A New Petri-Net-Based Synthesis Technique for Supervisory Control of Discrete Event Systems

Authors : Murat UZAM

Pages : 85-110

View : 16 | Download : 9

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :A new Petri-net-based top-down synthesis technique for supervisory control of Discrete Event Systems insert ignore into journalissuearticles values(DES); is proposed to solve the forbidden state problem. The supervisors obtained are compiled supervisors, whose control policy is represented as a net structure, as opposed to mapping supervisors, whose control policy is computed as a feedback function of the marking of the system. The compiled supervisors obtained by using the technique proposed in this paper are both nonblocking and maximally permissive. The supervisors to be synthesised consist of a controlled Automation Petri Net model of the system. Automation Petri Nets insert ignore into journalissuearticles values(APN); include the following extensions to the ordinary Petri net framework: sensor readings as firing conditions at transitions and actions assigned to places. Ladder logic diagram insert ignore into journalissuearticles values(LLD); code is used to implement the supervisors on programmable logic controllers insert ignore into journalissuearticles values(PLC);. It is important to note that the supervisors obtained are correct by construction; therefore there is no need for verification. The supervisory control synthesis technique proposed in this paper is applicable to both high-level discrete event control, where the role of the supervisor is to coordinate control of-in the discrete manufacturing sense-machines, workcells, etc., and low-level discrete event control, where the role of the supervisor is to arrange low-level interaction between control devices, such as motors and actuators. In this paper, the applicability of the proposed technique to low-level discrete event control is demonstrated by considering an experimental discrete manufacturing system.
Keywords : Supervisory Control, Petri Nets, Discrete Event Systems DES, Manufacturing Systems, Programmable Logic Controllers PLC, Ladder Logic Diagrams insert ignore i