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Subject: 
Re: WWW spider
Newsgroups: 
lugnet.robotics
Date: 
Tue, 9 Dec 2003 10:49:50 GMT
Viewed: 
1617 times
  
hi
i just developed this sequencer

DL
http://www.brickshelf.com/gallery/pixsrv/Ideas/pneumatics/pseq01.gif

maybe there is no purpose for this mechnism :)
it shows 2 things
1. even small and simple changes in the circuit make it a little bit
complicated :)))
2. it can be done :)

it's just a first trial
i'll work on the next "functions"

and here goes my answer to your post....

----- Original Message -----
From: "Kevin L. Clague" <kevin_clague@yahoo.com>
Newsgroups: lugnet.robotics
Sent: Monday, December 08, 2003 4:57 PM
Subject: Re: WWW spider


A common method used in the past was to use a central pneumatic timer • circuit
that control the muscle pistons and make them move.  This is what Doug • Carlson
did in his beatiful and ground breaking pneumatic hexapod:

http://www.visi.com/~dc/hexapod/index.htm

yes it's very good moc
i'm far far away from mocs like this

The central timing circuit feeds the muschle pistons in the hips and legs. • One
downside to this is that the timing circuit and its piston switching is
independent of the muscle expansion/contraction rate of the legs and hips. • Doug
had to make sure that the load on the timing pistons was greater than the • load
on the legs or hips.  This way Doug made sure that the legs and hips • always hit
their expand/contract limits.  The downside to this is that the heavy load • on
the timing circuit means his hexapod had to have high pressure to walk.

I tried using this technique on some designs, but didn't like the result.

in some aspects my idea also needs heavy load :(

My strategy for making sure the pistons hit their limits is to make the • muscle
pistons also play the role of timing pistons.  Quad 242 has a total of 10
pistons.  Eight are both muscle and timing pistons (which is why they all • have
switches used to instrument their state).  Only two of the pistons are • timing
only.

When you "clear" the pistons to create alternate behavior you'll have to • decide
whether you really want to change the muscle/timing system's state, or • simply
ignore the switch outputs of the hung leg and instead use alternat values • to
pass into the state machine.  It sounds like the second plan might be
inexpensive.

clear clears timing and muscles... i have to think...
what would be simpler to create

Expanding my sequencer design methodology to full blown state machines • will be
interesting.

it will need tones of valves and pistons
because every clear will probably need 1..2 pistons and 3..5 valves
it will be veeeeery complicated and it will be a lot of fun

the same is with my new hexapod
i want to do all movements from one motor which will rotate in one • direction only :)

Will you have two groups of three feet, where the two feet groups are 180
degrees out of phase?

yes 2 groups with 3 legs in a group
but there will be no pneumatics
just levers and gears :)

pixel



Message has 1 Reply:
  Re: WWW spider
 
(...) It is a very cool mechanism. Your circuit can change from a 3 piston timer to a four piston timer, right? Kevin (21 years ago, 9-Dec-03, to lugnet.robotics)

Message is in Reply To:
  Re: WWW spider
 
(...) Good luck! I look forward to it. (...) Hmmmmm.... I wondered if you might be thinking of this. A common method used in the past was to use a central pneumatic timer circuit that control the muscle pistons and make them move. This is what Doug (...) (21 years ago, 8-Dec-03, to lugnet.robotics)

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