Experimental results of two free-flying robots capturing and manipulating a free-flying object

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