Team Update 14 (2016)

[ChuckDickerson]

First let me say that I consider my team to be a typical “mid-resource” team. We are more fortunate than some but far from an “elite” or “powerhouse” level team. We have never won a regional competition but are usually competitive and at least play in eliminations. We do this by building as simple and robust of a machine as we can that achieves our game strategy and objectives. We pride ourselves on the quality of our robots even if they aren’t CNC’d and powder coated. Our robots are 100% student designed, fabricated, and built using a miter saw, band saw, drill press, and small benchtop manual milling machine and lathe.

FIRST is not fair. It never has been and never will be. That’s not the point and I don’t think we should be trying to write rules that try to limit the “haves” just to try to artificially “level the playing field” for the “have nots”. Every team is different and every team has their strengths and weaknesses. It should be up to each team to be able to maximize their strengths where they can.

In my own team’s situation, one of the ways we “level the playing field” against the more “elite” teams with lots of high end in house fabrication capabilities and mentors that are way smarter than me is we use a lot of 80/20 T-Slot extrusion. Another way is we design for modularity, reliability, redundancy, and maintainability. We may not be able to design and fabricate the fanciest robot parts but we can design simple reliable parts that are easy to manufacture given a simple machine shop and a bunch of kids learning as they go along. We also rely heavily on COTS items from AndyMark and VexPro, etc.

With that said it has also become the norm in this modern era of FRC that more and more teams are building 2 machines during their build season. Most would call these two machines a practice robot and a competition ROBOT. In the old days this was less common but so was going to more than one regional competition in a season. Now a days it is almost a given that to be competitive you have to build a practice robot to continue driver practice after bag & tag and go to more than one competition. It’s not an absolute rule but it sure helps if you have the resources to make it happen. In my opinion it is the biggest reason that bag & tag simply hurts teams with fewer resources than those that can afford to build a practice robot.

For a couple years now, my team has strived to raise ourselves to the level of that later group. We have built a second practice robot and gone to 2 competitions now since 2012. Over these last few years we have also increased the amount of spare parts we fabricate during build season and bag on bag and tag night. We essentially build as many spare MECHANISMs as we can afford and think we might need as replacements. In 2013 we built an entire spare Frisbee shooter and bagged it on bag & tag night. In 2014 we built an entire spare catapult and bagged it on bag and tag night. Last year we had spare mecanum drive modules and lift parts and a spare mechanism we called the P.O.T. (Pusher Outer Thingy) that was designed solely for doing coopertition and bagged all of it on bag and tag night.

This year we took it to the next level. We built 3 complete machines. We started with a prototype robot as we always do and were satisfied enough with it by about the end of week 4 of the build season to start duplicating pieces and parts for the competition robot and spare parts. Again, our robot is really simple this year. It’s a “rebuilding” year for our team and we knew going in that our collective student “experience level” was lower this year. We lost some top notch seniors last year. So we didn’t even try to design for the high goal or hanging. We bought Rhino tracks from AndyMark and built a simple but hopefully reliable drivetrain around them and added a simple ball collector/arm/low goal scoring mechanism. The entire robot is 80/20 t-slot, lexan cut on a bandsaw, and some plates and brackets here and there made from aluminum flat bar, angle, channel, etc. We have 8 motors total. 4 CIMS, 2 Mini-CIMS, and 2 BAG motors. All the gearboxes are COTS (2xAM ToughBox Minis, 2x AM RAW Boxes, and a half dozen VEX Pro VersaPlanetaries. No custom gearboxes for us. Throw in the RoboRIO, PDP, VRM, 8 X Talon SRXs, the main breaker and RSL and that’s about it. 85 lbs total inspection weight (no battery, no bumpers). We think it works well but I guess we will find out when we get to our first competition in a couple of weeks.

Knowing the reduced level of student experience on the team this year we made a conscious decision right up front after kickoff not to shoot for the moon this year but instead build our robot to be easily maintainable and repairable and have plenty of simple “spares” that we can quickly replace on the robot if needed in the hopes of being able to “win the war of attrition”. It was obvious to us that this game is going to be brutal on the robots. We hope one of our strengths this year is to follow the K.I.S.S. principle and be the “last man standing” when others have built over complicated machines that are prone to failure under the stress of this game. We may have missed the mark completely but that was our strategic decision.

Thus the decision to build the 3 identical machines. One “practice robot”, one “competition ROBOT”, and a complete set of spare parts. In addition, we built additional spare parts of things we are particularly worried about including the gearboxes and our ball collector/arm. We are potentially most vulnerable when our ball collector/arm is outside the FRAME PERIMETER due to impacts with other robots. The only difference in our practice robot and our spare and competition robots is the wiring on the practice robot isn’t quite as neat and tidy and it doesn’t have the orange RSL. The competition ROBOT and its twin spare parts robot are as identical as we could possibly make them given the limits of our manual machine shop capabilities and students fabrications skills. The only significant difference may literally be the length of wire stripping. The robots weigh exactly the same.

Here is a photo of the 3 robots lined up side by side:



In the photo the “practice” robot is on the left, the “spare parts” robot is in the middle, and the “competition ROBOT” is on the right. The kids literally had to put a little piece of blue painters tape on the back of the “competition ROBOT” that said “comp bot” to keep the 3 straight when they were fabricating and installing pieces and parts. I made them pick one.

Here is a photo of just the “competition ROBOT”. Note the piece of blue painters tape on the back bar of 80/20 t-slot:



As I have stated above, the entire machine is modular. It essentially can be broken down into 5 major “modules”. The core “chassis”, the left and right Rhino track modules, the ball collector/arm, and the electronics module. The Rhino track drive modules can be removed via 3 X ¼-20 SHCS each and unplug the 2 CIM motor Anderson connectors. The ball collector/arm removes from the “shoulder” motors via 4 screws and unplugging of 2 more Anderson connectors for the BAG intake motors. The entire electronics “module” can be removed via 6 wing nuts.

Here is a photo of the “competition ROBOT” disassembled into its major “modules”:



We have run drills on how long it takes to disassemble and reassemble the entire robot. It takes under 10 minutes for only two of my students (that know what they are doing) to completely disassemble the robot using only a handful of hand tools. Re-assembly takes slightly less time. I am confident that even under “competition stress” two of my students could completely disassemble and reassemble our entire “competition ROBOT” in under 30 minute, probably closer to 20 minutes, while replacing any faulty “module” from our spare parts supply.

This photo was taken just after a “re-assembly” drill:



It represents our fully functional “competition ROBOT”.

Our desire is not to gain any sort of “competitive advantage” by entering more than one ROBOT into any FRC competition where we compete. Or intention is to simply enter our one “competition ROBOT” and have a complete set of spare MECHANISMs available in our pit for repair and replacement if needed.

Here are our “spare parts”:



To a “reasonably astute observer” it may look like a robot but as far as me as an LRI and me as a team mentor can tell it doesn’t meet the FIRST definition of a ROBOT because we pulled the RoboRIO off for safe travels reasons. The RoboRIO can be mounted back in seconds. It Velcros down and just plug in the power (Anderson), the CAN bus (2 pin connector), the RSL, and a USB camera. The RoboRIO will count against our 30 lb withholding allowance because we have “assembled” it by adding the Velcro and wires and connectors. The yellow tote in the above photo contains additional spare parts that we didn’t want to count against our withholding allowance including more spare COTS but assembled Toughbox-Mini gear boxes and VersaPlanetaries, and additional spare set of assembled Rev4 pulleys for our Rhino track modules, and some misc. fabricated structural plates and pieces. Strapped to each side of the yellow tote are two spare ball collectors/arms (one on each side of tote so one isn’t really visible as it is on the far side of the yellow tote).

To be continued in the next post due to image count limitations...