Anybody building anything?

[hlreed]

Is anyone building anything out there. Let us know.

[bwts]

Hiya H Im currently working on a 2 frequency tetrahedron. Each of its side has a different colour it then jumbles itself up into different shapes then reassembles itself back into a tetrahedron but nw with the colours on each side all muddled up. I have a few models of this + fink I still have some digtal photos if ur interested. Unfortunately when scalled up to a meter and a half prtotype it keeps breaking all the driving mechanisms Ive tried so work is still in progress <p>B)

[hlreed]

We used to have a system called hexagons. They are flat polygons with numbered sides. You can flex the hexegan to show 3 sides. These scale up to hexa hexagons with 4 sides. They are made of paper. If you are making a big model of this, all I can say is wow!

[ad5mb]

Not what would normally be considered a robot, but it is robotic. A pan-tilt unit for a surveillance camera. If an alarm sensor is tripped, camera pans to the region monitored by the sensor. Uses standard burglar alarm sensors, an OOPic-R and 2 servos.

[hlreed]

Anything that moves is interesting. This is a classic problem. What are your primary sensors?

[rionredinger]

I'm gearing up to build a Battle-type bot and have come up with some interesting ways to design it. I have decided to go with a design that resembles the TIE-FIGHTERS from Star Wars but it will have two bicycle size wheels on the sides and all the motors and stuff will be hanging in the middle around the axle. I want to make it so that the drivetrain doesn't involve the axle for more that support. Have you seen the motorized scooter type thing from some place in Austrailia? the one that you stand on the rims of the wheels? i would like to use that type of drive system, but attach it to the top of the wheels.

[hlreed]

I used to watch an English show on PBS with these telerobots. It was a competition. The best machine I saw on there was a little wedge shaped thing that basically ran under the other machine and flipped it. If this machine was flipped it could flip itself back up.
In these radio controlled machines, the main design is motors and tactics.
These machines will teach motors but don't do much for sensors and brains.
Thanks for posting.

[Gilbert]

Hi Harold
I am interested in motor drives.
4 wire steeping motors.
I would like to invite you and your frinds to my sit.
http://home.earthlink.net/~gsteele1455/ ... ge_1x.html <p>[email protected]
look for questions when done looking.

[hlreed]

Hi Gilbert,
Welcome to the forum.
I tried to pull up your web site but did not go.
We would all like to know about stepper motors.

[bwts]

A regular tetrahedron can be split into five regular polyhedrons, 4 smaller tetrahedrons and a central octahedron (think of a tetrahderon with its corners snipped off and u get an octahedron). This shape exibits some great behaviuor when motion is applied to its componant parts and this is the premise of my tetrabot (some would have u believe that this is also the premise upon which the observilbe universe is built).<p>B)

[hlreed]

You got any algebra for that? I can't see the geometry. In other words, what the hell are you doing?

[bwts]

Its at times like this I wish this message board took pictures or I had a web site! I have tried to explain this to alot of people and it has always sounded like gobbledeegook, but when Ive shown them a model it is imediatly obvious. If u have the time make an octahedron out of 8 equal equalateral triangles, then using the same size triangles make 4 tetrahedrons (4 triangles), these 5 shapes can now be arranged to make 1 large tetrahedron (leave this 4 u to workout its pretty obvious), this shape is known as a 2 frequency tetrahedron (the component tetrahedra are known as single frequency tetrahedrons). This method of putting tetra and octahedra together is well known in civili engineering circles as the basis of the octet-truss. So far so good??? Now get some tape + put it along one of the edges where a tetrahedron meets the octahedron so that it acts like a hinge (ie the tetrahedron can be flipped from one face of the octahedron to another) do this for the other tetras there are all sorts of arrangements possible allowing the shape to be transformmed into other shapes by flipping tetras. More interestingly there is one such arrangement that "inverts" the original 2 frequencey tetrahedron. If any of this made sense I will continue with the second part of the discription which involves the adding of colour to the system <p>B)

[hlreed]

Ok,
I am sort of getting the picture. These shapes that you are flipping; are they the only shapes or can other shapes be used?
Still say you should check out hexa flexagons.

[bwts]

Only the tetrahedra move (well strictly speaking only the tetrahedra move relative to the central octahedron as the whole system actually moves about once in motion). Id like to know more about the hexagon thing as hexagons can be used to make my favourite polyhedron the cubeoctahedron (or vector equalibrium as BuckminsterFuller calls it) which exibits some truely bonkers behaviour when set in motion. I plan to extend my ideas to to other polyhedra but at the moment am focusing on the tetrabot (dont really like the name tetrabot was finking of Triana?).<p>Anyhow back to the discription, once u have ur 2 frequency tetrahedron colour each side a different colour, then move the tetras about and colour any blank faces (hedra) one of the four colours, and u get a system that is capable of jumbling up colour and rearranging colours! Again changing the arrangement changes the possible states the system can exibit.<p>Is this making sense? Again at this point I wish I could shown u a model.<p>Once the system is started then it will continue to operate until its power source can no longer drive it. On the full scale prototype this is quite a scary prospect as the frame is made from stainless steel (the next prototype will be made from aluminium) and due to its weight makes one hell of a racket. I was using wind screen wiper motors as the muscles but they dont have enuff start up torue so have switched to starter motors (u'no electric motors that turn a cars engine over) which have fantastic intial torque, but unfortunatley too much and have a tendancy to rip the drive chain appart <p>B)

[hlreed]

Well sounds like you are having fun.
When I build hardware, like structures and moving parts I use model airplane techniques. Use balsa wood and glue. You can make very strong structures with this if you do not worry about weight. The less mass you have to move, the less motor you need.
I use little 5 volt motors with gear trains.
You can get these at web page