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RC models by Robert Holsting

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  Watchdog.
When the crane is erected and hanging a load app. 3.5m up in the air, then it does pose a risk of personal injury, should it fall.
I therefore wanted to build a system that watches the utilization of the crane, and issues a warning if the center of gravity is about to step outside the footprint of the crane. I could measure in which direction the boom is pointing in ref to the carrier, to which degree it's extended, the angle of the boom, the weight of the counter weight, and finally the weight of the load... but I found a shortcut to all that.

I will make two systems: One that help me setup the crane in level, and one system that will continuously monitor the load on each outrigger and alert me if the balance is about to shift.

About software: If you download the software, then you might notice that the two sets of code can be merged into one. This way I can choose to have the whole thing in one unit, if I find that funny later on. :-)

  First: The leveling system is based on an accelerometer ADXL 335 and my trusted friend, the Atmega32 microprocessor.
I bought the accelerometer from www.Sparkfun.com and wrote a piece of software that reads the X, Y and Z output via the analog->digital converter and so on.

The software for the leveler can be downloaded by clicking here. (No support, no liability blablabla..)

  I display the result in two ways: First in a LED cross giving a pretty good feeling with the operation of leveling the crane.
It is heavily inspired by the good, old bobble in the glass-type of levelers that we all know.

Here the sensor is tilted toward the front and towards the right.

  -and here the sensor is closer to level.

  I included a small LCD just to make it cool, and to have an alternative readout to the above..
Here the sensor is not in level!

(An idea: I might subtract 641 from the reading, and display a big, fat zero when in level, and then plus or minus something when not in level.)

  -and here the sensor IS in level, note the "OK!".

This system will go somewhere on the crane itself, most likely on the upper half.
(The Z axis are not used right now.)

  Second: The other system monitors the weight via four load cells (not yet bought), again read via the analog->digital converter. I have simulated a little weight for this demonstration. The software for the weight monitor can be downloaded by clicking here. (No support, no liability blablabla..)

How it works: First setup the crane in the needed configuration including counterweight and what-not. Then press the button called "Tara".
That puts the total weight of the entire system into a variable, so that we can calculate other things...

  The system monitors each outrigger all the time, and if the weight starts to shift too much, it'll trigger a loud alarm. Here the monitored, total weight has increased! But because we know how much the system weighs on it's own (Tara), then we can calculate the weight of the load, which is the only thing that can add weight to the system at this point, besides dust.
The system will sit on the ground, allowing me to keep an eye on stuff from where I operate the crane.
I also monitor the air temp through an LM35 just for fun (why not...).

    (Image will follow of the installed systems.)


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