The secret to a great cocktail, most connoisseurs would agree, has something to do with the ice, the liquor, the glass — and the bartender.

But what if the bartender is not a warm-blooded human with a sympathetic ear, but rather a cold, soulless machine made of pistons, valves and servos?

At a bar in San Francisco, a group of artists, engineers and tinkerers sought the answer with their creations: robots designed specifically to pour out a nice drink.

The booze-making bots included an all-mechanical, lever-operated robot; a Cosmobot with a rocket-shaped body; and Barnold, who is “strong and big, just like Arnold.”

“We really just like robots and cocktails, and both together seemed like the perfect thing,” said Simone Davalos, one of the organizers of the Barbot 2010 event. “There is no real aim for world-changing, paradigm-shifting technological achievement, at least not from our perspective, but who knows? Lots of amazing things have happened over cocktails.”

From cosmos to appletinis, these robots measured, mixed and poured out drinks that were precisely assembled. And those droids were mesmerizing to watch.

As for the drinks themselves, having sampled drinks from almost all the robots, my verdict is that the robots still have a long way to go. The cocktails taste just a little too clinical. There’s a missing ingredient in there. Could that be the human touch?

The Corpse Reviver

Even a humble cocktail robot can be an engineering marvel. The imaginatively named Corpse Reviver is a cleverly designed robot that’s completely mechanical.

“It’s all levers and linkages,” said Benjamin Cowden. who created the robot.

The Corpse Reviver has four levers that are attached to four bottles arranged in a circle. To make yourself a drink, place a glass at the center and pull the first lever. This pushes the attached bottle up, then tips a measured pour of a little more than an ounce into a bowl-shaped holding container. Do the same with the two other levers, and finally pull back on the fourth to release the stopper and push the liquid from the holding container into a second chamber that’s full of ice. A few seconds later, the drink is in the glass.

“This is my favorite robot in this room,” said Lillian Fritz-Laylin who had come to check out the event . “It’s interactive on multiple levels. It’s not just ‘push a button and walk away.’ And the drink was really good.”

Cowden designed the entire mechanism and sketched it out on a 2-D design program. All the parts for the robot have been custom laser-cut. And it’s the attention to details that really make this a winner. For instance, once a lever is pulled and the bottle tips out its pour, a hydraulic damper and spring mechanism make sure it slowly and steadily returns to its original position.

Photos: Jon Snyder/Wired.com

Drink-Making Unit

Clunky moniker aside, the Drink-Making Unit, or DMU, shows that creating a robot isn’t necessarily about having laser-cut parts and some gee-whiz machinery. All you need is a few hours of tinkering and a splash of ingenuity.

The DMU can churn out cocktails that include up to three ingredients. On Wednesday night, it was busy slinging some White Russians for the crowd.

But here’s the interesting part. This cocktail robot uses a rather unusual component: A breast pump to dispense the liquid.

“We looked at ketchup bottles and food-safe pumps to use, and eventually found that the best type of pumps for this idea would be breast pumps,” said Windell Oskay, who is known in the DIY community as one of the partners at Evil Mad Scientist Laboratories. “They are cleanable, don’t use much power and they’re inexpensive.”

Oskay and his wife Lenore Edman bought 3 breast pumps on eBay for $27 each.

Here’s how the DMU works. At the bottom are three carafes with the different fluids. Tubes connect each carafe to a breast pump that is controlled with a microcontroller. The other end of the pumps feature stoppers with tubes that end in three champagne glasses that have had their bottoms cut out. (Check out his detailed post on how the Drink-Making Unit works.)

The glasses, which now act as funnels, open into an ice tray that chills the drink before it drips out into the serving glass.

A panel of buttons controls how much of each ingredient is mixed. Next to the buttons is an integrated 8×8 RGB LED matrix for displaying information.

Unlike more sophisticated cocktail robots, the Drink-Making Unit isn’t automated. To get a glass of White Russian, you have to press a button on a panel, then repeat for each of the other two ingredients.

Oskay said he and Ledman ended up having two glasses of cocktails each while testing the robot. It’s a good reward for a day’s work.

Photo: Jon Snyder/Wired.com

Barnold

Who said robots would make humans lazy? Getting a shot of whiskey from Barnold means taking on an arm-wrestling challenge.

Barnold is an unusual cocktail robot. The robot is almost the size of a bar table. At one end is a skeletal metal arm that connects to a set of weights at the opposite end. When the arm is pressed all the way down, it triggers a mechanism controlled by an Arduino board that brings a glass out of a tray to the mouth of the whiskey bottle. Once the glass is beneath the bottle, a second engine lifts the bottle and pours out a shot.

“It’s fascinating because the robot is interactive,” said Mikolaj Habryn, one of the crowd at the Barbot event. “It feels almost human, like something out of one of those cowboy bars where you have to arm wrestle to get a drink.”

For the six students from Austria’s University of Applied Sciences who created this robot, the the Barbot competition in San Francisco was a place that would help cement their position as the masters of cocktail robots.

The students had created Plasmastaub, a similar cocktail robot, to show at the Roboexotica event in Vienna last year. The Barnold is an updated, revamped version that they started work on in November. Check out the video that offers a glimpse of Barnold.

Photo: Jon Snyder/Wired.com

Cosmobot

There are cocktail robots and then there are cocktail robots with ambition. The Cosmobot isn’t content with just automatically dispensing cocktails. It’s ultimate goal is to become a bartender in space.

“Ultimately, we want to modify the design so it can dispense drinks in zero gravity,” said Sam Coniglio, one of the three team members who created the Cosmobot.

Cosmobot was first built for the 2009 Robogames competition, but in its first version it could only mix up a cosmopolitan. Now the robot can create three additional drinks: a Cosmopolitan, a Cape Cod and a Kamikaze. It has also been painted a snazzy silver.

The key to a good cocktail robot lies in being able to determine how long a pour will take, said Coniglio. The Cosmobot’s rocket shaped body houses bottles of liquor and mixers. When a button is pushed, a pour of vodka is dispensed for, say, three seconds. That goes into a red plastic funnel that also holds dry ice. Five seconds later, the flash-chilled alcohol gushes out into the glass below. An Arduino board helps control the operation precisely.

Created out of salvaged parts, the Cosmobot cost about $500 to put together, said Joe Phillips, the machinist on the project. Philips used salvaged metal parts from a pool filter for the rocket body.

As for the dream of mixing drinks in zero gravity, it will be a while before Cosmobot can get there, said Koniglio. “We will have to change the design and find a way to get compression containers…. Liquids tend to get spherical in shape in zero gravity. We will have to see how our design works in that environment.”

And then there’s the small matter of securing space aboard a spaceflight or zero-G plane flight. Still, now that the International Space Station has a killer view, wouldn’t a cocktail robot be the perfect addition?

Photo: Jon Snyder/Wired.com

iLush

Recipe for a great cocktail PC: 1 tablet PC, 1 pour of vodka and a good hacker. The iLush uses a convertible laptop from HP as its controller and a .net-based application written in C#.

Futuristic in its style and looks, the iLush allows you to make a selection from four available cocktails. Once the machine gets whirring, it lines up the correct container against a syringe that pulls up a vial of the liquor. It is then pumped through a compartment of ice water with copper tubing to chill it before it hits the glass.

“I have used PC parts throughout the robot, including a PC coolant pump seen in gaming machines,” said Stuart Ferguson, “and cold cathode lights for effect.”

The iLush is one of the veterans of the cocktail-robot scene. The gadget has won the gold medal for two years at Robogames.

Photo: Jon Snyder/Wired.com

Chapek

With more snappy comeback lines than James “Sawyer” Ford on Lost , the Chapek is a chatty cocktail robot with some attitude. The robot has been around for four years and gone through a number of revisions.

“It’s always a work in progress,” said David Calkins, its creator.

In its latest version, Chapek can be activated using an RFID token. The robot’s hand then grabs a glass and brings it in line with the area where the second step takes place. Sensors then tell a relay to open the dispenser valve of the bottle holding the alcohol. A shot then splashes into the glass, and your drink is ready.

And just so you don’t really miss talking to the bartender, Chapek has a few smart lines to spew out. As I walked past him, Chapek called out “Hey, have you ever dated a robot before? I used to date a vacuum cleaner. It sucked.” And then I heard what sounded like robot laugh — or it could be just the electronics crackling.

Photo: Scott Beale/Laughing Squid