Team Toad: Blizzard

I could have fixed the design flaw in the chain drive of Avalanche 2, but that would still leave me without a powered weapon and with a slow robot whose best opponents would just run away faster than Avalanche could give chase.

I spent two months drawing various configurations, but nothing really clicked. Then while rummaging around the shop I spotted the spare body from FrostBite 3/4.

Built by Quality Manufacturing in Pittsburgh back in 2001, it's a thing of beauty made from 3/16" 6061 aluminum bent and TIG welded by professionals. I could never make something this nice, and it was a shame for it to just sit on a shelf.

So I decided to go "back ot the future", but update it for newer parts. First I love the NPC 10" rubber tires, so that was an easy choice. Since Avalanche 2 was too slow, I decided to upgrade to AmpFlow A28-400 (AKA long MagMotors). FrostBite used Thomson-Micron planetary gearheads donated by Thomson. While these are still available, they cost $1500 each, and are large and very heavy.

Fortunately, Team Whyachi now make their own P-3 planetary gearheads that are significantly smaller than the Thomson's.

Another upgrade is the addition of torque limiters on each axle. One common failure mode at Robogames was that Avalanche would box-rush the other bot into the wall and break itself. The heavier 10" tires generate more force and transmit it back into the drive, so the heavier bearing mounts of the FrostBite design and the clutch to absorb rotational shocks may be the answer.

We'll find out next month at Combots Cup.

Overvolting AmpFlows a Bad Idea

During initial drive testing, I was planning to use a Vantec RDFR 47e dual speed controller. I used a 12V battery to check the wiring, but when I plugged in a 36V NiCad pack, the wheels locked up, vibrated a little, and there was a loud "pop" and a puff of smoke from the Vantec.

After a long discussion on the Internet, I found that it was foolish of me to expect a single Vantec 47e to control two A28-400's, even at 24V, much less 36V (never mind that FrostBite 4 ran with exactly those motors and speed controller at exactly that voltage -- must have been a mirage).

So now I have two single Vantec 48e's running at 26.4V (custom 22-cell BattlePacks). Dropping the voltage means I have few cells, so that saves some weight, but I needed to save even more to make room for an extra Vantec. That meant going high-tech with titanium shafts and bolts.

Things are going well now with the build, and we hope to find out how well these choices work out.

Specifications

Custom 26.4V and 33.6V NiCad Battlepacks
Two AmpFlow A28-400 "Long MagMotors"
Team Whyachi P3 8-1 planetary gearheads
Four McMaster 1" bore, 120 ft-lb torque limiters
Two Vantec RSFR 48e's, one per side
Titanium axle and weapon shafts from Team Whyachi
Titanium fasteners from Whitebread Racing Enterprises

Record

At Combots Cup 2011, Blizzard went 1-2 (ironically the same day a record blizzard hit New York City).

Son of Ziggy	win (20-13)	Son of Ziggy is a wedge-shaped block of titanium with a throwing arm. The fight was very tough; the disc kept spinning the entire match. Son of Ziggy flipped Blizzard twice, but since Team Toad has fielded many invertable robots, Fuzzy has spent a lot of time driving upside-down robots. That mean that Blizzard kept on the attack the whole fight. Son of Ziggy started slowing down in the last minute of the fight, and Blizzard's disc could just barely spin. But the drive train was solid and Blizzard kept on pounding into Son of Ziggy. The result was a decision for Blizzard. For almost a whole hour, Fuzzy had an undefeated robot.
Original Sin	loss	Fuzzy wanted to get revenge for his loss to Original Sin at Combots Cup 2009, bud sadly it was not to be. The spinning disc dished out a couple of good hits on Original Sin, to the point of bending Sin's blade attaching rod. But about halfway through the fight, Sin got behind Blizzard and pushed the spinning disc into the wall. That bent Blizzards 1-1/4 inch weapon shaft and the disc stopped spinning all together. The torque limiter on the weapon motor saved the 4 inch MagMotor, but with Blizzard's weapon disabled, the judges' decision went to original sin. Sin did lose one tire in the match, which was a tiny consolation. Next time Blizzard just needs to chew off the other 3.
Mosquito	loss	The last time Stephen Felk met Fuzzy in the arena was November 2000 when Voltronic defeated Frostbite in the quarterfinals of the heavyweight division. Fuzzy spent a long time replacing the bent weapon on Blizzard, but the fresh oilite bearings weren't run-in, and the disc spun slower. He did get one good hit on Mosquito's side, ripping out dozens of flathead screws in the process, but once again, Mosquito pushed Blizzard into the wall with the disc spinning, and the weapon seized up. Fuzzy tried to salvage the match by digging Blizzard's bearing mounts into the top of Mosquito and running out his batteries. It worked to some extent: one of Mosquito's battery packs got hot enough to melt its shrink wrap. But with Mosquito still driving and Blizzard's weapon not spinning, the result was an inevitable decision for Mosquito.

Lessons

The reason for bringing a new robot to Combots Cup was to test ideas and provide a shakedown for Blizzard.

On the plus side, the modifications to FrostBite's drive train were a stellar success. Son of Ziggy threw Blizzard several feet into the air on multiple occasions, and Blizzard just kept on going. The torque limiters on the axles did their job of protecting the motors and speed controllers well.

The weapon was half and half. When it worked, it was very effective. Blizzard fought three opponents designed specifically to beat spinners, and did severe damage to all three opponents.

Clearly the bearings need to be addressed, and either the weapon shaft made stronger or some way to keep the disc off the arena walls is needed.