Shortest Path Control Of DRDES Based On NCES

In order to meet control requirements continuously in case of component failure,partial communication blocks,or energy deficiency,some systems,such as safety-critical ones need to reconfigure at run-time.These systems can be studied as dynamic reconfigurable systems(DRSs).A DRS consists of several configurations.Normally,a system runs in one of the configurations.Once reconfiguration requirements are received,the system should reconfigure to another configuration.Since uncontrolled reconfiguration behavior of DRS may make the system unstable,and violate the control specification of consistency.The control of reconfiguration behavior is of great importance.With the improvement of technology,many man-made systems have been developed,such as flexible manufacturing systems,traffic control systems,and communication network.These systems can be considered as discrete event system(DES)if their logical behavior is concerned only.A DES is a discrete-state,event-driven system,in which the state evolution depends entirely on the occurrence of synchronous or asynchronous discrete events over time.Net condition/event systems(NCESs)are formalisms for analysis and control of DES.They are the modular extensions of well-known Petri nets.Compared with other DES formalism,the modular structure of NCES makes it more suitable for studying DRS.When studying control problems of DRSs from a DES perspective,one can consider DRSs as dynamic reconfigurable discrete event system(DRDES).This work studies the reconfiguration control problems of DRDES based on NCES and makes the following contributions.In order to keep stable,a DRDES normally reconfigures at specific states.This thesis proposes a path optimization strategy such that the system is able to reach a reconfigurable state before the maximal permissible reconfiguration delay.An integer linear programming(ILP)method is developed for calculating the optimal path.Without searching for DRDES state space,the result can be calculated by a single linear programming.A virtual guiding controller is given for guiding the system to evolve along the calculated path.Both firing regulations of NCESs: ”maximal single spontaneous transition steps” and ”arbitrary maximal steps” are considered during the shortest path computation and control procedure.The virtual guiding controller is effective for guiding the system to evolve along a specific path.However,it greatly constrains the original system behavior.In order to maintain the system behavior as much as possible while supervising the system,formal languages are applied to represent the desired system behavior before and after any dynamic reconfiguration and a consistency controller design method is developed.Consistency control with uncontrollable transitions is considered as well,in which an invariant-based control synthesis strategy is applied.