Laser rangefinder and vision-based 3D structural displacement monitoring

Abstract

Although the structural displacement monitoring methods based on computer vision and laser projection have been raised, they still suffer from drawbacks including that the relative orientation between the laser and the receiving board must be known and the out-of-plane displacement is lost. This paper proposes a laser rangefinder and vision-based method for monitoring 3D structural displacement. The method uses computer vision techniques to extract pixel coordinates of the laser spot and utilizes the circular grid pattern on the receiving board to recover its coordinates in physical domain. Several known displacements are applied to the laser rangefinder to solve for the unknown system parameters using numerical optimization. Two laboratory experiments were conducted to prove the accuracy of the method, in which the maximum error of estimated displacements was less than 1 mm. A low-cost prototype was also developed and validated, showing the feasibility and effectiveness of the proposed method in practical applications.