[MOC] 8 Legged Walker

[ord]

It is essentially two Tchebyshev Plantigrade Machines mounted to the sides of a technic hub.

The most difficult part was getting the ratios of the linkages right (and relatively form locked):

The Studio file is on my bricksafe if anyone wants to build it (it doesn't go too well on carpet - that's what the round feet are meant to help with. Also, the file shows frictionless pins at the tops of the legs - replacing these with loose-fitting friction pins if you have them will make the legs sturdier):

https://bricksafe.com/pages/ord/8-legged-walker

Cheers!

Edited March 22, 2022 by ord
Added note about friction pins

[gyenesvi]

That's some pretty smooth movement I have never seen before in Lego, exactly the pattern I have been looking for, I'll have to look into the mechanics behind it. Thanks for posting this cool incarnation of the machine!

[howitzer]

I always admire the walking machines that people create from Lego, as those seem to be really hard to make work well and when successful, they're really cool. Nice work!

[ord]

@gyenesvi thank you! The link I posted has a very nice video explaining the mechanics.

@howitzer thanks! 

[Jundis]

Whoa! The movement is sooo smooth. Great job!

[Davidz90]

Amazingly well optimized geometry. I've never seen lego walker that remains so level. There is almost no vertical motion at all!

[Jonas]

This is a very clever design. Thank you very much for providing the sketch of the main linkage and the stud.io file. I have just build a pair of legs to learn how it works.

I admire your creative solution to these three 2.5-stud-long arms.

[technicfanatic]

Very nice. I especially like your diagram showing the geometry, though I would appreciate it if you could add an explanation for why that geometry is important. Very nice walking motion!

[ord]

Thank you everyone. A lot of respect to Tchebyshev for creating this mechanism nearly 150 years ago.

This diagram helps to show why the geometry is important:

For half of the cycle of the input, the output smoothly moves nearly in a horizontal line. For the other half, it lifts up and moves back to the start at a higher speed.

So, with two of these mechanisms 180° out of phase with each other (and connected to feet) there will always be at least one foot on the ground.

[technicfanatic]

Aaah! Thanks for this diagram. I encountered this while researching mechanisms for converting circular motion to linear motion. You make clever use of it as a walker.

https://en.wikipedia.org/wiki/Straight_line_mechanism

https://en.wikipedia.org/wiki/Chebyshev's_Lambda_Mechanism

 

 

 

[iLego]

1 hour ago, ord said:

For half of the cycle of the input, the output smoothly moves nearly in a horizontal line. For the other half, it lifts up and moves back to the start at a higher speed.

So, with two of these mechanisms 180° out of phase with each other (and connected to feet) there will always be at least one foot on the ground.

Thank you for sharing the cool Walker. And thank you especially for this very succinct and clear explanation of how it's working !!

[tom1]

Great job!

[tom1]

Please, do you have any pdf scheme.

Thanks

Tom1

[ord]

5 hours ago, tom1 said:

Please, do you have any pdf scheme.

No sorry, just the Studio file that I linked (it is grouped into eight steps that should be followed in order).

[tom1]

Thank you ,

Tomislav