Richard Sutherland
PhD Candidate
Aerospace Engineering

Disjunctive Sensing and Control (DSC) arose from a complication when working on a small satellite attitude control. Time-optimal waypoint-following model predictive control (MPC) was inspired by missions such as fast-slewing imaging spacecraft, which must capture as many ground images as possible before their orbit and the Earth's rotation move the target out of line of sight. In this work, novel solution approaches to both problems are developed and simulations are presented to illustrate effectiveness in implementation.

The satellite problem is presented, then a more general switched controller and estimator system is analyzed that activates one subsystem at the expense of the other. Conditions are derived to construct periodic switching sequences that guarantee eventual satisfaction of probabilistic state and error covariance chance constraints.

The time-optimal waypoint problem is described in detail and a Mixed-Integer Linear Program (MILP) solution approach proposed. The ability to handle multiple waypoints, exclusion zones, and flexible mode dynamics are demonstrated. As the time-optimal solutions are in general non-unique, a secondary objective function is added. This secondary optimization problem is chosen to be convex, and so yields a unique solution, which also is shown to restore Lyapunov stability to the equilibrium.

Dissertation Committee:
Co-Chair: Prof. Anouck Girard
Co-Chair: Prof. Ilya Kolmanovsky
Cognate: Prof. Anthony Bloch
Member: Dr. Frederick Leve
Member: Dr. Christopher Petersen