Space Systems Design Studio

• Overview
• Applications
• Publications

Project Overview

CMGs help orient satellites and astronauts alike. Photo details on NASA website.

Our research investigates the feasibility of using control-moment gyroscopes (CMGs) in actuating agile space robotic systems. A CMG consists of a constant-speed rotor and a gimbal that changes the direction of the rotor's angular-momentum vector. This internal momentum exchange leads to largely reactionless actuation, in which the dynamics of the robotic linkage are decoupled from the spacecraft attitude control system. In addition, since the change in the rotor angular momentum generates a gyroscopic torque that is purely a constraint torque, it does no work, and therefore requires virtually no input power. This low-power feature of a CMG makes it an attractive alternative to other momentum-exchange devices, including the reaction wheel assembly (RWA), which applies torque by simply changing its rotor spin rate. CMGs have been used for many years to efficiently produce high torques in large spacecraft, including Skylab, MIR, and the International Space Station.

We are constructing a testbed to measure the improvements possible using CMGs on a robot arm. This testbed differs from the earlier proof-of-concept models built by the Cornell CMG teams in that we can conduct tests in the lab, not just in a weightless environment. Air bearings support the robot arm on a glass surface using an onboard pressurized air tank. Wireless USB provides a link to the control algorithms written in Matlab with the Data Acquisition toolbox. A presentation and on the testbed is included in the Publications link.

For information on the undergraduate CMG teams, visit the Cornell MAE Microgravity Research Team