Re: degrees of freedom Was: Angle Iron Ways

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Raymond Heckert" <jnr@...> wrote:

>
> This is as close as I can get textually...
> Traditionally, the hexapod can be 'constructed' thusly: an equilateral
> triangle is 'fixed' in a horizontal plane. A second equilateral

triangle (of

> the same size, usually) is located some distance away, and directly

above

> the first, in a plane parallel to the first, except that the

verticies of

> the second triangle are situated 60° (CW or CCW) with respect to the

first

> triangle. An extensible strut is then placed from a vertex of the fixed
> triangle, to the vertex of the second triangle that is 60° clockwise (or
> arbitrarily, CCW) offset. An identically extensible strut is placed from
> that same vertex on the second triangle to the vertex of the first

triangle

> that is clockwise from the first strut. Then a third extensible strut is
> placed from that vertex of the first triangle to the vertex of the

second

> triangle, offset by 60°. Continue in the same manner, until you have

all 6

> struts located. The struts are all assumed to be connected to the

respective

> triangle vertices via ball joints. If all the struts are constrained

from

> extending or retracting, the structure is absolutely

(mathematically) rigid.

> How ever, if any two adjacent struts are allowed to move, the second
> triangle will move, but only as much as the extension/retraction

allows. I'm

> sure that the struts must act in adjacent pairs i.e. two adjacent

struts,

> four adjacent struts, or all six struts moving at the same time, in
> mathematical co-ordination (That co-ordination is known as kinematic)..
>
> RayHex

I think you are both probably talking at cross purposes, why not
sketch something and upload it somewhere, it is the internet you know :)