Rotating a spacecraft in space can only be achieved in two ways. Firstly thrusters (small rocket motors) that are positioned at points around the spacecraft can be briefly fired to rotate the spacecraft. This has the drawback of using some propellant which will eventually be used up. This clearly needs careful planning as any extra weight on a spacecraft by its very nature is inhibitively expensive. It also means that the thrusters are used when only necessary as it will reduce the spacecraft’s life (assuming it can’t be refuelled) or at huge cost (if it can be refuelled).

The second solution is to use a Control Moment Gyroscope (CMG). This is one or more gyroscopes that are forcibly rotated using an electric motor. The resulting gyroscope torque rotates the spacecraft. Up to 3 axes can be controlled this way. Extra gyroscopes can be used for redundancy. The benefits are clear; Provided the spacecraft has electrical power, by solar power for example, then the aircraft can rotate. With a CMG this can be gone on a regular basis or simply used consistently to keep the spacecraft pointing in the same directional.

Control moment gyroscopes have been used with great effect on the international space station, Hubble space telescope and many satellites.

Although most also used exclusively in space there is actually no reason they cannot be used for some interesting earth bound projects.

This kit allows anyone to understand all the fundamentals of Control Moment Gyroscopes.

The kit:

• 4 electric powered gyroscopes with servo motors to provide torque (photos show 3)
• 3 or 4 gyroscopes can be used (more or less can be added if need)
• Gyroscopes can be placed at 15 degree angles
• Simple gimbal allows movement in 3 axes
• Supplied with 4 continuous rotation servos AND 4 x 180 degree servos
• Ideal for teaching students CMGs
• Allows numerous simulations, including CMG failure
• Unique uses in robotics
• Useful in the fields of Robotics, Aerospace, High altitude balloons and possibly photography

FAQ

What is the weight/rpm of each CMG rotor?
The brass disk is 111g, rpm is about 12,000rpm.

What is the maximum gimbal rate for each CMG?
The servo motor has a maximum speed of 50 rpm (continuous rotation servos)

Can the gimbals rotate without constraint?
Yes they can. They have gold plated slip rings. The slip rings have redundancy to insure no power-loss when rotating.

What is the orientation of each CMG on the platform, and what can be done to reconfigure these orientations?
The platform has quite a complex design for mounting points at 15 degrees. Allowing 3 gyros to be place equally apart and 4 gyros can also be placed equally apart. The gyros can also be tilted at 15 degree angles from 0 to 90 degrees.

How is the platform suspended or mounted to the ground?
I finally settled on suspending the platform from a cable which also supplies power to the gyros. Admittedly this does mean yaw rotation is limited to a few turns. An extra slip ring could be added if needed. If you need a frame to suspend the CMG please contact us.

How is power supplied?
Power to the DC motors for the gyroscopes is 6 volts. A battery pack running from 4 AA batteries is supplied. However it does drain the batteries quickly and is really just so people can get up and running quickly. I highly suggest buying a DC benchtop power supply. Something that can provide around 10amps at 6 volts. The servos and servo controller run from a separate power supply and use a lot less power. So ideally a benchtop power supply with dual output would be ideal.