H/sub ∞/ control of an experimental inverted pendulum with dry friction

The incorporation of dry friction in a standard plant setting and the application of H/sub ∞/ optimal control design to find a controller that is insensitive to dry friction are discussed. The approach is applied to an inverted penulum setup, to show that a significant improvement of behavior can be obtained. It is shown that the application of an H/sub ∞/ optimal controller does not result in a satisfactory behaviour if dry friction is not taken into account and cart position reference error minimization is demanded. The effect of dry friction is considered in developing a controller that is insensitive to this effect but has no reference tracking property. The trade-off between the tracking objective and the insensitivity of dry friction is reviewed, resulting in a controller with good behavior in both respects. This behavior has been validated by implementation on a laboratory setup.