基于单目视觉和近红外靶标的竖直变形监测方法

Vertical Deformation Monitoring Method Based on Monocular Vision and Near-Infrared Targets

为了满足桥梁、隧道等大型设施的全天候、高精度、在线变形监测需求,提出了一种基于单目视觉和近红外靶标的竖直变形监测方法,在被测结构上若干测量点处安装近红外靶标灯,采用基于最小二乘法椭圆拟合的中心定位方法自动跟踪并识别近红外靶标灯光斑中心图像坐标,再通过基于真实仰角的成像几何关系计算得到被测结构上测量点的实际竖直变形。通过室内精度验证试验可知,该方法在8.457 m距离内的最大示值误差为0.043 mm。通过某轨道桥梁变形监测应用试验可知,该桥梁在24 h内竖直变形监测情况与该线路的地铁运营情况高度相符,受地铁载荷作用影响,其竖直变形量在−4~6 mm范围内,表明该方法可应用于实际工程结构的全天候、高精度、实时在线监测。

To satisfy the requirements of all-weather,high-precision,and online deformation monitoring of large facilities such as bridges and tunnels,a vertical deformation monitoring method based on monocular vision and near-infrared targets is proposed.Near-infrared target lights are installed at several measurement points on tested structures.A center positioning method based on least-squares ellipse fitting is used to automatically track and determine the center image coordinates of the near-infrared target light spot.Subsequently,the actual vertical deformation of the measurement points on a tested structure is calculated using the imaging geometric relationship based on the true elevation angle.The indoor accuracy verification experiment determined the maximum indication error of this method to be 0.043 mm at a distance of 8.457 m.In the deformation monitoring application test of a certain track bridge,the 24 h vertical deformation monitoring results are highly consistent with the subway operation time.Also,the vertical deformation is within the range of−4‒6 mm under the effect of subway loads,indicating that this method can be applied to all-weather,high-precision,realtime,and online deformation monitoring of actual engineering structures.