Assembly Sequence Planning with Deformable Linear Objects in the Smart Factory: Dilemmas and Injections

Abstract

Smart factory consists of extensive automation (e.g., robotic actors) and minor human interventions. Additional characteristics are manufacturing a variety of products rapidly and accurately. Many of the products contain rigid objects assembled with deformable ones, especially deformable linear objects (DLO) such as wires. Deformable object behavior results in modifications of objects' shape and position thus influencing assembly processes. Assembly sequence planning (ASP) is an intractable issue in production management. ASP in a robotized environment such as the smart factory with objects deformations is even more challenging. Deformable objects assembly by robotic actors increase uncertainty and influence factory performances. The theory of constraints (TOC) suggests tools for improving factory performances by concentrating on production flow. The literature is lacking TOC-based tools investigating smart factories and Industry 4.0 aspects. One of TOC thinking process tools is a conflict resolution diagram. This diagram describes a dilemma influencing achieving desired goal and aids in identifying potential solutions (called "injections"). This paper describes ASP dilemma in smart factories regarding robotic manipulation with deformable objects. The dilemma between generic, unified automatic assembly on one hand and customized, designated assembly, on the other hand, is elaborated. An entity called "interaction" is introduced as an injection to the smart factory ASP dilemma. Interactions are defined based on physical, geometric, and manufacturing attributes. Defining interactions categories is an important step toward comprehensive automation of assemblies containing deformable objects. By so interactions are promising direction from both research and industrial perspectives for robotic ASP with deformable objects in smart factories.