Largest spinning disc on a lightweight!

[knightrous]

Largest spinning disc on a lightweight!

Sorry, but we have infact beaten you all Thwackbot T2M being used as a melti brain translational spinner is a full 12kg spinner

[typhoon_driver]

Largest spinning disc on a lightweight!

o im sorry i thought we were still on light weight spinners.........my bad!

[jamesb]

Largest spinning disc on a lightweight!

humm... sceptical there Aaron, ill bet a few grammes of it doesnt rotate or you are a whizz with the electronics. how does that work then?

[jim]

Largest spinning disc on a lightweight!

Translational spinners do have everything rotating. Think of a 2-wheeled bot spinning on the spot, then speed it up a bit. You move around the arena by making very brief adjustments to the wheels steering or speed. Y-Pout is an example.

[Guest]

Largest spinning disc on a lightweight!

Theyre also a myth, Y-Pout uses a smaller inner nav-bot.

*Still believes a true spin-drive system is impossible*

[mikeyg]

Largest spinning disc on a lightweight!

Well its not, cos CycloneBot has managed it to some success. And at a lesser cost, too. Thats unless you count smoking out three mags in one day LOL

[mark_m]

Largest spinning disc on a lightweight!

Another true example of a translational spinner is Teslas Tornado. Its been around for quite a while and won two fights at Battlebots season 4.0.

Interesting thing is it uses an infra red based remote with sensors on either side of the bot which it uses as a reference direction.

http://mchargue.org/William/BattleBot/http://mchargue.org/William/BattleBot/


Id also be interested to hear how T2M works.

I used to think translational spinners were the way forward because they could potentially allow you to have large amounts of energy stored and still be very manouverable with a powerful omnidirectional drive system. I looked into it more and found its not physically possible though. Motors just have too much inertia to change their speed significantly as the bot rotates and youre limited by only having your wheels pointing in the right direction half the time. Im sure theyll work with some success in the future but theyre never going to be particularly effective IMHO.

Trying to pull this thread back on topic; the heaviest disk I can think of is Backlashs at 7kg.
Theres probably heavier but it depends if you class them as a disk. I used the Big Bang teams site cause its got the specs of most good American spinners on there:
http://www.geocities.com/bigbangrobotics/testspin.htmhttp://www.geocities.com/bigbangrobotics/testspin.htm

Mark

[team_ireland]

Largest spinning disc on a lightweight!

T2M is a twack bot. Not exactly High Tech.

Regards
Ian

[Guest]

Largest spinning disc on a lightweight!

I can see why people would say that electric motors would have too much inertia to just quickly switch off and back on to a useful translational spinner. At 600rpm abd with the wheel being turned off for about 30 degrees of the rotation thats about 0.008333 seconds that the motor has to be off for, and at 10 times a second too. Even if you turned the motor off for 180 degrees thats 0.05 seconds. The motor wouldnt have enough time to get much slower. The only this sort of robot would work is if it only spun about 200rpm and thats boring.
Maybe a central wheel that touched the floor at the center of rotation that you turned on when it was facing the right way for about 30 degrees might work, but youll only do it every5 or so revolution other wise the constant turn on current would fry something (like mag motors).
But Ive got an idea. Why not use a single internal combustion engine and feed that into a differental gearbox then to the wheels. You need to add an ideler gear to one side to get the wheels spinning in oppiste directions. You then add a fast acting break to one side thats able to engage and release in 0.008333 seconds (OK, Im still dreaming) which will lock one wheel and speed the other up giving you translational motion. The added bonus is the engine will alway remain running at one speed during the movement.

And Aaron, why havnt I seen T2M translate? You still owe mw a re-match with T2M too.

[knightrous]

Largest spinning disc on a lightweight!

lmao. T2M is a stinger style thwack bot, but it cannot attack vertical. I just full body spin it and adjust the radio sticks so one wheel is slower then ther other and it translates in an elliptical pattern. Tot high tech, but the full body mass rotates, with the current mods on T2M it weighs about 13kg, we have to drill some holes out of it. Removing the 3kg 7amp and replacing it with a small 3amp or 4 drill NiCD packs will solve this problem.

Daniel, anyday mate, bring your bot and well rumble. Just remember, we have a wedge and traction now

[jim]

Largest spinning disc on a lightweight!

I knew Y-Pout was a bad example after I posted it!

I think it could be done, using brakes as Daniel suggests. I was thinking of quickly firing a brake onto the floor rather than the wheel though.

Its obviously possible to make a low speed translating spinner, its just a question of how fast you can go.

*Still believes a true spin-drive system is impossible*
Ah, well, if it was possible, thered be no fun in building it

[Guest]

Largest spinning disc on a lightweight!

Mike, Mark, I had never heard of either of these bots.... I will have to do some research.

[bugs]

Largest spinning disc on a lightweight!

Im not sure, but i thought teslas tornado breaked on the motors.
If you read the facts & Specifications it mentions the active breaking of the speed controlers

[jamesb]

Largest spinning disc on a lightweight!

the only way to really have a heavier disk than halfwit (who was 12.2kg at Preston, and as such the disk was 12.2) is to have a walking spinner. If anyone can come up with a walking meltybrain (transitional spinner) where all 24kg spins, and getts over 1000 rpm, Ill be very impressed

[fluppet]

Largest spinning disc on a lightweight!

Now *thats* a challenge I like. :-) Almost enough to overcome my dislike of spinners. Possibly I should actually get as far as building something normal, first, though!

I like the idea of the infra-red LEDs on the transmitter for direction finding. Having done a bit of a web search (only just back at work, and still I spend all my time waiting for things to build...) Tesla Tornado does seem to use braking, although whether its physical brakes or whether it just means that the engines brake it I dont know.

Ive finally managed to source a bit of stuff about CycloneBot (you get really weird things if you put Cyclone Bot into Google - I presume there *isnt* an official web page?) at http://www.geocities.com/Hollywood/Set/9859/sc4_1.htmlhttp://www.geocities.com/Hollywood/Set/9859/sc4_1.html. If its accurate (well, GPS is nonsense, but extrapolating), its direction finding system is genius: use a magnetometer to measure the Earths magnetic field direction, then steer it with the compass points. Cool.

Ive been having a bit more of a think about translational spinners, just to divert the thread off-topic (as is my want). So far the mechanisms I can think of for actually inducing translation (disadvantages and explanations in brackets) are:

1) Speed up/slow down the motors (efficient in weight, but hard on the motors - speed limited by the motor response?)
2) Tilt the wheels with a cam/navbot as in Y-Pout and Why Not (navbots waste weight, are fallable, problems sitting still, tiltable wheels weaker than fixed ones?)
3) Tilt the wheels manually, with a motor on each (complex, waste of weight, but no nav-bot and more speed control)
4) Manage the speed of the wheels without changing the motor speed (e.g. by having an eccentric gear somewhere in the drive train which gears the wheels up and down in sync with the rotation of the robot, or have a cam-controlled driven differential; mind you, this might just result in the load on the motor changing rather than achieving translation, but a flywheel effect might offset that - also a very complex [and heavy] drive train)
5) Change the size of the wheels, e.g. by variable pressure pneumatic tyres (might have the same problem of just changing the strain on the motor, although probably less so; does require some waste of weight getting the tyres inflation mechanism working - but the words CO2 and doesnt count towards weight limit spring to mind)
6) Brake the thing on the ground (inefficient, possibly unreliable, probably bad with ramps)
7) Cheat - give it Razer/Groundhog style wheels and shove it around with a driven navbot

...and the means of controlling the direction of locomotion:

a) Navbots (waste of weight, possibly fragile, invertable ones hard, but they can shove a bit and drive a cam directly)
b) Gyro-navbot (not in contact with the ground, motor-driven to counter-rotate and keep the gyro still; still a waste of [less] weight and cant do any shoving, although the gyro could be mounted on a cam)
c) Emissions from the transmitter (prone to reflection/interference problems, but no waste of weight)
d) Optical profile matching (measure the light levels on the way round and deduce when a circuit has been traversed; complex and large changes to circumstance [being shoved around by Storm] may confuse it)
e) Track the wheel rpm (error prone with [common] skidding, but very simple)
f) Magnetometer (I *like* it) or, at an unreliable push for outdoor events, GPS tracking

Given that I have a pathological dislike of spinners, anyone care to add to the above (with any designs theyre not keeping secret)? Know thy enemy, and all that. :-)

Incidentally, there seems to be a bit of confusion on-line as to what exactly a tornado drive is, and whether it differs from melty brain. Can anyone elaborate?

--
Fluppet