Control Moment Gyroscopes (CMG) are used as actuators in some applications such as attitude control of satellites, stabilization of two-wheeled vehicles, to avoid a ship from swaying, among others.
The LCA (Applied Control Laboratory in english) has an ECP (Educational Control Products) CMG unit, model 750, which has a versatile structure with up to 4 degrees of freedom (DOF), that generates from SISO (Single-Input Single-Output) systems with one DOF, for linear control techniques applications, till MIMO (Multiple-Input Multiple-Output) systems with four DOF, for nonlinear control techniques applications.
This electromechanical plant is composed of four rigid bodies (Bodies A, B, C and D, shown in the figure below), whose angular positions are measured by incremental encoders (Encoders A, B, C and D), and two DC motors (Motors # 1 and # 2). Motor # 1 rotates Body D, a bronze axisymmetric disc, and Motor # 2 rotates Body C, and Bodies B and A rotate only through the reactions generated in the structure.
Three articles were published by members of the LCA, from which on was in the Journal of Control, Automation and Electrical Systems and two in conferences, ASME and CBA. The student FAbio Y. Toriumi developed his Master’s thesis in this plant, and his text can be found here.