Development of a Real-Time Control System Architecture for Automated Steel Construction

Abstract

The National Institute of Standards and Technology (NIST) is developing a real-time control system for a robotic crane (the NIST RoboCrane) that will perform automated structural steel pick-and-place operations. The control system architecture is based on the NIST Real-time Control Systems (RCS) reference model, which defines a system development methodology and a hierarchical control architecture in which system tasks and associated information are decomposed and organized into more easily manageable components or subsets. The task of picking and placing a structural steel beam was decomposed into multiple sub-task levels that must be performed in order to complete the pick-and-place operation. Tasks were decomposed from high-level operator input, such as Install Beam A down through the controller to the sensor and actuator level on the crane, at which, for example, voltages are computed and output to individual motors. Each level was organized into a series of control nodes each responsible for executing the sub-tasks at that given level of control. The control nodes share a common generic node model for sensor information processing, world modeling, and behavior generation. The control system development effort and its implementation on RoboCrane are presented in this paper.