Pattern Of Temperature-induced Structural Displacement Measurement Error With Vision Measurement System

Displacement is a good descriptor of structural behavior and safety status.However,measuring displacement of structures under dynamic excitations is still a challenging task.videogrammetry shows great potential for dynamic displacement measurement,benefiting from its non-contact and long-distance characteristics.Video cameras have temperature effects,temperature change have an impact on the videometric measurement accuracy.This study therefore carried out videometric measurement tests with scenarios close to real applications,study on the temperature-induced measurement error of the long-term continuous videometric measurement.experimental results show that temperature variations cause significant measurement error in the displacement recorded with videogrammetry.In order to quantify the degree of correlation between them,the correlation analysis between temperature variation,displacement measurement errors have been performed respectively.Statistics indicated that the temperature change of camera surface and zoom lens have a satisfactory relationship with displacement measurement error,especially,the temperature change of zoom lens and displacement measurement error are very highly correlated.Considering that the displacement measurement error and temperature change have a satisfactory linear relationship,the displacement measurement error is linearly fitted with temperature change data of the different components of the vision measurement system respectively.The prediction model is established for short-term linear regression prediction,it is observed that the predictions ability of the model is unsatisfactory from the comparison between the predicted value and the measured value,so the uncertainty of model fitting parameters is discussed as follows.It can be seen that the uncertainty of the slope is relatively small,however,the uncertainty of the intercept is large by calculation.The influence of tripod on the displacement measurement error mode is explored by wavelet transform under the effect of temperature.It is concluded that the tripod has a significant effect on the vertical displacement measurement error,but the displacement measurement error can produce periodic fluctuation under the influence of temperature,whether in the case of a tripod or not.