Showing papers by "Ching-Chih Tsai published in 1997"

Averaging, aggregation and optimal control of singularly perturbed stochastic hybrid systems

Abstract: This paper develops methodologies for the averaging, aggregation and optimal control of stochastic hybrid systems whose state equations depend on continuoustime, nearly completely decomposable finite state Markov chains. Such Markovian switching models are assumed to have several identified groups of strongly interacting states. The random sample solution process of the system state can be well approximated by a deterministic trajectory, for the duration of an interval of which the switching process sojourns in a group. Aggregated models are obtained by utilizing the aggregation method over the infinite time interval. By using the perturbation approach, necessary and sufficient conditions of stochastic stabilizability and controllability proposed by Ji and Chizeck (1990) are presented for the systems. With the aggregation models and the known results of stochastic stabilizability, near-optimum finite time and infinite time Markovian jump linear quadratic control laws are also investigated. The limiting be...

Discrete-time VSS temperature control for a plastic extrusion process with water cooling systems

Abstract: The plastic extrusion process with water cooling is a variable structure system in nature. To implement discrete-time variable structure control, three important problems are considered: 1) choice of dynamic sliding surface for a system with relative degree greater than one; 2) computation of the discrete-time dynamic sliding surface variable (s/sub k/); 3) and self-tuning of the switching control magnitude to reduce chatterings. A simplified lumped parameter model is constructed to decouple the original multi-channel system into multiple single-channel subsystems. Experimental results show effectiveness of the proposed method.