Abstract
In order to reduce the conservatism of LMI-based multiobjective control design, we attempt to solve mixed problems with non-common LMI solutions, while focusing on the state-feedback case, in particular, H2/H∞control, regional pole placement, and their joint problem. Completing the square in terms of the controller variable and replacements of negative semi-definite quadratic terms by their upper bounds provide a new technique to convert BMIs into LMIs. A suitable choice of the parameters in these upper bounds with iterative algorithms guarantees their convergence property. Through an illustrated example, H2 performance is found to be considerably improved.
