Let's Make Robots!


jumps like a bull on hot coal


Your browser is not able to display this multimedia content.


Added video. I know it's motion stinks.. But it is work in progress, I only made / show you the video because I find it interesting myself to sit and figure stuff out by watching it :)


Well at leat this time I have managed to make something that jumps.. Like crazy :D And that is the problem, it goes nuts!

It's late & dark now, so I cannot get it on video.. outside.. and trust me; one does not want to attempt it inside :)

  • The "pins" are fiber glass, very springey, I found out the Polymorph is quite absorbing / dull as spring compared.
  • At the tips it has steel reinforcement, as it was getting shorter and shorter legs :)
  • The reason for the long stick in front is that I experiment with moving the battery / weight.
  • The motor is from an old RC,I have locked the axle, no dif drive.

More to come, and then better images, and video not made with my cell.. I guess :)

I'd REALLY whish I had a high speed camera, that would make analyzing the jumping SO much easier. This is too big and crazy jumping for any strobe-analyzing.




Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Ahhhhh - No Video !  you kill me! , your such a tease!

Instead of having it run, where analysis would be difficult - can you just record dropping it?  It might be easier to try to understand what is going on and where a natural harmonic of motion is.

I  don't know where you are going with this but it looks like fun.  rHex was pretty nifty for the simplicity of it, but I would guess a kangaroo actually can feel the best time to contract its muscles - rather than just blindly sending 100% duty into a rotary motion.

A kangaroo hits the ground after a leap - on impact the tendons and muscles stretch like springs and I would guess they can feel the appropriate time to apply "leaping" pressure

could you put switches on the feet so you uProcessor knows when its in contact with the ground?

Interesting project, looks like fun - good luck

I am holding final judgment until I see video! (But I love this series progress!!)

Those sensory switches need not be on the actual feet. Anywhere along the leg, where it can sense tension (flection) in the leg, would do. I took some X-rays of your leg and drew an extra tendant along the rear of the leg. This shows just one example of placing the sensor near the "hip joint".

tendant along legswitch in joint

In red is the tendant when the leg is flexed (has tension). In green the same tendant when leg is relaxed. The top of the tendant is not fixed in the left image.

In the detail image it is fixed to the joint. A levered microswitch is placed between bone and tendant. It takes up the slack of the relaxed tendant. In this position it would be sensing "airtime".

Analogue sensors would even be awesomer!


 Man, I got to get me a real robolab! Too ... many ... ideas ... Must ... choose ... one!!!

Good ideas :)
Men!! That video is awesome!!!!
Keep up the good work   ;)
Hey, what if instead of motors turning all the way around, you could somehow have them as fast servos that just pop the bot up and forward?
or a pair of solenoids with spring feet

Thank god this one isn't so terrifying. Good aesthetic though -- the legs look like a bird's muscular legs. Looks like you need another set of fiberglass "antennae" on the other end to keep it from flipping over. Looks like good progress though.


I was thinking the same thing when watching it flip over all the time. Why not make it four sets of antennae?


/         \


Then it would no longer have a topside or a bottom. And it would jump again whichever way it landed (except maybe on its side).

The flipping over is like ketchup on your pasta running down to the table. One could of course (as you suggest) make an extra plate to pick up excessive ketchup.

I like ketchup, but I think I will try just to learn to control the amount ;)

And probably the most sensible attitude. But I was really hoping for a hedge hog jumping around your garden.