Design, simulation and robotic assembly of reversible timber structures

Abstract

Wood is more and more seen as a sustainable solution to offset carbon emissions from constructions. In response and in parallel to this, the research in robotic timber construction is evolving rapidly, pushed by Industry 4.0 technologies and the integration of digital and physical robotic assets. This paper presents an approach for the design and assembly automation of layered timber structures, with the use of a flexible cell based on collaborative robots. Advanced assembly procedures and digital design of non-standard timber structures are here established and integrated. The automation process is here enhanced by the (1) use of feedback systems based on the location and force signals, (2) the introduction of a flexible robot setup with automatic screwing, and (3) human-collaboration to provide immediate assistance to the robot in the case the signals do not match the defined assembly conditions. The paper discusses the development and use of a Cyber-Physical System to govern the entire construction process, including reflections on the integrated approach to the design, modelling and simulation of the process.

Robotic Assembly of Timber Structures in a Human-Robot Collaboration Setup

“…Extensive research has been conducted internationally with a particular effort on enhancing the robotic assembly of timber structures (Stumm et al, 2018;Thoma et al, 2019;Helm et al, 2016;Eversmann, 2017;Søndergaard et al, 2016;Naboni et al, 2021;Kunic et al, 2021b). Recent works have been looking into robotic assembly strategies for structures that rely on friction-based wood/wood connections to achieve structural strength through tight-fitting.…”

“…This data is directly linked to a parametric structural model that can autonomously generate such data for different design cases. For more information on the parametric design of timber structures we direct the reader to our previous work Naboni et al (2021). On this basis, geometric data is utilized to plan and simulate robot trajectories from the material stock feed to the location of insertion above a specific joint connection.…”

“…Operating System (ROS) as the underlying communication between the service oriented control structures. Each robot action e.g., point to point movement, screwdriver operation, etc., is represented as service with specific inputs and outputs Naboni et al (2021). Section 5.3 describes how the demonstrated data is utilized in the service oriented control structure.…”

“…On the other hand, the Execution cell consists of two robots with dedicated tools, mounted on three tables, covering a full range of 4.6 m. With this configuration large timber structures can be assembled. Furthermore, in the execution cell, we combine timber layered assembly methods, consisting of pick and place, automatic and collaborative robotic screwing and vision localization of timber trusses, presented in our previous work Naboni et al (2021), with the newly developed methods based on LbD. Each robot is equipped with a custom designed end-effector suitable for handling of wooden trusses and assembly of complex and tight timber joints, which allows for both the manipulation and screwing procedures (Figure 5).…”

“…Finally, a custom interface for Human Robot Interaction (HRI), is mounted on the fourth joint of the robot. In our previous work (Naboni et al (2021)), we applied this interface for collaborative task executions with a human operator. In this work we make use of the interface primarily in the demonstration phase.…”