Parrots: A Range Measuring Sensor Network

This paper presents the implementation and design of a wireless sensor network developed to facilitate indoor mobile robot localization. The sensor network consists of homogeneous nodes, termed the Parrot, that can measure range to other nodes within the network using ultrasonic signals. This information provides algorithms running on mobile and static nodes to analyze and learn their physical location within the network. Since the location of the nodes can potentially change with time, the system we have developed allows us to “map” the topology of the network from the range measurements in a nearly dynamic manner. Through the use of a media access control scheme the Parrots are able to coordinate node transmission timings. In addition to the control scheme, Parrots are also able to switch between four different operational modes that manage the information flow between the nodes. The system has been successfully tested to localize and map individual nodes within an office environment. We present experimental results of accurately mapping and localizing the network structure with the presence of a mobile node.