Double-command feedforward-feedback control of a nonlinear plant

In this paper, a design approach is proposed for feedforward-feedback control systems. As the basis of the proposed design approach, steady state control command is defined as the control command which maintains the desired situation of the system. Steady state control law is derived form system's mathematical model and employed as feedforward controller. Using such a feedforward controller, for a wide class of systems, the stability of system is proved if the feedback controller is a gain with an arbitrarily high value. That is, the only limit for the feedback (transient) control command is the actuator's practical limit; moreover, there will be no overshoot and control system is capable to damp sever disturbances. In this article, the proposed method has been applied on a Catalytic Stirred Tank Reactor (CSTR) with two control inputs leading to an excellent control response.