Network protocols for mobile robot systems

Communications and communications protocols will play an important role in mobile robot systems able to address real world applications. A poorly integrated "stack" of communications protocols, or protocols which are poorly matched to the functional and performance characteristics of the underlying physical communications links, can greatly reduce the effectiveness of an otherwise well implemented robotic or networked sensor system. The proliferation of Internet-like networks in military as well as civilian domains has motivated research to address some of the performance limitations TCP suffers when using RF and other media with long bandwidth-delay, dynamic connectivity, and error-prone links. Beyond these performance issues, however, TCP is poorly matched to the requirements of mobile robot and other quasi-autonomous systems: it is oriented to providing a continuous data stream, rather than discrete messages, and the canonical "socket" interface conceals short losses of communications connectivity, but simply gives up and forces the Application layer software to deal with longer losses. For the Multipurpose Security and Surveillance Mission Platform (MSSMP) project, a software applique is being developed that will run on top of User Datagram Protocol (UDP) to provide a reliable message-based Transport service. In addition, a Session layer protocol is planned to support the effective transfer of control of multiple platforms among multiple control stations.