Autonomous Cooperative Robotics Testbed

A robotics demonstration test-bed has been constructed at NASA GRC to provide a facility that will allow robotics researchers to implement and test their multi-robot algorithms on a real hardware system and enable them to validate the feasibility of using autonomous robotic sensor platforms to perform inspection operations. The demonstration test-bed resides in a laboratory environment and consists of an 8’ x 6’ horizontal arena populated by a team of demonstration robots that serves as the hardware platform upon which control algorithms can be implemented and tested (Figure 2). The arena design is flexible, with moveable obstacles of arbitrary shape and quantity. Electric current-carrying copper tape is used to make the obstacles and arena boundaries detectable by the robots’ proximity sensors.

The arena is surrounded by an optical motion-capture system manufactured by PhaseSpace Inc. This system will be used to track the positions of each robot in real-time during experiments. The motion-capture data can be used as a control input for online processing/analysis while the experiment is running, or kept as a record of the experiment for off-line analysis.

This measurement system is composed of a Linux-based server/hub connected to linear Charge Coupled Device (CCD) cameras, each of which possesses a 60° conic field of view. Three such cameras are ceiling mounted and have been positioned and calibrated to allow full view of the entire arena surface. The CCD cameras are used to track Light-Emitting Diode (LED) markers mounted on each of the robots. Each of these LED markers is set with a unique flashing frequency by a wireless control box. As a result, the tracking system is capable of differentiating the various markers. The system perceives markers at a maximum of 480 frames per second. The position of each marker, in terms of Cartesian coordinates, can be reported with a latency of 20 µ-secs over an Ethernet connection, thereby allowing the tracking system to track and record the position and orientation of each robot over time during the course of experimental runs.

Although restricted to 2-dimensional motion, the demonstration test-bed will allow for the integration and validation of cooperative search algorithms with real hardware robots. This capability is invaluable since it provides the opportunity to confront the challenges and limitations associated with implementation on a real-world system. Additionally, it will enable the transition of the concepts to a more realistic 3-dimensional test-bed.

Publications

Litt, J., Wong, E., Krasowski, M., Greer, L. Cooperative Multi-Agent Mobile Sensor Platforms for Jet Engine Inspection—Concept and Implementation. KIMAS, Boston, 2003. pp 716-721.

Wong, E., Litt, J. “Autonomous Multi-Agent Robotics for Inspection and Repair of Propulsion Systems”. AIAA 1st Intelligent Systems Technical Conference, 2004.

Wong, E., Saad, A., Litt, J. “Towards Autonomous Inspection of Space Systems Using Mobile Robotic Sensor Platforms”. AIAA Space 2006 Conference, 2006.

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last updated: 2.29.08