ACM Transactions on Graphics(SIGGRAPH Asia) 35(6), 2016.
Figure 1: Given a frame shape (a), we propose an algorithm for generating a feasible fabrication sequence of struts which guarantees that the already-printed part is in a stable equilibrium state and that the extrusion head avoids collision with the printed part at all fabrication stages. This is verified by a built prototype robotic fabrication system consisting of a 6-axis KUKA robotic arm with a customized extrusion head: (b) and (c) are intermediate fabrication states and (d) is the final fabrication object for the given frame shape (a).
Abstract:
Frame shapes, which are made of struts, have been widely used in many fields, such as art, sculpture, architecture and geometric modeling, etc. An interest in robotic fabrication of frame shapes via spatial thermoplastic extrusion has been increasingly growing in recent years. In this paper, we present a novel algorithm to generate a feasible fabrication sequence for general frame shapes. To solve this non-trivial combinatorial problem, we develop a divide-and-conquer strategy that first decomposes the input frame shape into stable layers via a constrained sparse optimization model. Then we search a feasible sequence for each layer via a local optimization method together with a backtracking strategy. The generated sequence guarantees that the already-printed part is in a stable equilibrium state at all stages of fabrication, and that the 3D printing extrusion head does not collide with the printed part during the fabrication. Our algorithm has been validated by a built prototype robotic fabrication system made by a 6-axis KUKA robotic arm with a customized extrusion head. Experimental results demonstrate the feasibility and applicability of our algorithm.
Video:
The following two videos show the differences how 3D printing with FDM technology and the proposed robotic fabrication technology print the frame shapes.
Video 1: Frame shape fabrication by 3D printing with FDM technology. As FDM technology alway deposits the material layer by layer to approximate the input 3D model, it is a unnatural way and not suitable for printing the frame shapes.
Video 2: Frame shape fabrication by the proposed robotic fabrication technology. It fabricates each strut in a single stroke by extruding the filament directly in 3D space. The fabrication order of the struts is optimized by our path planning algorithm to avoid the collision constraints, and the printed part is guaranteed to be in a stable equilibrium during all the fabrication process.
Source Code and Hardware Setup:
We release the source code on how to design the fabrication order of the struts via the link. Besides, the hardware setup is also very important for the fabrication system, and some technical details are given in the supplementary material.
Acknowledgements:
We thank Zishun Liu, Shizhe Zhou, and Zhipei Yan for the insightful discussions and the anonymous reviewers for their valuable comments. This work was supported by the National Key R&D Program of China (No. 2016YFC0800501), the National Natural Science Foundation of China (Nos. 61672481, 61672482, 61303148, 11526212), and the One Hundred Talent Project of the Chinese Academy of Sciences.
BibTex:
@article{HuangZHSLYL2016,
author = {Yijiang Huang and Juyong Zhang and Xin Hu and Gongxian Song and Zhongyuan Liu and Lei Yu and Ligang Liu},
title = {FrameFab: Robotic Fabrication of Frame Shapes},
journal = {ACM Transactions on Graphics},
volume = {35},
issue = {6},
pages = {},
year = {2016}
}
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