Control of Dynamic Systems Using Semi-Active Friction Damping

摘要

The control of vibrational motion in mechanical systems has long been a problemof interest. This research investigates using friction damping for flexible structure control and for automotive suspension control. The hallmark feature of this approach is that the normal force at the frictional interface is actively controlled. This eliminates the undesirable stick-slip motion found in systems damped by friction in which the normal force is constant. Since the normal force is physically constrained to be positive (compressive) or zero only dissipative work can be done by the controller. Actively controlling the normal force therefore classifies this as a semi-active controller. Friction damping is used to dissipate vibrational energy in a pinned-pinned two beam system in which a single semi-active joint connects the beams. The results of the research indicate that significant damping (modal damping ratios up to 0.20) can be added to the structure by the semi-active joint. A controller designed using linear quadratic regulator theory with an energy related cost functional is shown to be particularly effective at dissipating the flexural motion.