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Colloquium - Voyles

Wireless Video Sensor Networks over Bluetooth for Small Search and Rescue Robots
University of Denver

Urban Search and Rescue (USAR), which generally implies collapsed structures, presents a challenging environment for robotics research because of profound difficulties in sensing, mobility, and communication. Sensing is difficult due to poor lighting, high clutter, the lack of engineered landmarks, and airborne particulates. Mobility is difficult due to the quantity and variation of rubble, the variation in surfaces and obstacles, and the need for small size to access small spaces. Communication is difficult because wireless is hindered by concrete, steel, and water; antennas are de-tuned by close proximity to unpredictable ground planes; and tethers get snagged in the environment.

In this talk I plan to touch on aspects of all three of these difficulties. The core of the talk discusses our efforts to develop multi-hop ad-hoc networking over Bluetooth for urban search and rescue robots. We completely abandon the idea of single-hop communication as unsuitable for the environment and embrace multi-robot networks. Multi-robot teams can solve the communication problem, the search coverage problem, and the search speed problem if an appropriate infrastructure can be developed. (We'll ignore, for now, the problems multi-robot teams create.) We choose Bluetooth over Zigbee because its higher bandwidth is better suited to the high resolution imagery required for USAR and the power budget and complexity are better suited to small, resource-constrained robots than WiFi. We have developed a hybrid routing protocol that combines the latency benefits of a proactive protocol (cluster head gateway switch routing) when a broken link is discovered with the overhead benefits of a reactive protocol (similar to ad-hoc, on-demand distance vector routing) in a highly volatile network. We show preliminary results in simulation and implementation that this new hybrid protocol outperforms other protocols for sparse, highly volatile networks required for the USAR domain.

To put this work in context, I will also discuss the TerminatorBot, the soda can size, two-limbed, crawling robot we use for exploring voids and difficult-to-reach spaces. Its small size means it must be very agile to deal with the great variability of the environment. To enhance its self-adaptability, we are developing a reconfigurable computing platform that allows both hardware and software dynamic reconfiguration in response to unknown terrain.

Department of Computer Science
University of Colorado Boulder
Boulder, CO 80309-0430 USA
May 5, 2012 (14:13)