Development Of Control System For High Power Direct Output Semiconductor Laser Processing Equipment

In recent years,high power direct output semiconductor lasers have obtained rapid application in material processing,due to their characteristics of small volume,high photoelectric conversion efficiency and excellent operation stability.With the rapid development of laser processing technology and automation technology,and the increasing demands of the laser processing quality,much attention has been paid to develop laser processing automation equipment in countries all around the world.The development of the domestic semiconductor lasers have made great progress,but related research on automated processing equipment and control system for the domestic high power direct output semiconductor laser is relatively less.In this paper,control system based on dsPIC30f6014DSP has been developed for high power direct output semiconductor laser equipment,the hardware control circuit and control software for the system have been designed,the application of PID control algorithm and the fuzzy control algorithm have been explored in the system,closed-loop temperature control was carried out,and good control effect was achieved.The main work includes the following aspects:1)The design of the control system hardware circuit which was based on dsPIC30f6014Modular hardware circuit mainly includes:master control module based on DSP,A/D sampling module,matrix keyboard input and LCD display module,powder feeding module for step motor driving,D/A conversion module,the control panel interface board module,RS232 communication module,etc.2)The development of modular control softwareThe system software was developed on the basis of the hardware circuit.Through calls of subroutines,the required control function was achieved.The software includes the human-computer interaction interface module,data acquisition,filtering module,data processing module,feeding powder module,D/A driver module,state of laser signal detection and processing module,etc.3)The study of closed-loop control algorithmIn order to obtain better control performance and precision,PID and Fuzzy feedback control algorithm were designed respectively,appropriate control strategies were determined for this system by analyzing the control effect.PID control adopted incremental control algorithm and the online real-time adjustment of laser power was achieved through the setting of PID control parameters by the matrix keyboard,with the employment of improved fuzzy control,different control parameters were also set to realize online debugging.4)System performance test and analysisThe control platform include the control module of hardware and software,the laser,the robot,the powder feeder and the temperature sensor.The temperature control accuracy and stability experiments based on this control platform show that fuzzy control system has good adaptability and high control precision.For example,The laser surface treatment experiments(Start-up power:500W,Set temperature:1250?,Scanning speed:2mm/s,45steel substrate)show that the temperature of the steady-state RMS error can be controlled within 2.34?.Powder feeding experiments show that the feeding rate can reach to 3-50g/min continuously and steadily,the error rate was controlled within 2.6%.