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I didn't win a trip to space!

A project log for Honeybee Hive Monitoring

Recording weight, hive temperature, and weather data toward better management and understanding of honeybees.

Ken Meyer 10/13/2014 at 18:264 Comments

On one hand, I was hopeful, but I've really been pushing my free time to meet the competition deadlines! I'll be able to actually take a break now and again and work on other projects as my interest drifts!

I'm so close that I WILL be finishing and installing a prototype very soon, but polishing of the documentation will wait until I have something I'd want people to copy.

As always, let me know if you are trying to copy my work (or any part of it). I don't need any attribution (unless you copy my revision of the Apitronics firmware that is covered under GPL 3.0) but I probably have a list of improvements and suggestions that haven't been published but could save you a lot of time!

In other news, I have a frame built around a load cell! I want to replace the cheap little washers with spacer plates for more stability, and I'm a bit concerned about how much the system can bend, but I'll test it out with a dummy hive first and make sure that it's not too bad before installing it semi-permanently.

Again, I don't really recommend using OpenBeam for this application (although it could probably work with some additional cross-beams) but I'll learn a lot from it before I jump into a welded frame.

On the electronics side, last night, I was about to put together a circuit to drive the load cell at 10V when I realized I need an inductor I don't have on hand -- I really should read datasheets more carefully BEFORE ordering components...

Discussions

jupdyke wrote 09/12/2015 at 06:31 point

I just wanted to send you a note and see if you have made any progress. I have two hives in my backyard and have thought about adding something like this a few times. Your work looks great. I was just curious if you made any progress in the past 11 months or so. Also, I wanted to offer my help. I am a mechanical engineer and have access to two full machine shops. Wood shop, metal shop, cnc mill, waterjet, anodizing, powder coating, laser cutter, 3d printers. I am quite lucky. So if you could use any help fabricating parts or something like that, I would be happy to donate my time and skills. 

Josh

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lister wrote 10/26/2014 at 07:47 point
I've also found your posts on setting up a scale interface helpful. I naively assumed there wasn't much to setting up a scale and thought this would be a quick task in my project, especially when i saw the HX711 as a chip specifically created for load cells - but the little bit of personal experience I've gained recently, and your detailed posts, have helped me understand there's a lot to setting up a robust weighing solution. In my application, I'm trying to dispense a material precisely by putting the HX711 into a control loop driving a small fluid pump or motor to dispense a fluid or granular solid, and response/settling time can become an issue, in addition to the thermal modeling you've done a good job describing. Like David I'm interested in lower weighs <1kg, so I bought a small $10 ebay scale and reused the platform/mounts and load cell. When I first approached this I assumed weight could be treated just like other simple sensors (temperature) - but depending on your application, there's much more to consider. I've developed an interest in computer vision lately so I haven't played with this in a while, but thanks for your posts, and I look forward to seeing your progress.

I collected examples of setting up scales and using the HX711 (in simpler applications), and found some quite helpful. You may already be aware of these, but here they are :
http://www.scottcutler.net/catpoop/catpoop.html
https://github.com/chuankai/hx711
https://github.com/ggurov/hx711
https://github.com/georgeredinger/HX711/
https://github.com/bogde/HX711
http://www.dfrobot.com/wiki/index.php/Weight_Sensor_Module_V1
http://www.dfrobot.com/index.php?route=product/product&product_id=1031

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Ken Meyer wrote 10/16/2014 at 13:35 point
Yeah, I was pretty thrilled to make it this far -- I'm doing the project either way, and the deadlines really accelerated my progress!

I'm pretty wary of the HX711. I won't trust the temperature stability of the on-board amplification until I've properly tested it, and I'm annoyed that it limits the excitation voltage to under 5V.

That said, I think most indoors applications will have great results running at 5V (with the excitation at around 4.3V). That said, I'd still put some temperature calibration in software over the expected temperature range if accuracy is a concern.

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Analog Two wrote 10/16/2014 at 02:12 point
Good job anyway. I am working on a project with a load cell (much smaller scale < 100g and indoor environment) and I am finding your posts on HX711 very informative.

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