Re: Loki (David Buckley robot)
- --- In SeattleRobotics@yahoogroups.com, Alan KM6VV <KM6VV@...> wrote:
>led R.J. Full to conclude that, across the animal kingdom, legs and
> >Yeah, I think Rbt Full was mainly comparing the more common gaits,
> >biped walk/run with quadruped trot with hexapod tripod gait.
> >Hence the quote:
> >These measurements, plus the considerations mentioned above, have
> >locomotion work in an analogous fashion - namely, "... 1 human legRaibert found a similar result relating quadruped gaits to a virtual
> >works like 2 dog legs, 3 cockroach legs and 4 crab legs ...".
> >gait [Raib84].crab work like 3 cockroach, which work like 2 dog, or 1 human.
> I like that observation! Although I see it the other way around, 4
>BTW, this was all discussed several months ago before you got into
the conversations, but I have been working on a new quad, named Poco.
I **finally** built and operated the first leg yesterday, while
everyone else was celebrating college football bowl day. I've been
gathering parts and making plans for months. Doing mechanical stuff
is like getting root-canals for some of us.
In any case, I was looking at the Toejammer design for sometime, and
thought the hip rotator mechanism might be good on a quad. Peter has
talked about adding the fore-aft axis to aid turning, while I'm
trying the vertical rotation axis for this. It's similar to how
humans do most turns. While standing straight, rotate the foot into
the new direction, and step forward, etc.
So, I scrapped Toejammer [R.I.P.] to build the front end of Poco. The
idea is to attach regular 2-DOF legs to the frame with the hip
rotators. We'll see how this goes. Basically, the idea is to get
something similar to the dogs turning in these pictures.
To a large extent, the dog turns by angulating its entire body,
and "crossing-over" the front foot, while Poco will turn by rotating
the foot like a human, to produce approximately the same effect. The
trick will probably be to make sure the CoG stays inside the
- Dr. Bruce.
> Interesting question and explanation - except that butterflies actuallyhave
> 6 legs.... 4 long and 2 short.OK, I looked it up. In Danaidae (monarchs), Satyridae (whites, graylings)
and Nymphalidae (emperors) the two front legs are very short, have no claws
and are useless for walking. I thought Papillionidae (swallowtails) were
the same but they're not, they have 6 good legs.
It gets wierder. In Riodinidae, the males have 4 walking legs but the
females have 6.
Lycaenidae (blues) and Hesperidae (skippers) all have 6 legs.
What on earth can one learn from that?
Anyway, Alan asked what "bugs" are quadrupeds. I said mantises, monarchs
and swallowtails. I was wrong about swallowtails. I was taught all this
stuff decades ago so forgive me if I'm a bit rusty. I even spent one summer
as a student doing fieldwork in the west of Virginia catching swallowtails
and monarchs so I certainly _ought_ to have remembered the details.
I still can't think of any other arthropods with just 4 walking legs. I
think some crustacean larvae have only 4 legs but they don't use them for