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My father is a farmer, and he has a ball wrapper such as this one: http://www.hardwickagricultural.co.uk/controlpanel/shoppics/IMG_1266.JPG. For now, we can work quickly with it only if we are at least two people: one on a tractor to put balls on the machine, and arrange wrapped balls, and another people who needs to action the machine using hand controller. This machine is hydraulic, but we need to action hydraulic command by hand. So, I talked with him, and we agreed that it could be great to be able to work alone with this machine, and I proposed him to have a look at it.

Why am I telling you that? Because I started thinking about doing this using a Raspberry PI. I know that we can control some GPIO pin to emit electricity or not, so, this would be perfect to control some hydraulic valves. I am a computer scientist, so, I am not afraid to writing needed programs to control it. However, what I am missing is some electronic requirements. On the Internet, I found plenty of captor, so, I will look for the ones I need to do what I want. However, what I am missing is the remote controller. On the beginning, I looked to use bluetooth from a mobile phone, but I know that bluetooth pairing can take some times and bluetooth range is about 10m, so, lots of bluetooth pairing may be needed as we arrange balls far from the machine, and I do not want to have to wait 30 seconds each time I need to control the machine. So, what I need is a wireless command with a pairing almost immediate within a range of about 10 meters (also, I need that we can work with it through glasses, and with an pairing as fast as what I explained). Do you have any suggestion regarding this? Maybe some technologies I could use? If you could point me to some hardware that could work with the PI to do this, it would be great.

Thanks for your replies.

  • Do you have access to internet for this device? It sounds like a wifi based solution with network communication would be much better for you. Easier to implement and probably more features available if you ever wanted to do any more automation. – MD-7 Jan 7 '16 at 16:49
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As both a Raspberry Pi and Arduino tinkerer, I find that when interacting with the physical world, usually Arduino is a better choice. The Arduino IDE is very limiting for advanced programmers but there are work-arounds and for simple programming with GPIO requirements, it can't be beat. There are tons of peripherals available for Arduino for any kind of sensor and remote control interfaces are available for Bluetooth, WiFi etc.

  • Hello Bartman, I had look at Arduino too (after I posted this post), and I think I will go for this technology, as it looks better than the Pi to do what I want. – Loic Feb 9 '16 at 18:50
  • Upvote and mark as answered please – BartmanEH Feb 9 '16 at 18:53
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Two approaches come to my mind: Get yourself a remote control like they have it in model-aircrafts. Let the servos act the valves/switches of the ball roller. A decent 4 channel RC with receiver and 4 servos should be around $ 150 max. Thus you save the hassle of dealing with AC mains.

If you want to raspify your ball roller just get you two Pis with 2 WiFi dongles. The one on the ball roller you want to set up as an access point. It's GPIO must be galvanically seperated from AC mains. You achieve this by using a set of opto-couplers. The output of the optocoupler might trigger a relay/contactor which in consequence switches the valves. The other Pi you set up as a WiFi client. Its GPIOs connect to push buttons. The rest should be some Python coding, that you are obviously familiar with.

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    Thanks for your answer. I talked with a colleague, and he mention RF433 modules that seems to do what I want. I will try using those modules to send data from the remote command to the PI that is on the machine. – Loic Jan 22 '16 at 18:09
  • Also, you are talking of "opto-couplers". Do you know what could be the benefits of using this? – Loic Jan 22 '16 at 18:10
  • Optocouplers isolate two electrical circuits from each other by using LED light to bridge the physical gap between them. Reasons for doing this are usually safety - separating the high voltage part from low voltage circuit, for example - and sometimes noise reduction/immunity on digital signals. They can also be used on user inputs as a kind of level-shifter where user can apply quite a wide range of voltages and polarity and the optocoupler output will be a safe voltage for your circuit. – Roger Jones Oct 25 at 11:05

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