An interactive design procedure yielding robustness and sensitivity

An interactive design procedure to meet the requirements of robustness and sensitivity is given using servomechanism controllers. It is assumed that the external signals, namely disturbances and reference inputs have rational spectra and their bandwidths are known. A set of signals is chosen such that their power spectral frequencies lie within the bandwidths of the external signals. A sequence of controller structures is generated consisting of a stabilizer, (for simplicity on LQG state feedback stabilizer is used) and an internal model for a subset of this set of signals. The parameters of the stabilizers are obtained by iterating the weighting matrices of the LQG cost functional. The main contribution lies in the development of an interactive design procedure based on generating a sequence of low sensitivity controllers and using 3-dimensional graphic displays of sensitivity, robustness and transient response to choose a controller that meets the design specifications.