Computational LEGO Technic Design

TL;DR

This paper presents an automated system for generating LEGO Technic models from sketches, incorporating mechanical properties and symmetry, and validated through comparisons, expert evaluation, and user studies.

Contribution

It introduces a novel computational approach to automatically design LEGO Technic models from sketches, considering structural and mechanical constraints.

Findings

Generated models closely match input sketches.

System outperforms four baseline methods.

User-created models are physically realizable.

Abstract

We introduce a method to automatically compute LEGO Technic models from user input sketches, optionally with motion annotations. The generated models resemble the input sketches with coherently-connected bricks and simple layouts, while respecting the intended symmetry and mechanical properties expressed in the inputs. This complex computational assembly problem involves an immense search space, and a much richer brick set and connection mechanisms than regular LEGO. To address it, we first comprehensively model the brick properties and connection mechanisms, then formulate the construction requirements into an objective function, accounting for faithfulness to input sketch, model simplicity, and structural integrity. Next, we model the problem as a sketch cover, where we iteratively refine a random initial layout to cover the input sketch, while guided by the objective. At last, we provide a working system to analyze the balance, stress, and assemblability of the generated model. To evaluate our method, we compared it with four baselines and professional designs by a LEGO expert, demonstrating the superiority of our automatic designs. Also, we recruited several users to try our system, employed it to create models of varying forms and complexities, and physically built most of them.