SpacecraftResearch.com - CMG Robotics

CMG Applications

Enhancing Agility

In many applications, only the optics or other specialized sensors may need to point at their targets. Imagine if you wanted to look from right to left, but you had to turn your entire body rather than just your head or your eyes. A robotic telescope system can act like your neck, allowing the optics to quickly move to a target while the rest of the spacecraft moves slowly.

For more information, see:

Carpenter and Peck, "Dynamics of a High-Agility, Low-Power Imaging Payload"
Peck, "Low-Power, High-Agility Space Robotics"

Reactionless Robotics

CMG scissored pairs actuate this prototype prosthetic arm in our lab.

Anyone who has walked across ice has experienced the difficulty of control in a reactionless environment. The ice will hold you up, but it will give you precious little support in the direction you want to go. Reactionless robots act in reverse. We want to move the robot without any reaction onto the base. Reactionless robots have a variety of potential benefits on spacecraft of all sizes:

Lower intertia of an object being pointed as compared to maneuvering an entire spacecraft.
Motion avoids exciting vibration modes of the spacecraft bus.
May help reduce bandwidth requirements of the controller.

For more information, see:

Carpenter and Peck, "Minimum-Power Robotic Maneuvering Using Control-Moment Gyroscopes"
Peck, "Low-Power, High-Agility Space Robotics"
Jarc, Kimes, Pearson, and Peck, "The Design and Control of a Low-Power, Upper Limb Prosthesis"

Scissored Pairs

The complex dynamics of a CMG cause the torque on the spacecraft or robot to change direction. A robot, however, typically requires torque only about its joint axis. A simple solution to this problem is to connect two CMGs that mirror each other. The torques add together along a single axis, which can be aligned with the joint, and cancel along other directions.