chrishillcox
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Sat Feb 04, 2012 6:38 pm

I am looking to team up with someone who has the skills to add an air temperature sensor to Raspberry pi. It is to be used in a weather balloon project sent in to near space. I am hoping to get schools involved. A thermometer is the start. I am hoping other environmental sensors can be flown on the RPi. there is also the oportunity to help students programme the sensor…maybe? Please contact via a PM.

mightygoose
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Sun Feb 05, 2012 11:53 pm

i plan on using my first Pi for something similar. I would be happy to compare notes at various stages of developement.

oxgoth
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Mon Feb 06, 2012 12:23 am

I am also planning on doing something very similar and would be more than happy to share notes.

greypower
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Joined: Sat Jan 07, 2012 10:00 am

Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Mon Feb 06, 2012 10:03 am

Another possible solution is to use a Picaxe microcontroller

Ref: http://www.picaxe.com/

Specifically, the picaxe forum has quite a few references to atmospheric monitoring using this device.

See: http://www.picaxeforum.co.uk/s.....h+altitude

there are other references on the forum. There is a range of prototyping  boards if you don't want to "roll your own".

See: http://www.techsupplies.co.uk/.....ectID=3909

mightygoose
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Mon Feb 06, 2012 3:24 pm

[linkie]

I am trying to negotiate shipping to get one of these big boys over here.

error404
Posts: 351
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Mon Feb 06, 2012 11:59 pm

For a balloon I think you are much better off with a microcontroller. I don't expect you're going to be doing a ton of processing onboard, usually just datalogging and the like, which you can do on a $3 micro that also happen to consume about 50x less power than the Pi. Batteries are heavy and you want to avoid them.

Just buy an I2C temperature sensor like the TMP175 and hook it up to the Pi's I2C bus. Not sure what the status is on an I2C Linux driver, but one should be coming eventually. You might need something a little more complicated depending on the temperature range you want, not sure how cold the atmosphere gets up there...

chrishillcox
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Wed Feb 08, 2012 10:12 am



I am going to look at micro controllers but despite the battery issue I think the Pi may be a really good platform to send up in the school environment. It seems like kids would be able to have a go at setting it up, launching it in a balloon where it would record environmental information and then on recovery, downloading the data. I think a couple of issues are

Pi and battery weight (a 1200g balloon could have as much as 700g after catering for trackers )


        Moisture proof case

         The fragility of the Pi

But there are some clear opportunities (if I understand what people write in the forums) with it carrying a number of sensors. It could also be interesting to the balloonists interested in telementry. In Australia I have contacts who use the Beagleboard for balloon telemetry.

Are there any cases out there that look like they keep out moisture?

Does anyone understand the chatter about batteries? What are people suggesting?

How robust does the Pi look? In the balloon trip the landing would be broken by parachute but it may still be doing a couple of metres per second.

mightygoose
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Wed Feb 08, 2012 1:08 pm

you need to insulate and potentially use some form of heater. It depends if you only want thermal data, i mean How do you plan on tracking the balloon? do you want live radio telemetry, GPS? video feed?

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Wed Feb 08, 2012 3:14 pm

error404 said:


For a balloon I think you are much better off with a microcontroller. I don"t expect you"re going to be doing a ton of processing onboard, usually just datalogging and the like, which you can do on a $3 micro that also happen to consume about 50x less power than the Pi. Batteries are heavy and you want to avoid them.


Although, if you want video and stills capture as well, with a camera the Raspi could handle the entire system for you - sensors, data logging, GPS and imaging. Just using a Raspi camera would save a lot of weight over a separate compact - enough to offset the higher power requirements.
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mightygoose
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Thu Feb 09, 2012 12:30 am

Precisely what i was thinking, and as I want a sub 1kg payload, weight is everything.

error404
Posts: 351
Joined: Wed Dec 21, 2011 11:49 pm

Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Thu Feb 09, 2012 12:52 am

JamesH said: 


Although, if you want video and stills capture as well, with a camera the Raspi could handle the entire system for you - sensors, data logging, GPS and imaging. Just using a Raspi camera would save a lot of weight over a separate compact - enough to offset the higher power requirements.


Yeah, that's a great idea. Can we start badgering you about the high quality camera release date before the Pi board is for sale?

chrishillcox
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Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Thu Feb 09, 2012 4:58 pm

mightygoose said:


you need to insulate and potentially use some form of heater. It depends if you only want thermal data, i mean How do you plan on tracking the balloon? do you want live radio telemetry, GPS? video feed?


Thermal data is a start but it would be any kind of sensor the school project wanted. It could be dust, gasses, temperature, UV or a range at the same time. If it is a school project then they may just want it logged. It just depends on what 'off the shelf' systems are available and what the school are comfortable with using. It makes sense to use as much of the Pi's processing power as possible and as the weight of the sensors allow. I would suggest tracking independent of the Pi through a Spot messenger and SMS enhanced GPS e.g Cattrack. That gives about 800 g to accommodate the Pi and it's protective thermal box.

chrishillcox
Posts: 10
Joined: Sat Feb 04, 2012 6:24 pm
Contact: Website

Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Thu Feb 09, 2012 5:05 pm

mightygoose said:


Precisely what i was thinking, and as I want a sub 1kg payload, weight is everything.


JamesH said:


error404 said:


For a balloon I think you are much better off with a microcontroller. I don"t expect you"re going to be doing a ton of processing onboard, usually just datalogging and the like, which you can do on a $3 micro that also happen to consume about 50x less power than the Pi. Batteries are heavy and you want to avoid them.


Although, if you want video and stills capture as well, with a camera the Raspi could handle the entire system for you - sensors, data logging, GPS and imaging. Just using a Raspi camera would save a lot of weight over a separate compact - enough to offset the higher power requirements.


This is a my point as well and the reason for suggesting a Pi. It could image and sense at the same time. All you may want is independent tracking devises which I have suggested in a previous post.

error404
Posts: 351
Joined: Wed Dec 21, 2011 11:49 pm

Re: Rasberry Pi to drive temperature sensor / weather balloon- school project

Thu Feb 09, 2012 8:43 pm

chrishillcox said:


Thermal data is a start but it would be any kind of sensor the school project wanted. It could be dust, gasses, temperature, UV or a range at the same time.


You're probably going to want some sort of external analog I/O board then. Perhaps a gertboard is appropriate, or an Arduino, or something custom. It's something you should think about though as the Pi's I/O capabilities for sensors are pretty limited. This really depends on where you want to take the project - if you're designing the sensors, you can just build an I2C ADC or such inside them if an I2C sensor isn't available directly. If you want to use off-the-shelf or user-designed sensors, you should probably provide a design giving analog inputs. Adding things to the GPIO port may conflict with any forthcoming camera module (?), so perhaps it's not feasible at all?

I'm not sure what use it is to 'use as much of the Pi's processing power as possible'. While the thing is flying you're probably not going to be communicating with it in realtime to do data analysis (though with amateur radio...maybe...but only if it is lower bandwidth than just sending the data). Yeah you could do your analysis on the board, but if you have to wait for recovery to have a look at it anyway, you may as well save on batteries and just do the data analysis later. If the power requirement is low enough that you can do it inexpensively within your weight budget though I don't see why not to try it, it's certainly easy and flexible.

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