Sunday, October 10, 2010

Week TechVideo, 2010 #40 - Legs, legs and more legs

Today I decided to post differently. Two videos from different authors in one single 'Week TechVideo' post.

Spiders and insects are quite different animals as we all know. In common there is the fact of them having multiple pairs of legs, unlike us humans which have one pair and most of other mammals which have two pairs.
If it is not easy to capture the several types of leg movement sequences from a 4-legged animal, it is incredible more difficult to understand real hexapod and octopod gait sequences.
You may find several good articles in the net about different types of gait, but they won't make it trivial their realization with a LEGO robot.

Spiders belong to the arachnids class and have 8 legs (4 pairs), and insects have 6 legs (3 pairs) among other well defined differences.

The realization of hexapod and octopod walker LEGO robots, is something that could go from relative simple implementations to quite complex ones. The result could be more or less effective but is almost always fascinating and difficult to achieve. Making this walkers turn is even more difficult.
On top of this, you may achieve really slow realizations or instead quite fast ones. It all depends on your skills.

Despite totally different in their complexity, approaches and solutions taken, I decided to post side-by-side two of the most impressive and actual LEGO walker realizations, of my preference (not to mention pure LEGO pneumatic realizations) - Respectively one 8 and one 6-legged, robots.





On the left side we have the "PF/NXT OMNI-Spider" by Menno Gorter (A Dutch AFOL) who has been building incredible LEGO walkers for decades.
Realize on how natural the movements look like, the legs placement are and how it is capable to walk in any direction, like a Killough Platform robot with omni-wheels.

The model here highlighted features a brilliant 8-legged spider, with four PF motors controlling them in pairs.
It is a preview from a prototype to display at Legoworld (Zwolle) starting next week. If it is a prototype, I would like to see how the final version will be. Hopefully we should get access to new videos soon.
Dammit if I understand the moving sequence of this legs... But we all know it was filmed to be not understood. Isn't it Menno?



On the right side a video for an "Hexapod Walker" by Gus Jansson.This six legged robot driven by 3 NXT motors (one for each two legs). Legs move in a boxy figure 8 pattern, and this I can understand much easier.

According to the author description at YT - "The left and right motors control their respective sides corner legs. The motor in the back controls the middle set of legs so that either left or right corner legs can be lifted. When left middle goes down, left corner legs go up and right middle goes up.

First program just walks in a simple pattern. The second program was for a walking robot race and uses the small LED lights as navigation aids. Light sensor, mounted in the back but looks forward, sees the light and with every step adjusts step size to aim for light."

Also the color schema used, is awesome!
Just in case you want to try something similar, you may find detailed pictures from this model, at Gus flickr stream (LEGO Hexapod Walker).

12 comments:

santi said...

I've to admit I'm not too excited about the 8 legged one, since (unless I'm mistaken) it seems to drag several legs depending on the direction of movement, and I don't think that is very elegant. But I love the 6 legged one!!! it's pretty impressive, and unbelievable fast!

Any good 4 legged ones? I think 4 legged ones are quite challenging, since you have to address the equilibrium problem. With 6 or 8 legs there are always plenty of legs always touching the floor, and equilibrium is not an issue.

santi said...

Btw, I've been looking at the Brickshelf folder of Menno Gorter (the authro of the spider), and I'm VERY impressed. Too bad there are no videos of those walkers!! I'm specially curious about the 1987, 1993 and 2001 ones. Awesome work!

Barman said...

Next week I'll be at Legoworld and Menno is past of our stand. I have the privilage to see his amazing omni spider in action. I'm looking forward to that.

Gus's Hexipod walker is brilliantly simple. It just works great. I Love watching the video.

For the ones who are able to come to Legoworld (The Netherlands), I will see you there.

Barman

Conchas said...

I visited Legoworld two years ago.
Unfortunately at that time I didn't not yet knew about some of you, cause it was a great opportunity to meet you in person.

Looking forward to return and meet you, at a not so distant year to come. :)

Conchas said...

BTW, at the time I stayed on the MINDSTORMS area, with Robotica (Martyn Boogaarts) et all. :)

Anonymous said...

Santi; Obviously you've missed the YouTube link in Menno's name. ;-)
If it's almost impossible to compare these two bugs, since one is omnidirectional and the other is very fast and clever designed, so what's the use of asking for a four legged one?
Is it ever enough?
At least these two walkers really need the NXT to make walking possible and they are self-contained.
Conchas; I think twisting studless beams was indeed a lot of fun, but you could have seen 3500 square meters filled with Lego. ;-)
NXT time ask Martyn who told him to make tall things....

santi said...

@Anonymous
Indeed I missed the link! nice!

Conchas said...

@Santi,

you may find two videos from a very successful quadraped realization, at Menno's YT channel.

Look for NXT-Coyote.


@Anonymous ;)

I've indeed seen the studless beams twisting, but Ive also seen all the other LEGO at exhibition at IJsselhallen. :D

Anonymous said...

Of course the Mindstorms booth was at the end of the exhibition; therefore you should have crossed the area a lot of times.
But it seems you managed to miss the booth in the centre of the first hall with people like Menno, Barman, Mahjqa, DrywFilthiarn, etc. ??? :-)

The NXT time I'm sure you want to be in their booth the whole time.

Dryw Filtiarn said...

I agree with Anonymous user above. This year will be worth coming to our booth. There will be a factory that is capable of building (small and simple) models that you design using LDD :) (I'm currently finishing that project and I'm close to getting it finished)

Conchas said...

In fact I've seen the booth you're mentioning as well. Took some photos and even still remember some of the models.
I was inclusive there speaking with Mahjqa who was also LA at the time.

It happen that I just didn't knew the other names by then, and thus I didn't spoke with you. :(

But I'm sure there will be a second chance. :)

Conchas said...

Also Martyn was one of the Dutch AFOLs I speak most at the time, so I was very happy to in their both for sometime and knew the people. :)

All good people as well! :)

I see next time will be really great. :)

Maybe you have seen also the large vending machine in the 1st hall, from one of the local friends who visited the event with me.

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