Yijiang Huang

Last Name

Huang

First Name

Yijiang

ORCID

0000-0003-1820-2535

Organisational unit

09620 - Coros, Stelian / Coros, Stelian

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Publications 1 - 7 of 7

A differentiable structural analysis framework for high-performance design optimization
Lee, Keith J.; Huang, Yijiang; Mueller, Caitlin T. (2025)
Structures
Fast, gradient-based structural optimization has long been limited to a highly restricted subset of problems—namely, density-based compliance minimization—for which gradients can be analytically derived. For other objective functions, constraints, and design parameterizations, computing gradients has remained inaccessible, requiring the use of derivative-free algorithms that scale poorly with problem size. This has restricted the applicability of optimization to abstract and academic problems, and has limited the adoption of these potentially impactful methods in practice. In this paper, we bridge the gap between computational efficiency and the freedom of problem formulation through a differentiable analysis framework designed for general structural optimization. We achieve this by leveraging Automatic Differentiation (AD) to manage the complex computational graph of structural analysis programs, and implementing specific derivation rules for performance critical functions along this graph. This paper provides a complete overview of gradient computation for arbitrary structural design objectives, identifies the barriers to their practical use, and derives key intermediate derivative operations that resolve these bottlenecks. Our framework is then tested against a series of structural design problems of increasing complexity: two highly constrained minimum volume problems, a multi-stage shape and section design problem, and an embodied carbon minimization problem. We benchmark our framework against other common optimization approaches, and show that our method outperforms others in terms of speed, stability, and solution quality.
Constructability-driven design of frame structures with state-space search methods
Huang, Yijiang; Garrett, Caelan; Mueller, Caitlin (2024)
Automation in Construction
In the design of frames and trusses, the relationship between the structural form, the construction sequence, and the structural behavior during construction is rarely systematically considered. This paper proposes a method to systematically consider constructability in design, specifically focusing on minimizing the maximum displacement or stress during construction. The paper presents the formulation of the optimal assembly sequencing problem as a state-space search with a unique design of the search heuristic and constraint bounding schemes. It proposes three variants of heuristic search algorithms for finding a feasible sequence, a diverse set of feasible sequences, and an optimal sequence, respectively. These algorithms are tested on a case study structure to showcase their ability to navigate the combinatorial space of assembly sequences, and provide means for designers to incorporate sequence-related performance into conceptual structural design.
The CantiBox - Robotic Assembly of Interweaving Timber Linear Elements Using Bespoke Interlocking Timber-to-Timber Connections
Tanadini, Davide; Boller, Giulia; Leung, Pok Yin; et al. (2022)
Hybrids and Haecceities: Projects Catalog of the 42nd Annual Conference of the Association of Computer Aided Design in Architecture
The robotically fabricated CantiBox project presented here constitutes a novel application of the design and automatic assembly of interlocking timber- to-timber connections. The structure is composed of 60 linear elements of solid spruce interconnected through half-lap joints to form a reciprocal network.
A Temporal Coherent Topology Optimization Approach for Assembly Planning of Bespoke Frame Structures
Wang, Ziqi; Kennel-Maushart, Florian; Huang, Yijiang; et al. (2023)
ACM Transactions on Graphics
We present a computational framework for planning the assembly sequence of bespoke frame structures. Frame structures are one of the most commonly used structural systems in modern architecture, providing resistance to gravitational and external loads. Building frame structures requires traversing through several partially built states. If the assembly sequence is planned poorly, these partial assemblies can exhibit substantial deformation due to self-weight, slowing down or jeopardizing the assembly process. Finding a good assembly sequence that minimizes intermediate deformations is an interesting yet challenging combinatorial problem that is usually solved by heuristic search algorithms. In this paper, we propose a new optimization-based approach that models sequence planning using a series of topology optimization problems. Our key insight is that enforcing temporal coherent constraints in the topology optimization can lead to sub-structures with small deformations while staying consistent with each other to form an assembly sequence. We benchmark our algorithm on a large data set and show improvements in both performance and computational time over greedy search algorithms. In addition, we demonstrate that our algorithm can be extended to handle assembly with static or dynamic supports. We further validate our approach by generating a series of results in multiple scales, including a real-world prototype with a mixed reality assistant using our computed sequence and a simulated example demonstrating a multi-robot assembly application.
The new analog: A protocol for linking design and construction intent with algorithmic planning for robotic assembly of complex structures
Huang, Yijiang; Leung, Pok Yin; Garrett, Caelan; et al. (2021)
Proceedings SCF 2021 ACM Symposium on Computational Fabrication, October 28–29, 2021
Construction robotics are increasingly popular in the architectural fabrication community due to their accuracy and flexibility. Because of their high degree of motion freedom, these tools are able to assemble complex structures with irregular designs, which advances architectural aesthetics and structural performance. However, automated task and motion planning (TAMP) for a robot to assemble non-repetitive objects can be challenging due to (1) a nonrepetitive assembly pattern (2) the need for a continuous robotic motion throughout a sequence of movement (3) a congested construction scene and (4) occasional robot configuration constraints due to taught positions. Recent work has already begun to address these challenges for repetitive assembly processes, where the robot repeats a pattern of primitive behaviors (e.g. brick stacking or spatial extrusion). Yet, there are many assembly processes that can benefit from a non-repetitive pattern. For example, processes can change tools on an element-by-element level to accommodate a wider range of geometry. Our work is motivated by the necessity of robotic modeling and planning for a recently published timber assembly process which utilizes distributed robotic clamps to press together interlocking joints. In addition to pick-and-place operations, the robot needs to move numerous tools within the construction scene, similar to a tool-change operation. In order to facilitate an agile process for architectural design, construction process design, and TAMP, we introduce a flowchart-based specification language which allows various designers to describe their design and construction intent and knowledge. A compiler can then translate the assembly description, sequence, process flowchart, and robotic setup into a plan skeleton. Additionally, we present a linear and a non-linear solving algorithm that can solve the plan skeleton for a full sequence of robot motions. This algorithm can be customized to take into account designer intuition, which can speed up the planning process. We provide a comparison of the two algorithms using the timber assembly process as our case study. We validate our results by robotically executing and constructing a large-scale real-world timber structure. Finally, we demonstrate the flexibility of our flowchart by showing how custom assembly actions are modeled in our case study. We also demonstrate how other recently published robotic assembly processes can be formulated using our flowcharts to demonstrate generalizability.
Algorithmic circular design with reused structural elements: Method and Tool
Huang, Yijiang; Alkhayat, Latifa; De Wolf, Catherine; et al. (2021)
fib Symposium Proceedings ~ Proceedings of the International fib Symposium on the Conceptual Design of Structures
Computational design and fabrication of reusable multi-tangent bar structures
Huang, Yijiang; Wang, Ziqi; Hung, Yi-Hsiu; et al. (2025)
Computer Aided Design
Temporary bar structures made of reusable standardized components are widely used in construction, events, and exhibitions. They are economical, easy to assemble, and can be disassembled and reused in various structural arrangements for various purposes. However, existing reusable temporary structures are either limited to modular yet repetitive designs or require bespoke components, which restricts their reuse potential. Instead of designing bespoke kit of parts for limited reuse, this paper investigates how to design and build diverse freeform structures from one homogeneous kit of parts. We propose a computational framework to generate multi-tangent bar structures, a widely used jointing system, which allows bars to be joined at any point along their length with standard connectors. We present a mathematical formulation and a numerical scheme to optimize the bar spatial positions and contact assignment simultaneously, while ensuring that the constraints of tangency, collision, joint connectivity, and bar length are satisfied. Together with simulated case studies, we present two physical prototypes that reuse the same kit of parts using an augmented reality-guided assembly workflow.

Publications 1 - 7 of 7

Yijiang Huang

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