It started out as a kit called the Mark III available from the Portland Area Robotics Society. I highly recommend this kit as an excellent starting place for anybody interested in getting into robotics. It is very expandable and very cost effective.

A Mini-Sumo robot needs to fit in a 10cm square tube and weigh under 500 grams. The official Mini-Sumo rules are available from the Seattle Robotics Society.

Well, I finally decided to post Marauder's source code. Marauder.zip contains all of the source, along with the Makefile. The makefile is setup to run under cygwin, and you'll probably need to modify paths to make it build.

Marauder made its first appearance at the North West Robot Sumo Tournament. At the time his name was called "Blue" after the tires. I received the kit two weeks before the competition. It took one evening to assemble the kit and the remaining two weeks to program it. Unfortunately Blue was eliminated by its first two opponents: Goliath and RAM. Sigh. Bigger...

After the NWRST, I decided to make some tires which had more grip. You can see the original tires at the top, with blue elastic bands around a hard plastic hub. I filed the half circles using a circular file to make sure that the tire didn't slip. Bigger...

Here's a closeup of the new tire. Click on the link to see more information about making the tires. Details...

This picture was taken by Rick Washburn at Robothon. Here Marauder is sporting the new grippy tires, and a couple more batteries. I mounted the batteries over the scoop to give more weight on the front, and to provide more speed. There are 6 NiMH AA cells for the motors, and a 9v battery for the controller. Bigger...

Another picture taken by Rick Washburn of a rather unfortunate encounter with Goliath. At Robothon, Goliath beat Marauder, Marauder beat RAM, and RAM beat Goliath. Nemesis beat them all. By luck of the draw, Marauder took 2nd place. Bigger...

Marauder got a flag, and a couple more line sensors (one for each of the the screws you see at the top of the scoop), as well as some additional electronics for the additional line sensors. Bigger...

I removed the mounting tabs from the line sensors, and bolted the AA cell holder directly to the chassis. This allowed the battery holder to be moved up and forward. The most significant advantage is that the battery holder no longer projected out the back, disturbing the wheel profile. This means that Marauder can be tilted back quite far before losing traction. Bigger...

Here's the same view as above, but with the wheels removed. I used some small pieces of magnet wire to help organize the wires. The magnet wire over the servos was originally to keep some weights in place, and to keep the servo sires from getting into the wheels. Since I added the batteries on the front, I don't need any extra weight. Bigger...

This is the front view, and you can see the main sensors. Click on the link for more details. Details...

Here you can see the five line sensors. Only the outer two are used for Mini-Sumo. All five are used for line following. Click the link to see more information about how the battery case was mounted. Details...

Here you can see a better view of the circuitry for the extra line sensors. I also added a couple of slide switches. You can see one of them just above and to the right of the brown circuit board. One of the switches toggles between Mini-Sumo and Line-Following modes, and one of them provides an initial Left/Right hint for the initial direction to turn in Mini-Sumo. I've never actually used this feature, but it's there. Bigger...

Nothing new here. You can see my attempts to keep all of the wires neat and tidy. Click on the link to see more information about the line sensor circuitry. Details...

Another View. Bigger...

An extra scoop was added for line following so that the Mini-Sumo scoop wouldn't catch on the lines. The lines at the WCRG line following contest were basically black electrical tape laid on a white surface. Bigger...

The scoop started out as a piece of brass tubing. For anybody who thinks that this was a wimpy line following track, check it out here. Bigger...

This is a closeup the removable line following scoop. I made a paper template of the outline of the line sensors and transferred this to the brass tubing. Some careful cutting with tin snips and some filing gave the finished outline. Bigger...

Bottom view of the scoop. The nuts are soldered to the bottom. A screw comes through a folded over piece of brass, which allows the scoop to friction fit on the Mini-Sumo Scoop. Bigger...

Here are some pictures of the prizes that Marauder has won. Details...