Control design for variations in structural natural frequencies

The lightly damped nature of flexible structures can lead to controllers that are highly sensitive to modeling errors in structural natural frequencies and damping levels. An approach to directly incorporating these modeling errors into the control design process is presented that leads to less sensitive and more robust controllers with improved performance/This approach is used to synthesize controllers for the NASA Langley Mini-Mast experimental structure. The resulting designs obtain good performance in the presence of significant modeling errors in the structural natural frequencies.