Measuring the weight of a beehive

Clemens: The most load cells are temperature compensated, I don't know how problematic creep is. For the accuracy we need to measure hive weight is seems to be not problematic. But please read the whole thread there are useful information and a hint to use not 3 wire load cells.

If you're talking about "creep" due to changes in temperature, yes, a three-wire load cell used singly will not be accurate. When you use them in pairs, however, the temperature effects are equal within each three-wire load cell, the change in resistance in the strain gauges will be cancelled out, and the "creep" isn't an issue -- or at least no different than a four-wire load cell.

I will research shortly, but I need a bit of a break from all the reading!- are there further power savings on the seeduino via library function? - or is it just so low out of the box that it isn't worth it? Am repairing other honey extraction now for a change.

For load cells I will probably build 2 identical side by side but use the 4 x cheap load cells as used in body weight scales, etc.

I dont think solar charging is going to be a requirement but will deal with it if and when I do, no point going down that path just yet and it seems as though the sealed lead acid will be surplus - just going to need to figure out a good voltage regulator now.

I have bought the HX711 for now, it gives me more flexibility for resolution and will be more straightforward I hope.

I dont see the advantage of using a one side mounted load beam opposed to the double end mounted? The beewatch configuration is exactly how I imagined building mine - with the spread of the "H" platform I would have thought the weight would register fairly accurately on the load beam? - exact weight is less import than weight trend, though an accuracy of +/- say 3kg would be tolerable.

Also, in this article

he designs a custom ‘power controller’ - is this essentially unnecessary if using an RTC module to control power on/off?

NZBeek I am building a very similar set up to yours. However I will be using 2x 50Kg load cells in a full bridge and a HX711 to measure 1 side of my hive (1/2 of the weight).

I have purchased a DS3231 RTC that has an alarm to wake the arduino, I am assume this will use less power than the 8s sleep cycle. I am hoping that a 3600mAh Lithium battery will be enough to upload twice a day for a couple of months.

I am still waiting on the components to come from China. I think my code will be based on this http://arduino.cc/en/Tutorial/GSMExamplesXivelyClient or possibly the water temp sensor you mentioned earlier.

If i was to use the GSM example code could I just add the hx711 library, set the pin and configure the scale in the setup, then add this in the loop?

scale.power_up();
  int sensorReading =(scale.read_average(5));   
scale.power_down();

As an int will it be rounded to the nearest kg?

Sorry so many questions its just taking so long for things to arrive from China

Great questions gopster, unfortunately I am too much of a newb to answer. I have similar questions though, maybe some one else on this forum could come up with some suggestions? It might be useful to post your Proposed code?

Bump

Pictures of my DIY low profile beehive, prototype. For inspiration https://www.dropbox.com/sh/0idzsdf4dc6vw4h/AAA-4wGEl7ZlYfUeIJx4jRLFa

Gert_O: Pictures of my DIY low profile beehive, prototype. For inspiration https://www.dropbox.com/sh/0idzsdf4dc6vw4h/AAA-4wGEl7ZlYfUeIJx4jRLFa

Hi Gert, good idea to use a checker plate as scale top. I have seen a similar solution in a YouTube video for a scale with much less weight than a bee hive, is it working for about 100 kg? You have two different versions in your gallery. Which is your prefered one? And are two screws sufficient for the load?

NZbeek: Also (just making the most of the time difference) - instead of using watchdog which only allows an 8s sleep, would it be better using a real time clock to sleep it for the 1 hour? - assume this would be more energy efficient.

(deleted stuff...)

Thanks all

if you want more than 8 seconds using the watchdog, you can use the code I wrote here:

http://forum.arduino.cc/index.php?topic=248263.msg1774201#msg1774201

Hi Clemens - The little red weight (27 x 27 cm) is just made for testing and calibrating the software (indoors beside my wrighting-desk). The grey weight vas made for my beehive. I use a single beam loadcell rated for 150 kg. I'm not sure that the two screws are sufficient, but as you can see on the foto there is just two holes in the loadcell. I have to test it. I tried to make a low-profile weight, but it's not stabel enough, so a have to make another platform. I'm so lucky that my neighbour is a plummer with a workshop and lots of tools i can use.

first imagine an upturned box that is big enough for your beehive to sit on. (say about 8 inches tall).

Now sitting on top of this box is a platform that overhangs the box by quite a reasonable extent (maybe a couple of feet).

This platform is then attached to the edge of the box by means of hinges. So if you were to stand on the platform and walk past that pivot point, it would tip.

Underneath the platform (on the far side to the hinges) is a microswitch that will detect when the platform is tipped.

You can now place your beehive on the platform over the box.

In the meantime, underneath that overhang is a very heavy weight. This heavy weight is suspended beneath the overhang on a runner. It can also be moved towards or away from the pivot point by means of a lead screw.

So all the arduino needs to do when it takes a measurement is draw the weight all the way in unitl it finds the end stop. Then slowly move the weight (by turning the lead screw) until it detects that the microswitch has been tripped.

From calibrations carried out before you deploy this gizmo you can then use a lookup table to see what weight that distance implys.

Naturally, you could have a saftey catch to prevent the platform rising any more than a couple of millimetres, so there's no danger of the beehive ever being tossed off.

If you like I could probably knock up a diagram in paint to explain better.

OK I decided to go ahead and draw the thing.

So the idea is. When a measurement needs to be made, the arduino will spin the motor up to make sure the counterweight is all the way in to it's home position.

It will then slowly move the counterweight away from the pivot until it detects that the platform has lifted on the far side. The distance it has moved the weight will be able to be used to assess the weight of the hive on top.

Oh I've just noticed that I didn't label the hinge (it's that blue blob near the counter weight. It's this hinge that allows the platform to tip when the counterweight is moved away from it.

Microswitches do tend to wear out, I have a collection of dead computer mice to attest the fact.

You might take a look at light interrupt though a led as light source has a finite life even only lit during measure. You might take a look at piezo disks as touch sensors, the sensitivity can be varied and the life is very long. You might look into some form of capacitance sensor also with a very long lifetime and can be made really cheap.

I had mentioned putting the hive on a counter balance just to reduce the load cell required, months ago. It's nice to see some physics used to engineer the parts needs down but running a motor will up power requirements.

Microswitches do tend to wear out

a magnet and a reed switch would do the job nicely.

As an alternative to the weight on a motor, you could have a tank that fills with water sitting on top of the platform. Then all you need to do to trip it is open a valve (that allows water from a separate reservoir) to add more water. When it starts to tip, the level guage is read. A separate valve could also be opened to allow water to drain back out.

The reservoir could collect rain water to keep it topped up.

KenF:

Microswitches do tend to wear out

a magnet and a reed switch would do the job nicely.

A reed switch will trip over a range of distance, much less tunable than capacitance or piezo touch. Capacitance is still not as good as physical touch or light interrupt can be. Piezo can tell how hard is the touch.

I am a fan of piezo disks after experimenting with them. There are cheap ones that work just fine as buttons. They don't need debounce, give pressure data and can take a good bang. I got 100 for just over $10. Downside is they need other components to work as I did. I used diodes, transistors and resistors.

Hi Lars, I'm doing a similar project.

I bought a simple bathroom scale. Removed the 4 sensors en mounted them on a board of wheaterproof pliwood. On top of that is my beehive. This 4 sensors to the INA125 and to the Arduino.

Also I installes a humidity and temperature sensor in the beehive. Future expansion is a counter to measure the activity at the gate of the beehive.

From the arduino a WiFi module to my home network.

http://www.ebay.com/itm/171495443192?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I have to do this 20 times. Me and my friend we have 2 times 10 beehives.

The final goal is to publish the weight results into HTML to be viewed in graphs everywhere I am.

So how far are you in the meantime?

Regards, Wim

Hi Wim / Paysan,

I work in electronic and have also beekeeping as hobby. This project is very interesting: great job realized. I have just a few questions:

Have you thought about using pessure sensor as MPX5100 to measure hive weight: using simple smooth hydraulically linked containers placed on 4 corners's hive? Preesure is then, function of weight.

About battery, why don't you use a lithium battery size D: it's what is used in industry for GPRS system, which is adapted to Temperature, long life duty and high current need for GPS?

Could you please share your realisation (schematics, ref for OTS parts and SW code)?

Thanks and regards

Alain

Thanks for all the diffrent suggestions. But i still think, why get it so complicated when it can be done simple. hydraulically, mecanically etc.

I use a single beam Loadcell (8 $ each (when bying 10 pcs)) and a cheap ( <5$ ) HX711 Dual-Channel Weighing Sensor Module.

And it Works.

Hi i working on similar project,i made scale for my beehive.I use arduino uno r3,gprs gsm shield sim 900,7.4V 1000mah lipo batery,DS1302 Real Time Clock,HX711 24 Precision AD Module Pressure Sensor Module Weighting Sensor, DHT-11 Digital Temperature and Humidity Sensor,and four cels from home body scale. two times in day i recive sms with weight,humidity and temperature.i nead resolve problem with batery,does someone know how i can recive in sms how much i have power in batery,or alarm whan i hawe low power? thank you for any help? if you want i can post picture of my prototipe!

Hi, KenF, I love it, a work of art, you could sit and watch it weight all day.

It would be a great educational tool to teach these hi-teched kids these days, that a controller and programiing and some HeathRobinson (not sure of US equivalent, I know Art Goldberg, new knew the Mythbusters would eventually help my edjamacation) can do.

Rather than just poke a iphone at it and get google to come up with the answer.

Tom.... :)