[HELP] Pneumatic Walker

[Zerobricks]

I built this walker with 4 legs. Each leg uses one cylinder to lift/lower the leg and a second cylinder to move the legs sideways. Also each cylinder has a valve linked to it, so it can move the valve when the leg functions reach their end positions.

The problem I have is how to 'wire' the tubing so that the legs are synchronized...I can easily make each leg walk on its own but due to uneven nature of pneumatics this means most of the time only the leg with least pneumatic resistance moves and the other 3 are stationary.

[skppo]

Maybe try to make the sequence be controlled by one mechanism for all legs and it needs to have more resistance than the moving cylinders combined.

So the walker would have a "brain" that won't do the next movement before the last one is completed.

[Captainowie]

So you want to synchronise the movements of a given pair of pistons.

Years ago I remembered reading something about this from Kevin Clague. A few months ago I tried to find it again, but had no luck. The only thing I could find was from the Wayback Machine, but there are no pictures to go with it.

http://web.archive.o...encer/index.htm

This might help you, if you can figure it out from the text alone.

Owen.

Edited March 16, 2014 by Captainowie

[Brick_Sticker]

I like that you have the valves controlled by whatever cylinder they are closest to, but you will probably have to use the electric motor to operate the valves in a certain sequence and timing, kind of like a walker that is mechanical, except that it is the valves that are controlled, not the legs. Maybe a lot of gear racks and cranks for the timing, and a very healthy supply of air. Due to the nature of lego pneumatics, I don't see it being very reliable otherwise.

Looks very interesting though, hope to see more progress on it.

Brick_Sticker

Edited March 16, 2014 by Brick_Sticker

[aeh5040]

I would definitely check out the brickshelf folders of Mark Bellis and Kevin Clague.

There is also a list of old LUGNET posts that may be helpful.

Since you only have 4 legs, you might need something like Kevin Clague's "one leg at a time" hexapod in order to keep balance:

[darsedz]

looks like you creating Darpa Big Dog walker :)

[arik]

That's interesting! I've been thinking of building a four leg walker myself, and found it much harder than six legged. Basically you can either move the legs in opposite pairs (like a lizard), or move legs up and forward one at a time. Instead of keeping the other legs stationary as in the video above, I think the most realistic way would be to move the other three legs 1/3 of the speed back, keeping up continuous gait. But I don't think it will be simple to do either mechanically or pneumatically. (I'm sure I'll try to build a mechnical one anyway some day.)

Did you have a gait pattern already in mind?

Oh and the leg design looks very nice! Any chance to get a video of it?

[Zerobricks]

Sure I can make a video, but it wont walk as it should... Maybe I'm gonna make an 8 legged one, but with simpler mechanism.