An ABB robotic arm was outfitted with a sheet-metal folding device. A computer program was then developed which took in a codified folding sequence and produced robot code for executing that sequence with the robotic arm (called RAPID code for the ABB robot). Various patterns of folded sheet metal were produced, including low-resolution fractals and simply repeating patterns of varying complexity.
The project was for a semester long course called Fabrication Customization in the school of architecture at Carnegie Mellon University.
Our goal was to produce a robotic sheet metal folding process that mimicked the versatility and morphological freedom that 3d printing techniques offer. Some processes involving robotic sheet metal folding have been developed. However many are for producing a single, repeated part. Others make varying parts, but which follow some set description; their parameters are merely altered, but there overall qualitative features are the same. The later processes can be tailored to one type of part, but an entirely new process must be developed for a new part or shape. Given the wide range of motion and precision of robotic arms, it seems likely that a robotic sheet metaling folding process could be developed which took in a computer model of an arbitrary form (of course subjected to some constraints) and produced the subsequent sheet-metal shape.
To address this gap in robotic sheet metal folding, the project consisted of finding a suitably simple method of folding that could demonstrate a 3d-printing-like workflow.
The following methods and simplifications were made
Given these simplifications we explored some of the possible forms that could be created with the robotic folding apparatus. I created a simple python script which, given a number of moves before a sequence repeated, displayed random combinations of right and left folds. The user could then select which pattern to ‘print’ with the robotic folding apparatus. (See above for an image of the display) This sequence would then be fed to the robot and subsequently folded.
If a gripper module was used that had either variable force or controllable displacements, the folding apparatus could produce a continuous range of fold angles. This would allow for an extensive range of folded sheet metal forms. Such forms could consist of shapes which involved varying angles between flat faces.
In addition, the current setup could be modified to allow for folds that were not in the vertical direction. This would create folded forms which moved in 3d space.
In the same way that bitmap images can represent smooth curves and complex shapes using discrete elements (pixels), the robotic folding apparatus developed here could be used to make large smooth curves which would be composed of many small, discrete folds.
The presented workflow could produce models very similar to the structures of proteins, which are composed of long chains of amino acids which are folded and twisted into helices and pleated sheets.