The Agrippa: Final Status / Event 1999

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Final / Event 1999

"People always clap for the wrong things."
- Holden Caufield, Catcher in the Rye
"It's Showtime"
I've learned that I am not alone in waiting until the last minute to get things done for robot competitions. So in the month before BattleBots 1999 in Long Beach, California, my shop exploded in work to finish off Agrippa. All I wanted to do was put on a good fight.

Pictures

	I took some aluminum plate and folded up a master control box to house and protect the switches for the major subsystems: drive, steer and electronics. It opened toward the center pivot which is both accessable to humans while being a hard target to hit in the arena. The drive enable switch is a nice 75 amp push-pull type: push it in to disconnect the circuit. This makes it a good "emergency stop" switch. I sell these in the electronics part of my website.
	In a sudden burst of cleverness I figured out how to armor that pivot joint with a hinged assembly - it stretches flat or gets pointy depending on the steering angle. The magnesium plates are 0.400" thick and the hinges are steel.
	Where do you get thick Mg plate? Well for me the least expensive method was to buy it surplus and mill it down to size. At only $3/lb. it was a good deal even though the pieces were irregularly shaped and some had holes in the middle. But it was thick - 0.75" thick!
	How do you cut thick Mg plate? Plant it in the vise and lay into it with the Sawzall. And no it doesn't "create its own oxygen" when it burns so I wasn't worried about putting out any fires with a bucket of sand. It is a strange metal to work with though - it's very stiff, almost brittle.

	Clamped to the mill bed I'm making one side straight to form the basis for the remainder of my operations.
	Chips are flying from the fly cutting operation. Steam rose from the cutter as I converted the really thick plate down to just pretty thick. In the end I filled this black waste basket three times with shavings, which are still everywhere in the shop.
	Done. This thick material was the basis for a "hybrid armor" I wanted to try out on rear electronics box - 3mm carbon fiber backed up by the magnesium plate, all shock mounted to the frame. The idea was to build something stiff that could absorb a few hits from a hammer weapon.
	Also to note is that I swapped out the three Yuasa NPH4-12 batteries for a single Hawker GX13. In the process I saved a pound of weight, decreased my wiring and moved from thee 800mah chargers to a single 10AH charger - no limit on charging current for those Hawkers!
	I also installed a keen Hella 250A disconnect for the LBW motor. You can buy these from West Marine and like their name suggests, they are hella cool. The safety disconnect was mounted in the front segment near the CO2 tank and its regulator. Its big red handle just screams "turn me in case of emergency."

In the final version an air cylinder powered the LBW chopping motion, controlled by a foot switch wired to the R/C transmitter.

I didn't have time to take any more construction pictures before the event but my friend Dean did have time for a last-minute photo shoot the night before. So here is the Agrippa before it tasted the bites of Ronin, Razer and Ginsu.

Taking Damage

	Before the Agrippa took damage at the event, I did. While standing in the queue at the entrance to the arena, I noticed Agrippa twitch once on the steering actuator. As I turned to look at it with bewilderment the main drive motor pulsed forward. My TX was off and Agrippa was out of control, heading into the team in front of me. I yelled "watch out" and ran after it, jumping into the gap between the wheels so I could hit the e-stop switch in the middle. I didn't escape the sharp edge of the magnesium hinge plate. Turns out a middleweight robot in the arena was on my frequency, an honest oversight by the frequency coordinator. The team queued in front of us was angry for their scare, even after we both apologized. So as Ian commented later, "they were just being wankers."
	My first fight was against my friend Peter and his robot, Ronin on Saturday night. Here's what the LBW abrasives looked like after our fight. In the middle of it we switched sides, each running the others robot. I stripped off my T-shirt revealing a Team Sinister shirt, as did Peter revealing a Team Delta one. It was great but casued a dilemma for the judges - who won? Trey Roski, BattleBots co-founder, called it a draw.
	On the front of the LBW I bolted a pike of 4130 chromally steel to use as a ramming spike. In the middle of my fight against Ronin I was perfectly lined up and managed to t-bone him at full speed, square in the side.	photo courtesy Peter Abrahamson
photo courtesy Vincent Blood	My next fight was first off Sunday morning against Razer, and I had lost some nuts on the LBW in the fight with Ronin. So at 10PM on Saturday night I drove around trying to find grade 8 fine pitch 1/2" hex nuts. After banging on the door, I convinced an auto parts store manager of the seriousness of my plight and he sold me the $2 in hardware after-hours. My fight the next morning against Razer was a disaster; I couldn't have possibly been matched against anyone worse. They out drove me and through hydraulic crushing action, penetrated my hydrid armor and took out my entire electrical system. The only thing that survived was my RCE110 4QD controller due to the optoisolators on its inputs.

My friend Bob Pitzer helped me wheel the "car wreck formerly known as Agrippa" out of the arena on a gurney, where we assessed the damage. While I laughed at the incredible beating my robot took, Bob snapped some pictures. It didn't really sink into me until later when Mark Setrakian walked over, saw the inside of Agrippa and exclaimed "Holy Christ!"

photos courtesy Bob Pitzer

As you will read below, Agrippa did recover to fight one last time. But it took me twelve hard hours of work. During my repair marathon I received invaluable aid from the following fellow competitors, to whom I am quite grateful:

Bob Pitzer, who acted as my PR man so I wouldn't have to stop to answer "can you fix it?" questions every five minutes
Amy Sun, who kept appearing at exactly the right time with a helping hand, a flashlight or some part that I really needed. (Amy and Curt's robot Kill-o-amp also suffered the bite of Razer)
Patrick Campbell, who cruised over just to offer a helping hand, and successfully beat my armor back into shape (Razer also pulled the can opener maneuver on Patrick's robot, FrenZy)
Jascha Little, who loaned me a 4QD NCC-series controller to examine (and who's dad wore a necklace of blown HEXFETs. Very cool.)

	When Razer's pincer came through my armor it went right into my electronics array, smashing and shorting out everything. If you look at the polycarb guard on my 4QD controller, there is a hole where the steel tip of Razer's beak went right through, brushing the main power connector and shorting out my 60v Nicad pack. What a shot. That beak took a second bite and cracked the brush holder of my main drive motor. Mark Setrakian recommended I use some "steel stick" metalized epoxy to fashion a new holder, so that is what the gray blob is on the motor case. Worked fine.
	Here is what the new electronics package looked like when I was done; most things I replaced except the 4QD controller which I repaired on site. Jascha loaned me his controller and I compared the PCB traces to discover where the now-vaporzied copper path used to lie. Parts destroyed: two RCE200 switches, the RCE300 analog converter, the Copley servo amp, the 4QD controller, the DC-DC converter and the Hitec PCM receiver. Total cost to repair/replace everything: $700. But hey, it's a contact sport, right?
photo courtesy BattleBots	During my repair effort I had to forfeit all my fights in the loser bracket. So on Sunday evening I was just waiting around for the Rumble when event co-founder Greg Munson started asking for volunteers to get in the arena against Ginsu. I thought "no way, pal - I just fixed my robot." After a few minutes I discovered that everyone else in earshot felt as I did: no takers.
photo courtesy Jerome Miles	Then after talking with Greg and learning that there was a pause coming up in event flow and they wanted to fill it with some maximum destruction fight, I figured "Well, better to go down at the hands of an excellent robot then get lost in the Rumble." So I agreed. While in line, my friend Peter walked up and said "Want a hand?" Five minutes later it was Agrippa and Ronin vs. Ginsu. Man did I get creamed.

Agrippa ended up impaled on the arena spikes, disabling both wheels on one side. Ginsu drove over and over my robot, breaking everything its screaming-saw-bladed-wheels-from-hell could. Since I had no intention of repairing it for the Rumble, Bob once again helped me drag it back to my pit area. Once there I prompty opened a cold beer and started enjoying the rest of the show.

Now, here is what the Ginsu damage looked like back in the shop:

Last Few Things...

	An excerpt from a postcard-sized advert for the event. I helped write the copy. <META NAME="keywords" CONTENT="Emergency entry saw, unguarded blade array, rocket fuel, McShunt, metal fatigue, carbide tipped, sheared bolts, 6061 T6 aluminum, neodynium magnets, mandibular crusher, 400 psi pneumatic battering ram, hybrid armor, four foot drop test, geared servo motors, stall torque, rubout, thermal runaway, counter EMF, transient voltage, cobalt steel, inelastic collision, point impact, resonant frequency, plastic deformation, stress test, nonlinear strain, chain flail, hydraulic pressure accumulator, melted.>
	The cool metal trophy I received from my fight with Ronin. Suitable for bolting to the side of your robot.
	Trey wanted everyone to get something for being a competitor, so he chose a giant silk screened hex nut for a 1.50" diameter bolt. Just one more reason I felt great about the way I was treated as a competitor.

The End

That's it for the Agrippa project! Final disposition of this robot is that it was disassembled for useful parts, while the remainder was chucked in the trash. Some people are in love with their robots and keep carting them back year after year. Well, that's unacceptable to me (and largely boring to the dedicated audience.)

So on to the first new robot of 2000!