The Battling 'Bots of Bloomsburg

Cheers and yells reach a fever pitch as the sound of metal bashing on metal echoes off the high walls of the futuristic arena. The two warriors circle each other, looking for a chink in the carefully crafted armor, swinging hardened blades and weighted hammers. Suddenly, a well-placed thrust of a spinning blade pierces a briefly exposed underbelly and one of the warriors is sent to a screeching "death," eliciting unbridled shouts of success from the champions of the victor. No, this is not the latest episode in a revised Gladiator or Star Wars flick, but the robotics-laced culmination of many hours of computer-aided-design (CAD) and computer-aided-manufacturing (CAM) in Kirk Marshall's industrial technology class at Bloomsburg Area High School in Bloomsburg, Pennsylvania.

	Kirk Marshall (center) discusses BattleBot robot design with his Bloomsburgh Area High School industrial technology students.

"About five years ago," says Mr. Marshall, "we were working on some robotic projects that dealt with the Technology Students Association (TSA) when an exchange student from Germany approached me with an enthusiastic request. He had been watching a cable show featuring battling robots, billed BattleBots®, that are built by competing teams and display a great deal of design expertise. Intrigued, I watched the next show that aired and quickly saw how these BattleBots could expand the CAD/CAM curricula in our classroom."

Turning to the internet, Mr. Marshall went to BattlebotsIQ.org and learned that they were looking for high schools to get involved in an educational challenge, bringing the professional version of the show to the high school level and providing a new engineering opportunity for the students. Battlebots, Inc. has the National Tooling and Machining Association (NTMA) as a sponsor and provides the curriculum for designing and building 120 lb. robots and 15 lb. mini-robots. They also hold national, and soon regional, tournaments for teachers and students to show off the fruits of their industrial tech labors.

"In designing our first 120 lb. battling robot," says Mr. Marshall. "we had to be really creative in matching the design parameters to the types of materials and components we would be able to obtain. Not having very much of a budget to work with, we reached out to neighboring businesses and industry for contributions of materials, relays, wiring, and other parts needed in the construction phase. It's amazing how receptive those businesses are to helping out students embarking on an exciting new engineering curriculum. We received donations of aluminum, titanium, voltmeters, and a plethora of other needed components and devices. In exchange, we put their corporate logos on banners in the school and at the competition arenas, as well as on our BattleBots, much like a NASCAR race. Our students held 'basket bingos' and other fund raising activities in order to purchase those items not donated. We went online and purchased some Bosch EV (electronic vehicle) motors that had been recommended by a number of robot builders as being effective yet modest in cost. We also purchased, for $1,200, a high-end remote control system that would ensure performance-as-planned. All told, we spent about $2,000 in cash, mostly raised by the students, yet received over $30,000 in donated materials and devices from the surrounding business community for an ongoing BattleBot engineering program. These companies have continued to invest in our programs because they see what we are doing - teaching practical applications of math and science in results-oriented industrial technology - as an answer to their own future need for a productive workforce."

	Mastercam software is used to program the tool paths for machining the many structural components that go into each robot.

Designing and building one of these complex robots, according to Mr. Marshall, would be virtually impossible without CAD/CAM capabilities. Mastercam® software from CNC Software, Inc. is used to design all the intricacies of the robot, from the framework to the outside armor, and then program the toolpaths for machining the components on the classroom's CNC machine tools. They machine each piece out of wood first to proof the program and then machine the final piece out of metal, usually aluminum. There are 15 Mastercam programming workstations set up in the classroom. "Mastercam lets us program holes, contours, and surfaces," says Mr. Marshall, "to tolerances that often need to approach a thousandth of an inch."

When designing the robots, the work envelopes of the machine tools must be taken into consideration. Their Grizzly CNC bench top mill, for example, has an X-Y capacity of 19" by 6", so no part can exceed these dimensions. They also have a Techno-Isel CNC router, as well as welding equipment for final assembly. For each piece, a computer file record is maintained. If a piece needs to be duplicated down the road, due to breakage, for instance, it can be done so quickly to keep the project moving forward.

There are hundreds of components in each 120 lb. robot that must fit exactly. It is important to put as much power into those 120 lbs. without going over by a single ounce. Even one ounce over would disqualify the robot from competition. "Our first robot," says Mr. Marshall, "was about 30 lbs. over the weight limit. We used Mastercam to determine how much material had to be removed, based on weight-per-volume of known materials, and then programmed new toolpaths to pocket out the various framework segments while still maintaining structural integrity. This brought the robot in at just under 120 lbs. and prevented disqualification. The kids were thrilled."

	Kirk Marshall with four of his BattleBot design team members.

During the past five years, Mr. Marshall's class has designed five completely different BattleBots and built several more based on those five basic designs. Sometimes the parts do not act as efficiently as planned. Or, the dimensions may not give the proper ground clearance once the arena floor starts becoming peppered with debris from damaged robots, decreasing its 'battling' efficiency. Or, drive and weapons motors may lack the endurance factor to complete a match. "Initially, the motors we were using failed to handle the high current load we were demanding of them," says Mr. Marshall. "But then, they weren't designed to do what we were asking of them. Some motors we were over-volting to get higher RPMs or more horsepower and they ended up melting down. Over the years we've changed entire drive concepts and construction methods as we've learned the intrinsic capabilities of the parts and materials available to us. By the same token, we've stuck with those that have proven themselves more than capable in the rugged environment of the BattleBot arena."

The time frame for the design and manufacture of a BattleBot fits nicely into the school year, leading up to the annual national competition. "About 28 of our students are involved in the robotics program and it takes about three months for all the design work," says Mr. Marshall. "That includes everything from the drive train, to weapon assembly, to sizes and densities, to making sure it can be done in a 120 lb. envelope. Once the design work is done, it takes only about a month to build the robot. We're taking each individual part out of the program, machining it, and assembling it into the whole. Remember, the robot already exists in the computer. Once we know that it functions on-screen, we can begin the actual build. But, we learned early on that certain glitches can occur because we did not take something or other into consideration. When we started putting wiring into our first robot, we realized we had not allowed enough space. We had designed a very compact robot with very little extra space. Oops! We couldn't close the top of the robot. Going back to the CAD program, we redesigned some of the framework to accommodate all the wiring for our speed controls and our controllers. It worked! We were learning the need for design creativity that has helped guide us past pitfall territory with ensuing robots."

	After the program is proven on the computer, the structural components are machined on a CNC milling machine.

The Bloomsburg 120 lb. BattleBots use one drive motor for each wheel to achieve 4-wheel drive flexibility in the arena. Weapon assembly is designed to be mean and powerful. Last year, a robot named "X" had four Milwaukee drill motors spinning a 24 lb. tool steel blade at 3,000 RPM. "This year," says Mr. Marshall, "we're going down to two motors to power that same blade, but they're heavy-duty servo motors rated at 3 HP each. This will give us 6 HP powering that top blade, which is a little scary. If it works - other robots, beware!"

Another BattleBot in their arsenal is named "Chrome Dome." It has a 42 lb. spinning upside-down "wok"-shaped shell, laced with projecting tool steel teeth, welded to structural steel ribs, as its weapon. Eight drill motors power the shell and bring it up to a speed of 3,000 RPM within five seconds. In the arena, the BattleBots move at speeds up to 12 MPH, fast enough to move quickly from point A to point B, but not so fast as to create a control problem. The students become very adept at developing good hand-eye coordination during many hours of practice runs. The arena itself measures 30 x 30 feet with 8-foot high, inch-thick clear Lexan® walls and ceiling to prevent "pieces of Bot destruction" from flying out into the audience.

At last year's 2005 National Competition, held at Universal Studios in Orlando, Florida, over one hundred high schools and twenty-five colleges and universities, including MIT, Carnegie Mellon, and Penn Tech, brought more than 150 robots to square off in the BattleBot arena. Kirk Marshall and his 8-student team entered four robots in the 15 lb. and 120 lb. matches, each displaying the logos of their primary sponsors that included Milwaukee, Mastercam, Harley Davidson, and Merck. After 4 days of 12-hous a day competition, they had won 9 straight matches in the 15 lb. class and were awarded the prize for 2nd Place in performance. They also walked away with the prestigious "Best Overall Engineered Robot" award. In the 120 lb. class, "Chrome Dome" won its first match, but proved to have too much kinetic energy for the drive train design and the drive motors burned out due to the gyroscopic effect of the spinning "wok" weapon during the next two battles. Their "X" robot, after seven wins at last year's competition, also had a few weapon motor problems…in this case spinning the 24 lb. steel blade…but the new heavy-duty motors should, hopefully, do the job this year at the national competition to be held in Miami.

	Bloomsburg High's "X" BattleBot in action at the last national competition.

This year in Miami, they finished the tournament with a sweep in the Mini Robot division, finishing in first, second, and third place. They also earned an award for the "Best Documentation" and another for the "Coolest Robot" in the mini class. In addition, their big robot "X" finished its tournament in 6th place, recording five KO's in the process.

"The entire process is a team event," says Mr. Marshall. "From raising funds, to designing the concepts, to machining and assembling the robots, to the energy-charged competitions, the students work extraordinarily well together. They want to win, but at the same time, they respect the teams from the other schools. During the matches, they will lend tools and assistance to other teams having problems with their robots and other teams will help out our kids. They don't want their win to happen only because the other team's robot didn't work. Seeing this display of good sportsmanship at the competitions lets us know, as teachers, that the lessons learned go well beyond classroom CAD/CAM to include personal Can-Do."