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Welcome to the third installment of Team 1079's second FIRST experience. This month, will cover the rest of the FIRST build-up to the competition. You've already been introduced to two team members — Bryce Woolley and Justin Lyons — and this article will come from the perspective of another team member.

by evan woouev

I'm Evan Woolley, twin brother of Bryce and co-captain of Team 1079. I'm a senior at Chaparral High School and have been involved in FIRST for two years. This article will focus on Team 1079's trials and tribulations during the six week build time, while addressing some parts of our team dynamic that most all FIRST teams know about and other aspects that make us unique.

While Justin's group took care of the arm project, my dad, myself, and other team members worked on the frame and drive train. Inspired by other designs last year, this year our team wanted to build a four motor drive train with the two Bosch 1/2" drive

Standing, from left to right: Bryce Woolley, Jairus Ciocon, Bryant Nelson, Kristen Baber, Justin Lyons, Ryan Potts, Jack Gordon. Kneeling: Evan Woolley.

Standing, from left to right: Bryce Woolley, Jairus Ciocon, Bryant Nelson, Kristen Baber, Justin Lyons, Ryan Potts, Jack Gordon. Kneeling: Evan Woolley.

cordless drill motors and the two CIM motors supplied in the kit. This year, the FIRST kit of parts contained 11 motors, though never more than two of any type.

Quite a bit of flexibility is allowed in extra parts choices for the robot, with the main exceptions being the motors and the control system. Only the motors supplied in the kit and the complete control system from Innovation First can be used on the robot.

Another limitation, at least for our team, manifested itself in the extensive safety regulations required by FIRST concerning the electronics. All of the powerful motors were required to use breakers and Victor 884 speed controllers. Safety is a good thing — don't get me wrong — but our team was tight on resources. The kit only came with enough Victors for the four

strong motors that comprised our drive train and we couldn't afford to buy any more.

The kit came with plenty of Spike relays for the lesser motors, but it limited us, nonetheless. Basically, our quest for a strong drive train eliminated our hopes of a hanging mechanism. Hanging would require more strong motors, which would require more Victors, which would require more money. We didn't have any extra money, so no hanging for us. The team was, nevertheless, satisfied with our design, though it's not like we had much choice.

Another motivation for this design was that we thought it would be sturdy and reliable; one of our main goals was a robot that drives — and drives well. The same basic principles that apply to all other areas of robotics apply in FIRST, too: If you want to even have a chance of doing well, you need a reliable drive train.

This point was even more important to us, due to our rookie season experience last year. Our robot last year had a great design for the game and looked cool, though we had built the robot in such a way as to render it almost impossible to work on. So, in keeping with Murphy's Law, we naturally had to work on it to rectify some of our "rookie" mistakes. This led to our robot sitting in the pits with our hands inside of it instead of playing the game on the field. We learned from our mistakes and we were darn sure that — this year — our robot was going to be running for every match!

Our first idea was to pair the motors in a custom gearbox, but — when we found out that such a design would come with a price tag of $500.00 — we decided to look for more affordable alternatives. This year, our team was on a very tight budget, so we had to get creative with some of our designs.

A side note here: Another great aspect of the FIRST program is that all teams across the country freely and gladly share any design ideas that they develop. Many of the teams have been in existence for a number of years and have an extensive engineering base filled with some of the sharpest engineers from some of the largest companies in the country. These brilliant minds come up with some really cool ideas — some of which are very tricky, multiple motor gearboxes — but, alas, it was not meant to be.

A visit from one of our esteemed, professional engineering mentors proved fortuitous, though. He suggested using four smaller wheels instead of the two larger wheels. This was a great idea for several reasons. First, this made it so that not having a gearbox was no longer a problem — with two smaller wheels, we could just match them closely with sprocket arrangements and dial them in through the programming. Second, that same mentor said he would donate the wheels — FREEBIE! Lastly, this new design was far cooler than the old one.

Everyone agreed to this plan and it kept with our design motto: "Keep it simple, dadgummit!" We used the Bosch motors with their stock gearboxes locked in low by means of a custom machined internal spacer ring. These powered the front wheels via a pair of sprockets and #35 chain at a 1:1 drive ratio. The CIMs or "Chips" drove the rear drive wheels through a double chain reduction arrangement with both #25 and #35 chains and sprockets being used. This resulted in a very close match between the front and rear drive wheels.

We were able to borrow a stroboscope from Cosworth Racing to allow us to check the individual wheel speeds very accurately and then adjust them through the program. As was mentioned earlier, the complete control system is supplied by Innovation First. The system is comprised of the robot controller, the operator interface, a pair of RS-422 radio modems, and a pair of multifunction joysticks.

The robot controller contains two Microchip PIC18F8520 microcontrollers, the master processor, and the user processor. The robot controller has 16 analog inputs and 18 digital input/output pins, as well as 16 PWM and eight relay outputs. The controller is programmed in C to take full advantage of the flexibility of this powerful unit and a default program is available to all teams on the Innovation First website to provide a great base to work from.

By the middle of the build, things seemed to be moving along smoothly. Justin, Jack, and Bryant were making good progress on the arm, Bryce was forging ahead on the pneumatic kicker and goal grabber, and the drive train was agreed upon. Despite all of this progress, we really didn't have anything to show for it. Why? Because our floor hadn't arrived yet!

The first two weeks were devoted to finalizing a basic design for our robot so that we could draw out a floor design to be machined at our local sponsoring machine shop — Flashpoint Machine. Our build was centered around the floor. We designed the floor in such a way that it already had most of the attachment holes, so — theoretically — we could just throw the robot together once we got the floor back. (Not that we would actually throw it together — we do take a lot of pride in our work.)

The first week of our build was devoted to finalizing the floor design so that it would be easy to build the

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rest of the robot right on top of it. Why do these guys put so much effort into the floor, you ask? Our obsession with making a perfect floor may come from our background in combat robotics.

In combat robotics, the floor is an ideal mounting place to keep things safe because it is robust and rigid. Combat robots need to have robust floors because you never know when a saw or something of the like can get a shot at your underbelly.

While there are no saws in FIRST, the same basic design principles apply. We use our floor as a primary mounting point and we know that everything we attach to the floor will stay put. Additionally, since the floor is drawn on AutoCAD and all of the bearing block mounting points and motor mount locations are precisely situated, everything is in the right place. Mechanical losses due to inaccurate placement of driveline components are eliminated, thus allowing the available power to be properly utilized for desired motion instead of overcoming poor construction.

Unforeseen difficulties at the machine shop, however, delayed the completion of our floor. I'm sure most people (especially FIRST teams) can relate to the frustration of late parts. We weren't going to give up hope, though.

Week four and still no floor. It was starting to look like some of the team members' wishes for some all-nighters would come true. One bright spot was the arrival of our frame, custom welded by a friend at Cosworth Racing. Our frame was also heavily influenced by Cool Factor Engineering. Instead of doing things the easy way and just making a frame box, we angled in the sides so our cool four-wheel drive train would show. As you can see, "Keep it simple, dadgummit!" and Cool Factor Engineering sometimes butt heads. When that happens, we go with the

Circle #95 on the Reader Service Card.

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