Gyroscopes that work in weightless conditions

January 03, 2016 //By Bill Schweber
Bill Schweber talks about some of what is going on with gyroscopes for space applications.

It's always interesting to see how engineers adapt older devices for radically new uses. A good example is the work being done at Draper Laboratory to counter the difficulties of working and having tangible motion feedback when working in the weightlessness of space. The IEEE Spectrum article “A New Spin on Space Suits” explains how an array of classic gyroscopes is being used in spacesuits as an analog sensor and actuator to counter the lack of "weight" feedback that astronauts must deal with, especially when doing projects, repairs, or spacewalks. Just remember: weightlessness sounds like so much fun, until you have to do work in that environment, and there are the other weightlessness-related issues such as body-mass and muscle deterioration, among other consequences.

The Draper design, which has been prototyped and is in preliminary tests including zero-g flights, uses the gyro's spinning mass to sense motion and create a force which resist such movement. Unlike MEMS-based gyro sensors and accelerometers which have become ubiquitous for motion and acceleration sensing in many products, this application needs mass to generate force, so the classic spinning wheel gyro must be used; this configuration is known as a control moment gyro (CMG). There's something that the MEMS-based devices cannot do despite their well-known advantages.

A new Control Moment Gyroscope (CMG) sits in its cradle in the payload bay of the Space Shuttle Discovery prior to its installation on the International Space Station in 2005, to replace one which failed in 2002. The International Space Station has three of the 600lb (272kg) gyroscopes controlling its attitude (photo courtesy NASA).