화학공학소재연구정보센터
IEEE Transactions on Automatic Control, Vol.53, No.5, 1273-1278, 2008
Feedforward control design for finite-time transition problems of nonlinear systems with input and output constraints
The article extends a recently presented approach to feedforward control design for nonlinear systems to additionally account for input and output constraints. The inversion-based design treats a finite-time transition problem as a two-point boundary value problem (BVP) in the coordinates of the input-output normal form. To account for constraints on the output and its time derivatives, the input-output dynamics is replaced by a new system, which is systematically constructed by means of saturation functions. The solvability of the BVP requires a sufficient number of free parameters in an ansatz function. The resulting BVP with free parameters can be solved in a straightforward manner (e.g., with the Matlab function bvp4c). Input constraints can additionally be considered as constraints on the highest output derivative. The approach is applicable to nonlinear and nonminimum-phase systems, which is illustrated for the side-stepping of an inverted pendulum on a cart.