Lynxmotion Tech Support

I'm currently starting a project from scratch, involving 4 servos and 4 legs. I am basically trying to have my robot be able move in all directions using only 4 servos. The leg movement will be 3-dimensional. Legs will rotate and lift. The question is, where can i find the appropriate parts and pieces to accomplish this? There will be mechanical movement involved, since the leg's life is dependent on the leg's rotation.

A simple reality check is that if it was simple/practical to do, people would already be doing it. Since you think it can be done, you will need to design your bot, and make a working prototype to verify the design (you will probably need to make most of your parts). You may want to try the below three servo design first to get the feel of things. You can use the lynxmotion electronics to operate it.

http://www.kronosrobotics.com/FirstWalk ... lker.shtml
http://www.kronosrobotics.com/FirstWalk ... Walker.pdf

That's quite an ambitious project! For omni directional walking robots, 3DOF legs are generally considered to be needed. getting complex rotation and lift will need some thought. For 4 servos, you might consider something like the Loki robot I've posted about. This is a biped robot, with two servos per leg. However, the inventor of this robot states that in experimenting with it, he has been able to get sideways walking.

http://davidbuckley.net/DB/Loki.htm



I've just added some pix on the Loki topic.

Alan KM6VV

From your posting, it sounds like you have a mechanical design worked out that will accomplish the motion that you describe. Without any more details however, we can't really give you too much advice on what parts and pieces would be appropriate, or where you might turn to acquire them.

Achieving holonomic walking motion with just four servos sounds like it will require a fairly complex mechanism, so I'm thinking that some drawings or sketches would probably be in order so far as describing just what it is that you're trying to accomplish.

Lynxmotion carries a number of general mechanical and structural pieces and brackets, which can be found on the main website in the various merchandise categories. For mechanical parts not listed here, a local hobby shop, particularly one dealing in radio-controlled cars and planes, can prove to be a valuable resource.

Let us know a little more about what you're trying to do, and we may be able to provide more detailed assistance.

Unfortunately I don't have a solid mechanical design worked out, but I do have a plan of the overall design of the 4 legs.
Here it is:
img295DOTimageshackDOTus/myDOTphp?image=blueprintgv7DOTpng
when you copy this into the address bar, replace all the "DOT" with a period.
(This anti-spam filter won't let me post any links, sorry!)

What I am looking for is a sort of mechanism that will lift the leg when the leg is rotated at a certain angle.

You should be able to post the link in a day or so.

It will be interesting to see your sketches!

Alan KM6VV

just dropping by...

ever heard of BEAM walker?

They use no programming. Only simple circuit and basic mecanics.

Have a look here

http://www.beam-online.com/Robots/vwalker1/index.html

http://raysbeambots.solarbotics.net/harold/harold.htm

here is a 4 motors walker
http://haroldsbeambugs.solarbotics.net/trooper.htm

The motor push and goes forward at the same time.

J-

Hm, that's pretty awesome!
I checked out all 3 websites, and this is exactly what I was thinking about, in terms of mechanisms. I was thinking of a more solid chassis and leg frame, but this will allow me to explore the mechanics of the robot.
The Beamtrooper was not what I had in mind, but the other 2 beambots's leg motion was what I had planned. Too bad there are no closer views of the mechanism they use.
I think the main challenge will be to find the materials needed. Most of my hardware stores do not carry any small springs or items, so I will need to find everything on the net.

edit:
also, what kind of mechanism would allow the leg (see diagram) to rotate up or down as it rotates left and right?
I was thinking of using gears, but that would not make the leg push down when rotating either left or right from it's initial position...