This paper is concerned with the modelling of safety requirements using Petri nets as a tool to model and simulate a Flexible Manufacturing System (FMS). The FMS cell described comprises a pick and place robot, a multi-head drilling machine together with a vision system and illustrates how the hierarchical structure of Petri nets can be used to ensure that all fail- safe requirements are satisfied; block diagrams together with fully detailed example Petri nets are given. The work demonstrates the use of cell and robot control Petro nets together with robot subnets for the x, y and z axes and associated output nets; the control and output nets are linked together with a safety net. Individual machines are linked with the control and safety nets of an FMS at cell level. The paper also illustrates how a Petri net can act as a decision maker during image inspection and identifies the unsafe conditions that can arise within an FMS.
[1]
Paul Freedman,et al.
Time, Petri nets, and robotics
,
1991,
IEEE Trans. Robotics Autom..
[2]
Miroslav Jocković.
An application of petri-nets in the control system of the FTC
,
1988
.
[3]
Chih-Ming Liu,et al.
Using Petri nets to solve FMS problems
,
1993
.
[4]
Duc Truong Pham,et al.
Expert systems in mechanical and manufacturing engineering
,
1988
.
[5]
Mohsen A. Jafari.
Petri net based shop floor controller and recovery analysis
,
1990,
Proceedings., IEEE International Conference on Robotics and Automation.
[6]
MengChu Zhou,et al.
A hybrid methodology for synthesis of Petri net models for manufacturing systems
,
1992,
IEEE Trans. Robotics Autom..
[7]
C. Eswara Reddy,et al.
A Petri net based approach for analysing tool management issues in FMS
,
1992
.