On the optimal control of nonlinear systems
Systems & Control Letters
Genetic Programming and Evolvable Machines
A separation theorem for nonlinear systems
Automatica (Journal of IFAC)
A series-based approximate approach of optimal tracking control for nonlinear large-scale systems
CCDC'09 Proceedings of the 21st annual international conference on Chinese control and decision conference
Automatica (Journal of IFAC)
Finite horizon optimal tracking control for a class of discrete-time nonlinear systems
ISNN'11 Proceedings of the 8th international conference on Advances in neural networks - Volume Part II
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A new method is introduced to design optimal tracking controllers for a general class of nonlinear systems. A recently developed recursive approximation theory is applied to solve the nonlinear optimal tracking control problem explicitly by classical means. This reduces the nonlinear problem to a sequence of linear-quadratic and time-varying approximating problems which, under very mild conditions, globally converge in the limit to the nonlinear systems considered. The converged control input from the approximating sequence is then applied to the nonlinear system. The method is used to design an autopilot for the ESSO 190,000-dwt oil tanker. This multi-input-multi-output nonlinear super-tanker model is well established in the literature and represents a challenging problem for control design, where the design requirement is to follow a commanded maneuver at a desired speed. The performance index is selected so as to minimize: (a) the tracking error for a desired course heading, and (b) the rudder deflection angle to ensure that actuators operate within their operating limits. This will present a trade-off between accurate tracking and reduced actuator usage (fuel consumption) as they are both mutually dependent on each other. Simulations of the nonlinear super-tanker control model are conducted to illustrate the effectiveness of the nonlinear tracking controller.