Alt-BEAM Archive
Message #03225
To: beam@corp.sgi.com
From: davidperry@mail.geocities.com
Date: Tue, 12 May 1992 14:27:42 +0000
Subject: [alt-beam] re: incapable robots give em feet
has anyone noticed that turbots are pretty good this way? I've just
finished my mechanics for my modified snakebot and it'll crawl over
anything, infact i changed the leg design and now it sort of tumbles,
now i've just got to save some money to buy the rest of the parts,
this mostly original design is turning out to work really well, just
how many people are entering chius contest, i better win something,
i've already forked out $50 :-)
Now once again, does anyone have a substitute for the 2N7000 mosfet
as used on the PM1 and D1 solar engines?
-David Perry
> Date: Tue, 11 May 1999 14:48:09 -0700
> From: Bruce Robinson
> To: beam
> Subject: Re: Incapable robots-Give 'em feet.
> Reply-to: Bruce Robinson
> > Dennison wrote:
> >
> > ... I have a few suggestions for building more capable robots.
> > Make them larger. With this increased size they will have greater
> > weight (A nessesity for nagivating grass and stuff). Give them Paws.
> > All our robots are these things balanced on the ends of wire.
>
> One of my long term BEAM goals (gotta learn to crawl first) is to make a
> walker than can wander about my back yard. As my back yard (and front
> ard, for that matter) consists primarily of forest on the side of a
> mountain, your average walker will have problems. I figured something
> between the size of a cat and a smallish dog would be about right,
> although I don't think extra weight is necessary.
>
> A few reflections on the walking motion of such a critter:
>
> The Tilden patent gives an example of a four-leg/eight motor walker.
> Each leg alternately lifts (motor A), moves forward (motor B), lowers
> (A), and moves back (B). And each leg is triggered in sequence by a 4Nv
> loop. This is similar to the motion of most "legged" mammals. However,
> the patent then goes on to state: "... the control circuitry must
> synchronize leg movement such that no more than one leg is raised at any
> one time; because of this the legs must be somewhat resilient, so that
> movement of one leg will draw the torso in the desired direction rather
> than being merely resisted by the three stationary legs."
>
> Therein lies a problem -- only one leg moves through its cycle at a
> time, so we get a resistance/dragging action.
>
> So what if we did this. Make the lift, forward, lower motions
> considerably faster than the backward (walking) motion. A leg would
> typically move backward s-l-o-w-l-y, and then lift, swing forward, and
> drop very quickly (all three actions completed in 1/3 the time the leg
> is in contact with the ground). This means that all three supporting
> legs would be moving forward simulatneously. Timing should not be a
> problem -- just put a larger resistor on the Nv that moves the leg
> backward. But we have to do more than lengthen the delay -- we need to
> make the motor run slower as well. And the only way I can think of to do
> that efficiently is to lower the voltage. How? Haven't a clue. I'm a
> mechanical engineer. Wilf?
>
> I figured it would be pretty hard to do this with less than one motor
> per leg, but it occurred to me that Chiu's 5 motor walker might be
> adaptable to this type of motion, using different circuitry.
>
> Anyway, that was my thought for the day. By the way, that's how my dog
> walks when she's just ambling over for a pet. Her other three gaits have
> only two legs in contact with the ground.
>
> My $.03 (Cdn) worth.
>
> Regards,
> Bruce
>
____________________________________________
I'm sure David sinceraly apologises if he
insulted anyone, it won't happen again.
____________________________________________
____________________________________________
I'm sure David sinceraly apologises if he
insulted anyone, it won't happen again.
____________________________________________
------------------------------------------------------------------------
eGroup home: http://www.eGroups.com/group/alt-beam
http://www.eGroups.com
- Simplifying group communications
Home