When the members of Holy Cross High’s “VEX” robotics team designed their wheeled, aluminum-and-steel robot resembling a miniature shopping cart, only one name would do: “Maximus.”
Maximus proved to be true to his name, taking top honors at last February’s State VEX Robotics Championship at the University of Louisiana at Lafayette. As a result, Holy Cross’ VEX team of seven ninth through 12th graders – a subset of the school’s larger, award-winning robotics team of 25 students – became one of three Louisiana teams to qualify for the World VEX Competition in Anaheim, Calif. In that contest, slated for April 23-26, the Holy Cross robotics students will compete against 15,000 of their peers from 25 countries.
Holy Cross’ strong performance also qualified the team to compete in another prestigious competition – the International VEX Competition in Honolulu, a July gathering that will welcome 80 high school robotics teams from around the world.
A ‘pushy’ robot
“The robots have to move BuckyBalls (plastic, softball-size orbs) and beach balls to different scoring zones of the playing field,” said sophomore team member Ricky Blount, describing the intense two-minute competition rounds in which the robot’s driver, using a control panel of levers and buttons, maneuvers the battery-powered robot over and under road hazards such as a two-inch high “speed bump” and a foot-high “overpass” obstacle.
Complicating matters is the fact that four robots take the field at once and have the ability to “de-score” points made by their opponents by moving the color-coded balls out of the scoring zones.
“We decided early on that we wanted our robot to be able to go over the bump and under the (foot-high obstacle),” Blount said of the team’s first design imperative. “Then we said, ‘Now, how are we going to design a chassis – or a base – for the robot to move?’”
While each competition robot must be made with VEX-manufactured parts, it is up to each team to design its own robot by integrating various accessories and materials.
Maximus features a steel chassis – designed in a U-shape to more easily capture balls – and a six-piece aluminum arm powered by 10 motors. This articulated arm, made of lightweight aluminum after team members realized Maximus’ original steel arm was causing too much stress on the motors, holds a basket for the collection of the smaller BuckyBalls, and “spinners” that capture and launch the beach balls.
“The VEX kit is really just a more complicated erector set – a bunch of pre-fabricated pieces that you can alter,” noted team member Lance Relle, a junior.
Maximus’ wheels went through a number of redesigns, with the team finally settling on a configuration that lessened the wear on the motors.
“Because we wanted the two front wheels to have different diameters, we had to gear one of them down to make sure they went the same distance,” explained team member Keefe Meyers, a senior, recalling how the robot’s original front wheels, which had the same diameter, tended to overheat the motors whenever Maximus turned.
“VEX didn’t have a gear ratio that could gear (the wheels) down correctly, so we had to do a bunch of mathematical calculations to put it in the program, so the wheels (of differing diameters) would go the same distance,” Meyers said.
Best in Louisiana
At the state contest, the Holy Cross team prevailed against the best 16 teams in Louisiana, earning the crown after 30 rounds of preliminary play.
The team won two additional awards at ULL: first place overall in the Drivers Skills Challenge; and the “Excellence Award” – for best overall performance in four categories: driver skills; engineering journal; team interview; and autonomous, the latter the phase of competition in which the robot must perform its tasks without the guidance of a driver. Instead, its every movement is pre-programmed into its microcontroller, or “brain.”
In the weeks leading up to the Anaheim competition, robotics team members were exploring the possibility of installing a pneumatics kit in Maximus’ arm, with the hope that pressurized air might enable him to hurl beach balls to their target instead of the robot having to push them toward their destination.
“It would save a lot of time if we could launch the ball across the field,” Blount said.
Speaking of time, the team’s moderator, Dale Turner, said he has been impressed by his robotics students’ grace under pressure. Holy Cross didn’t receive its kit of VEX robot parts until the second week of January. Most of their competition received their kits the previous April.
“We literally had a week before the first competition to build the robot,” Turner said. “It was a lot of work packed into a very small window. It was a steep learning curve for us!”
Beth Donze can be reached at firstname.lastname@example.org.