Command governors for constrained nonlinear systems: Direct nonlinear vs. linearization-based strategies

Two command governors (CG) are described for solving set-point tracking pro blems for nonlinear systems when pointwise-in-time input and/or state relat ed inequality constraints have to be fulfilled. A CG is a nonlinear device which is added to a primal compensated system. The CG action, based on the current state, set-point and prescribed constraints, is finalized to select , at any time, a command sequence under which the constraints are possibly fulfilled with acceptable tracking performance. The two CGs, both based on the receding horizon control philosophy, differ in that one directly exploi ts the nonlinear model of the primal system, whereas the other is based on the property that, under some conditions, all trajectories of a nonlinear s ystem are embedded within the trajectories of a linear time-varying (LTV) u ncertain system. An example is presented so as to exhibit the relative meri ts of the methods. Copyright (C) 1999 John Wiley & Sons, Ltd.