3 EXPERMENTAL RESULTS AND ANALYSIS

3.1 Image acquisition scheme for crane grab boom

The automatic grabbing device for segment beams is connected to the automatic grabbing lifting tool through the crane’s crown block. The bottom two sides of the lifting bracket are equipped with automatic grabbing lifting rods, which are used to insert the segment beam lifting hole to complete the grabbing task. After it is fully locked, the position of the crown block and the posture of the lifting tool are adjusted through the control system, and the segment beam can be grabbed and placed in a designated area. The layout of the industrial camera is shown in Figure 16. The camera is installed at the bottom of the hanger at a 30 ° angle to the vertical direction. The industrial camera follows the movement of the hanger and maintains its relative position with the automatic grabbing boom, ensuring that the bottom of the automatic grabbing boom is always in the center of the industrial camera’s field of view.
Under working conditions, the overhead crane pulls the lifting tool to a certain distance directly above the section beam to be grasped, adjusts the posture to make it basically consistent with the posture of the section beam to be grasped. The industrial camera automatically takes photos and sends the captured image of the suspension rod back to the local computer through the image transmission module. The method described in this article is used for image processing, and the captured photos are also transmitted to the crane driver’s cab for reference by the operator. Using a local computer to calculate the intersection coordinates of straight lines, provide image point coordinates for photogrammetric 3D space calculation, and locate the 3D spatial position of the lifting tool. Output the parameters to the control system, which drives the adjustment mechanism of the suspension rod based on the parameters to achieve precise alignment between the suspension rod and the lifting hole. Finally, the lifting tool is lowered to achieve the purpose of automatic grasping of the segmental beam.