A novel digital twin-based evaluation method of clearance and step-off for thermal protection system

Abstract The thermal protection tile system is one of the most critical structures of reusable launch vehicles, and its assembly quality directly affects the flight performance of the aircraft. The assembly clearance and step-off of thermal protection tiles are essential parameters for assessing the assembly quality of the thermal protection system (TPS). Additionally, digital twin technology provides real-time feedback and the ability to control physical processes virtually. Therefore, this paper proposes a novel digital twin-based evaluation method of clearance and step-off for TPSs. The paper first introduces the automated assembly system for thermal protection tiles used in this study, which consists of three assembly stages. Based on this system, a digital twin model of thermal protection tiles is constructed using a theoretical model and physical entity as inputs through three layers: theoretical data layer, actual measurement data layer, and reconstruction of data layer. This twin model is coupled with the assembly pose dataset of the thermal protection tiles to create an assembly deviation model, which is then used to calculate the assembly clearance and step-off. Finally, the paper also experimentally verifies the proposed measurement method by building an experimental platform using seven thermal protection tile test pieces. The standard values of the clearance and step-off are measured using a laser tracker, and these standard values are compared with the measurements obtained from the proposed method. The results indicate that this method significantly enhances measurement efficiency and realizes the real-time measurement while maintaining accuracy within ±0.027 mm.