A formal structure and implementation of a robotic material handling controller in an automated shop floor environment

This paper proposes a formal structure and framework for a robotic material handling (MH) equipment-level controller in a hierarchical shop floor control architecture. This framework essentially attempts to integrate shop-level process planning with material handling at the workplace. Handling operations are therefore integrated with manufacturing functions in order to ensure 'seamless' material transfer and processing. The responsibilities of the MH equipment controller include: interface with a MH robot; read and interpret handling plans from a database (in the form of an AND/OR graph); plan and schedule MH activities; perform path planning and grasp planning for the required task; generate generic robot-level commands automatically; and convert generic robot-level commands to robot-specific instructions. A MH equipment-level controller has been designed and implemented for a PUMA 560 robot in the CIM lab at the Pennsylvania State University. The proposed controller can work for various situations and job volumes. In addition, by creating the framework described in this paper, extending the concept for other parts and obstacles with various features, coordinating the vision system or the CAD system to the proposed controller, and combining complete path planning and grasp planning systems, a fully operational MH equipment-level controller can be realized.