May 27, 2014

Yu Jiang Tham, a graduate from UCLA with a B.S. in Electrical Engineering, has designed and built a bartender robot that mixes drinks called Bar Mixvah. All the parts were 3D printed. Bar Mixvah uses a system of 5 peristaltic pumps that are switched by 5 bipolar junction transistors (TIP120), all controlled by an Arduino. The Arduino is controlled by the Johnny-Five package on the node.js/express web server that is running on your laptop/windows tablet.

A peristaltic pump is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained within the plastic tube which extends through the pump. Peristaltic pumps work by rotating rollers so that they pinch a loop of silicone tubing against an outer surface and pushes liquid through the tube. The advantage of these pumps is that they are capable of pumping very precise quantities of liquid.

The peristaltic pumps you can buy from the market come with some very short plastic tubing. So all Tham needed to do was to replace the plastic tubing for this application.

Image: Wikipedia

Tham created the 3D model of the bartender robot in Blender, and printed all the parts on a 3D printer. Total time to print the pieces is about 18 hours, says Tham. In addition he also purchased 11x 5/16" steel square 12" rods, clear tubing, Arduino Nano, 5x TIP120 w/ Diodes, 400-point breadboard and jumper wire, 5x 2.2kOhm resistor, 4x #6-32 2" machine screws, 12V power supply and Male pin connectors. The total cost is just about $180.

The robot utilizes the MEAN stack (MongoDB, Express.js, Angular.js, Node.js) and an Arduino to control the pumps that make the drinks. The best part about this design is you can control it from an iPad. According to Tham,

MongoDB for saving the drink and pump data
Express.js for the web server so that I can access the robot from the iPad
Angular.js for front-end filtering of the drinks based on ingredients chosen for each pump
Node.js for controlling the arduino/pumps

Having it on a web server allows users to order from any device such as a WiFi enabled phone, tablet. "Practicality-wise, maybe it's not necessary. However, in my experience, people seem to enjoy ordering from a tablet that they're holding in their hands more than a stationary screen attached to the robot." Tham says.

Tham has shared the stl files of the 3D model and the code on GitHub for everyone to download. If you are interested, you can follow his instruction here and build your own drink mixing robot. (As of writing, only first part of tutorial, the 3d model, printing, and assembling the physical robot is posted. The second part of the tutorial will be software design, and the third part will deal with the operation of the robot.)

Watch below the video of the robot:

Posted in 3D Printing Applications


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Gr1f1th wrote at 5/28/2014 5:53:12 PM:

too simplistic in it's current form but with self priming and pause when an ingredient is empty this could be really useful. I actually was thinking about this exact type of machine for Essential Oil mixing on a smaller scale.

Andrei wrote at 5/28/2014 1:01:58 AM:

It seems a bar automation season is open. First and now this.

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