Challenges of CAD conversion to 3D development environments with respect to kinematic dependencies Philipp Braun Martin Sliwinski Johannes Hinckeldeyn Jochen Kreutzfeldt Institute for Technical Logistics, Hamburg University of Technology, Germany, {philipp.braun, martin.sliwinski, johannes.hinckeldeyn, jochen.kreutzfeldt}@tuhh.de Abstract Due to the increasing utilization of 3D development environments for industrial use cases by emerging topics like virtual reality, new challenges in the conversion of computer-aided-design (CAD) models to 3D models have become visible. Particularly, the conversion of the kinematic constraints turns out to be complex and requires extensive manual efforts. This paper discusses these challenges with a focus on the problems in the conversion of kinematic constraints. Further, a new approach is proposed and validated regarding the automated conversion of the kinematic constraints of an exemplary CAD model. Thereby, this work contributes to an accelerated and simplified development process of industrial applications within 3D development environments. Keywords: computer aided design (CAD), 3D, kinematic dependencies, CAD conversion, constraints 1 Introduction CAD systems are indispensable in industrial product development processes and represent the state of the art in the area of product design software. However, product development tasks often go far beyond pure product design and require additional software solutions for simulation, visualization or other tasks. While CAD systems are the preferred tools for product development, 3D development environments 1 (3DDE) are used for visualization in high-quality renderings, videos or virtual reality applications (Davila Delgado et al., 2020). Because of the limited compatibility between CAD systems and 3DDE, file conversions are usually required and lead to a loss of information (e.g. parameters, materials, kinematic constraints) (Raposo et al., 2006). Manual restoration of lost information can be time consuming and must be repeated with every adjustment of the design. Even existing CAD conversion tools are not able to fully convert kinematic constraints (Stelzer et al., 2014). Other scientific publications identified this problem as well but could 1 Popular examples are 3DsMax, Cinema4D, Blender or Unity. not present a general applicable solution (Whyte et al., 2000). For that reason, this paper will present existing challenges regarding the conversion of kinematic constraints followed by an approach for an automatic conversion concept. This paper is structured as follows: In section 2, the state of the art highlights current challenges regarding the conversion of CAD models to 3DDE compatible files. Further, problems of current approaches to overcome the existing challenges in the file conversion will be discussed. In section 3, an approach for a concept which addresses the identified issues is presented. A validation and discussion of the presented approach is given in section 4. This work closes with a conclusion in section 5. 2 State of the art The following section focuses on the state of art and identified challenges in the conversion workflows from CAD models to files supported by 3DDE. First, currently available file formats will be discussed. Second, challenges regarding the conversion of kinematic constraints are presented. Finally, current approaches to overcome the conversion issues will be presented. 2.1 File formats for 3D-data exchange Challenges in the conversion of 3D models from CAD systems to 3DDE arise, because most software systems use their own native file formats. In addition, the most software systems offer only limited capabilities to export or import data to other software. In order to overcome these issues, neutral exchange formats have been developed, which can generally be read by any common CAD- or 3D-system. However, the converted content often does not go beyond pure geometry (Dimitrov and Valchkova, 2011). The possibility to store additional information like materials, parameters, kinematic constraints etc. can vary from format to format. Furthermore, only a limited number of CAD systems offer the possibility to export these data. SIMS 61 DOI: 10.3384/ecp20176215 Proceedings of SIMS 2020 Virtual, Finland, 22-24 September 2020 215