This paper presents contributions on the use of abstractions in modular control of discrete event systems. First, the W ○ T-strategy is presented for the construction of abstractions for the nonconflict test of local modular supervisors. Second, an efficient computational tool is introduced for the problem of verifying if given abstractions of modular supervisors satisfy the so-called observer property (OP); the observer property plays an important role in the validity of the nonconflict test over abstractions. Finally, this new computational tool is used to validate the W ○ T strategy in the context of a case study of a comprehensive manufacturing example.
supervisory control; discrete event systems; modular control; observer property
