Starting
Design Blue Prints:
Weight Planning Document
Ok, only a few weeks and a lot to do before Seattle Bot Battles 2008, complex weapons and creative artsy crap out the window for a bit,.. this is war,.. and its time to put a plan into action that can be accomplished within a short time frame.
Red Rover is a fairly simple design in principle, 4 wheel drive, low profile wedge, with a lifter poker, grabber arm. but this bot has multiple design elements worked into a seemingly simple concept to deal with all forms of spinners, and packs quite a bit into 1 lb using a large range of specialty parts and materials to get the job done.
Basic stats (assumed at this time)
H, W, D,:
~1.5", 7", ~9"
Weight: 1lb ant
Drive: 4 - BaneBot 16mm 38:1 gear motors
Wheels: 4 - 1-1/2" hobby light foam rubber wheels w/Aluminum hubs
Chassis: 1/16" Carbon Fiber
Standoffs & Supports: 1/4" Aluminum Standoffs & Honey
Comb Fiberglass
Wedge: Aluminum & Steel Springs
Battery: 6 Cell AAA 1000mah pack
ESC: Ant 100 w 2A per channel 5A peak.
Radio: Spektrum AR6100
Combat Tactics: Red Rover employs a spring mounted plow/wedge, its most
forward edges are slightly curved inwards allowing low spinners to
simply slip under the wedge, not grab on, this wedge is mounted
to the bot with a spring buffer zone allowing the wedge to stretch in
all direction and absorbing impact damage then bounce back into
position. On the other "front" I have 4-6 vertical gravity wedges,
these wedge/flaps will be made out of either thin UHMW, Spring steel, or
Carbon fiber whichever works best in testing. these flaps will be light
and flexible and if deployed correctly should neutralize high mass
horizontal
spinners. In addition Red Rover will hopefully have enough weight
left over to carry a lifting grabber arm made of carbon fiber and
powered by a high torque servo.
Construction Begins:
(4/26/08)
A lot to do and only a little time. Quite a bit of testing pre dates
this starting point, I did a lot of work comparing Tamiya crank axel gear
boxes to Bane bot 16mm gear boxes, and even though through heavy
modification (hand made carbon fiber axels, metal gears, Atomic tuned
motor, and Aluminum Screws) I was able to bring the weight of the Tamiya
box down to match the Bane Bots ~1.15oz. In addition the Tamiya gear boxes
where faster at 6V, but the Bane bots motors where almost as fast and
had a bit more torque behind them. Secondly it came down to stall
current, the bane bots stall out at 2A max, the Atomic tuned motors
which are much better then the stock motors where nice but they stalled
out well past 5 amps and tended to let out smoke when left stalled for
longer then a second. If that was not enough finally it came down to space, I was not
able to position the innards how I wanted to with the Tamiya gear motors
so the Bane bots won out.
Continuing
with drive train I decided the aluminum hubs that I purchased with the
bane bots wasted a lot of weight so I set to work shaving off about .1
oz from each by cutting into the thick back stock of the hub. Notice the
burnt wood, these hubs are anodized so cutting through them takes quite
a bit of effort, they sure got hot when I dug into them with the band
saw. If need be
ill cut even more off. From the get go, I am shaving every 1/10 of an
ounce I can as my design packs a lot into very little weight, I know ill
need it down the line when I am deciding how thick the armor can be.
I
have decided to keep things really low to the ground So I figured I
would use either 1-1/2" or 1-3/4" D,
1/2 thick foam hobby wheels. I mounted them to the modified hubs with the provided hardware
replacing the metal washer with a plastic one and some loc-tight, I also
added a single brass #0 wood screw through the hub and into the wheel to keep the
tier from loosening during competition I may add a second one if
needed.. all-together it feels as if they will have a lot of grip. I
have ordered a set of the slightly larger tiers for testing who knows ill
likely make the wheel holes wide enough to fit either tier size..
I
spent some time deciding on materials to use for the vertical supports. I
played around a bit with UHMW, but I wound up deciding on kitchen cutting board
plastic for its ability to flex a bit and take damage without structural
loss, and 2 sided Honeycomb Fiberglass for its excellent strength to
weight ratio I also decided to use aluminum standoffs through the two
materials to hold everything in place.
I
wanted everything to be as low to the ground as possible so I set a goal
of fitting everything in a package only 1/8 taller than the Banebot Gear
motors that would fit inside (16mm). I started out making my side walls
~13/16ths tall, and factored in 2 - 1/32nd thick plates to make up the
top and the bottom,.. this made the robots total height without wheels ~
7/8ths of an inch tall. At this point I also decided to go with the
1-1/2 tall wheels I then factored in ~ 1/16" for button head hardware
and this gave the robot ~ 1/4th" clearance on either side. A little more
than I wanted, but smaller wheels would make the robot slower so I decided
this was acceptable as I did not want to lose any speed.
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