Largest spinning disc on a lightweight!

[jim]

Largest spinning disc on a lightweight!

Whatever you use to move the robot will have to be fast - at a rather leisurely 1000 RPM, the robot will make a complete revolution every 60 ms.

Andrew, do you have any other source for the magnetometer idea? I have doubts that youd be able to detect the earths magnetic fields inside a metal box full of motors but it may be possible.

For simplicitys sake I would favour a dead reckoning scheme based on wheel RPM, but with additional feedback to the driver - a set of LEDs which pulse once per revolution to indicate the current heading; the driver can then provide fine control of the heading if need be.

[fluppet]

Largest spinning disc on a lightweight!

The only source was the comment in the above link:

To tell the robot which way to go, the driver uses some kind of global positioning system that informs the robot which direction is magnetic north.

The idea of GPS is nonsense (at least indoors), so I took the above to mean a carefully positioned magnetometer - but it occurred to me, too, that the interior of a robot isnt exactly free of distracting magnetic fields. Neat idea if that *is* how they did it.

I missed off the simple idea of just sitting a gyro in the robot and tracking rotation rate with it. I suspect off-the-shelf gyros are limited in the rotation rate they support, though - Ive only seen this reported (in one of the web sites Google gives you with a search for tornado drive) for a thwackbot with a low RPM. This assumption was the basis of my idea for counterrotating the gyro, but if there are standard gyros out there which can accurately represent the difference between 1000rpm and 1001rpm then it wouldnt be necessary.

I like the LED feedback idea, although it could get a bit hypnotising!

As for speed of locomotion handling, certainly a problem. The wobbly-wheel method used by Team Whyachi probably puts less strain on the drivetrain than the alternatives. Looking on the spec page suggested above, the Team Whyachi spinners are capable of appreciably higher rpms than CycloneBot (1000rpm for Why Not and 900 for Y-Pout, vs 400rpm for CycloneBot), but Teslas Tornado (with wheel braking?) has reached 870 rpm according to its web page. I wonder where the limits actually are on the different drive options. I dont know whether the various people suggesting translational spinners - if thats what they meant by them - in this section of the forum (I *so* dont dare build a feather...) have any estimates of RPM yet. Mind you, of course, the faster the spin the less the tweaking required per revolution to get the same final rate of locomotion.

Theyre certainly an interesting technical challenge. Id still like to know whether anyone has a solution for the batteries self-destructing, though!

--
Fluppet

[madoverlord]

Largest spinning disc on a lightweight!

My kids just went 5-0 and were crowned US SouthEast Division Champs (in the 30lb US featherweight class) with their new Magmotor powered spinner.

Totally Offensive swings a 22 6.9lb tool steel blade at about 3000rpm. The impacts are huge. One of them sent the bot about 20 feet through the air.

Im working on a frame redesign that will get it down to UK featherweight standards and may bring it over for the FRA world championships, if she-who-must-be-obeyed will consent.

http://www.madoverlord.com/robots/offensive.thttp://www.madoverlord.com/robots/offensive.t for a build report.

On a related issue, we in the colonies are not used to fighting on wooden arena floors (everything here is steel plate). Whats the surface like, what clearances do you really need, etc?

[woody]

Largest spinning disc on a lightweight!

Surface is/was painted chipboard......clearance needed .... Ummmmm This varies as the arena floor distorts under the stress of the battles.

You may well have seen some bots.. with little or no clearance .. come to a full stop as they hit a raised sheet.

[robotic_ants]

Largest spinning disc on a lightweight!

*double post*

[robotic_ants]

Largest spinning disc on a lightweight!

Yep theres nowhere you can hide without your Uk cousins knowing.
quote:

Im aiming to get it down to UK featherweight (26.4lbs) so I can go perhaps over to the FRA championships and wreak havoc on our European cousins.
You sound very sure that you are going to do alot of damage.
quote:

we need a contingent of feather spinners to spread the joy of kinetic energy. I think after Eds feathers we know about the joy of KE in feathers but im sure theres still alot to learn, while we are at it maybe we can teach our US cousins the joy of FP C02 flippers.

Looking forward to see how you do in competition.

Chris - http://www.featherweights.org/forum

[glen]

Largest spinning disc on a lightweight!

you need VD3 to go over to the UK and show you that spinners are better at launching the robots into the air..

i guess robert would know from experience

[madoverlord]

Largest spinning disc on a lightweight!

You sound very sure that you are going to do alot of damage.

Well, all bets are off when the box is locked, but with a 22 diameter blade weighing 6.9lbs spinning at 3000+rpm, it does store up a fair number of joules.

while we are at it maybe we can teach our US cousins the joy of FP C02 flippers.

Diversity is the spice of the sport, and planes fly both ways across the big pond. Cmon over and educate us poor colonials (I should talk, I was born in Tumbridge Wells!)

you need VD3 to go over to the UK and show you that spinners are better at launching the robots into the air.. i guess robert would know from experience

Glen is referring to an infamous hit that VD3 laid on my other feather, Anorexia, at last years San Diego BotBash. Bounced the bot off the 8 foot ceiling, still going about 20mph. Chopped and bent 1.5 steel C-channel. We estimate the bot went from 0-30mph in under 2 inches, several hundred Gs of accel. Shock killed the radio and a couple of victors.

http://www.madoverlord.com/movies/botbashhit.movhttp://www.madoverlord.com/movies/botbashhit.mov

[maddox]

Largest spinning disc on a lightweight!

Bof, spinners. Not that I cant build them, but I do not like the idea do destroy several £100 of the opponent, just to get them immobilized.
No, then flying lessons are more my style.
Now about the total height and distance the 70*100 ram(the owner knows), when placed in a good system, can trow a feather.
I did do that a few years ago ,with my heavy Project II/hexem.About 5m high and 15 m far, without the rebounds on the cold hard concrete floor. Some wanted to test the feather they builded.It survived mechanicaly.

[Guest]

Largest spinning disc on a lightweight!

I guess youre refering to this?

http://westlandstc.com/dominic/videos/heavyflipfeather.mpghttp://westlandstc.com/dominic/video...lipfeather.mpg

Aa for the 70*100 ram, I still cant understand how you can squeese that into a feather!

[jamesb]

Largest spinning disc on a lightweight!

cant see the vid, but that aint a 70x100 if its Doms flipper. Cant see how hes have a vid of the 70x100 if I aint

It fits..... I think.

[Guest]

Largest spinning disc on a lightweight!

Its not Dominics flipper, its a video from his website where Project II flips a featherweight (which is what Mario was speaking about earlier).

Youre likely to get similar results if you get the flow right. Cant wait to see it!