Development of a framework for real-time 3D positioning and visualization of construction resources

Abstract

With the development of automated data collection technologies, construction resources can be tracked and positioned with ease and high accuracy. On the other hand, 3D computer graphics technologies have rapidly evolved to maturity with much reduced application cost. However, the lack of an approach to integrating real-time site data and 3D virtual design models has handicapped application of emerging technologies to the benefit of the construction industry. Real-time 3D positioning and visualization of construction resources entails frequently updating the position and orientation of 3D models of site objects based on positioning and sensor data fed back from site in real time. This provides construction engineers with accurate spatial information about building elements being handled, and construction equipment in operation. The frequently updated 3D models also produce sufficient and accurate virtual references for locating and positioning building components and construction equipment in the field. This research has developed a framework that consists of data models, algorithms and techniques to facilitate real-time 3D positioning and visualization of construction resources enabled by resource tracking on the jobsite. The construction resources are generally divided into two categories, namely: solid objects and articulated systems. A "points to matrix" algorithm is developed to compute the position and orientation parameters for a solid object on site. In contrast with the solid object, construction equipment normally consists of a set of rigid bodies connected by joints, which is termed as a kinematic chain. The relative motion and constraints between successive bodies of the chain make the real-time 3D visualization a challenge, which requires minimizing the number of sensors as needed on practical applications in construction. The Denavit-Hartenberg (DH) technique which is widely used in robotics research is introduced and adapted for computing the relative motions of various components in the articulated equipment system based on a minimal quantity of input parameters. Considering the dynamic nature of construction industry, where new construction methods and equipment are being continuously adopted, coding the proposed methodologies in the computer system in an "ad hoc" manner entails substantial efforts for programming and system development, thus making application of the proposed methodology prohibitively expensive and practically infeasible. A graphic network modeling technique which is used in mechanical simulation systems is adapted to model the real-time 3D positioning and visualization applications. To summarize, this research has contributed three aspects of new knowledge in the field of construction industry. First, instead of using expensive devices, the 3D position of solid objects can be analytically fixed by tracking the least amount of control points. Second, the 3D position of articulated construction equipment can be analytically fixed by analyzing point coordinates and joint movement parameters. Last, the possibility of applying the developed methodologies in real-time 3D visualization of microtunneling operations has been evaluated. The kinematic chain of the tunnel boring machine (TBM) is modeled without the need of programming. The positioning of TBM cutter head which is not visible in most TBM guidance systems can be visualized in computer 3D graphics. Thus, a TBM operator in a remote control station can make more informed decisions as regards how to steer the TBM drilling in the complicated underground space along the as-designed tunnel alignment. The method for positioning and visualization of single solid object has been successfully validated by numerical analysis and laboratory experiments. The analytical method for positioning and visualization of articulated system has been validated by simulating a backhoe excavator in a computer environment, where the location of the backhoe' tracks is computed by using the "points to matrix" algorithm, and the positioning states of the cabin, boom, stick and bucket are deduced by using the DH technique.