LOOPSHAPING FOR ROBUST PERFORMANCE

Robust performance is said to be achieved if the performance specifica tions are met for all plants in a specified set. Classical loopshaping was developed decades ago to design for robust performance for single -loop systems with simple uncertainty and performance specifications. Specifications are often not so simple-multiple real parameter variati ons are not handled by classical loopshaping, for example. Also, it is important for multivariable systems that uncertainty may be present a t different locations, for example, actuator uncertainty is located at the input of the plant whereas sensor uncertainty is located at the o utput of the plant. In this work classical loopshaping is extended to multiple parametric and unmodelled dynamic uncertainty descriptions, t o multiple performance specifications, and to the design of decentrali zed controllers. The authors refer to this more general loopshaping te chnique as robust loopshaping. Robust loopshaping is applied to a coup led mass-spring problem studied by numerous researchers.