A novel substation robot camera calibration method based on vanishing visual points

Smart robots equipped with cameras, radar and other devices play an increasing role in power substation inspections, condition monitoring, fault identifications and maintenance. Due to complex substation environment, robot cameras require re-calibration to ensure accurate robot route movement due to the problem of angle change of the camera in the actual motion. This paper proposes a novel robot camera calibration method based on vanishing visual points. It utilizes the physical configuration characteristics of electric lines/equipment and busbars in the substation, combined with traditional offline calibration in the initialization phase, the reprojection error cost function in the image plane is defined with camera pitch, yaw and roll calculated using vanishing visual point characteristics under the image plane. The robot camera is calibrated to control the reprojection error within the acceptable range. The proposed method is applied and tested in the laboratory environment. Results show that the camera's external parameters can be controlled within 2 degrees of engineering acceptable error, which has a certain practicability in dealing with special conditions such as drift and bumps of the inspection robot.