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Community => Exhibition / Gallery => Topic started by: rbqaa on Mar 05, 2013, 12:09 am

Title: LED POV project, with a spin
Post by: rbqaa on Mar 05, 2013, 12:09 am
Hello everyone!  I guess it is finally time to unleash my project on the Arduino community.  Who doesn't like staring at blinking colorful lights all day?

This was my very first project with an Arduino, and I couldnt be more pleased.

Definitions:
POV:  Persistance of Vision
RGB:  Red Green Blue
LED:  Light Emitting Diode
WS2803:  World Semi 2803 Led Drivers ( http://www.world-semi.com/en/Driver/Lighting_LED_driver_chip/WS2803/ )

The set-up:

Some miscellaneous other parts and LOTS AND LOTS of research and development.  I think I spent 10x as much time on researching how to accomplish individual parts of this project as the entire thing took to make.  I was almost certain that Google was going to start rejecting all my searches regarding everything that has to do with POV and Arduino.  The project started out on a bread board and then morphed into what you see below once each part worked on its own.  Enough blabbering and onto some photos!

Here is what I ended up with








Right now I am in the process of porting everything over to the Arduino Due.  I outgrew the Mega before I even got half way through this project and kept putting band-aids where necessary just to get the proof of concept working.

Max speed right now is about 32mph before the system lags and cant keep up with the refresh rate necessary to display the image, this is .  I will post more as I get things ported over.

Thanks for looking.
Title: Re: LED POV project, with a spin
Post by: tytower on Mar 06, 2013, 08:30 am
These bloody acronyms are a pain.  There are 20 different definitions. How about you warn us of which one you refer to at least once in each post then use the initials by all means

So this switches on  LED's in a set pattern once per revolution and that makes it visible as a still image --right?
How do you pickup and time each revolution
How does the arduino know when to switch on and how do you convey that instruction to the arduino?
How do you get power to the LED's

I would imagine a world full of rotating wheels each with the advertisers message flashing out . That would be another bloody pain. but I think you have let the cat out of the bag.
Title: Re: LED POV project, with a spin
Post by: rbqaa on Mar 06, 2013, 07:05 pm
Thanks for the response!  Sorry, I have just been working so closely with this project, that I sometimes forget that they don't really make sense unless you are familiar with them.  I have edited the first post and put in a definitions section.  If there is another definition that is not clear, just let me know and I will clear them up as well.

Yes, so there is a set pattern, that is repeated each rotation.  The theory of persistence of vision makes the individual parts of the pattern look like a full image.  Here is a wiki on the topic: http://en.wikipedia.org/wiki/Persistence_of_vision

As for timing, I only track the time per revolution, which is triggered by an infrared emitter and collector.  My original plan was to use a magnet and hall effect sensor, but the hall effect sensors that I ordered were not sensitive enough.  I had the infrared parts sitting around so I made adjustments and used that for timing instead.

The Arduino is manually switched on, and the data is stored in flash.  The main problem with the Mega 2560, is that only a few images can be stored in flash at start-up.  At setup, the images are read from flash into the Quad Ram chip where the data can then be pushed out to the LED drivers.  The order of images and duration is preloaded at setup and is the same every time the Arduino is powered up.  This can be reset each time a new sketch is uploaded.

All power is mounted to the hub/spokes of the bicycle wheel.  The Mega 2560 and all of the LED's are powered from the hub mounted battery pack.  The run-time depends on the actual images that are being displayed.  For example white colors suck the life out of the battery pack much faster than a primary color.


I do have to say that from the side at night, my bike is WAY more visible.  Generally riding at night, the front is visibly because of a headlight on the handle bars and the back is visible from red/yellow flashing lights, but it is fairly difficult to see a cyclist from the side.  That is not the case with this project.

That should shed some light on your questions (pun intended).
Title: Re: LED POV project, with a spin
Post by: jlizotte on Mar 06, 2013, 08:32 pm
Really impressive work! Thanks for sharing!
Title: Re: LED POV project, with a spin
Post by: tytower on Mar 06, 2013, 10:20 pm
Ditto thanks
There are bike wheels with built in dynamos in the hub and you can also get a click on type side mounted dynamo which runs on the tyre. They might give you an option of longer running time . Good project.
Title: Re: LED POV project, with a spin
Post by: fungus on Mar 07, 2013, 10:26 am
nice!
Title: Re: LED POV project, with a spin
Post by: rbqaa on Mar 08, 2013, 12:45 am
Thanks for the kind responses! 

I have looked at the hub dynamos and I am just not sure if I can justify the increased drag for the power.  The drag would make it about 15% harder to pedal in order to power the system.  It is not out of the question though.


There are some more features that I am working on, and should have them added in the next two months (really busy with some other projects unfortunately).  I won't dive into details, because I want to ensure that they work first.
Title: Re: LED POV project, with a spin
Post by: tytower on Mar 08, 2013, 11:06 am
OK the beauty of these is they don't have to be switched in all the time only when going downhill for a battery recharge. Off when going uphill or not needed.
Title: Re: LED POV project, with a spin
Post by: Simpson_Jr on Mar 08, 2013, 01:20 pm
Or... add some Epo to your BOM ;)
Sorry, couldn't resist, beautiful project !
Title: Re: LED POV project, with a spin
Post by: fungus on Mar 08, 2013, 01:49 pm

OK the beauty of these is they don't have to be switched in all the time only when going downhill for a battery recharge. Off when going uphill or not needed.


There's no hills around here...

Title: Re: LED POV project, with a spin
Post by: rbqaa on Mar 08, 2013, 05:44 pm
That is a great idea!  ROIDstrong! 

Thanks for the tip on the hub dynamo's.  I started looking at different models last night to see price comparisons and efficiency.  The interesting part will be modifying them to how the power connectors on the in-between the spokes rather than outside.  The other option would be to completely remove the battery pack from the wheel, and wire a connector that would work when the wheel is rotating.  The latter option would be the most efficient, and complicated.  Well, looks like I have some more options to look into.

@fungus:  That is unfortunate that you have no hills.  Wait, no you are lucky.
Title: Re: LED POV project, with a spin
Post by: Quick5pnt0 on Mar 12, 2013, 01:48 am
Just wanted to say how great this project turned out. I have been thinking of doing something similar but never thought the images could ever look as good as you got them to. Nice!
Title: Re: LED POV project, with a spin
Post by: toxman on Mar 12, 2013, 12:05 pm
Very interesting project!
Title: Re: LED POV project, with a spin
Post by: Pauly on Mar 14, 2013, 01:32 am
Very nicely done. 
Do you have any pictures of the actual setup as to how you wired it all up?
Title: Re: LED POV project, with a spin
Post by: rbqaa on Apr 02, 2013, 08:23 pm
Hello,
Thanks for the nice comments.  I do not have schematics drawn up of the actual wiring/connections.  I am in the process of upgrading the system, and will draw up some sketches of how things are connected.

Sorry for the delayed response.
Title: Re: LED POV project, with a spin
Post by: Maischta on May 24, 2013, 06:28 am
nice work!!!
i am planing to build a very similary project.
a pixelpoi! maybe you have heard about it:

http://www.youtube.com/watch?v=YuVXndVujG8

not so many led´s but hard enough!!
is it possible that you load up the code you wrote?  i am very bad in programming,
only want to solder;)
Title: Re: LED POV project, with a spin
Post by: ffgudgin on Mar 15, 2014, 07:30 am
hey I was wondering if you had any documentation as to what parts you used and board schematics.