relying
only on the electrical currents from body mounted solar panels. The online attitude filter is
applied in post processing to orbital data from NASA Ames Research Center's O/OREOS
and the University of Michigan's RAX-1 spacecraft.
9:20 AAS Development of the Illinisat-2 Attitude Determination and Control System
13-365 Testing Suite
Alexander Ghosh, University of Illinois at Urbana-Champaign; Erik Kroeker,
University of Illinois at Urbana-Champaign; Patrick Haddox, University of Illinois
at Urbana-Champaign; Victoria Coverstone, University of Illinois at Urbana-
Champaign
9:40 Break
This work discusses the development of a magnetic-based attitude determination and
control system for the Illinisat-2, and the ground support equipment needed to validate the
system. Its attitude determination is performed using magnetometers and coarse sun sensors
applying Kalman filtering method, while the attitude control is performed with magnetic
torquers. To perform the flight testing of this system, a Helmholtz cage was developed. This
work will discuss the lessons learned of developing the system, and of the testing apparatus,
as well as outline the method for calibration of the system and the next steps in its
development.
10:05 AAS Estimation of Spacecraft Angular Acceleration Using Linear Accelerometers
13-366 Vivek Nagabhushan, University of Florida; Norman Fitz-Coy, University of
Florida; Shawn Johnson, University of Florida
Several challenges in the attitude determination and control of a spacecraft like mass
property and misalignment may benefit from the measurement of spacecraft angular
acceleration. Differentiation of angular velocity measurements from a gyroscope has
undesirable effects like noise amplification. This paper will describe methods to estimate
spacecraft angular acceleration using linear accelerometer and gyroscope measurements.
Two configurations, that use uni-axial, and tri-axial accelerometers, respectively are
presented and compared in this paper. The effect accelerometer bias and noise on the
angular acceleration estimate are evaluated. An EKF to identify the effective bias in the
angular acceleration estimate is developed.
10:25 AAS Closed-form Optimal Maneuver Control Solutions for Under-actuated
13-367 Spacecraft
Donghoon Kim, Texas A&M University
All spacecraft are designed to be maneuvered to achieve pointing objectives. This is
accomplished by designing a three-axis control system which can achieve arbitrary
maneuvers, where the objective is to reorient the spacecraft and suppress the residual
angular velocity at the end of the maneuver. If one of the three-axis control actuators fails
then new control laws are required. This paper explores optimal sequential Euler angle
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23 rd AAS / AIAA Space Flight Mechanics Meeting