CONCEPT/STRATEGY

Ringo Starr, our robot, is named after the Beatles Singer for the robots general synonymous appearance to an actual beetle. This robot started out as a prototype with a skeletal structure consisting of simple gearboxes with a 125:1 gear ratio. Each of the two wheels were powered by one motor that had been "LEGOized". The first model of our robot had front and rear wheels with front wheel drive. The rear castor wheels seemed to get caught up on each other and this idea was quickly disposed of. Instead, the rear wheels were then replaced with ski-like structures in which the robot slides on. This structure proved to be much more functional for turns.

The initial strategy was to have a plow that doubled as a dumping mechanism to remove the opponent's balls from the board. With the time restraints, this idea was discarded in an attempt to focus on more important things such as driving straight in order to score our own balls.

In order to drive straight, a gyro was used. A program that determined how far off Ringo was from the desired angle was designed so that Ringo would correct the angle by compensating with a higher speed in the corresponding wheel. At first, the program was created such that Ringo could drive for a desired amount of time. The program was then modified so that a check for a bump sensor happened. When the bump sensor became activated, the robot was to do some desired action. This action was determined by the number of times the bump sensor was activated.

Another key task that Ringo needed to accomplish was orientation. In order to figure out the correct orientation, infrared sensors were placed in three corners of the robot. This seemingly simple task ended up being one of the most difficult things to accomplish. The Infrared sensors were very touchy and often came up with bogus readings. This was a problem that plagued our team during the entire competition. Fortunately, the infrared sensors did not fail in competition, but they were very inconsistent. It may have been better to use visible light sensors.

A defining feature in Ringo Starr's design that was much different than any other robot was the bumper wheel mechanism. The gyro was not extremely accurate, causing the robot to drift. When Ringo drifted into the walls, it would get caught up and stuck to the wall. To prevent getting stuck, wheels the parallel to the horizontal plane were attached on either side of Ringo Starr. This allowed for Ringo to wall follow rather than get stuck onto the wall. The unfortunate problem with wall following to go straight was that Ringo was only capable of capturing two balls if rolling against the wall. This was due to the one foot width restraint.

Since the best way for Ringo to straight was to glide along the wall, the wheels were extended using rods, but attached to rubber bands and on a turning axel. The wheels were set up such that they could be folded within the correct dimensions and released using a servo opening in the beginning of the round. This change proved useful and was a last minute change that happened after the seeding round.

The final design for Ringo Starr was stunningly close to that of the original design. The gear boxes originally constructed were the exact models used in the final bot. More bracing and strength was added to the original design. A concave structure was used to collect and push the balls into the scoring zones.