Project feasibility and board advice.

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HLA91
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Joined: Sat Aug 02, 2014 9:02 pm

Project feasibility and board advice.

Post by HLA91 » Thu Jun 29, 2017 8:38 pm

Hi everyone,

I work for an engineering company and I've been asked to look into the feasibility of a remote monitoring station. The scope I've been given is that the end product will be attached to a building or structure and will measure the angle that the device is attached at. Each week the device checks its angle again, and using a sim connection, reports this angle back via SMS to someone/something.

I immediately thought of micropython, and the micropython board. Partially as I'm not a very experienced coder, having done some basic Python in university, and I do kind of have a crush on it, and the other reason was due to the low power consumption of the pyboard if I can put it into a low power state for 6 days. The power will be provided by a battery, and also a solar panel to recharge the battery. The SIM card board would be the one Damien used in a thread he wrote about sending SMS successfully from the pyboard.

The only part that I'm thinking might be too difficult for myself, well to be honest most of it would be difficult, but the bits that's I think would really kill me is the additional requirement to measure temp/humidity and wind speed. These would be accomplished using parts liberated from an arduino weather station which we have lying around.

So what do you guys/gals think? Is this project feasible for someone new to microelectronics?

Thanks

HLA91


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pythoncoder
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Re: Project feasibility and board advice.

Post by pythoncoder » Fri Jun 30, 2017 6:49 am

The most difficult part for beginners is probably writing device drivers. So aim to avoid it by using devices where a driver already exists. A forum search and a check on the wiki helps here. There are a number of cheap temperature and humidity sensors with existing drivers. I'm not sure about wind speed but it's likely to be a single pulse train where all you need to do is to measure the frequency. This is easy with one of the Pyboard's timers.

I'm more concerned about the angle sensor. Presumably this is measuring very small changes in angle. The Pyboard's accelerometer has precision far short of that needed to measure deflection of a building. If you're using a specialist sensor how does it interface to a microcontroller?
Peter Hinch

HLA91
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Re: Project feasibility and board advice.

Post by HLA91 » Fri Jun 30, 2017 2:14 pm

For the Angle sensor I've been looking around and this one popped up more than once: ADXL345 any thoughts on using this?

loboris
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Re: Project feasibility and board advice.

Post by loboris » Fri Jun 30, 2017 4:00 pm

HLA91 wrote:For the Angle sensor I've been looking around and this one popped up more than once: ADXL345 any thoughts on using this?
There are special angle sensors like NXP Semiconductors KMA200 (http://www.nxp.com/docs/en/data-sheet/KMA200.pdf) with resolution better than 0.05 deg.
If you need measuring once a week, you probably dont need solar panel, a small LiPo battery can power the device for years....

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pythoncoder
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Re: Project feasibility and board advice.

Post by pythoncoder » Sat Jul 01, 2017 5:08 am

@HLA91 You need to define a specification for the angle range and required accuracy before we can give meaningful advice on sensors.
@loboris That KMA200 sounds interesting. What is the angle measured is relative to? The spec seems to indicate it's relative to an externally applied magnetic field - the characteristics are listed as "in homogenous [sic*] magnetic field at saturation field strength of minimum 35 kA/m". If so, I'm not sure how you might use it to measure a building deflection. You'd need to arrange a magnetic field that was referenced to gravity, e.g. a pair of permanent magnets on some kind of very low friction gimbal mechanism protected from wind or other disturbance.

* They can't spell ;)
Peter Hinch

HLA91
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Re: Project feasibility and board advice.

Post by HLA91 » Mon Jul 03, 2017 10:33 am

I've spoken to the guys and the accuracy needs to be as close to 0.01° as possibly. I've looked at that KMA200 and it's resolution is
Resolution better than 0.05°
so I've forwarded that spec onto them to see if it suits there needs.

mosi
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Joined: Tue Oct 07, 2014 12:07 am

Re: Project feasibility and board advice.

Post by mosi » Fri Aug 25, 2017 10:37 am

I have a solution, depending on the requirements and range.
This angle deflection sensor is being used on large cranes.
Components needed:
1. linear CCD array compatible with micropython
2. focused laser pointer
3. mirror on top of crane

Laser pointer turns on, is aligned 90 degrees with the mirror on top of the crane. Light reflects and falls into the middle of CCD sensor. Deflection in both angles with resolution of delta X of 14micrometers (theoretical limit) is possible.

Look at myspectral.com, they (we) have a linear CCD array shield to get someone started very quickly. Do not be affraid it is masked as Spectrometer.

With micropython experience, system integration is easily done for someone with experience.
My estimation on prototype build is a few days on breadboard as proof of concept and some weeks if proper PCB board is required.

Let me know if you have further questions and if this approach is feasible for your application.

inakto
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Re: Project feasibility and board advice.

Post by inakto » Sun Aug 27, 2017 2:04 am

This is interesting to me as we are developing plug and play modules based on MicroPython. Sounds like SMS capability is useful for simple remote monitoring.

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