IWL's Maxwell Pro At DARPA Robotics Challenge Test Bed
Key issues: robots’ handling of burst traffic, port numbers, and bandwidth limitation
IWL, experts in network emulation and degraded communications solutions, tested its Maxwell Pro Network Emulator at the DARPA Robotics Challenge (DRC) Test Bed at Joint Base Charleston, South Carolina in March 2015.
In anticipation of the DRC Finals (June 5-6, 2015 at the Fairplex in Pomona, California), DARPA created a Test Bed for the participating teams to optionally experiment with the tasks and communications setup that will be implemented at during the finals event. Acting as a Degraded Communications Emulator (DCE), the Maxwell Pro will simulate the types of adverse network conditions that occur during real-world disaster events (such as Fukushima, Hurricane Sandy, etc.)
The Test Bed consisted of four test tracks with a communications infrastructure. The two main goals for the experiment were:
To assess the network and wireless systems and to ensure capability with the robot and operator controls. Multiple robots performed on multiple courses concurrently to create these conditions.
To assess the performance of the robots in tasks similar to those tasks at the Finals.
During the testing activities, IWL and its Maxwell Pro helped teams improve the robustness of their systems. Maxwell Pro introduced patterns of selective and periodic rate limitation and packet size limitation.(1) This created a challenge for the communication between the robots and the Robot Operator Control Station.
Teams explored the interaction of their software with little-examined, but serious, network conditions such as traffic bursts. Maxwell Pro introduced controlled traffic blackouts and rate limitation. Because these real-life network limitations often cause packets to be dropped, teams must use care in the design of the communication pathway to avoid bursts of packets. Buffering and limits on buffering are a key issue on the Internet. Maxwell Pro helped teams understand how their software is affected by these issues.
Teams must follow the rules for the use of assigned port numbers.(2)
Finally, some teams expected bandwidth limitation to follow a synthetic pattern, similar to a metered onramp on a freeway entrance. However, the degraded communication emulation uses a realistic algorithm more like multiple cars arriving to cross a one-way, one-lane bridge. The synthetic pattern is less realistic, but easier to work around.
The DRC Finals event, to be held June 5-6, 2015 at the Fairplex in Pomona, California, will test the ability of 25 robots to perform specific tasks; robots will communicate with their operators over a wireless network.
IWL is excited to be involved in the DRC competition and the effort to improve robotic communications. For a full description of the type of Communication Degradation planned at the DRC Finals, please refer to the Robot Communications Document.
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(1) DRC Finals Rule Book DRC Finals Rule Book, Part 2. Communications between Operator and Robot for the DRC Finals, 3.7.1 Throughput Restrictions
(2) DRC Finals Rule Book DRC Finals Rule Book, Part 2. Communications between Operator and Robot for the DRC Finals, 4.2 IP Version, IP addresses, Subnets, Ports, and Packet Size.