Robust tracking performance enhancement through uncertainty division

When the process uncertainty size increases, even linear minimum phase systems must sacrifice desirable aggressive feedback control benefits to avoid an excessive ‘cost of feedback’, while preserving the robust stability. With a suitable uncertainty division and a QFT controller-prefilter to command each uncertainty subset inside a controller-scheduler structure, it is possible to enhance the feedback tracking performance without an excessive bandwidth. To preserve the robust stability from any failure in the switching, each controller is designed to be stable in the whole uncertainty domain, and as accurate in command tracking as desired in its uncertainty subset.