RFC Cambridge is a Robocup team that is a joint effort between the MIT Competitive Robotics Club, and the Harvard College Engineering Society. We’re in our second year competing, with the international deadline coming up soon. For RFC, I’ve done a variety of different things. Last year, my largest single contribution was the refbox. Robocup uses a serial connection to send referee commands to each team. I developed a drop in component for our AI system that could read the commands from a serial port asynchronously. To avoid reinventing the wheel, it was composed of two subsystems. One was the serial reader, which read from the serial port, and placed any received values into a memory mapped file used as a buffer. The serial reader was in Managed C++, and used the Microsoft .NET serial reader class. Inside the actual AI was an unmanaged C++ component which read from the same memory mapped file buffer to read the commands.
Strictly speaking, the design was non-thread safe, and avoided issues mainly by having a guarantee that the input data could not exceed the size of the buffer, to cause a wrap-around race condition, and that each thread would never be in the same area. While not the best design, it was sufficient for our needs. Since the AI was reading the buffer every 33ms (or so), and there was no way possible that more than 255 commands would arrive in that 30ms, there was never an issue.
Another major unused contribution was a new pattern recognition system that was part of the vision module. This was to have been used to detect the location and orientation of each robot, using a “butterfly” pattern, rather than the much simpler two dot pattern that our team used. However, because of time constraints (it was written about 3 days before the competition, and fully integrated the day before the team left) it was not used at the international competition.
I also developed a small control system that allowed users to drive our robots with an Xbox 360 gamepad. This was useful for non-autonomous demos, as it allowed more effective control of the robot. It was done over the course of about two days, using C#, and a third party wrapper for the XInput technology with the Xbox 360 Gamepad for PC. It worked quite well, and was rather popular with people when we were doing demos at the MIT Activities Midway, as we could allow students to drive the robots, without any real training (one thumbstick to drive, the triggers to rotate), and it was fairly intuitive.
This year, I’ve been doing bits here and there, and will probably redevelop the 360 control system for our new platform (which is quite a change, but I’m not sure I can post about it just yet). Otherwise, I’ve mostly become the web guy. This is mostly because I know how to get at the servers (I didn’t make it complicated, that was someone else), and I’m one of the few people who has a lot of web development experience (4 years, including 2 years profesionally). This is the latest page I’ve done, which uses Lightbox, a rather neat little set of Javascript to display full size images as an overlay on the current page. I also redid the HTML for the main site, to replace a mess of tables from Dreamweaver with a CSS version of the same thing. It reduced the page size by about 50%, and also makes it much easier to read. I’m planning to port the existing content into some sort of script, so that changing one link doesn’t require editing every page, but that is a bit off yet (I need to sort out what the web server actually runs).
