Millimeter-level position control in modular construction using laser scanning and tolerance chain

Compared to conventional construction, modular construction requires stricter tolerances due to the assembly of prefabricated bulky modules. Therefore, effective positional tolerance control (PTC) is critical to ensure quality modular buildings. However, the status quo using conventional tools like tapelines is time-consuming and risks accuracy. This paper presents an accurate and efficient PTC method using laser scanning and tolerance chain. The method integrates a corner-aware module detection algorithm for extracting critical geometry features from point clouds and a tolerance chain of module assembly for disclosing tolerance accumulations from the module, floor, and building levels. Laboratory experiments using scaled module specimens based on a real-life modular building (1:20) are conducted for the validation of PTC. Results show a high accuracy of less than ±3 mm and timely tolerance feedback within 8 min. The paper contributes a method for quality assurance of module assembly by facilitating efficient and millimeter-level tolerance control.