2013-04-09

Robot Bartender Would Not Be Complete Without LEDs

Like any self-respecting party robot, the Kickstarter-funded, open-source Bartendro puts on a light show with its LEDs while dispensing cocktails.

Bartendro's Kickstarter campaign closed out at the end of last month, having raised nearly one-and-a-half times the targeted $135,000. Bartendro is a sort of Keurig for mixed drinks.

Rob Kaye and Pierre Michael, the two principals at Party Robotics (one of the finer company names anywhere), have been developing Bartendro for nearly three years. In the Kickstarter video they explain some of the background of the project, including the engineering challenges it presented.

Tradeoffs
As it turns out, dispensing liquids precisely and automatically is not easy. There were no suitable pumps available at hobbyists' prices when Rob and Pierre started -- they were all precision manufactured for medical or industrial markets, and cost hundreds of dollars each. So Pierre ended up procuring a CNC milling machine and designing and manufacturing pumps, valves, flow meters, and other parts for Bartendro in his garage. The partners claim that the current iteration of the Bartendro design can dispense liquids to within milliliter tolerance.

Pierre goes into a lot of satisfying detail on the pump tradeoffs in this blog post.

The Bartendro lineup, which is something like the fifth design iteration, features a version with one pump (i.e., dispensing from a single bottle), one with three pumps, and deluxe units with seven and 15 pumps. For all, the mixing process is controlled at a high level by selecting a drink recipe from a menu on an iPad or iPhone, and a Raspberry Pi controls the pumps' actions.

The LEDs
The pumps are housed under transparent plastic covers and lit by four RGB LEDs each. (So far I haven't located details of the LEDs or their drivers on Party Robotics' site; if you uncover any specifics, please let us know in the comments.) Up until the most recent GitHub check-in, the color patterns these LEDs displayed were fairly rudimentary. Now they fade from one color to another while a drink is being dispensed and flash green when it is done. The video below gives a good look at the current state.

In a blog posting, the partners fess up to sometimes giving short shrift to the LED components of their projects. With Bartendro, the LEDs were designed in from the start; but their programming hasn't always been top-of-mind. I asked Pierre by email what consideration was being given to making the LEDs more easily programmable by the Bartendro owner. His reply:

Our LED situation is still being figured out. While the LEDs can certainly be reprogrammed at the low level in C firmware, and higher level Python software. We are looking at figuring out a way to make the LED programming more manageable for non-programmers.

Open-source
The entire project is open-source and is hosted on GitHub. Software is licensed under the GNU Public License 2.0; hardware schematics and layouts are licensed using the Creative Commons Attribution-ShareAlike 3.0 Unported license. The principals say in their Kickstarter writeup that the reason they have opened up Bartendro as a platform is so that others can implement some of the many suggestions they hear whenever they show the device:

Can it accept credit cards? Can you make it detect if someone is intoxicated? What about RFID or facial recognition. These are all possibilities we'd love to see implemented, but our resources are limited.

Forums
Party Robotics has recently opened up forums on its site, and a few discussions about LED programming are under way. Here are suggestions for LED modes and a question about how to put more (external) LEDs under the control of Bartendro's Raspberry Pi. If anyone here can help the questioner out with that one, please weigh in over there.

Pierre Michael will be speaking on two panels at UBM's Design West conference later this month. I'll miss his talks because I'll be at LightFair on the opposite coast. If you're going to Design West, catch Pierre on the Open-Source Hardware panel and the Gadget Freak DIY panel.

— Keith Dawson , Editor-in-Chief, All LED Lighting