Ph.D. Defense

Andrew Fear

(Advisor: Prof. Lightsey)

"Implementation of Model Predictive Control for Autonomous Rendezvous and Docking of Small Satellites"

Thursday, April 13 

9:30 a.m.
Montgomery Knight Building 317
 

Abstract

Autonomous rendezvous and docking (AR&D) maneuvers are a key enabling technology for many types of space missions. One mission type of interest to the proposed work is the use of small satellites for on-orbit construction of larger assemblies. The volume and mass limit constraints are a crucial challenge imposed by the small satellite form factor. To this end, the AR&D guidance algorithm must be robust to disturbances in the dynamics uncertainty, actuation errors, and measurement noises while also adhering to constraints on the system. The proposed work investigates the use of model predictive control (MPC) due to its strong ability to handle constraints in obtaining an appropriate control solution. A simulation designed for the AR&D of small satellites was created to assess an MPC guidance algorithm. The MPC algorithm was split into three phases based on distance to the target: the rendezvous, approach, and the docking or final phase. Each phase considers the constraints needed to be met by the system to reduce overall fuel consumption. AR&D to a non-maneuvering target has been considered for both a non-rotating and constant tumbling cases. A sensitivity to the chosen MPC parameters such as initial state, prediction horizon lengths, and sampling times is performed. Additionally, an investigation of the resilience of the guidance algorithm from disturbances in the thruster actuations and assumed models is investigated. Finally, verification and benchmarking the validity of the guidance algorithm to run onboard flight system-like hardware is performed.

Committee

• Prof. E. Glenn Lightsey – School of Aerospace Engineering (advisor)
• Prof. Brian Gunter – School of Aerospace Engineering
• Prof. Koki Ho – School of Aerospace Engineering
• Prof. John Christian – School of Aerospace Engineering
• Prof. Srinivas Bettadpur – Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin