Four-axis motion control based on PLC

1 Control Task

The control system design requirements of the test diagnosis platform are as follows:

(1) According to the instructions of the on-site installation personnel, the operator issues the servo electric cylinder action command, and the four servo electric cylinders act independently within the total stroke range and stop reliably at the stroke limit position:

(2) The control box should have the function of displaying the stroke and indicating the action of each electric cylinder, and should be easy to operate and move.

2. Control object analysis

The test diagnostic platform is shown in Figure 1.

The host computer operating system is to control the standard I/O servo driver of the L7s series of Lexing MacPien. The driver can operate in torque, speed, and position modes according to the connection method with the host controller, and can switch the operation mode according to the parameters and I/O input contact signals. Under the condition of completing the position control function, the mode selection has a large difference in the functional requirements of the host controller. Among them, the torque mode has the highest requirements for the host controller, and the position loop and speed loop control must be completed. The position mode has the lowest requirements for the host controller, but it will not affect the positioning accuracy. Its accuracy depends on the feedback accuracy of the servo motor encoder and the mechanical accuracy of the electric cylinder. Therefore, considering simplifying the host computer function, the servo driver and the electric cylinder APM AC servo motor are used to form a fast and accurate positioning full-digital position servo system.

3. Control system design

Based on the analysis of the control task and the controlled object, the control system should provide a friendly human-machine interface, be able to complete the semi-closed loop position control of the four servo electric cylinders, and the operation modes include JOG continuous operation, JOG stepping and electronic handwheel mode, servo motor start/stop with S-shaped acceleration and deceleration, motor enable and brake control and other functions.

Since an AC servo position control system is used as the drive, according to the L7s series standard I/O type servo drive terminal input position operation mode wiring, the upper control system needs a programmable motion controller with PTO (pulse train output), motion control card or PLC, and an upper human-machine interface HMI touch screen that can communicate and connect with the controller or control card.

3.1 Control system based on four-axis motion control PLL

The entire control system includes power supply, Xinjie TH765 series HMI touch operation display, Xinjie XDM-32T-C four-axis motion control PLC, electronic handwheel, L7s series standard I/O servo drive, etc. The HMI touch operation display, motion control PLC and L7s servo drive form a monitoring system through the serial communication network MODBUs-RTU protocol. The system structure is shown in Figure 2.

3.2 Human-computer interface design

The Xinjie TH765 series HMI touch operation display screen can quickly configure the human-machine interface through the TOuchwin editing software to realize multiple interfaces, as shown in Figure 3, including the operation and position display interface, servo drive status interface, alarm and history record interface, etc.

Recording interface, etc.

4 Applications

The AP inclined operating table integrated control system is adopted. The operating platform is shown in Figure 4, which is mainly divided into two parts: HMI touch operation display screen and electronic handwheel. The left side of the electronic handwheel is the axis selection knob, which is divided into five gears: OFF, X1, Y1, X2, Y2: The right side of the electronic handwheel is the magnification selection knob, which is divided into three gears: X1, X10, X100. When it is set to OFF, the hand-cranked metal code disk is invalid: when it is set to the corresponding axis, the electronic handwheel hand-cranked metal code disk can be operated clockwise and counterclockwise, and the corresponding axis moves forward and backward.

5 Conclusion

The domestically produced Xinjie XDM series motion control PLC introduced in this article integrates motion control functions with ordinary PLC functions. It can support up to 10-axis pulse output and realize two-axis linkage. It supports both ordinary motion control instructions, such as circular arc and linear interpolation, and plane conversion instructions. It can perform two-axis linkage conversion of Xy, yZ, XZ, etc. It is simple and easy to use, with high reliability, and has certain reference value for realizing multi-axis motion control.