Robots and rodents: A rat and spider-legged robot make mobot history

Despite Friday's rain cancellation of buggy sweepstakes, the annual MOBOT competition takes place rain or shine. A light drizzle near the end motivated some participants to cover their vehicles with bags, but the rain for the most part was not a hindrance. This year's competition had several unusual entries, including a legged vehicle and a rat.

MOBOT, which stands for "MObile roBOT," is held each year during Spring Carnival on the 212-foot course in front of Wean Hall. The competition offers generous prize money, with $1,000 going to the first-place winner. The prize money is provided by the competition's sponsors - Lockheed Martin Corporation and Harris Corporation.

This year's competition had 12 entries, with six using the CMUcam system, five using traditional infrared sensors, and one using biological sensors (the rat). The CMUcam system is an inexpensive vision system developed at CMU. It utilizes a standard camera and handles image processing tasks to pick out the course line and can do color tracking.

Sebastian Scherer, a junior in computer science, won the undergraduate competition by reaching gate 11 in three minutes and 23 seconds. His team name was Kuhman. This was not Scherer's first success in MOBOT - he proved himself when he won the Open Class competition in 2001. Scherer also won this year's $99 Mini-Challenge which was held on April 2 as a preparation for the actual MOBOT competition.

Scherer's vehicle this year used two wheel encoders, a mercury switch, and a gate sensor. The gate sensor was a wooden stick which stuck off the side of the car and was triggered any time it hit the metal bar of a gate. By determining how many gates had been passed, the car could have more information for choosing a path through the decision point section of the course.

The decision points are at the end of the course where the white line splits several times and has the appearance of a circular pattern. The vehicles need to correctly decide whether to go left or right at each branch.

Scherer's car also determined when it was at the decision points by keeping track of total distance traveled and whether it had gone down the two hills on the course yet.

The car used a JStamp microprocessor board, which runs Java. "It's really fun to program," said Scherer, who liked being able to program the car using the object-oriented Java syntax.

The Open Class competition, which is open to anyone associated with the university, was won by team Jimmy: Alok Ladsariya, a masters student in computer science, and Anthony Rowe, a senior in electrical and computer engineering.

Ladsariya and Rowe also won the undergraduate competition in 2002 and 2001. Last year they delivered an impressive performance in which they completed the entire course, for the first time in undergraduate history.

This year they designed a new car that used CMUcam2, which is the successor to the CMUcam vision system. CMUcam2 has a higher resolution, and can do motion tracking using frame differencing. The new system is not yet available, but should become available within the next several months according to Ladsariya.

Their car was the fastest to ever navigate a significant portion of the MOBOT course. They reached gate 8 in 36 seconds. Ladsariya and Rowe explained that the improved capabilities of CMUcam2 helped them to achieve this high speed.

"A combination of higher frame rate and higher resolution let us look out further," said Ladsariya. The camera took images at 52 frames per second, a very large increase over the original CMUcam which does 17 frames per second.

Warren Saunders, a CMU graduate who competed in the Open division under the team name John Henry Project, had the most unusual MOBOT by far. His MOBOT was a rat named Pavlov. According to competition rules, "animals (except primates) may be used to assist with vehicle control as long as such use is humane." Saunders's rat created a great deal of interest - it was the first time an animal has competed on the MOBOT course.

Unfortunately, Pavlov the rat was easily distracted. She quickly wandered off the line to inspect more interesting things - like sticks, dirt, and candy wrappers. Pavlov also was probably not used to being near large crowds of people. Saunders trained the rat prior to the competition by rewarding her with pieces of tuna fish when she moved along the line far enough. Saunders said he trained the animal in sessions of no longer than two hours because it would get tired or bored after a while. A more intelligent animal, such as a dog small enough to fit through the course gates, would be easier to train, he said. He chose a rat this year because of the expense and difficulty of keeping a dog in an apartment. Saunders won the competition's Judges' Choice award.

A team named Hex developed a legged MOBOT - the vehicle, which looked roughly like a giant spider, walked on six legs. Hex was the first official legged entry in MOBOT history. According to the team members, the vehicle moved by pivoting around a single foot when it turned. The team redesigned their vehicle several times because initial attempts didn't work well.

The second place finisher in the undergraduate category was team Runaway. They passed the third gate in three minutes and 22 seconds. Their car was very slow, which team member James Chan Lianghong, a first-year in electrical and computer engineering, explained is because when they ran it at higher speeds they had problems with slipping on the course downslopes.

There was no third place finisher because teams are required to pass the second gate in order to receive prize money. The Pikachu team came the closest, passing the first gate in 29 seconds.