In-plane rotation-displacement cooperative-relay videometric method of long structures

Structural vertical displacement, lateral displacement, and torsional deformation are important indicators for the health monitoring of long linear engineering structures such as bridges and tunnels, but there is currently a lack of practical engineering monitoring methods and technologies for multi-parameter collaborative measurement. In this paper, an in-plane rotation-angle-relay videometric model for torsional deformation of long structures is first established based on the perspective projection. Furthermore, a new method of serial camera network videometric for collaborative relay of in-plane rotation angle and displacement of long structures is proposed by using an optical target that fuses point and line feature information and combining it with the classic displacement-relay videometric method. The effectiveness and engineering practicality of the proposed method were verified through simulation experiments and laboratory-scale physical experiments. The experimental results show that the method proposed in this paper can achieve the angular minutes-grade (1.44 angular minutes) measurement of the torsional deformation of long structures, even when the measurement platform itself is unstable. In addition, the measurement results of vertical and lateral displacements can be corrected for the influence of platform shaking, with a correction effect of up to 86.75%. This validates the high-precision measurement of displacement and rotation angle that can be achieved with the proposed method even when there is shaking of the measurement platform, demonstrating strong potential for engineering practicality.