simpleWalker: 4-legged 2-servo walking robot

Arduino (own design with atmega88) controlled walking robot, made with two RC servo's and 1 A4 of sheet material

Step 1 Get the materials

materials needed:

1 sheet of birch plywood (4mm) of 21 x 29.7 cm (A4) (this can be any material, really. You can also use scrap bits, and cut the individual parts from them)
2 RC servo's (standard size) with mounting materials
8 screws m2 x 8 including nuts
8 screws m3 x 12 including nuts
2 screws m3 x 10
1 battery container with clip, wires
4 niMh batteries (preferably rechargeable..since servo's use quite a bit of power)
1 arduino or compatible microcontroller board (cheapduino)

Comments

[gaurav300489]

sir it can follow the line??? and wats the use of electronic circuit here?

[ShoopDaWhoop]

i dint had the time to browse trough this instuctable but ive got one question, is it capable of steering or does it just walks straight on?

[kapoysignup]

what the freaken believe it

[ElectricUmbrella]

Pretty sick looking, I hope I get to try this!

[albylovesscience]

sorry to bug you but can you make a schematic for this

[bluegirltulbo]

is it programmable?

[bluegirltulbo]

greeeee.. nice mennnnnnnnnnnnnn...

[overslacked]

Hi Andy, I'm curious, why did you decide to add a microprocessor? You seem to describe your little guy here as a BEAM device, but it doesn't seem (to me, at least) very common to introduce a microprocessor at this level of complexity.

[edwindertien]

You are right. You could take out the electronics of the RC servo's and put in a BEAM bi-core. In 'the old days' of Tilden's beam robotics (when there were chunky 6502 or 68HC board around) a system with only two analog IC' s and a couple of capacitors was a great improvement. Now a microcontroller is just as easy (one atmel IC costing less than two dollar) and offers a great deal of flexibility in terms of adding sensors etc..

[Kiteman]

That's nice - are there any plans for sensors or steering?

[andy]

I believe steering is a function of timings with this morphology. Specifically (as far as i understand) the rear legs are normally (optimally?) a half phase (180 degrees or "anti phase") from the from legs - when the front leg is rotating in one direction the rear legs are rotating in the opposite direction. There are ways (given this configuration) to turn left and right, reverse, go forwards and "stomp" (where the robot is moving its legs but such motion doesn't cause it to move forwards) without any further physical alterations. Forward, stomp and reverse are a function of the phase. Steering is related to the amplitude of the signal sent for any given step forwards; a long left step and a short right results in a slight turn, over a number of steps this becomes an arc to the right. Hope this is useful, Drew p.s. "stomping" may appear useless but it can be very useful; for example your robot detects that moving its legs is harder than normal it could summarize that it has become stuck or bogged down. Imagine its traveling through a pile of leaves and is walking into and through the pile rather than over it, stomping could get it atop the otherwise untraversable pile of leaves.

[Kiteman]

I know how it steers, but this project lacks steering (either by remote control or as a consequence of sensed obstacles), which is why I asked.

[andy]

Sorry, my mistake, Drew

[andy]

Also, I'm currently experimenting with getting a beam robot walker to achieve static postures, so it would be able to posture for charging for example, or in order to get a better look around, would this be better as two Instructables (how to make the walker, how to get it to posture) or one with it all together? Thanks, Drew

[Kiteman]

Since the walker would have a fairly unique geometry to be able to pose upright, I would put it all in one - there's nothing wrong with a lot of steps in an 'ible.

[andy]

On the contrary its a fairly standard BEAM layout, the real trick is in circuit design. There needs to be one or two modifications to more standard designs but these can easily be added on to an existing robot. I suppose a "built from scratch" approach would be more accessible and generally more clear, so I think i should still have one larger 'ible, as you advise. Thanks for your input, Drew

[AndyGadget]

I love the leg movement. I was trying to remember where I'd seen it before and it's the same as lizards I'd seen scuttling up and across walls in France and Greece.
http://www.earth-touch.com/result.php?i=Large-lizard-on-the-prowl a bigger lizard demonstrating it.