This site is dedicated to our experimentation, designs and implementation of our own bar monkey.
What is a bar monkey you may ask. It is an automated mixed drink vending robot. Many people have worked
on this area before. Our goal was to make a more sophisticated system with a simplified design.
The design was broken up between us based on our areas of expertise. and seperate reproducable subcomponents.
For our initial revision we decided upon 16 different ingredient paths for ~200 different drinks. We also decided against
the pumps common in most other designs as solenoid valves and pnuematic systems are still required. Instead we went with
a constant pressure system with solenoid valves. This cut cost and complexity.
- 5 lb CO2 canister
- Pressure Regulator
- Gas Manifold
- 2 Liter Canisters
- Bulk head quick connect fittings
- Solenoid Valves
- Flow Rate Calculations
The solenoids that were selected were rated for running at 24VDC at X watts. I had an old power supply that met the requirements and decided to use that. They also were default
closed so if the machine loses power it won't be pooring drinks.
The controller circuit that was selected was the 0/16/16 Phidget. It was rated for 30V,
had Debian GNU/Linux libraries and 16 outputs.
At the Trenton Computer Festival, I came upon a used Fujitsu Stylistic LT C-500 for only $75. It has a touchscreen, battery backup, wireless IR keyboard, onborad sound
and a docking station with networking and power connectors. It was a donation so it had its harddrive wiped clean no OS and now drives from which to install, but I was
able to find an online site describing how to install a basic Debian GNU/Linux system.
The wiring was fairly straight forward. The phidget instructions make a good reference. I wired the negative terminal from my power supply to one of the common ground terminals on the phidget.
I then wired one lead from each solenoid to a common Positive source from the powersupply. I then wired each of the solenoids remaining leads to one of the output terminals on the phidget.
Now when the phidget output it turned on, the solenoid completes it's connection to ground and is able to switch on.
Note: The phidgets have overcurrent protection to buffer them against
the direct connection of an inductor. Other control circuits may need additional buffering if the teminal connects directly to a transitor or else extreme voltage spikes could result.
It seems unlikely that a control circuit without an external power supply could drive a solenoid valve. If you get solenoids designed for AC or high voltage, you may want to consider getting
more isloation by using one of the relay models, these will have a lower switching speed though.
A wealth of software went into building up the controller, fortunately we were able to largely leverage Open Sorce Software to speed up development. I will put the information on installing a
functioning Debian/GNU Linux environment on the Fujitsu Stylistic LT C-500, here. Once we had a working base Debian system we made sure we had
the following packages: libphidgets-dev, python-wxgtk2.8, python-numpty. We were running with the LXDE desktop environment and also installed a music player (gmpc/mpd) so that the machine
could function as a jukebox while dishing out drinks.
On top of this base I created a C based command line utility that would connect to the phidget and cycle thru each output turning it on for a certain period of time. This command
barmonk takes the Phidget USB ID (0x44) and the serial number as its first parameters to know which phidget to use. The remaining parameters are a list of how long to turn on
each output in microseconds. If you get errors, make sure you are in the
phidgets group and check this bug
A wxPython Graphical User Interface,
wxbarmonkgui, was the next piece of software. It parses the list of drinks, ingredients and controllers to create a menu for the user to select
which drink to make. The drinks.xml file is the configuration database of the entire control software. New drinks can be added for personal preference. Ingredient properties can be changed,
including the ever important multiplier field which is how long the ingredient must be on in microseconds to get 1 ounce (~30 ml). The shot drinks in the menu should pour that one multiplier
amount. We use them and a graduated cylinder to tune the system. For 20 PSI and 1/16" opening our times should be pretty close or use 1000000 for new ingredients. The controller section
needs to be set to use the correct serial number of the phidget. The system could be upgraded to 32 ingredients just by adding a second controller, 16 more ingredients and the drinks to use
them to the xml. Drink groups can be created and drinks moved between groups and favorties with the xml as well. In order to fill the dead space I chose a quite nice image from the Debian
version of the openclipart package. Of course, feel free to replace it with anything you'd rather look at.
We also created a cgi-bin that would allow other frontends, such as a flash interface in the works, to contact the backend and get a drink poured.
There is a more CPU/Memory intensive flash interface in the works. It has on screen tutorials, dancing monkeys and a more pleasing full screen mode.
If you have questions, feel free to drop us a line.
We will try to post answers to questions on this site. As well as update as we get more chance to add content/new releases. So keep your eyes open.
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