Experiments on Robotic Capture of Objects in Space

Abstract

In this paper, we describe an experimental facility for studying robotic grasping of objects in space. This problem arises in several applications, including on-orbit servicing of satellites and removal of space debris. The facility is based on a novel concept for experimental evaluation of robotic capture of freefloating objects. The central idea behind it is to use a small helium airship to emulate a free-floating object. Over the past year, a facility has been developed at McGill University to implement this concept in a laboratory setting. The main components of our facility are: a seven-degree-of-freedom robot, a spherical helium airship 5 ft in diameter, a stereo-based vision system and control hardware. One key issue that had to be addressed for the airship is how to make it balanced and neutrally buoyant. Control architecture has been developed allowing the airship to fly under computer control. The function of the robot is to intercept the airship and grab it by a grapple fixture. A ‘look then move’ visual servoing architecture has been implemented allowing the robot to follow a target. The paper describes the main components of the facility and the algorithms implemented for balloon balancing, robot control and visual servoing.