Reconfigurable Distributed Controller for Welding and Assembly Robotic Systems: Issues and Experiments

Industrial production systems for smart factories or the so-called Industry 4.0 will demand high interoperability and connectivity between production modules, so that modules could be monitored in real-time. Production modules should make decisions on their own without human intervention; and they must be modular and adaptive to changing circumstances and customers’ requirements. The autonomous operation of production modules in smart factories imposes asynchronous delays due to several reasons, such as object recognition time, grasping time or welding delays that change due to a newly reoriented or positioned component. Consequently, production modules need to be speeded up to compensate for the delays in the previous production stages. In this paper, we present a novel Reconfigurable Distributed Controller (RDC) for Intelligent Robotic Welding and Assembly Systems that autonomously compensate the production delays. The proposed RDC compensates for three types of major production delays that affect the total production time. (I) The first delay can occur at individual level. In this case, the module can fully compensate, since no other modules are affected and the total production time for this product can be met. (II) The second type of delay occurs at inter-module level, where delays are so long that more than one production module will need to be reconfigured. (III) Finally, the third type of delay occurs in the worst-case scenario when the total production time cannot be met by modifying individual module’s production time. A total cell reconfiguration is needed, which implies to speed up the next production cycle to deliver the following product before its deadline. By doing so, the mean production time is maintained. In this paper, issues and experiments that show the feasibility of the RDC are presented. Results of using a distributed reconfigurable manufacturing cell composed of three industrial robots, conveyor belts, and a positioning table demonstrated the effectiveness of our approach to compensate the major delays in real working environments.