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A: Mark J. Eggbeater weapons notoriously create a lot of aerodynamic drag. Assuming that you keep the 14:21 reduction:
A: Mark J. See Frequently Asked Questions #28 for our policy on discussing flame weaponry -- and read the rest of the FAQ while you're there. The flamethrowing beetleweight 'Dutch Oven' is currently ranked 144th in the NHRL standings.
As for the question, for the next competition I intend on building a multi-bot, since if you can't beat 'em, join 'em. For one part of the multi-bot I would like to have some control based archetype, a four-bar lifter to be exact. Thing is, nobody seems to build them nowadays, direct servo lifters (SSP, Jelly Baby, etc.) seem to be all the rage. Has anything changed in terms of the rule sets or in terms of material/manufacturing/electronics availability that would be unfavorable for a four-bar lifter over a plain servo lifter, or are people just taking the easy route?
Thanks!
A: Mark J. As I recall, your local tournaments have adopted a NERC-style multibot weight bonus. That's certainly an incentive to go multi -- particulary if you're up against sophisticated competitors like your reigning champion.
Four-bar lifters definately have become rare. The current design 'meta' favors more compact single-pivot lifters, structually strong enough to carry attached forks and still withstand spinner impacts. Such lifters also take up less room than 4-bar designs, allowing a more compact chassis layout. I think thoughful design might get you a 4-bar that will overcome these issues.
A: Mark J. Thats very easy to find. Per the websites for FingerTech Robotics, RobotShop, and Palm Beach Bots:
Alternately, you can use the 'Channel Reverse' function on your transmitter to reverse the response of your steering channel (most likely Channel 1 - Aileron). You didn't mention which transmitter you have, but most have this feature. This is handy if you have an "all-in-one" receiver/DESC with no channel plugs (like a Malenki).
I spent a good deal of time creating the Team Run Amok Combat Robot Mixer Fixer -- answer three questions about your robot and it will give you a complete and accurate solution to your mixing problems. Give it a try next time.
A: Mark J. Ask Aaron does not answer questions from builders competing in India.
A: Mark J. See Frequently Asked Questions #19 for a complete, annotated diagram -- and read the rest of the FAQ while you're there.
Q: sorry, i had a photo attached
A:
Yes, you attached a photo of your weapon ESC. It is an entirely standard brushless weapon motor ESC -- exactly as shown in the FAQ #19 diagram. I chose not to reprint the image here.
Q: also this is my esc [photo attached]
A: Yes, that is a Scorpion Nano. It wires up just as shown in the FAQ #19 diagram. A few specific comments based on your photo:
Q: Firstly I understand the whole George Collins with Boxster No Show Controversy (it is just coz I think it might be him unless we know which experienced Battlebots team it is). So, which team was it?
A: To the best of my knowledge the team in question has never mentioned their association with Robotica and I am hesitant to 'out' them if they choose to keep this quiet. I am also not entirely confident of my identification of the team member. I will note that 'Boxster' had design elements shared with other robots of the team in question.
Q: And Secondly REALLY!? A ROBOT CALLED 'LIVE WIRES' WAS IN ROBOTICA QUALIFYING!? REALLY! [Erskine]
A: Page 321 of "Build Your Own Combat Robot" by Pete Miles:
ps. i know not much about them [Atlanta, Georgia]
A: Mark J.The Robot Power Scorpion Nano is a very small, full-featured, dual channel (two motor) speed contoller for brushed motors.
A: Mark J. RBI productions didn't want the competitors to be in contact with each other, so their emails to us had the mailing list hidden. It wasn't until about a month before the filming that a partial list of the builder emails came to light. The only team I was in contact with was Team JuggerBot, who happened to be based about 40 miles to the south of my Oregon home. Our emails were largely about battery chargers for the Hawker SLA batteries both of our 'bots used -- nothing of general interest.
In terms of the interview schedule, I'm fairly certain Pete Miles' mystery robot is "Live Wires", which he shares a bunch of information and pictures about its Robotica adventure about in his book "Build Your Own Combat Robot". Hope that helps someone out there. [Alberta, Canada]
Response: I'm glad to hear you enjoyed reading the Robotica emails and I am grateful for the pointer to Pete Miles' book. I have a copy of "Build Your Own Combat Robot" in my library, but I last read it in 2006! Right there in chapter fourteen is a twelve-page write-up on building "Live Wires" and attempting to qualify at season 1 of Robotica:
Pete's team arrived at the Robotica filming in time for the last day of qualifying but ran into both electrical and mechanical problems. Although their effort ended in a cloud of grey smoke, the design was solid. A few more days for testing and their story might well have been different.
A: Mark J. I like designs that other builders dismiss as "mostly harmless" so I can take advantage when their guard is down. Weaponry is over rated -- I think a build with visual/fan appeal and a heart of cold rolled steel would work for me these days.
Q: Hi Mark! It's the guy from the "Shore of the Mediterranean" again. Quite a bit of time has passed since my last question and I managed to get second place in one of the two competitions I have attended locally. I lost to the as of yet, still reigning champion (see attached photo) mostly due to my own failings, forgetting to purchase spares and even bring some ready parts.
Q: Is the fingertech viper kit underweight? If not, how much weight does it have to sacrifice to use an addon? [Hot 'Lanta]
A: Mark J. Yes -- your ESC channels are plugged into the wrong receiver ports. If you are using channels 1 and 2, unplug the receiver connectors and plug the connector that was in channel 1 into channel 2 and vice versa.
Mark J. Our friend in Erskine, Scotland read my compilation of emails sent from the Robotica producers to the contestants prior to the competition - mentioned farther down this page. He has a theory about a mystery builder whose name appears on a schedule for video interviews for the show and a mystery robot that was seen near the storage area backstage during the competition He writes:
Q: what are scorpion nanos good for (Wedge bots? hammers? lifters? etc, etc)
The Nano is more expensive than no-name ESCs, but is full featured and well documented. The two channels cannot be combined for greater power capacity, so it is best suited for brushed drive motor control in 1-pound antweight or smaller bots.
Q: I read the compilation of Pre-Production Emails to Robotica Season 1 Competitors from the event organizers that you put together for the 25thanniversary of the show. Great stuff, but I wonder about the emails between you and the other builders. Are you going to release them as well? [Chicago, Illinois]
Q: If you were to build a robot today, what would it look like? [Northampton, England]
A: Mark J. There are multiple posts in the Ask Aaron Archives on flywheel flippers. The archive search box will provide assistance in finding them.
I was watching an NHRL stream and was interested in a beetleweight (3 lb) overhead saw robot called "Mako". I was having trouble figuring out how exactly the circular saw was mounted to the weapon motor, as it appears to be held on only by a TPU hub and lock nut (no screws or fasteners threaded directly into the motor. Any feedback is greatly appreciated. [Zanesville, Ohio]
A: Mark J. Mako's weapon is not the usual hobby brushless outrunner with a printed hub like 'Cheesecake'. As disclosed in this video Mako's saw is "...a literal off-the-shelf circular saw that you could walk into Home Depot and buy." It's likely a 4.5" cordless framing saw torn down to just the motor and hub.
Q: Hi Mark. I met you way back at the 2002 Botbash tournament in Tempe, Arizona. I was with a friend who had a robot in the antweight tournament and I remember that you were one of the event judges. I've found some videos of the bigger Botbash robots from that tournament but nothing from the ant fights. Did you happen to take video of any of the ant matches? [An iCloud Server]
A: Mark J. That was a great event. My flight got in too late to register 'Rat Amok' for the antweight tournament, but I did get a couple of pick-up matches and I was able to sneak into the ant rumble. I did also sit in as a judge for the SozBots ant tournament.
Although I didn't shoot any video, a search of my robot combat archive turned up a CD with twenty ant combat matches from the SOZBots 1.4 tournament at BotBash! I have no idea where the videos came from but they are so nicely captioned and edited that they may have come directly from SOZBots.
I've uploaded this set of videos to my YouTube channel as a playlist titled "SozBots 1.4: Antweight Combat Robot Tournament". I also found a bracket tree for the event: SOZBots 1.4 brackets.
My favorite fight from SOZBots 1.4? One Fierce Beer Coaster vs. Tsunami -- it has a very suspenseful ending.
A: Mark J. Tip-Top was not a gyro-walker -- the description at the Robot Wars Wiki is misleading:
When the disc was spinning at full speed, the actuators could be fired to tip the disc mechanism, and the resultant gyroscopic forces from the dome pressing against the ground would move the robot. This form of locomotion, nicknamed in the modern day as "gyro-walking".
Gene Burbeck's beetleweight One Fierce Low Ryda used this propulsion method quite successfully -- racking up a six-win/two-loss record at the 2008 Motorama tournament. Gene calls this style of propulsion 'wackerdrive'.
The earliest combat true gyro-walker I know of is Team Misfit's antweight 'Gyrobot' which first fought in 2009.
However my maths is failing me (See bad drawing attached for definitions of symbols). For calculating the force on the lifter arm from the servo in the setup is it as simple as x*sin(theta)? However isn't that just the force transmitted between the servo arm and the arm of the linkage? What about transmission of force between the arm linkage and the lifter arm itself? Are there further losses there?
And then to calculate whether you can lift something or not, is it (F * y) - (W * z) (Where F is the force from the lifter motor on the arm, W is the weight of the robot being lifted, y is the distance between pivot and lifting point and z is the distance between pivot and robot being lifted)?
Hope this makes sense
Thanks in advance.
A: Mark J. You've opted to open up the jumbo can-o-worms, eh? What you have is known as a 4-bar mechanism, and the calcs are especially nasty because the lever advantages keep changing as the lift progresses. In your sketch the initial advantage is poor and a good deal of torque is needed, but as theta increases the advantage improves and less torque is required. The general approach is to calculate the actual rise in the tip of the lifter for each change of say 1 degree of servo arm motion and convert that into a torque requirement for each progressive angle.
I know this because I wrote a pair of 4-bar Excel spreadsheets that perform these calculations for standard "Biohazard" style 4-bar lifters (movement up and forward) and for the servo linkage you describe (single pivot hinge motion). That is the good news.
The spreadsheet I wrote for the servo-powered single-pivot lifter has the correct geometry for your purpose, but the example layout has a hinge point much farther forward than your design. You will need to adjust bar lengths and angles to morph into your longer rear-hinge design. This may well take some time. Here are the spreadsheet link assignment letters as they apply to your sketch:
Give it a shot. If the calculations balk, you can wade thru the "Equations" tab on the spreadsheet and make adjustments as needed. Download the Team Run Amok Servo Lifter Spreadsheet from our Combat Robot Design Tools page.
A: Mark J. I've never actually tried, but it shouldn't be very hard. You can only go where the rails go, so just give it a little throttle and toot the whistle once in a while.
Q: What do your combat robots think of the current COVID-19 pandemic? [Kansas City, Missouri]
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Remembering Aaron Joerger, 1991 - 2013
The 'Ask Aaron' project was important to Aaron, and I continue the site in his memory.
Thank you for the many kind messages of sympathy and support that have found their way to me.
Aaron's obituary
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Q: how can robots help us deal better with hurricanes and why? [Ontario, California]
A: [Aaron] Few people in Nebraska are threatened by hurricanes, so send a swarm of killer robots into low Atlantic and gulf coastal areas to drive the puny human inhabitants toward Nebraska. Problem solved.
Robot haiku:
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how to design and build a battlebot
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