Experimental Testbed for Large Multirobot Teams
General Robotics, Automation, Sensing and Perception Laboratory
Experimental validation is particularly important in multirobot systems research. The differences between models and real-world conditions that may not be apparent in single robot experiments are amplified because of the large number of robots, interactions between robots, and the effects of asynchronous and distributed control, sensing, and actuation. Over the last two years, we have developed an experimental testbed to support research in multirobot systems with the goal ofmaking it easy for users tomodel, design, benchmark, and validate algorithms. In this article, we describe our approach to the design of a large-scale multirobot system for the experimental verification and validation of a variety of distributed robotic applications in an indoor environment. Our research focusses on decentralized multirobot algorithms that rely on an integrated approach to mobility, perception, and communication, with such applications as environmental monitoring, surveillance and reconnaissance for security and defense, and support for first responders in search and rescue operations . In all of these applications, robots must rely on local sensing, computation, and control and exploit the availability of communication links with other robots whenever possible. To enable scaling up to large numbers, computations must be decentralized, and the systemmust be robust to changes in the numbers of robots and to the dynamic addition and deletion of units. There is also the need to provide some degree of centralization with an interface to one or more human operators for programming, tasking, andmonitoring of the system. These research applications serve as the motivation for our experimental testbed. While there is a rich body of work to build on, there is currently no inexpensive multirobot system that allows users to move easily from conceptual ideas to algorithms and then to experimentation. We begin by motivating design considerations for the testbed in the context of our research and existing multirobot control and experimental architectures.We next arrive at a set of design requirements for the system based on the driving applications as well as practical considerations. Most importantly, we are driven by the pragmatic considerations of ease of use, robustness, flexibility, and scalability to enable the easy inclusion of more robots and sensors with minimal changes to the existing infrastructure. We also review some of the applicable hardware and software options currently available. The experimental testbed is discussed in detail with overviews of the robots, software, and the supporting infrastructure required for multirobot experiments. Since simulation is of great relevance in the experimental process and the testbed design, we discuss its role and detail the transition from simulation to reality. Finally, we present several multirobot experiments for formation control and cooperative manipulation, which demonstrate the capabilities of the system for verification purposes and elucidate the experiment design process with our testbed.