College

College of Engineering

Department

Mechanical Engineering Department

Degree Name

BS in Mechanical Engineering

Date

6-2019

Advisor(s)

Peter Schuster

Abstract/Summary

Satellites need a way to make precise corrections to their orbit and positioning. The purpose of this project is to design a gimbal mechanism for Astranis that orients an ion thruster along a requested vector. The gimbal must produce any vector within a 2.5° cone in a thirty-minute window. Current systems are expensive and not well suited to this application. The design must be operable in a space environment and optimize mass, size, and reliability. Our design toggles between four discrete positions to achieve an average thrust vector. The gimbal accomplishes this using four solenoids that tilt a plate about a central hinge. The hinge allows for low friction rotation in only two axes. It also contains an integrated restoring force, which will passively restore the thruster to center in event of actuator failure. A linkage assembly connects the solenoids to the thruster plate, allowing for mechanical advantage and a low profile. Four hard stops in the linkage assembly physically define the actuation angles. We initially pursued several designs in parallel before narrowing down to a single design for our confirmation prototype. After manufacturing this prototype, we tested our design to verify range and accuracy of the vector and the ability of the gimbal to move an ion thruster on Earth. The gimbal produced a 2.445° cone with a vector precision of ±0.01° and successfully actuated a 5kg load with a similar center of mass. The gimbal has an envelope of 199x199x44mm and a total mass of 0.926kg. Future testing should include environment tests and complete system tests to ensure full functionality in the intended application. Although our final prototype is not intended to be launch ready, the work accomplished for this project will benefit Astranis as they pursue a flight ready design.

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