*4.5. Welding Actuator*

The schematic diagram of the welding actuator is shown in Figure 15. The welding actuator can move back and forth in a straight line along the X axis and Z axis. The stroke in the X axis direction is 100~150 mm, and the stroke in the Z axis direction is 150~200 mm. The double welding torch is symmetrically distributed on the welding torch bracket of the X axis linear slider. The movement of the X axis and Z axis is completed by the stepper motor electric drive synchronous belt module, and the movement speed is controlled by Siemens S7-1200PLC and the stepper motor driver. The Z axis selection has a brake stepper motor, which is locked when power fails, to prevent sliding.

**Figure 15.** Welding actuator structure diagram. 1. Welding torch; 2. welding torch bracket; 3. X axis linear slider; 4. Z axis linear slider.

#### *4.6. Control System Design*

The cotton seeder duckbill welding robot controller is the Siemens S7-1200PLC. The communication between PLC and human–machine interaction (HMI) is Ethernet. PLC realizes manual and automatic control of the girdle, static duckbill, and hinge feeding operation. It also controls welding parameters, fixtures, welding actuators, and welding platforms. HMI enables manual and automatic program switching of welding robots and monitors the working conditions of welding robots to ensure the safe and smooth operation of welding operations. The control system flow chart is shown in Figure 16.

**Figure 16.** Control system flow chart.
