A robustness synthesis method

This paper discusses how the frequency domain optimality conditions of the linear quadratic system can be used in system design synthesis. It attempts to show that the control and state weighting matrices in an LQ design can be used to facilitate tradeoffs of feedback properties such as performance, disturbance rejection, system robustness and sensitivity, in order for the control system to meet a set of specifications. The fact that an additional tradeoff dimension is provided by the directionality of the multivariable structure of multiinput-multioutput systems is discussed.