Robust state-feedback H/sub /spl infin// control of a nonlinear two-mass system

In this paper, a positioning control of a nonlinear elastically coupled two-mass system is presented. Structures of two-mass systems can often be found, e.g. in robotics or machine tools. The contained mechanical parts, like gears and shafts, can lead to limited cycles and stick-slip effects. In order to avoid these unwanted effects, an H/sub /spl infin// control design is used for the system. In the control, parameter uncertainties and elastic torsion are also taken into account. In the standard H/sub /spl infin// control structure, a basic change is needed. This leads to a state-feedback H/sub /spl infin// control. The result is a linear H/sub /spl infin// control, that can handle the nonlinear system. The control shows good dynamics, robustness and can handle disturbances. Measured results are shown in this paper.