Laboratory Investigation of Multipoint Displacement Measurement

This paper develops a synchronised multi-camera contact less vision based multiple point displacement measurement system using wireless action cameras. Displacement measurements can provide a valuable insight into the structural condition and service behaviour of bridges under live loading. However conventional displacement gauges or GPS based systems have limitations in terms of access and accuracy. Computer Vision systems have been validated as a means of displacement calculation, however existing systems in use are limited in scope by their inability to reliably track multiple points on a long span bridge structure. The system introduced in this paper provides a low cost durable alternative which is rapidly deployable in the field. Commercial action cameras were paired with an industrially validated solution for synchronisation to provide multiple point displacement readings. The performance of the system was evaluated in a series of controlled laboratory tests. This included thedevelopment of robust displacement identification algorithms which were tested and validated against displacement measurements obtained using a fibre optic displacement gauge. This research will significantly advance current vision based Structural health monitoring (SHM) systems which can be cost prohibitive and provides rapid method of obtaining data which accurately relates to measured bridge deflections.