At present, PC-based and PLC-based controllers are commonly used in manipulators. The control mode of six-axis manipulators mainly introduced in this article adopts the controller based on PLC. Before the development of programmable logic controller (PLC for short), a large number of relays and counters are needed to achieve the automation function. The appearance of PLC greatly simplifies the hardware space needed for automatic control.
 
1. Periodic Mode

(1) The manipulator presses the left limit switch and the upper limit switch in situ. Press the operation button once and the manipulator starts to descend. After descending to the left station, it automatically stops after pressing the lower limit switch.

(2) The manipulator starts to rise after clamping the workpiece. It rises to the original position and automatically stops after pressing the upper limit switch.

(3) The manipulator starts to move right until the right limit switch is pressed and stops automatically.

(4) The manipulator descends. It moves the lower limit switch to the right station (two stations use one lower limit switch) and then stops automatically.

(5) After the manipulator relaxes the workpiece, it starts to rise until the upper limit switch is pressed and then stops automatically (one upper limit switch is used for two stations).

(6) The manipulator starts to go left until it stops after pressing the left limit switch. At this point, the action of one cycle ends, and then press the operation button again to start the operation of the next cycle.
 
2. Continuous Mode

After starting the manipulator, the above-mentioned action process of each cycle is repeated, that is, periodic continuous operation.
 
3. Single-step Mode

Each time the operation button is pressed, the manipulator completes a work step. For example, when the operation button is pressed once, the manipulator starts to descend, and the lower limit switch is automatically stopped when it descends to the left station. In order to run the next work step, the operation button must be pressed again.