The objective of this project was to integrate a mechanized airbrush as the end effector of our 6-axis UR5 robot arm, and create paintings with it as part of an installation at Sotheby’s auction house in Manhattan.

 

I was responsible for designing the end effector, building any necessary electronics, and programming the tool paths for the arm. The project can be divided into three categories. mechanical hardware, electronics, and code.

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Mechanical Hardware

The end effector hardware consists of the following subsystems. The airbrush mechanism, two paint reservoirs, a paint delivery manifold, a camera, two microvalves, and the electronics needed to run it all.

 

The airbrush mechanism, which is the assembly sitting on top of the end effector, was designed at Artmatr’s hardware development lab in Israel. They sent over CAD files, which I modified as necessary, 3D printed, and assembled in Brooklyn. A couple months later I would redesign this mechanism to suit our updated needs. Read more about that project here.

 

I designed a frame to situate all of these components and handed it off to our neighbors for fabrication from aluminum by cnc milling with spot welding.

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Electronics

After prototyping the electrical systems on a breadboard, I soldered everything together in a small package on a protoboard. The robot arm outputs analog signals to the microcontroller onboard the end effector, which controls how and when the airbrush sprays. As a minimum viable product, these two systems were controlled separately before being merged. Having the UR5 motion controller synced with the airbrush greatly expanded the capability of the platform.

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Code

The toolpaths for the robot arm were extracted from a 3D model of the brain in Blender, processed in a python script, and injected into a URscript template which gets executed on the robot arm.

 

Platform

Additionally, the UR5 is mounted on a secondary robot arm. This arm, initially developed for the motion capture film industry to hold camera equipment, adds an additional three degrees of freedom to the platform when employed. The two are mounted together with this adaptor plate, which was milled from 1/2in aluminum stock.