A new system for measuring bridge deflections based on laser imaging process is introduced. Firstly, principle of this system is analyzed with geometrical optics theory. Secondly, hardwares of measuring system are illuminated in detail, and the key software problems are discussed, including laser spot center location and accurate control of motorized TV zoom lens. The laser spot center location is realized by using image fuzzy edge extraction algorithm and Hough transform algorithm. The accurate control of motorized TV zoom lens' motors is realized by using a control-driving card based on ISA bus. At last, the contrastive experiments are operated on a certain continuous steel bridge with this system and dial test indicator. The experimental results show that this system is equal precision with dial test indicator, and can get over defects of traditional measuring methods. The security and reliability is much higher relatively and the precision can match to the engineering requirement.
Optimized algorithm of laser spot center location in strong noise
