Abstract: By analyzing the characteristics of the laser shock processing technology, a laser shock processing CNC system based on industrial PC, motion controller and servo motor is developed, and its hardware and software design are described in detail. Key words: Motion Controller, NC, Laser Shock Processing In recent years, with the rapid development of the performance of industrial PCs, their reliability has been greatly improved, while their price has been greatly reduced. Control systems based on industrial PCs have been widely accepted in the field of industrial control. In the field of machine tool control, the use of industrial PCs and the development of general CNC systems under popular operating systems has become the latest trend in CNC technology development [1]. Laser shock peening is a novel surface strengthening technology. It utilizes high-intensity stress waves caused by intense pulsed lasers to impact the metal surface, inducing plastic strain in the material surface layer. This improves the mechanical properties of the metal surface, such as strength and hardness, and obtains a residual compressive stress state (as shown in Figure 1). Currently, the application of this technology is no longer limited to strengthening materials such as aluminum alloys, titanium alloys, stainless steel, and high-temperature alloys for aerospace applications, but has also expanded to aerospace, automotive, and medical fields. To improve the automation level of laser shock peening technology, a laser shock peening CNC system based on a motion controller was developed. [align=center] Figure 1 Schematic diagram of laser strengthening process[/align] 1 Hardware structure of the CNC system 1.1 Galil motion controller In a computer numerical control system, the computer digital control device and servo system play a key role. The system's calculation speed, real-time performance, servo update speed, resource management capability, digital communication, precision control, and micro-feed performance all depend on these two parts. In particular, the computer numerical control device, namely the motion control unit, is the core unit module of the numerical control system. The performance and accuracy of the numerical control system depend to a certain extent on the rapid control capability of the motion control unit. It can complete the interpolation, position control, and switch I/O control tasks with high real-time requirements in the numerical control system, and realize the interpolation calculation and position control functions of multi-axis linkage in the CNC system. Using such a motion module and other equipment components, it is convenient and flexible to build motion control systems for different occasions [2]. The PCI bus DMC-1842 motion controller is a product of the American GALIL company. It uses a 32-bit microprocessor and can control 1 to 4 axes. It has multi-axis linear interpolation, circular interpolation, contour control, electronic gear and electronic cam (ECAM) functions. The board has 2M Flash erasable memory and 2M RAM, which can store user programs, quantities, arrays and control programs, and can run offline. The main performance of the DMC1842 controller: ▲ Receive 12MHz servo encoder feedback signal and 2MHz stepper motor command (pulse + direction). ▲ PID with speed and acceleration feedforward, integral limit, Notch and low-pass filter. Sampling period 62.5μs/axis ▲ Motion mode: JOG, PTP positioning, contour, linear and circular interpolation, electronic gear, ECAM ▲ 2M non-volatile memory: store application program, variable, array; 2M RAM ▲ Forward and reverse limit and zero return input per axis ▲ General I/O: 8/8 ▲ High-speed position latch and comparison (0.1μs) ▲ Sine wave commutation control of brushless servo motor ▲ Automatic program operation upon power-on In addition, the matching WSDK software tool is used for automatic adjustment and analysis of servo performance, ActiveX control is used for VB programming, and extended DLL file is used for C/C++ advanced application programming, making development and application convenient. 1.2 Overview of mechanical body structure [align=center] Figure 2: Schematic diagram of the mechanical body structure of the system [/align] The mechanical body of the CNC system adopts a gantry structure [3], with four transmission axes, namely X axis, Y axis, Z axis and R axis. The X, Y, and Z axes are driven by lead screws connected to servo motors, enabling three-axis linkage with strokes of 800mm, 600mm, and 400mm respectively. The rotating axis is driven by a servo motor via a reducer, allowing continuous movement and a load capacity of 10kg. The worktable is a water tank, with water serving as the constraint medium for impact strengthening. In practical applications, the turntable can be used to clamp workpieces (such as blades), and different parts can be strengthened through worktable movement. The movement of the laser spot can also be achieved through mirrors on the motion axes, thus enabling dual working modes. 1.3 Control System Hardware Structure This laser shock strengthening CNC system uses an industrial PC as its base. A DMC1842 multi-axis motion controller is inserted into the PCI expansion slot on the industrial PC motherboard, forming the system's control center. The CPU on the industrial PC and the CPU on the motion controller form a master-slave dual-microprocessor structure. Each CPU performs its corresponding function, with the DMC1842 primarily handling the motion control of the machine tool's four axes and the input/output control of related switching quantities. The industrial PC manages the entire system. The hardware block diagram of the CNC system is shown in Figure 3. Among them, the PICM2900 interconnect module converts the controller cable into a plug-in terminal method. [align=center] Figure 3: System hardware block diagram[/align] 2 Software development The system is developed using a combination of Visual Basic and Galil card's own language. VB is mainly used for interface design, initialization and parameter setting, instruction conversion and communication with the motion control card [4]. The main functions that the entire system can achieve are: ISO standard G instruction programming, circular and linear interpolation, motion path demonstration, fault monitoring and display, and real-time display of various coordinate values. The reasonable use of the two languages ​​makes programming simple. For example, the X-axis moves in JOG mode, and two buttons are used to control the start and stop of the axis respectively. After the corresponding initialization is completed, the program is as follows: Private Sub Command1_Click() 'X-axis start Command1.SetFocus DMCShell1.Command = "JG10000;" DMCShell1.Command = "BGX" End Sub Private Sub Command2_Click() 'Stop motion Command2.SetFocus DMCShell1.Command = "STX" End Sub 3 Conclusion The system control scheme proposed in this paper, due to the adoption of an industrial PC-based control platform and the excellent control performance of the Galil motion controller, gives the system strong openness and expandability, and a user-friendly human-machine interface. The system hardware has strong stability, real-time performance, good reliability, fast operating speed, and high control accuracy. References [1] Zhang Sheng. Development of CNC system for flame cutting machine based on PMAC. Mechanical and Electrical Engineering, 2002, 19(2):38-40 [2] Wu Zhong. Control system for cutting machine based on Galil motion controller. Mechanical and Electrical Engineering, 2003, 20(4):44-46 [3] Li Xian, Yin Sumin. Research and development of CNC system for glass engraving machine based on PMAC. Journal of Lanzhou Institute of Technology, 2003, 10(4):25-28 [4] Wang Hao. Advanced Windows Programming Technology [M]. Shanghai: Tongji University Press, 1997