[Lab] Controlling Light with a Ventilator

The Big Plan - Chris B tbp at ghostwise.com
Sun Mar 24 16:05:45 EDT 2013

Hi Modlabbers (and especially Kirk, Roman and Henri in this message)!

Thanks so much Kirk for going ahead and programming a RaspPi dimming  
function for the projector.

I think the projector is probably the best way to control the lighting  
versus investing in LED lighting. How would I
connect the RaspPi to the projector?

 From all the suggestions I've received on the list, I'd like to use  
these two items to control the lighting via the ventilator:

A pressure sensor <http://www.digikey.com/product-detail/en/MPVZ5010GW7U/MPVZ5010GW7U-ND/1168379 
Raspberry Pi

I've never used a RaspPI so I don't know would I need for it. What  
kind of cables, enclosure, PSU does it need?
If the order requirements could be spelt out to me I'd appreciate it.  
I would then go ahead and order the equipment
needed to do this.

Last night a friend suggested a possible problem: If I backlight the  
painting, the squares on the front may end
up simply looking dark. Would it be smarter to project onto the front  
of the painting? I was hoping the light source
wouldn't be so apparent but if the visual doesn't work with  
backlighting, I may have to.  It is a pretty thin layer
of acrylic paint so the light may glow through it.

I'm also trying to figure out how to suspend the canvas. It's not  
stretched on a frame. I'd like to keep it loose like a
sail with it bulging a little forward towards the viewers. My friend  
suggested using a fan on low to keep it bulging
forward. I wonder if the same effect could be done through tension.

As a BIG aside, If I had an iPhone, iPad and possibly a computer all  
working together to create music, what would
I need to make the painting into a giant visualizer for the music? :D  
I suppose video of a visualizer of some sort
would have to be projected onto the canvas.

Thanks again for all your interest! I hope I can put together version  
1.0 of the painting installation in May / June.


On 24-Mar-13, at 12:33 AM, Kirk Sutherland wrote:

> Hi Chris,
> I had a chance to try out the visual aspect of what you are  
> describing on a Raspberry Pi and it was pleasantly easy! The code  
> was written in Python on a stock install of the operating system  
> 'Rasbian', I simply turned on the Pi, wrote the code and ran it -  
> didn't have to install anything else!
> The code displays 5 'breaths', each cycle lasts 2 seconds going from  
> black to full white. If you had the Pi connected to a projector as  
> your 'light' I believe this could work nicely. There are some  
> artifacts as the colour changes because I am simply refreshing the  
> screen really fast, but if you have you canvas to act as a diffuser  
> I don't think you would see them.
> https://www.youtube.com/watch?v=QjOoXHBC5Ic
> Have you picked your sensor yet?
> Cheers!
> Kirk
> On Mar 22, 2013 9:03 AM, "Kirk Sutherland"  
> <kirk.sutherland at gmail.com> wrote:
> I second the raspberry pi as a projector controller! Its cheap,  
> projectors are bright (and can be borrowed!), and I don't think the  
> code would be that hard. You will have to use some external  
> controller with the Pi if the sensor is analog as the pi has only  
> digital io. I could try out some simple code tonight to see if the  
> video part is possible without getting into opengl code :)
> Cheers!
> Kirk
> On Mar 21, 2013 9:21 PM, "Henri Kuschkowitz" <henri.kuschkowitz at gmail.com 
> > wrote:
> Hey Chris,
> I know you already received tons of ideas, but i was thinking about  
> a mini fan put somewhere between parts of the tube (maybe after the  
> bacteria filter) and you then just measure the speed of it to  
> determine the power for your lights?
> For the question regarding lights, there are hundreds of  
> controllable led strips out there that could suit your needs. or  
> maybe EL solutions (though it would cost you more i think) like  
> this: https://www.sparkfun.com/products/10800
> Also, you can dim a projector simply by projecting grey scale  
> images… which means a raspberry pi connected to the sensor could be  
> a neat solution.
> Just my 2 cents.
> Cheers and good luck,
> Henri
> On 2013-03-21, at 5:46 PM, The Big Plan - Chris B wrote:
>> Hi Modlabbers,
>> Thanks for all the interest in my art installation!
>> So far it looks like the pressure sensor idea is the one I'm  
>> leaning towards. Having a microphone detect the ventilator breaths  
>> sounds more finicky to me.
>> Still trying to figure out how to back light the canvas. Would a  
>> projector work instead of using LED lighting? Can a projector
>> be connected to the pressure sensor set up to do the variable  
>> dimming?
>> Club SAW has 3 projectors available:
>> Panasonic PTAX200U HD Video Projector
>> 16mm Projector
>> 35mm Projector
>> As for a timeline / schedule. If I could do this in May / June that  
>> would be great but it may be more realistic to wait until September.
>> Here's a photo of the painting below. It's about 7 by 11 feet:
>> Thanks,
>> Chris
>> <2012-11-12 14.51.55.jpg>
>> On 15-Mar-13, at 8:41 AM, Michael Sepa wrote:
>>> Chris,
>>> The clarification of the project really helps out.  I looked up  
>>> the manual for the Puritan Bennet LP10 (http://www.meql.com/Manuals/Puritan-Bennett-LP6-Plus-and-10-Ops-Manual.pdf 
>>> ) in the hope that there would be a simple electronic monitor  
>>> connector on the back that you could hook into, but no such luck.   
>>> There are pressure alarms that can be set and a remote alarm  
>>> connection on the back of the machine, but you'll get audible  
>>> alarms off the machine at the same time.  Not what you intend.
>>> One approach would be to do the following:
>>> 1. Lights start off, no ventilator pressure
>>> 2. Ventilator turns on, a microphone beside the patient air tube  
>>> senses flow
>>> 3. Arduino detects change from microphone
>>> 4. Arudino uses pulse width modulation[2] to brighten an LED array  
>>> from off to full on in 1.5s, and holds
>>> 5. Ventilator turns off
>>> 6. Microphone detects stop of flow from patient air tube
>>> 7. Arduino uses pulse width modulation to dim an LED array from  
>>> current level to off in 1.5s and holds
>>> [1] pulse width modulation is just a fancy way to say turn on/off  
>>> the LED array fast enough to control brightness.  This is built  
>>> into the Arduino system, so it's very easy.
>>> Connecting to and dimming an LED array with an Arduino is well  
>>> understood.  No issues there.
>>> The microphone will require an amp chip to get it producing a  
>>> signal the Arduino can easily read.  If we can find a pre-made  
>>> microphone and amp, then it will be all so much easier.
>>> The programming of the system would be straight forward.   
>>> Certainly less than a day of effort.
>>> The system would work well if the room was reasonably quiet.  If  
>>> there was other noise it might trigger the microphone causing  
>>> premature light adjustment.  A better approach would be to use a  
>>> pressure sensor.  I checked ebay and see several pressure sensors  
>>> available, all use I2C interfaces.  That would take a bit more  
>>> programming effort, but certainly less than a day or two.
>>> If you go with a pressure sensor, we'd need to makes sure the  
>>> sensor has the right range to sense the ventilator pressure.  That  
>>> I couldn't get from the quick ebay search because they don't  
>>> usually publish specs with sale items.  I'm confident  we could  
>>> find an appropriate one on ebay, spark fun, or somewhere else.
>>> As for your budget, I'd think you should have no issues buying all  
>>> the tech plus paying someone a small honorarium for helping you  
>>> program it all.
>>> My big question would be what's your schedule?
>>> -Michael Sepa
>>> Date: Thu, 14 Mar 2013 17:49:08 -0400
>>> From: The Big Plan - Chris B <tbp at ghostwise.com>
>>> To: lab at artengine.ca
>>> Subject: Re: [Lab] Controlling Light with Sound
>>> Message-ID: <F3148EB9-8831-464E-92AA-2144AB15E72B at ghostwise.com>
>>> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>>> Hi everyone,
>>> Thanks for the awesome replies so far. I think I should clarify my
>>> intentions:
>>> My plan is to suspend a loose canvas that is approximately 7 by 11
>>> feet on an angle from the ceiling.
>>> I would like to put lighting behind it (I don't know what lighting  
>>> to
>>> use or whether it
>>> should be a set of lights). The rest of the room will be dark.
>>> A ventilator (Puritan Bennett LP10) will be on the floor. Every  
>>> breath
>>> of the ventilator
>>> should cause the lights to turn on in a gradual way and then dim  
>>> dark
>>> as the breath
>>> ends. Each breath should take about 1.2-1.5 seconds.
>>> I like the idea of an Arduino or Raspberry Pi controlling the  
>>> lighting.
>>> It sounds like I will also need a mic by the ventilator.
>>> Finally, I have zero programming experience or overall technical
>>> experience to do this. I'm the artist
>>> with a vision. I would appreciate assistance from anyone  
>>> interested in
>>> this project.
>>> It would be great if it could be done on a $250-500 budget.
>>> Thanks in advance,
>>> Chris
>>> On 14-Mar-13, at 4:11 PM, The Big Plan - Chris B wrote:
>>>> Hi!
>>>> Looking for some advice for an art installation. I'd like to have a
>>>> light or set of lights respond to an auditory
>>>> input. I'd like the lights to turn on in time with the sound of a
>>>> ventilator (a medical one). So when the ventilator is
>>>> not doing a breath, the lights would be off, but then when the
>>>> ventilator starts doing a breath they would
>>>> turn on for the duration of the breath. I'd like the lights to  
>>>> light
>>>> up and dim gradually, not just on an off.
>>>> What's a simple or best way to do this?
>>>> Thanks!
>>>> Chris
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