Remember Isaac from the Love Boat? Well, Ted Lange couldn't fit in your pocket. iZac, the Android Bartender, can. Or at least his brains can. Nick Johnson has an ingenius system to get your Droid to mix a perfect cocktail.
Inspired by the (uncreatively named) Drink Making Unit 2.0, Nick wanted to make a drink mixing bot of his own. He took a Motorola Xoom, hooked it up with the ubiquitous Arduino board, and wrote an app for the tablet. He programmed in a bunch of classic cocktails (Manhattans, etc.) and all you have to do is hit a button, insert a glass, and iZac does the rest. You can also try the "I'm Feeling Lucky" button, which will mix three random ingredients (as seen in the video), but I wouldn't recommend it.
The trickiest part was how to make it food safe. If humans are going to be eating it, that means that mechanical parts, generally, can't touch the imbibables. The system he came up with is very clever. He uses an aquarium pump to pressurize different beakers that are filled with various alcohols. He has pinch-valves (which only touch the outside of the tubes) hold off the booze from flowing. The whole thing works by constantly weighing the beakers, so just the right amount of each ingredient is added in. Here's the workflow, from Nick's blog:
User selects a cocktail from the list.
The Android sends a command to iZac "wait for glass", and instructs the user to place their glass on the scale.
Once the user places their glass, the Android sends a command "dispense x grams of liquid y".
iZac zeroes the scales and rotates the appropriate turntable into position.
iZac turns on the aquarium pump - each turntable has one - and opens the appropriate valve.
iZac then samples the analog input from the instrumentation amplifier connected to the scales repeatedly until it detects enough drink has been dispensed. 1024 times oversampling coupled with the Arduino's native 12 bit ADC provides 17-bit precision, providing theoretical accuracy of about 8 milligrams; due to physical constraints on the valves, real accuracy is about 1 gram without any tuning. iZac sends back regular status reports to the Android.
Once enough liquid has been dispensed, iZac closes the valves and turns the pump off.
The Android repeats this sequence for each liquid in the drink; once done, the user can take (and enjoy) their cocktail!
Don't get me wrong. When I go out to a bar, there's nothing better than a skilled bartender, but man, wouldn't it be fun to have one of these sitting around your house? [Nick's Blog via Hackaday via PC World]
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