Nonlinear design for command generation

The design structure of the command following control systems developed by Meyer and Cicolani can best be illustrated with the following problem (see Figure 1). Consider a plant P with input u, load disturbance d, and output y. A command signal r, which may not be known at design stage, is to be followed by the output y. The task is to design a control system which admits signals r and y and generates signal u as its output, such that the plant output y follows r within certain design requirements and constraints.