A field calibration method of robotic inspection system for coating thickness

A coating thickness inspection system based on the serial robot has 6 domination of freedom (6 DoF) was proposed to improve the precision and convenience of the procedure of inspecting. The system consists of one functional part, two movement facilities and one central processing unit. The line-structured light sensor is the key part which is responsible for obtaining the strip image generated by the intersection of the structure light plane and the surface of the inspected work piece. The calibration method for this system contains two steps: Firstly, based on the particular designed 2D plane target and the known position information of the movement facilities, the parameters about the hand-eye relationship and camera in the sensor were calibrated. Then, the parameter of the laser plane was obtained via the principle of perspective three points and double cross ratio invariance. Only one auxiliary tools, the designed plane target is used for convenience on the field. Experiments showed that this system was accurate and efficient, besides which a coating thickness inspection system was implemented.