This paper derives a decentralized object impedance controller (DOIC) especially suited for use by a team of robots and/or multiple manipulators. In contrast to the original object impedance controller (OIC), a separate DOIC operates on each robot to provide local computation of the manipulator force commands, thus removing the need for expensive high-bandwidth communication of force signals between the robots. The key advance of the DOIC that provides this benefit is a decentralized algorithm for estimating the external force on the object. This paper derives the DOIC, provides stability analysis, and verifies the theory with definitive physical experiments.

This paper presents an approach for the symbolic dynamic modelling of object/robot-team systems composed of an object manipulated by a team of r robots. The modelling approach merges the dynamic models of the object and robots into a system model. Derivations show that the system acceleration can be computed with complexity proportional to r. This paper demonstrates in a detailed example with physical experiments how the modelling approach can be used for symbolic analysis of a closed-loop object/robot-team system.

This paper presents the results of laboratory experiments performed at the Aerospace Robotics Laboratory (ARL) at Stanford University from 1987 to 1993 that successfully demonstrate a team, of two-armed free-flying robots capturing, transporting, and docking a large, freely moving object. In these experiments, the object and robots float on a thin cushion of air over a granite surface plate, simulating with high fidelity in two dimensions the drag-free, zero-gravity conditions of space. A human user indicates a desired object location and orientation through a graphical user interface. The self-propelled robots then capture and so position the object, with no additional input required from the user: the human is at the task-defining level. On command, the robot team docks the captured object with a stationary second object. The paper discusses the experimental facility, the control hierarchy that supports object-based task-level control, and the controllers for the object and robots. Experimental results are then presented for the capture, transportation, and docking of the object.