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Subject: 
Re: Seeking Strategies on Humanoid Robots/Walkers
Newsgroups: 
lugnet.robotics
Date: 
Thu, 21 Jan 1999 05:52:36 GMT
Viewed: 
1696 times
  
Jasper Janssen wrote in message <36a3ca48.45364286@lugnet.com>...
On Sat, 2 Jan 1999 04:19:43 GMT, lego-robotics@crynwr.com (Andrew
Phelps) wrote:

Well, that is the million dollar question, so to speak :)
posted.  Am I to assume then that no one on this list has done this ?  Let

I seem to recall that noone has succesfully solved the problem of
artificial biped locomotion even in traditional robotics, let alone


    This problem has been solved with both fuzzy logic and neural
    network control systems.  I believe that a traditional control
    system approach to this problem has yielded poor results.

    The sensors used in this type of robot are typically semiconductor
    based accelerometers and gyroscopes.

within the constraints of LEGO. Basically, what you need is a system

    No, I don't think anyone will be solving this problem using
    Mindstorms.  There is a whole list of limitations:

    - slow processor
    - wrong processor architecture
    - wrong software tools
    - inadequate sensors
    - inadequate actuators

    There are robots today that have actuators that simulate muscles,
    and I'm not talking about pulleys and micromotors, I am talking
    about technology out there on the cutting edge.

    I wish Lego had news and information about this kind of stuff
    on the Mindstorms site, instead of the lame-o stuff they usually
    show for excruciatingly long times.


that can sense very delicate shifts in balance, and shift its point of
gravity to account for that. This is _difficult_, especially if you
want to have your robot do anything else. And that's just standing
still. Of course, you could make him/her be very flatfooted (if you're
thinking about a model of say 50 studs high, think the 20*40
baseplates as feet :) ), and have the robot stand on one of the feet,
while moving the other forward, then shifting the COG (center of
Gravity) to above the other foot.., etc.


maybe you could have a foot profile such as:

1111111111111
1
1
1  2222222222222
1              2
1              2
1111111111111  2
1              2
1              2
1  2222222222222
1
1
1111111111111


where 1 is one foot, and 2 the other. But that doesn't lookmuch like a
human foot anymore, and dancing would also be difficult.

If you want, say, a leg to have motion in the groin, knee, and ankle
areas, you're already looking at 6 motors. Or rather, Servos or
Pneumatics/Hydraulics: Lego motors aren't nearly accurate enoughfor
most things.

Well, back to RCX reality: Unless you have _plenty_ of cash and can
buy a dozen RCXs and solder the interfaces between em (it'd prolly be
easier to just take a real microcontroller, btw), you're gonna have to
simplify. My solution, tentatively theoretical: use the extra "stalks"
as in the picture above on the feet to help it keep it's balance, have
the ankle fixed, and the knee and groin joints set at the same angle,
in reverse:

O
/
       /
             /
            /
           o
           |
           |
           |
       ---------


Then make something with a large gear so it runs in a somehwat
circular motion, with the leg lifting off of the ground at the back of
the cycle, then go back to the front, then put foot down, move to
back, etc. I think you coul prolly gear the l/r leg to work on one
gear train, with one, possibly two motors to drive it. I haven't
solved left right yet, have I? Hmm... need to think about that.


Thanks for giving me such an interesting idea to think about :)

Jasper





Message has 1 Reply:
  Re: Seeking Strategies on Humanoid Robots/Walkers
 
Patrick Gili wrote in message ... (...) Actually, they can be built with *relatively* simple, active-feedback systems for the balance and control. Simple legged robots (one leg is actually easier than two to control) have been around since ~1980. (...) (25 years ago, 21-Jan-99, to lugnet.robotics)

Message is in Reply To:
  Re: Seeking Strategies on Humanoid Robots/Walkers  [DAT]
 
(...) I seem to recall that noone has succesfully solved the problem of artificial biped locomotion even in traditional robotics, let alone within the constraints of LEGO. Basically, what you need is a system that can sense very delicate shifts in (...) (25 years ago, 19-Jan-99, to lugnet.robotics)

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