Eric Loy

Date of Graduation

2018

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Powsiri Klinkhachorn

Committee Co-Chair

Thomas Evans

Committee Member

Roy S Nutter

Committee Member

Chad C Panther

Abstract

There are a variety of stakeholders when it comes to space (the military, other governmental entities, private sector companies, consumers, the scientific community, etc.), and they would all prefer the operational lives of their satellites, observatories, space stations, and other assets to be maximized. Out of the large number of assets in space, only a few were designed with serviceability as a goal. The ability to service "non-cooperative" satellites is an ongoing project being investigated by the National Aeronautics and Space Administration's (NASA) Goddard Space Flight Center (GSFC) and Satellite Servicing Projects Division (SSPD), along with other industrial partners. This mission is known as Restore-L, which is also the name of the servicing vehicle being developed to capture, refuel, and relocate a government satellite. One critical aspect of this mission is capturing and securely docking the satellite to the servicer to allow robotic manipulators to refuel it. The Client Berthing System (CBS) is a custom grappling tool on the servicer that enables docking with a Marman ring present on most satellites. A wide variety of sensory systems can be employed on the CBS to increase the likelihood of a successful satellite capture and to reduce the chance of catastrophic failure.;This research explores two systems derived from widely available commercial-off-the-shelf (COTS) range and force sensors to allow the CBS to detect the pose of an inbound satellite and when contact is established. Monitoring pose enables nominal orientation of a satellite with the servicing vehicle, and sensing force allows the CBS to provide state information during the docking procedure. Testing revealed that the range sensors were able to track distances to a Marman ring with average errors of 3--8.5%. Testing of many CBS to Marman ring contact configurations revealed that the force sensors were within a 5% average error of the applied load. Additionally, they were able to determine x- and y-torque on the CBS within a 20% average error. Only one particular contact configuration resulted in average force and torque errors of 15% and 30%, respectively. This work provided the proof-of-concept for two systems intended to enhance the CBS. Future work involving these systems will include flight qualifications for an actual space mission.

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