Trying to design first robot

[Fractal]

I've been thinking about building a robot for a while now, but i will admit the repeats of robot wars extreme on dave (i have seen this discussed on here and am also happy with the increase of intrest) have turbo charged the effort somewhat.
Basicly i've done some simple designs so far and my team mate is set on one which im convinced wont work, and even if it did would be unusable due to the whole heavyweights with spinners thing (which i do understand, but it dosent stop me from being abit sad about it )



The idea is because we like spinners and as they can't be used currenty my team mate decided to try and find away around this..... So we've ended up with a design where (and i am reluctant to call it a full body spinner) there is a fixed disk and the idea is to have both wheels running in opposite directions to make the entire robot spin, the reason i don't like this is i doubt we would be able to get the robot up to a speed where it could do any damage, and even if we could, would then be classed as a spinner.
I have been unable to convince him of this so i would be grateful if some experienced roboteers could post their opinions of this, otherwise we could be undecided on what to build for a long time (however i would be just as gratefull if you guys prove me wrong)
Also could we avoid the topic of heavyweights being a bad idea for first timers to build as i have read that advice and decided to completly ignor it as i think we are up to the challenge, if we find we're not we'll put it on hold and build one for a lighter weight class!

[widow_twanky]

Re: Trying to design first robot

I seem to recall the rules say you can have a full bodied spinner up to 500rpm where it is driven solely by the wheels (which your would seem to be).

Only problem I can see is tactics with it. They would have to be 'sit in the arena and spin and wait for someone to drive into us' the only person whod do that is probably Jason (Thor) if you were close enough to catch him as he drove into the pit.

[Ellis]

Re: Trying to design first robot

I doubt it would do much in the way of damage though, and controlling it would be... Well you wouldn't be able to. If it is considered a spinner, don't forget that (as far as I know) only 2 events are held in a year that can house spinners, so you wouldn't get that much play time.

[Fractal]

Re: Trying to design first robot

If it is considered a spinner, don't forget that (as far as I know) only 2 events are held in a year that can house spinners, so you wouldn't get that much play time.

I thought that was featherweights? I didnt know there was one that could contain heavyweight spinners.

[Ellis]

Re: Trying to design first robot

Then there probably isn't, I forgot we're talking about a heavyweight, scratch what I said, sorry.

[Metal Demons]

Re: Trying to design first robot

That's a design which in different forms has been tried several times, by teams with enormous amounts of resources and engineering expertise, to very little success (Team Whyachi and CM Robotics come to mind).

The concept's called many things, cyclone drive, translational drift, or most commonly melty brain after the sheer frustration of getting it to work effectively.

In order to get the robot to move controllably while spinning on the spot, you need to accelerate the wheels slightly while they are moving in the direction of where you want the robot to go, and decelerate them slightly while moving away - that's the basics of it. (Alternatively you can hinge the wheels and modulate their angle using a complex internal steering system and mechanical linkage which was the Team Whyachi approach - it didn't work very well). In order to do that you need some form of positional reference for the robot in relation to the rest of the arena and a rpm monitoring system - methods that have been tried include encoders on the shafts to detect wheel speed (not terribly accurate due to slip) and even using the earth's magnetic field to use magnetic north as a reference, though probably your best bet is to use a gyro.

Even if you manage to develop an effective control system (the information on how to IS out there), your second problem will be that you're basically hitting the opponent with the entire mass of the drive motors, batteries, and all the internal parts - such robots tend to break themselves routinely due to the massive shock loadings put on everything upon impact.

All the current incarnations of such a concept have been painfully slow to translate, relatively low rpm, and unreliable - though they hit like a speeding truck; having the entire mass of the robot spinning makes one hell of a weapon. If you were to find a way past all these problems you'd be likely to end up with one of the most frightening machines ever made, though... :twisted:

Oh, and it would most certainly not be able to run in any UK heavyweight arena; you'd have to build a featherweight version.

[daliad100]

Re: Trying to design first robot

Mechanical translational drift spinner from cardboard, paperclips and straws

I had thought about shoving a 2 wheel drive version of Dale Heatherington's light seeking spinner together with the south pointing chariot mechanism.
It would use some sort of encoder on the pointer which would have some sort of optical sensor hooked up to the mosfets which stall the motor at the correct point. I would like to do it without stalling motors but that would require me to look at it properly.

I've also designed a full body drum spinner that might work where ~80% of its mass is in its drum and the rest is in the wheels and a free rotating rear wedge that should make it work.

Edit: If you can make the the system turn off and switch to normal drive then you can run it as a non spinner.

[jonophilpott]

Re: Trying to design first robot

OR you could look at the sucess of typhoon... incredibly effective.

[typhoon_driver]

Re: Trying to design first robot

Thanks

Although I wouldn't bother looking at any full bodied spinners or anything close. Nightmare to design and make reliable and there is nowhere to run it these days. Even the robot wars arena wasn't entirely safe to run Typhoon 2 in.

[swanaldo]

Re: Trying to design first robot

Design on a beer mate. cant go wrong