application of a torque on a spinning wheel results in a rate of rotation around the axis normal to the spin axis and the torque axis (direct effect)
making a spinning wheel rotate around an axis perpendicular to the spin axis creates a torque around the axis normal to these axes (inverse effect, used in the following demonstrations)
in the torque-producing use of the gyroscopic effect, there are three perpendicular axes involved in the vector product between the kinetic momentum and the rate of rotation: the spin axis, the precession axis and the output torque axis, which do not remain fixed due to the gimbal assembly motion
the gyroscopic effect is proportional to the kinetic momentum, product of the wheel inertia around the spin axis by the spin rate
Gyroscopic Pendulum
Pendule libre
The gyro spinning wheel is running at constant speed. The precession drive, which lies in a plane symmetric with respect to the gimbal is not controlled. When the gimbal becomes free, the gravity torque drives it around the horizontal axis, perpendicular to the symmetry plane, until it falls on the stop. This rate of rotation of the gimbal creates a gyroscopic torque that makes the spinner rotate around the precession axis in spite of the friction due to the gear of the precession drive.
Click on the image to start the video clip (183 ko)
Controlled Pendulum
The gyro spinning wheel is running at constant speed. The precession drive, which lies in a plane symmetric with respect to the gimbal is controlled to create a precession rate of the spinning wheel. Measurement of the rotation angle around the horizontal axis perpendicular to the symmetry plane of the gimbal is used to perform the precession control. This control aims to keep the center of gravity of the gimbal assembly over the rotation axis. The commanded precession rate is such that the gyroscopic torque counterbalances the gravity torque and the disturbing torques (as shown by the operator).
Click on the image to start the video clip (667 ko)
CMG Set-Up
Free set-up
The platform is suspended around three axes of rotation. The 4 wheels are running at constant speed. The 4 precession drives which control the gimbal assembly tilts around a diameter are held in a configuration such that the total kinetic momentum of the wheels is null. In this configuration, it is possible to move the platform without feeling any torque because there is no gyroscopic effect. The motion of the platform are unconstrained but by the stops.
Click on the image to start the video clip (630 Ko)
Controlled set-up
The platform is suspended around three axes of rotation. Around each axis, a detector measures the platform attitude. The 4 gyroscopic wheels are running at constant speed. The 4 precession drives which control the gimbal assembly tilts around a diameter are controlled in such a way that the platform follows a prescribed motion. The clip shows the sequence of the three elementary rotations: around an horizontal axis, around another horizontal axis perpendicular to the first one, and around a vertical axis. Complex, fast or precise motions can be performed.
Click on the image to start the video clip (1.388 Mo)
