Das Bot 2.0 – Now with more beer!

How quickly time goes by.  It seems like we only just completed Das Bot v1.0, but with Oktoberfest 2012 quickly approaching we started one of the biggest projects we’ve completed to date – Das Bot 2.0.  Instrumented beer on a grand scale!

The final setup, ready for the party to start.

 

Das Bot is a system for monitoring and controlling access to beer through RFID tags. Built on top of an internet-connected Arduino, the system accepts an RFID tag, checks to make sure you’re registered, opens the solenoid valves in the beer lines, lets you pour a beer and monitors how much you’ve poured, saves the data to a database, and prints out a receipt. Oh, and there’s prize badges you can win as well. There were three beers on tap this year (a homebrewed Dunkelweizen, a homebrewed Hefeweizen, and a Hofbrauhaus Oktoberfest) and each beer was tracked independently.

The Hardware

Das Bot contains the following pieces of hardware:

  • Arduino (with Ethernet shield) – the brains of the operation. This micro controller is what reads the RFID tags, talks to the PHP/MySQL site, controls the solenoid valves, prints to the thermal printer, and reads the data from the flow meters.
  • RFID Reader - reads the values from the RFID chips and sends the value to the Arduino.
  • 3 Solenoid Valves – similar to the ones on Adafruit’s site, these valves are normally closed (restricting access to vital beer) and are only opened when the Arduino gives the go ahead. After 10 seconds of no beer flowing, they close again. Since these draw more current and run at 12v, we used an old 12v wall wart we had laying around to power these (through the relay).
  • RelayThis relay controls the power to the solenoids.
  • 3 Flow Meters – we used the ones from Adafruit to send the flow data to the Arduino.
  • Thermal Printer – printed a welcome message, current stats, and final pour total for each pour.
  • Electrical Box – from the big box home improvement store, this water (and beer-proof) project enclosure was perfect for housing the Arduino, printer, and other electrical components.
  • RGB LED – when the light turns blue, pour your beer
  • Piezzo Buzzer – something this complicated needs to beep. Ours beeps when an RFID is successfully read.
  • Jockey Box – this converted cooler has a 7-pass plate chiller inside and once covered with ice, chills the beer as it flows through. This means no need to keep the kegs in giant plastic tubs with 800lbs of ice.
  • Tap Handles – no jockey box is complete without custom milled tap handles.
  • The Override Switch – this can not be over-appreciated. Buried in an undisclosed location was a switch that would override the arduino and open the solenoid valves. In the event of catastrophic failure, this is the switch represented the difference between beer and no beer. I’m always going to support the side with beer.

Closeup shot of the solenoids

The override switch. Luckily, this wasn’t needed this year. But it’s nice to know it’s there.

 

The Software

The hardware was almost the easy part of this project. We had experience with Das Bot v1.0, so adding some additional sensors wasn’t too difficult. The hard part was getting everything to talk to each other at the right times, with the right data.
Here’s what the software side looked like:
  • Arduino code – this is the air traffic control system. When an RFID chip is read, it sends the data to a web service and gets back the user’s current status. If they’re not registered, they get one (and ONLY one) free beer before they’re required to register. The flow meters are opened and activity from the meters is recorded. After 10 seconds of no flow, the system closes the valves and sends the pour volume data to the web service. The Arduino then prints out a receipt listing pour volumes and any badges that were won on this pour.
  • PHP/MySQL – a website used to store and present data during the party. The web service components were built using some simple PHP with a MySQL back end. The dashboard (running on an iPad taped inside the kitchen window during the party) presented current keg stats, leaderboards, badge summary, and other interesting bits of info. We also included the calibration for the flow meters in the database to allow for different keg sizes and to help more accurately record the data.

The welcome message displayed once an RFID tag is scanned

 The Dashboard

Want to become mayor of the Hofbrauhaus? Brag about having the largest drinking vessel? Why not turn an entire party into a drinking game? With all of the data we were collecting, it seemed natural to present this information back to the user. The thermal printer can only present so much data. The kegs were also under the table, making the “just lift it to see how much is left” method rather difficult. So, we created the dashboard to give a quick way to see how much fun we were having (note to self: next year, add a “fun” meter).

The dashboard presented the current leaders, the amount of beer consumed for each keg, the 5 most recent pours, and some other random stats. Some badges were mysteries, only visible once unlocked. Others were hinted at by the icon. Either way, the best way to win a badge was to drink beer. Actually, that was the only way.

How much fun are we having right now? Oh, THAT much. This was displayed on an iPad safely taped to the inside of the kitchen window. It was visible from the taps.

Future Enhancements

Some ideas for the 2013 Oktoberfest:

  • Integrate the photobooth - haven’t been inside the booth in the last hour? No beer for you!
  • More badges to win – need target different needs in people’s psyche, not just the “I drank more than you did” desire
  • Allow “offline” badges – someone won the beer stein race, but we’ll never remember who it was. We’ll need a way to award spot badges from mobile devices.
  • More notifications when a badge is won – I’m thinking car horns, disco balls, or fireworks. Perhaps all three.
  • Breathalyzer integration – imagine tracking this against the volume consumed overlayed with the photobooth pictures. None of our friends will ever be politicians.

Images

Additional images from the project:

 

RFID chips. Everyone got one. There were also zip ties to attach the chips to your beer stein.

The custom tap handles came out well.

The system, all condensed.

Water and electricity don’t mix, so we taped the electronics inside the cooler to the lid.

Additional photos can be found on Flickr

 

-Matt

 

*Disclaimer – Please note that this system was built for responsible adults. EVERY person in the “leader boards” either spent the night (and likely much of the next day) at the location or were driven home by a designated driver. We might mix water, beer, and electricity together from time to time, but we certainly don’t drink and drive.

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2 comments on “Das Bot 2.0 – Now with more beer!

  1. Fantastic build! Thanks for the details and photos!

    I notice the solenoids (?) look like they are running at 12V DC. What did you use for that? Are you running wall power and stepping it down with a transformer (wall wart)? Are you using a relay for the solenoid control, or transistor from a 12V lithium? Part numbers?

    On the beer side, in my experience, beer doesn’t like going through tubes of different diameters – makes it foamy. What’s your beer source? Mini keg? What hardware are you using from the beer to the tubes? Do the tubes stay the same size throughout? And what are you using for pressure on the other side of the beer? CO2? Hand pump?

    Sorry for the barrage of questions. I’ve worked through a similar build using Phidgets in the past – very successfully. I’ve been wanting to move to Arduino, but Phidgets abstracts some of the more challenging circuitry (e.g. higher voltage), so I’m eager to hear how you worked through the various details.

    Thanks!

    • The solenoids are 12v DC. We used an old 12v wall wart we had laying around. We use a relay (from Sparkfun) to turn the power to the solenoids on/off. I think I left the relay out of the post, so I’ll go back and add that.

      As for the beer, it’s all about balancing the system. We have about 5′ of 3/8″ tubing comeing out of the kegs (in this case, we had 2 5gal corny kegs with the homebrew and one half barrel keg). A CO2 tank was used to push the beer (at slightly less than ambient temp) through the chill plate at somewhere around 30psi. The diameter of the flow meters and solenoids stays at about 3/8″ to 1/4″ between all of the various fittings. The chill plate adds a lot of restriction, hence the need for high pressure from the CO2. So long as you either keep the beer cold or get it cold before the tap, and your pressure balances out with the flow restrictions (balanced system), you shouldn’t get foam.

      Thanks for reading and let us know if you have any more questions.

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