Corvis (temp bot name) rough ideas.

**Bacon Wizard** · 11th April 2013, 19:46

Well, this is the first post of hopefully many. On advice, this is my starting-place where ciggy-packet drawings become something a little more thought-out and eventually a working bot. Any and all advice/comments very much welcomed. I'd love advice on a newbie user-friendly CAD program.

Only one thing is certain. This is a walker. I'll be chuffed if I end-up with something that can be respected in the arena and really competes with rollers. Despite the extra weight allowance, my mantra is save, save, save on kilos, which new materials may help-with.

I'll post again on specific parts of the design, but my general thoughts lead to the following overall impression:

The plan is to use fluidic muscles to actuate the legs. These are light and powerful, also very fast with the right valves and enough CFM. They are available to buy, or are easy to home-make if I am prepared to get them tested for safety.

In order to use fluidic muscles, I wonder about using a scroll-compressor to drive them rather than an air-cylinder. We are talking a hundred or so psi only, but air-muscles don't need more.

For the drive train, I have a couple of ideas, and will return to the subject later. One has involved an in-depth study of gait, leverage, how joints work etc in running animals and humans. I've spent months obsessing about it. The other, involves hundreds of tiny legs, each vibrating at at least 20hz thanks to the air-muscles, hopefully more. The movement of the leg would be in 2 dimensions only, propelling the bot forwards almost like a massive bristle-bot, but actuated individually according to the regs.

For weight-saving, I want to look carefully at kevalr and carbon-fibre fabric, impregnated with sheer-thickening fluid. 6 layers of kevlar stops a 9mm bullet. The Sheer thickening fluid makes it stab-proof too. No composite required.

Carbon fibre for springs and structure when needed, and layers of the fabric made into scales or "feathers" overlapped like old scale-mail armour and each of which has a carbon fibre stem and rooted in a thick layer of more non-newtonian material (tempur mattress foam for example)..to absorb shocks and take the wind out of weapons.

I know impregnated kevlar will take a blow, and want to look at absorption as a method for armament too, hence non-newtonian padding.

Another issue with a walker is traction. So I'm hoping that Geckskin will become available in the next 18 months. Google the stuff!

For weaponry, A top-mounted spear. We don't see these much anymore, and perhaps there's a reason. But as far as I can tell, there's nothing in the regs to suggest that you can't have a serious spring to propel a seriously heavy bit of metal forward at blistering speed. This is something I know a little bit about. I am perfectly capable of constructing a reverse-energy compound cross-bow out of a multi-layered carbon-fibre composite leaf-spring, using very thick re-enforced cam-chain as if it were the string. I mucked about 2 years ago with ordinary leaf-springs for a cross-bow, and was able to turn breeze-blocks into dust before it finally self-destructed after many a replacement string (clutch-cable at the time!)

So you can see why one of the restricting factors for my grand plans, is dosh. Again, any comments from the more experienced.. (ie, everyone!) will be something I want to listen-to. I had thought that maybe I shouldn't advertise my ideas to the world, but actually if I don't get advice it'll fail, and if someone else does it before I do then that's my own fault now that I've decided to go for-it.

As it happens, today is my Birthday, so I'm off for a couple of pints now. Er.. so if I return to the forum later tonight, please ignore everything and it'll no-doubt get deleted in the morning!

**ady** · 11th April 2013, 19:56

Honestly? my first thought was what the.......To me it sounds very expensive, very complicated so best of luck lol
I'm sure others can help but I can't on this one! Except to say I can see reliability being a big issue and the weapon being inadequate against today's machines. Obviously this is a long term project if one of the materials is at least 18months away, I'd say get saving and get that workshop/shed built
Take a near 15 stone Thor or Tiberius for example, have you seen these compete live?? I think they would have a good time with your robot.
Honesty is always the best policy :-)
Happy birthday

**Bacon Wizard** · 11th April 2013, 20:14

Originally Posted by ady

To me it sounds very expensive, very complicated so best of luck lol
I'm sure others can help but I can't on this one! Except to say I can see reliability being a big issue and the weapon being inadequate against today's machines. Obviously this is a long term project if one of the materials is at least 18months away
Honesty is always the best policy :-)

Happy birthday

Tah!

Complicated comes with walkers, no? I'm surprised that you think the weapon wouldn't be enough though, but maybe I'm not understanding modern armour. I reckon that if I had a HW to play with, I can put a bit of spring steel right through a car's engine block. Not that I'm going for HW to begin with.

**TeamPsyclone** · 11th April 2013, 20:07

Well, I'd say one of the best, easy to use, and free CAD programs is Google Sketch- Up. The supposed 'Trial' version keeps on going, and has most of the features anyway. As for everything else, I can't really offer any advice or anything, never dealt with walkers.

Anyway, happy birthday! A night down the pub should be a good'un

**Bacon Wizard** · 11th April 2013, 20:23

Originally Posted by TeamPsyclone

Well, I'd say one of the best, easy to use, and free CAD programs is Google Sketch- Up. The supposed 'Trial' version keeps on going, and has most of the features anyway. As for everything else, I can't really offer any advice or anything, never dealt with walkers.

Anyway, happy birthday! A night down the pub should be a good'un

Many thanks, and hiya..

I'll try that. Walkers have inherent problems, but hence the weight allowance. I don't think a walker is the best way to win. OBVIOUSLY not! It's what I'm most interested-in.

**ady** · 11th April 2013, 20:17

cast block or Ali :-)
Soz I thought this was goin to be your initial build

**Bacon Wizard** · 11th April 2013, 20:45

Originally Posted by ady

cast block or Ali :-)
Soz I thought this was goin to be your initial build

Oh, it is, of a bot. But not of stupid crossbows, as I mentioned. I wasn't kidding when I said I was turning breeze-blocks to dust using standard leaf-springs (which are very crap in comparison with carbon, and reverse-energy version is also much better)

However, it may well be that I've underestimated the power that is required. If I aim to equal the force of a solid-slug shotgun at point-blank range, would that be good enough? Or am I out of the ball-park?

I know it's going to be complicated because it's a walker. I'm determined to do that, though.. it's not about winning the whole thing (in fact, qualifying would be lovely.. or even successfully WALKING!) it's about advancing walkers.

Expensive.. yeah

It really could be. The carbon and kevlar isn't too bad, and I can nick tempur from scrap. IF i can use self-made air-muscles, then that's very cheap too and there are no motors except to run the compressor, but THAT is serious money and there are lots of parts which will all need to be custom made. And it's a walker, and so will go wrong lots too.

I doubt I'm gonna go for HW to start-with.

**Max** · 11th April 2013, 20:31

I would say that all sounds hugely expensive (I am imagining near 5 grand but I'm not very sure) but really awesome, I wouldn't bother with a walker but if you are set on one then tats your choice.
I looked into using fluidic muscles but they were very expensive (festo ones were about £200 per muscle I seem to recall). Also remember that with fluidic muscles the amount of stroke depends on the pressure so you would need a good compressor to keep the pressure up, again I would instead go for a mechanism to make it walk based on 2 DC motors to save you a lot of weight as hassle. In the rules it says that all projectiles must be tethered so you would have to tether your spear thing, but it sounds like a cool weapon, but ok not sure on its effectiveness against materials like 6mm hardox, but I am planning a. Similar weapon so I am hoping it will have some effect.
I am sure you realise this but for your first robot keep it simple and work up from there, you will have more fun if you actually build a simple featherweight wedge than if you spend loads of money and set out to build an amazing heavyweight then never actually manage to build it as you have wasted all your money.