Thursday, October 29, 2015

NERC Franklin Institute 2015

Saturday, October 24th, we left in the dead of midnight to make the ~5 hour drive to Philadelphia for the NERC Franklin Institute robotic combat event. Although the competition supports up to 30 pound robots, I brought only DDT and Silent Spring because robots larger than 3 pounds were prohibited from using LiPoly battery chemistry. Even still, some of the best insect-class robots in the northeast were scheduled to attend and I predicted this would be the real test before Motorama in the mid-winter 2016.

Since MASSdestruction two weeks ago, the robots received minor upgrades. DDT at minimum received a replacement motor can and pulley since the last one was actually bent from years of abuse. DDT was also set to receive a new frame printed with carbon fiber instead of kevlar as the tension member because it was noted that the weapon shaft bore began to open up from all the spinner-spinner hits.

Unfortunately, the prints failed due to some trickiness in the CF thread and I whipped up a quick solution using two belleville washers on either side of the frame to distribute loads more effectively. Silent Spring felt the success of the upgraded drivetrain but suffered some difficulties in the tournament due to the scarcity of the choice motors. Now Silent Spring will run a OEM option, the Pololu 9.7:1 HP gearmotors. The leftover weight was spent to upgrade the disk. Thin sections that bent at MASS-D were beefed up which brought the disk weight up by 4 oz to about 16 oz.

For an added bit of fun, I decided to use some voodoo magic from the robot gods in this new disk. We were clearing out the crate where Overhaul lives and I decided to pull out the AR400 plates we salvaged at BattleBots off Witch Doctor. While one plate was pretty well bent by Nightmare, the other was relatively flat which made it a fine candidate for a blade. I never did get that green color palette from Mike so I ran it in AR plate's natural color: rust.

At 7:45 am we arrived in the museum and grabbed whatever tables were left. The arena was HUGE and pretty awesome in construction. Double doors for entry and exit, a nice kick plate, and great visibility all around. It left me wishing I brought the 12 and 30.

This time around, DDT drew only direct-drive brushless drums. The release of the new Kitbots "Saifu" kit was probably a large factor in that. This turns out to be advantageous to DDT because the drum standoffs pose a big weakness generally to undercutter weapons. As long as DDT can stay clear of direct hits from the drum, the match should go in his favor over several small hits as the standoffs wear away. As a result, DDT went 4-0 for 1st place in the Antweight division

W vs Saifu

W vs Poco Tambor

W vs Revy

W vs Revy (finals)

I was feeling pretty good about Silent Spring's destructive capability after MASSdestruction but utilization of that power ended up being its undoing. The unevenness of the floor and massive gyroscopic forces at high speeds meant that stability was low and its first two opponents took full advantage of that. Luckily, enough, Silent Spring was able to survive those outcomes and climb its way through the bracket. Silent Spring clawed its way through the loser's bracket to find 2nd place in a 5-2 record, losing in the finals to Speed Wedge 3, an extremely robust opponent.

W vs Mondo Bizzaro

L vs Project Darkness

W vs Best Korea

W vs Grande Tambor

W vs Trilobite
W vs Project Darkness
L vs Speed Wedge 3 (finals)

Silent Spring definitely managed to bring the pain just as he had at MASSdestruction. Below are some pictures of opponents after matches.



However, the robots didnt escape unscathed either. DDT lost a rear corner screw when Saifu clipped the edge during a gyro dance but otherwise remained unchanged.

Silent Spring suffered a fair amount of injuries from the first two matches and managed to keep it together for the rest of the tournament. In its first match vs Mondo Bizzaro, SS took a blow to the wheel axle which bent the shaft (and made the disk angle weird) but also seems to have seized up a motor. This caused one of the Vextrollers to fail and I ultimately had to use a postponement to replace the drive electronics. But it was the bent axle that proved to be the biggest issue going into the second match vs Project Darkness. Because it was slightly bent, the disk was no longer planar and so I could not spin up without tilting. Ian is an expert driver (in fact he won best driver award!) and took full advantage of this; he drove around SS while it was uncontrollable and delivered some nice hits deep in the UHMW back and got some nice shots on the drive pulleys which ironically bent the OTHER side's drive shaft. One of these hits actually snapped the wheel hub but somehow continued to drive just fine. I dont remember exactly how the match played out, but in the end PD was the victor and SS had to climb through the losers bracket for a second shot. When I was servicing both bent axles I managed to find a sweet spot where the blade was once again flat. Pretty much "OMG DONT TOUCH IT EVER". In its battered state, it was able to deliver the big hits and crawl back up to the finals without accumulating extra damage.

DDT can continue to compete as is but Silent Spring needs significant repairs to bring it back to a reliable state. Since it keeps doing so well, I must once again delay its retirement even though I want to build something else. I'll assess the extent of upgrades to be received in time for the next competition, MASSdestruction, in December. See you all there!

Monday, October 26, 2015

MASSdestruction at the Artisan's Asylum (Oct 10)

Not too long after the Dragon Con bouts, the crew went right next door to the Artisan's Asylum in Somerville, MA to fight at the first ever MASSdestruction event. As the date came closer, more and more robots registered which helped fund the brand new arena that Rob Masek put together. It was shaping up to be a world-class event.

I brought DDT and Silent Spring with me; neither bot had major upgrades since Dragon Con. Silent Spring received an updated drive train which in turn required re-fabrication of a few critical components. I decided to dump the 33:1 Spark gearmotors in favor of my KW hackmotor which are the drive units I used in Dominant Mode. You may recall, they consist of the KW beetle motors (which are now discontinued) mated to a ~10:1 spur gearbox from the "1000 RPM" gearmotors. Not only is this combination lighter, but it is also faster and more powerful (1500 RPM @ 12V). This change gave Silent Spring the agility it desperately needed to be competitive and deliver the big hit. These tests on an empty Stratasys material cartridge are evidence of its new destructive power.

Saturday morning, Lucy and I hitched a ride with Will and Max Bales who brought a few robots of their own. These included the last minute Hyperderp, lovingly named Turd Ferguson, and Hypershock as seen on TV. All our bots combined, we had 10 ants and 11 beetles. To keep matches rolling consistently throughout the day, Rob proposed a modified swiss tournament structure. All robots will have ~4 matches and points will be awarded for the conditions of the match.

  • A win is 4 points
  • A win by default (no-shows or forfeits before the fight) is 3 points
  • A loss is 2 points
  • A double loss (where both robots stop functioning) is 1 points
  • A no-show is 0 points

The top four robots in each weight class are then pitted in a semi-finals double elimination scenario to fight for 1st, 2nd, and 3rd.

In the end, DDT had 6 matches and went 4-2 for 3rd place. Silent Spring (in a weird turn of events) had 5 matches and went 4-1 for 1st place. The tournament results are hyperlinked here. Only a few matches have video from what I can tell. I will update this page periodically with embedded video as more pop up.

Overall, I am satisfied with the performance of the robots. DDT performed well (never stopped!) but was shown some glaring weaknesses to particular wedge designs. In the future, I'll need to practice driving and prepare special blades to handle these types of wedges. Silent Spring STILL suffers from random shutoffs which is incredibly infuriating but before it fails it delivers some of the most impressive blows I've ever seen in a beetle.

Before Franklin Institute, I'll be looking to redo the wiring and improve its overall reliability. One area that needs improvement is the blade durability; in this event I managed to bend both blades I had for Silent Spring not out of plane (say from a vertical spinner) but IN PLANE. This means its own hits are so hard it damages the disk. I would pay $$$ to see some high-speed video of the blade warping under impact! Stay tuned for 10/24 to see how these two bots shake it up at Franklin!