This project seeks to develop improved methods for spacecraft guidance, navigation, and control (GNC) through improved understanding of the spacecraft nonlinear dynamics. Spacecraft translational motion is dominated by orbital dynamics and the control is often constrained by a limited fuel supply. Therefore, translational GNC methods generally must be designed to work with these dynamics instead of fighting them. Spacecraft attitude motion is governed by the particular structure of rotational dynamics and robust performance of attitude GNC methods depends on careful adherence to this structure. Additionally, spacecraft operations are subject to significant nonlinear control-estimation interactions, an example being the lack of observability of control-free relative motion in close proximity when using angles-only measurements. Another example is visual-serving attitude control for object tracking by space-based sensors for space situational awareness. Research proposals that address one or more of these topics from a theoretical or experimental point of view are of interest. This research can use the experimental facilities at AFRL, including a spherical air bearing attitude control and determination testbed and autonomous multi-spacecraft testbed.

References

Jagat A, Sinclair AJ: “Control of Spacecraft Relative Motion Using Angles-Only Navigation”. AAS 15-444, AAS/AIAA Space Flight Mechanics Meeting, Williamsburg, Virginia, January 11-15, 2015

Sinclair AJ, Sherrill RE, Lovell TA: “Use of Cartesian-Coordinate Calibration for Satellite Relative-Motion Control”. Journal of Guidance, Control, and Dynamics 38(9): 1842-1847, 2015

Hurtado JE, Sinclair AJ: “State Transition Matrix, Motion Constants, and Ergodicity of the Euler-Poinsot Problem”. Nonlinear Dynamics 85(3): 2049-2063, 2016

Sinclair AJ: “Calibrated and Decalibrated Approximations of Nonlinear Dynamic Systems”. Nonlinear Dynamics 87(1): 281-290, 2017