Robot welding control system and control method based on PLC

The invention provides a robot welding control system and control method based on a PLC. The system comprises a robot body, a servo system of the robot body, a welding device, a visual sensing deviceand a control center, and the control center takes the PLC as a main controller; the visual sensing device generates and collects laser stripes projected to the surface of a welding workpiece and transmits the obtained groove information of the welding workpiece to the PLC, and the PLC plans a welding bead based on the groove information and conducts welding control; and the robot servo system comprises a program processing unit and a communication unit, and the PLC calls the program processing unit through the communication unit to control work of the welding device, the visual sensing deviceand the robot body. The coordination of the welding system device, the robot system, external equipment and the visual sensing device can be effectively promoted through the strategies of visual acquisition, PLC operation tra