Sequence Planning Using Multiple and Coordinated Sequences of Operations

Abstract

The sequential behavior of a manufacturing system results from several constraints introduced during the product, manufacturing, and control logic development. This paper proposes methods and algorithms for automatically representing and visualizing this behavior from various perspectives throughout the development process. A new sequence planning approach is introduced that uses self-contained operations to model the activities and execution constraints. These operations can be represented and visualized from multiple perspectives using a graphical and formal language called Sequences of Operations (SOPs). The operations in a manufacturing system are related to each other in various ways, due to execution constraints expressed by operation pre-and post-conditions. These operation relations include parallel, sequence, arbitrary order, alternative, and hierarchy relations. Based on the SOP language, these relations are identified and visualized in various SOPs and sequences. A software tool, Sequence Planner, has been developed, for organizing the operations into SOPs that visualize only relevant operations and relations. Note to Practitioners-This paper proposes methods and algorithms for a new sequence planning approach in which sequences are automatically created based on the relations among operations instead of having to be manually constructed. Using various views, the sequences of operations related to, for example, part flow, robot operations, and operator tasks, can be visualized. The use of various views helps the user better understand the relations between cell control and mechanical design, and between product design and total system behavior.

Supremica–An Efficient Tool for Large-Scale Discrete Event Systems

“…Having a computable model has the added benefit that it can be used as a base for preparation and implementation assisted by formal methods. In a case study (Bengtsson et al, 2012;Dahl et al, 2016), Supremica was used as an aid in generating operation sequences for validation during production preparation. The result showed significant promise, and currently this approach is further developed together with a European manufacturing company.…”

Sequence Planner: Supporting Integrated Virtual Preparation and Commissioning

“…Using the algorithms described by Bengtsson et al (2012), a map of relations between the operations in the system can be calculated. In this case, three different types of sequences can be visualized by SP: sequences for the complete cycle, sequences for each robot, as well as sequences for each shared zone.…”

Discrete event dataflow as a formal approach to specification of industrial vision systems

“…This specification can be made on various levels of details. For example, in an automation system, operations can model a complete assembly of a product or sending a signal to an actuator [19]. In the Supervisory Control Theory [20], the controlled systems is modeled in a form of finite automata.…”