Hi all, just got into this world of IC's and thought I would jump into the deep end.
I am building a POV but it is going to be a hand held (spun like POI) device.
I have created the sketch but the last thing that I am in need of is a device that will tell me how fast I am spinning so I can setup my delays correctly.
Any idea what I would need. I cannot use magnets or hall sensors as they require a fixed position.
but the last thing that I am in need of is a device that will tell me how fast I am spinning
Call me old-fashioned, but I'd say that was the first thing you were in need of. 
Have you thought about a gyro or accelerometer?
wot are POV and POI ?
You can do it with a hall effect sensor and a small magnet, or a "slotted opto interuptor" (maybe it's called somethinge else in the real world 
)
You can do it with a hall effect sensor and a small magnet
I had assumed "hand-held" meant that it was waved around, so a fixed TDC-type detector wasn't feasible.
yeah thats the thing. i need to use possible an accelerometer or somethiung to measure the spinning speed but i have no idea if it would work 
poi is a thing you spin, like fire dancing but this one is gonna be used with lights.
but i have no idea if it would work
Should do.
The accelerometer will give you data on the motion.
The issue is that the thing you are spinning presumably might not be pointing forwards all the time (things often rotate when you spin them) so calculating the movement from the accelerometer data would not be easy.
Mowcius
wot are POV and POI
The first is an acronym (Persistence Of Vision) - Persistence of vision - Wikipedia.
The second (without capitalisation) is a noun - Poi (performance art) - Wikipedia
thanks all, yeah thats my next topic is finding a way to keep a point of view, was just gonna create a 4 or 8 sided pov. right now i have a potentiometer acting as my rotation speed and it works well but not feasible for in show performances.
have looked up so many pov forums but they all use some form of hall sensor or display visual.
have a look at this. it is what i can find that shows what i am gonna create kinda:
thanks all
I know that most poi are held via rings or straps in the hands; I am certain this allows for a particular level of control that you couldn't get otherwise, and it is likely that after training one becomes used to using them in this manner. Plus, for close in body-spinning, the chains are "wrapped", so fixed-handles (something you could attach a rotation sensor/encoder to) are out as well...
Accelerometers are not going to work; in fact, for poi, I am not sure anything could work - except yourself. Your best bet is to make it "open loop", like a POV "message wand", and not to worry about rotational position. If you can pay quick attention to the pattern, you can likely speed up or slow down the spinning for that portion of your performance to make the pattern look good.
The only other way I could think of to make this work would be some kind of external magnetic 3D tracker system (I am already envisioning the setup and layout on the Playa) - if you had about $10,000.00 USD or more - got a grant?
Perhaps if you tied the animation to the angle of the poi using a gyroscope you could get it to display what you want as it moves trough an arc? Then the speed at which it is moving wouldn't squash or stretch the image... though the size of the arc would affect the scale on one axis.
Since the poi could rotate around the axis of the string though, you might have to use more than one gyroscope to determine the angle the poi is actually at. I'm not sure how getting angles from gyroscopes works.
loved the grant thing, may be a little out there for the system I am using now thanks tho...
think i am just gonna go ahead and create on with out the motion reader and include the potentiometer (so i can dial it in before the show)
will include pictures soon of the schemtacs soon.
dang this would have been awesome if I could find a way to measure the speed. I may just buy a few sensors and give them a spin.
Wow! I'm also developing POV poi! I may be a bit ahead of you, though! I'll post a link to pics in a reply to this post. The board won't let me post the link as this is my first post. If you're using the arduino, though, you would have the ability to do a true RGB display like Feeding the Fish. Are you going that far, or just single colors? Single colors are much, much easier on the programming side.
Also, to answer your earlier question, you really don't need any way to measure where your spin is. In fact, I really like the ability to spin slower and have more petals on a flower for instance, or spin faster and have less petals. If you're displaying logos or text, you'd want to spin at the correct speed, but you'll quickly figure out what speed that is and just automatically do it. They are super restrictive about what looks good, though, and you're pretty much limited to having your planes be perpendicular to the audience... if you're surrounded with people, there's just no way to get all of them to see the effect all at once. The classic audience all in one place and you on a stage works great though.
I'm very interested in developing an RGB set, but it's beyond my capabilities both in hardware and coding. I'm almost ready to start selling my single color version and I plan on using that money to put up capital and get the RGB version developed. I hate that Feeding The Fish is so selfish with their props. I offered to buy a pair for $1000USD and they snubbed their noses at me. Their loss.
Sorry that was so long, I just got excited to see someone else doing the same thing!
Photobucket | Make your memories fun! <-----That's where I'm at currently.
Photo Storage <-----That's where I'm at currently.
Very cool looking.
I'm very interested in developing an RGB set, but it's beyond my capabilities both in hardware and coding. I'm almost ready to start selling my single color version and I plan on using that money to put up capital and get the RGB version developed. I hate that Feeding The Fish is so selfish with their props. I offered to buy a pair for $1000USD and they snubbed their noses at me. Their loss.
I did a thing on RGB PWM library for (a lot) of LED's at a time. Heres the forum post:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1288285333
Nice! I just took a pov wand thing and turned it into poi, so all of the technical details of what you've done are greek to me. I found a wand I liked, talked to the manufacturer, made some changes (which quintupled the price), and then put about another $25 bucks worth of materials and an hour of my time to extract the light bar from the wand and house it in something durable enough to swing it around in.
I'm trying to find someone to make a few tweaks in the program that they wrote to control the wand. Because it was made to be waived from side to side in someone's hand, there is a point where all the lights shut off to give the person a split second to reverse direction and then they start displaying the pattern again. Since poi spinners do not stop spinning after each time the pattern displays, this results in a "hole" in the image. There's pics in the album below that have this pointed out in red.
Also, the poi have nine modes: 8 that are individual designs that stay the same, then a ninth mode that cycles through all eight images, but it only spends 3 seconds on each image. I would like the ability to control how long it spends on each image, and preferably have more than 8 images at a time, but I'm fine with 8 if that's all the storage space that's on the chip or whatever. The last software issue: currently, the canvas that I work with is 32x64. The "64" part, though, is only limited by the program; theoretically, it could be much longer. I would like it to be long enough so that I can make one image take up an entire rotation of the poi, or at least half of a rotation. This would make company logos and text in general much more readable.
Here are pics that might help you if you're interested in helping with an RGB set or helping re-write the controlling software for the single color version that I already have. Photobucket | Make your memories fun! The password is: arduino
I would definitely cut anyone in on future sales if they help with development; we can talk specifics via pm if you're interested. I also uploaded the program that I'm currently using for you to check out. Here's the link: http://www.megaupload.com/?d=5BJH7TEV
Thanks!
yeah got some help, thanks all, yeah amgonna planto make it rgb but for now just wanna get the general feel for it... 
Tim - Looks really cool.
Icewinds & Tim - I look forward to seeing your progress. Will you update in this thread or another?
I will also be doing a PoV Poi project, but as I'm brand new to Arduino and electronics, I'll be spending a lot of time with the starter kit I bought. So I'll be tagging along behind you guys.