Robotic Kinematics Analogy for Realignment of Defective Construction Assemblies

Abstract

Aligning and plumbing of construction assemblies is a fundamental problem because of reliance on manual solutions for geometric feedback control problem involved with practices such as pipefitting and steel structures erection. Where defective components and segments are not well controlled, the errors propagate in larger components and therefore cause more severe problems. In order to address such a challenging problem and tackle potential solutions, this paper presents a framework for automatic and systematic development of realignment actions required to achieve a target state by borrowing concepts from: (1) 3D imaging that enables the identification of the as-built status and then quantification of incurred discrepancies as a feedback by comparing the captured status with the designed state existing in the building information model (BIM); and (2) an inverse kinematics analogy that results in the calculation of required changes in the degrees of freedom defined where realignment and changes can be applied. Experimental results show that the framework can generate the required actions for achieving a desired state systematically and accurately.Keywords: Realignment and refit; 3D imaging; Robotics; Inverse kinematics; As-built status assessment. Problem StatementEfficient assembly and erection of construction components requires continuous monitoring and understanding of design drawings. Defective assemblies must be appropriately detected in order to plan for required actions such as realignment, repair and replace. The current approach for detecting discrepancies of construction components in fabrication shops and on sites relies on manual approaches, which are inefficient and ineffective. An inefficient approach is also a source of rework in projects. Rework emerges in a project as a consequence of quality deviations necessitating the repetition of processes or activities and is comprised of direct and indirect costs. While direct rework impacts are said to attribute to 3-5% of contract cost, the indirect impacts have a more profound effect on achieving production efficiency, reducing costs, improving productivity and retaining market competitiveness [1]. The majority of rework occurs during fabrication and onsite assembly. Rework emerges during fabrication in the form of errors and omissions, inefficiencies, and design and process misinterpretation. Rework emerges during module assembly as inefficient alignment and the measures and schedule impacts associated with realignment and rehabilitation. To remain competitive and align with emerging industrial trends, a comprehensive strategy needs to be developed to automatically detect the discrepancies in order to effectively plan forward and minimize the unfavourable rework occurrence.Fortunately, 3D imaging has been found as an effective tool to monitor processes automatically. Moreover, 3D imaging technologies, such as laser scanning, structure-from-motion and range imaging have been proven to be fast and accurate tools for detecting the state of indus...