H/sub /spl infin// multiple objective robust controllers for infinite-horizon single measurement single control input problems

摘要

A graphical method is introduced that solves the robust infinite horizon H/sub /spl infin// multiple-objective control problem for single measurement, single control input systems. The solution is obtained by describing boundaries on the Nichols chart. Each boundary defines the set of all admissible gain and phase values for the loop transmission at a given frequency. These boundaries are obtained by using the well-known parameterization of all the solutions for a single objective H/sub /spl infin// control problem. The new method links between the theories of H/sub /spl infin// and quantitative feedback theory (QFT). It can be used to design robust H/sub /spl infin// controllers with almost no overdesign, and it provides a convenient solution of H/sub /spl infin// multiple-objective problems that are difficult to solve by the standard four-block setting. It also extends the methods of SISO QFT to deal with a vector of disturbances. The latter may affect the controlled plant through any input coupling matrix and not necessarily through the controller input, or the measurement output.