Computer-aided real-time kinematic global positioning system positioning technique for deformation measurement and analysis

Abstract

Scientific justification and technical feasibility of using Real-Time Kinematic Global Positioning System (RTK-GPS) positioning as the technique in recording the responses (in term of coordinate / position) of deformable structures have been proven very promising. The major advantages are the real-time measurement (either online or offline) and direct measurement of relative displacement. Nevertheless, the research, through the sampled data, shows the need of additional steps to handle the possible errors in direct employment of manufacturers’ RTK positioning solution for deformation monitoring. In addition, most of the further applications such as online, automated, continuous, etc., however, have to be self customized and developed. The sampled data comprise short baseline (1.8km, collected in Universiti Teknologi Malaysia) and medium length baseline (27.7km, provided by Geodesy Section, Department of Survey and Mapping, Malaysia). The research thus suggests an additional approach for RTK positioning integrity monitoring and deformation detection. The RTK positioning integrity monitoring includes error identification, outlier filtering and reference station stability checking. The essence of the approach is the Normal Point technique as well as the Local Threshold and Global Threshold. Reference for Local Tolerance and Global Tolerance are also discussed. To get the additional approach running more efficiently in one single system, prototype software, Sparrow, was developed in Visual Basic environment and by deploying the Trimble bundled software, which are Trimble GPS Configurator and Trimble Reference Station. Sparrow is also developed to serve for online, automated, and continuous deformation monitoring. At the same time, Sparrow provides real-time and past result presentation in both graphical and numerical format. Three tests are taken to verify the applicability of Sparrow and the validity of Normal Point.