Optimal operation planning using fuzzy Petri nets with resource constraints

Traditional Computer Aided Process Planning (CAPP) systems produce rigid operation plans for each manufacturing feature. As a result, generated process plans lack flexibility and may not be optimal. This paper proposes a modified fuzzy Petri net, named OPN, to model alternative and optimal operation planning. Operation selection knowledge, which is a basis for operation planning, is formalized in OPN. By solving the T-invariants of OPN, alternative operation plans can be obtained for each feature of a machined part. After the execution of OPN, each alternative operation plan is assigned a numerical value that reflects its confidence degree. Based on alternative operation plans, the final optimal operation plan of each machining feature and the corresponding machine tools can be produced using resource-constrained algorithms.