Experimental Object- Level Strategic Control With Cooperating Manipulators

Abstract

This article presents the high-level control module and user interface of the Dynamic and Strategic Control of Cooperating Manipulators (DASCCOM) project at Stanford University's Aerospace Robotics Laboratory. In addition to cooperative dynamic control, DASCCOM incorporates real-time vision- based feedback, a novel strategic programming technique, and an iconic "object-only" graphical user interface. By focusing on the vertical integration problem, we are examining not only these subsystems, but also their interfaces and interactions. The control system implements a multilevel hierarchical structure interconnected via a real-time network. At the highest level, a mouse-driven graphical user interface allows an opera tor to direct the activities of the system conceptually. Strategic command is provided by an event-driven finite state machine. This methodology provides a powerful yet flexible technique for managing concurrent system interactions. The dynamic controller implements object impedance control —an extension of Neville Hogan's impedance control concept to cooperative multiple-arm manipulation of a single object. This article concentrates on user interfacing techniques and strategic programming capabilities. These modules allow the user to directly specify conceptual object relationships. Experimental results are presented, showing the system lo cating and identifying a moving object, "catching" it, and performing a simple cooperative assembly. Each of these operations is executed autonomously, with only object-level task-specification direction from a remote operator.