Title :
Nonlinear control of discrete-time linear systems with state and control constraints: a reference governor with global convergence properties
Author :
Gilbert, Elmer G. ; Kolmanovsky, Ilya ; Tin Tan, Kok
Author_Institution :
Dept. of Aerosp. Eng., Michigan Univ., Ann Arbor, MI, USA
Abstract :
Discrete-time, linear control systems with specified pointwise-in-time constraints, such as those imposed by actuator saturation, are considered. The constraints are enforced by the addition of a nonlinear “reference governor” that attenuates, when necessary, the input commands. Because the constraints are enforced, the control system remains linear and undesirable response effects such as instability due to saturation are avoided. The structure of the governor is a modification of the continuous-time reference governor proposed by Kapasouris, Athans and Stein (1990). Its nonlinear action is defined using an appropriate, finitely determined, maximal output admissible set. As a result, the governor can be implemented on-line for systems of significant order. Algorithmic details of the implementation are described. Theorems provide comprehensive results concerning the response of the overall system which are much stronger than those given in the above paper. The main result is global in nature: if the input command converges to a statically admissible input and the initial state of the system belongs to the maximal output admissible set, the eventual action of the reference governor is a unit delay. A tenth-order, helicopter system is considered as an example
Keywords :
convergence; discrete time systems; feedback; linear systems; nonlinear control systems; actuator saturation; continuous-time reference governor; control constraints; discrete-time linear systems; global convergence properties; maximal output admissible set; nonlinear control; pointwise-in-time constraints; state constraints; tenth-order helicopter system; Control system synthesis; Control systems; Convergence; Drives; Hydraulic actuators; Linear systems; Motion control; Nonlinear control systems; Optimal control; Tin;
Conference_Titel :
Decision and Control, 1994., Proceedings of the 33rd IEEE Conference on
Conference_Location :
Lake Buena Vista, FL
Print_ISBN :
0-7803-1968-0
DOI :
10.1109/CDC.1994.411031