2005 Volume 18 Issue 2 Pages 51-61
The problem of controlling the RTAC (Rotational/Translational Actuator) system provides a benchmark for evaluting various nonlinear control design techniques. The RTAC system, which represents a translational oscillator with an eccentric rotational proof-mass actuator, was originally studied as a simplified model of a dual-spin spacecraft to investigate the resonance capture phenomenon. This paper presents design methods of a controller that supresses oscillations of the RTAC system. The controller gives a dual-mode control that consists of an energy-based control that can effectively suppress the oscillations of the bed, and a stabilizing control that makes the whole system globally and asymptotically stable. The energy-based control is taken over by the stabilizing control when the oscillations of the bed become small to some extent. Two types of energy-based control law are proposed : one rotates the disk in normal and reverse rotation in a limited angular amplitude and the other rotates the disk in one direction. It is shown that the proposed controller achieves a performance comparable with that of the time optimal controller. Simulation experiments also show the effectiveness of the proposed methods.