Interaction measures for nonsquare decentralized control structures

A block relative gain measure for nonsquare systems has been derived. Evaluated at steady state, this measure serves as a performance-related tool for evaluating control structures prior to controller design. Both the nonsquare dynamic block relative gain and the relative sensitivities have been presented as dynamic interaction measures that depend on the controller tuning and are consequently applicable to design of nonsquare decentralized controllers. Rigorous relationships between the dynamic block relative gain and the performance and stability of a closed-loop system have been established.