This research investigates the robotic assembly of timber structures connected by wood–wood connections. As the digitization of the timber construction sector progresses, digital tools, such as industrial robotic arms and Computer Numerical Control machines, are becoming increasingly accessible. The new-found ease with which wood can be processed stimulates a renewed interest in traditional joinery, where pieces are simply interlocked instead of being connected by additional metallic parts. Previous research established a computational workflow for the robotic assembly of timber plate structures connected by wood–wood connections. This paper focuses on determining the physical conditions that allow inserting through-tenon joints with a robot. The main challenge lies in minimizing the clearance between the tenon and the mortise in order to keep the connections as tight as possible. An experimental protocol has, therefore, been developed to quantitatively assess the performance of the insertion according to different geometric parameters. Robotic insertion tests have been carried out on over 50 samples of 39 mm Laminated Veneer Lumber. Results showed the interest of tapering the joint with a 5 degrees angle, in addition to introducing an offset of 0.05 mm, to minimize friction forces during the insertion. This configuration was confirmed by successfully assembling a 2,50 m long box girder with the same parameters.

Wood-wood connections, widely used in the past, have been progressively replaced by steel fasteners in timber constructions. Currently, they can be manufactured and implemented more efficiently thanks to digital fabrication techniques. In addition, with the emergence of new timber plate engineered products, digitally produced wood-wood connections have been developed with a strong focus on complex free-form geometries. The gained knowledge through research and building implementations have pushed the development of more standardized structural elements. As a result, this work presents a new concept of building components using through tenon connections based on the idea of transportable flat-packs directly delivered and assembled on site. The main objective of this research is to develop a convenient calculation model for practice that can capture the semi-rigid behavior of the connections and predict the effective bending stiffness of such structural elements. A case study is used as a reference with three large-scale slabs of a 8.1 m span. Bending and vibration tests are performed to study the mechanical behavior and assess the proposed calculation method. The results show the high influence of the semi-rigid behavior of connections on the bending properties and, therefore, on the serviceability limit state. The model is in good agreement with the test results, and further improvements can be made regarding the local behavior of the connection. This study demonstrates the feasibility of the proposed construction system and the applicability of the developed calculation model to design practice.

Augmented reality in additive fabrication is predominantly applied to the manufacturing of structures from regularly shaped materials. Our work however embraces natural heterogeneity, by focusing on the assembly of irregularly shaped elements such as mineral scraps. We introduce a computer-aided framework with a 3D stacking engine and an augmented reality interface capable of guiding users through the balanced positioning of discrete and highly nonuniform objects according to an on-the-fly computed model and without prior trimming of the building unit. The pipeline is tested by the construction of two dry-stone structures (i.e., lacking any adhesives), and its accuracy is validated with a comparative study between the point cloud of the as-built digitized artifacts and the generated execution model, which shows an average 2.9 ± 1.8 cm error between the stones of the two models. We finally show how the proposed framework could be improved both in terms of software and hardware. In the interests of reproducibility, all the methods are shared as open source with the community. Graphical

We present TimberTool (TTool v2.1.1), a software designed for woodworking tasks assisted by augmented reality (AR), emphasizing its essential function of the real-time localization of a tool head’s poses within camera frames. The localization process, a fundamental aspect of AR-assisted tool operations, enables informed integration with contextual tracking, facilitating the computation of meaningful feedback for guiding users during tasks on the target object. In the context of timber construction, where object pose tracking has been predominantly explored in additive processes, TTool addresses a noticeable gap by focusing on subtractive tasks with manual tools. The proposed methodology utilizes a machine learning (ML) classifier to detect tool heads, offering users the capability to input a global pose and utilizing an automatic pose refiner for final pose detection and model alignment. Notably, TTool boasts adaptability through a customizable platform tailored to specific tool sets, and its open accessibility encourages widespread utilization. To assess the effectiveness of TTool in AR-assisted woodworking, we conducted a preliminary experimental campaign using a set of tools commonly employed in timber carpentry. The findings suggest that TTool can effectively contribute to AR-assisted woodworking tasks by detecting the six-degrees-of-freedom (6DoF) pose of tool heads to a satisfactory level, with a millimetric positional error of 3.9 ± 1 mm with possible large room for improvement and 1.19 ± 0.6° for what concerns the angular accuracy.

Open Access Dataset for "Ar-Assisted timber drilling with smart retrofitted tools" Andrea Settimi, Julien Gamerro, Yves Weinand Ecole Polytechnique F ́ed ́erale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering(ENAC), Institute of Civil Engineering (IIC), Laboratory for Timber Constructions (IBOIS), GC H2 711, Station18, Lausanne, 1015, Vaud, Switzerland Contacts: andrea.settimi@epfl.ch julien.gamerro@epfl.ch The present data set has been used to evaluate timber artifacts produced with AR-assisted fabrication methods. The scans, holes reconstruction, and comparison with the execution models can be inspected in the dataset. Two options are possible to access the dataset: [1] via Rhinoceros 3D [2] other visualizer/engines or CAD environments In addition, the statistical evaluation presented in section 3 of the paper can be verified with a matlab script: - ExpData.mat : raw data from the experimental drilling campaign used for the statistical analysis. - DataTreatment.m : matlab file used for the statistical analysis + results graph. All the necessary information to use correctly this script is available directly in it. For additional information, please consult the README.md file