| Humanity's destiny in space is intimately tied to highly automated mechanisms, and as such, the ability for humans and machines to cooperate as an integrated team will determine the success of ambitious space missions of the future.; Technologies related to the Global Positioning System (GPS) have matured to the point where they are well suited for real-time control of autonomous vehicles both in space and terrestrially. This dissertation reports research performed in The Aerospace Robotics Lab to demonstrate new basic knowledge and techniques for using GPS to increase the sensing capabilities of free-flying space robots, and more generally, to explore how this advanced sensor can improve the capabilities of the human-robot team in space and on earth.; A comprehensive prototype system was built and demonstrated. The system consisted of a microcosm simulation of the space environment, two prototype space vehicles, consummate software systems, and an intuitive human-robot interface. The space environment was emulated through a constellation of GPS pseudo-satellites (pseudolites) and an air-bearing support system which provided the drag-free, zero-g characteristics of space in two dimensions for the prototype space vehicles. Proof-of-concept demonstrations showed that GPS sensing alone can be sufficient to perform precise intercept and capture of a free-floating target by an autonomous free-flying space robot. Other demonstrations showed how this type of sensor could enable unprecedented capabilities in space such as performing distributed science missions using several vehicles flying in formation.; The breakthrough of Differential Carrier Phase GPS technology, combined with the novel, inexpensive local GPS pseudo-satellite transmitters, enabled the successful in-lab demonstration of GPS-based control for precise robotic navigation. Since the experiments were carried out indoors where GPS satellite signals could not be received, the constellation of six GPS pseudolite transmitters was used exclusive of the NAVSTAR GPS satellites. The indoor GPS environment created by the close-range pseudolite transmitters required development of new algorithms for resolving vehicle positions and attitudes from the carrier phase measurements.; By performing these proof-of-concept experiments, many new arenas for application of GPS sensing have been conceived, ranging from the use of pseudolites for advanced space missions to sensing of mobile manufacturing robots. |
