This approach is first to orderly conduct off-line computations of some special states or markings,such as dead(lock) markings,bad markings,and dangerous markings,of the system's Petri net model,and then make on-line the system never reach a forbidden state such as dead(lock) markings and bad markings.
This paper studies the problem of conflict controls that arises in a comtrolled Petri net model for a class of discrete event systems. We propose a new method to synthesize controls for conflicts. With this method,the conflict problem is first transformed into a forbidden state problem,and then through the resolution of the control problem of the forbidden state,the conflict controls in controlled Petri nets are achieved.
The supervisory control part: Firstly, the existence condition of maximally permissive multi-valued logic controller for the forbidden state problem is presented.
A novel controller synthesis method for solving forbidden states avoidance problem was presented by exploiting the structural properties of Petri nets.
Some discrete event systems are modelled by Petri Nets. The problems of avoiding a class of forbidden states,which are not expected in practice system,are solved.
The system is modeled by controlled marked graph with external input places. The number of tokens in each external place is controlled to guarantee that the forbidden states will not occur. Logical behavior of the system is described by min algebra and one-step permissive control policy withoutredundancy is obtained.
In this paper,the Problem of are kinds of forbidden states avoidance in discrete event systems modeled by petri netri is discused. A method,that designs a petri net with external input places(PNIP)which is based on Petri net N and implements control logic of coordination on N is presented. The control state of PNIP decided by N's current state ensures that N avoides forbidden states and has permissive maximally freedom.
In the transformation function based method, we propose reverse net analysis to compute weakly forbidden marking (WFM) set without constructing influence paths.
An algorithm relating to this objective of a subclass of controlled Petri nets (the spanning subnets of uncontrolled transition subnet in a net of this subclass is a TC net) is given in this paper.
Assuming that an uncontrolled bounded Petri net (PN) model of a (plant) DES and a set of forbidden state specifications are given, the proposed approach computes a maximally permissive and nonblocking closed-loop hybrid model.
More specifically, the forbidden state control problem with full observation, in which a discrete-event system is modeled as a colored Petri net with a symmetry specification, is investigated.
We perform calculations and comparative analysis of the off-shell scattering matrices and related pp → ppγ reaction observables for various types of NN potentials-with forbidden states and with short-range repulsion.
Optically forbidden states do not couple to light propagating in the growth direction yet they may have a considerable radiative broadening due to spontaneous emission in other directions.
It is shown that the appearance of discrete ambiguities in the optical potential of composite particles is caused by the existence of partly Pauli-forbidden states.
Problems concerning supervisory control of resource-sharing systems are addressed.Main results include equivalence of forbidden state control and marking control,a simplified design procedure of forbidden state controller,a procedure of designing deadlock-free forbidden state controller as well as a necessary and sufficient condition for the existence of infinite overtaking of the shared resource.Examples are given to illustrate the results.
In the paper, place-interconnected petri nets are introduced, which are composed of several subnets with some common places. For discrete event systems which can described by place-interconnected petri nets, a decentralized and coordinated control framework is introduced to realize the forbidden state control of them. A aynthesis method of coordinated control is developed for the minimal constrained control of them, it is efficient in computation.
In this paper,the Problem of are kinds of forbidden states avoidance in discrete event systems modeled by petri netri is discused.A method,that designs a petri net with external input places(PNIP)which is based on Petri net N and implements control logic of coordination on N is presented.The control state of PNIP decided by N's current state ensures that N avoides forbidden states and has permissive maximally freedom.