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

Murat UZAM

Article Details

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

Authors:

Murat UZAM

Publisher:

TUBITAK

Journal:

Turkish Journal of Electrical Engineering and Computer Science 2002 Vol.10 Issue 1, pp.85-110

Document Type:

Article

Publication Date:

12/2001

Document Language:

Turkish

Document ID (Org No.):

2000744360

Frequency:

Bimonthly

eISSN:

1303-6203

pISSN:

1300-0632

Abstract:

 

A new Petri-net-based top-down synthesis technique for  supervisory control of Discrete Event Systems (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 (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 (LLD) code is used to implement the  supervisors on programmable logic controllers (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.

 

A new Petri-net-based top-down synthesis technique for  supervisory control of Discrete Event Systems (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 (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 (LLD) code is used to implement the  supervisors on programmable logic controllers (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.

Article Details

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

Authors: Murat UZAM

Publisher: TUBITAK

Journal: Turkish Journal of Electrical Engineering and Computer Science 2002 Vol.10 Issue 1, pp.85-110

Document Type: Article

Publication Date: 12/2001

Document Language: Turkish

Document ID (Org No.): 2000744360

Frequency: Bimonthly

eISSN: 1303-6203

pISSN: 1300-0632

Issues

Authors:

Murat UZAM

Publisher:

TUBITAK

Journal:

Turkish Journal of Electrical Engineering and Computer Science 2002 Vol.10 Issue 1, pp.85-110

Document Type:

Article

Publication Date:

12/2001

Document Language:

Turkish

Document ID (Org No.):

2000744360

Frequency:

Bimonthly

eISSN:

1303-6203

pISSN:

1300-0632