| The placement is a kind of machine which welds PCB(Printed Circiut Board)automatically and precisely. In recent years, SMT machine become more and moreimportant along with component miniaturization and PCB complication. There are twoaspects to improve the system performance: the improvement of machine vision and theoptimization of motion control. In order to improve machine vision, the way usuallyinclude increasing the accuracy of camera and optimization of image processingalgorithm and so on. At the same time, the optimization of motion control include thebest choice of hardware, designing optimal control algorithm, etc. The paper is based onour independently researching SMT machion, focus on the X-Y platform and researchits law of motion. Summarizing the full paper, this article research mainly includes thefollowing four aspects:The first one is modeling and analysis of Single motor control system. The paperReference other scholars performance analysis of synchronous belt, establish theequations of dynamics of synchronous belt. Finally the Mathematical model ofsynchronous belt has been deduced. At the same time, aiming at the AC servo motor,mathematical description is derived by using system identification. Therefore, thecomplete model of single motor control system is given.Secondly, aiming at the instability of single axis servo system, fuzzy-PID Controlalgorithm is used to solve the problem. Fuzzy-PID can adjust PID parameter by positiondeviation According to the practical experience and equipment needs, fuzzy-PIDcontroller has been designed to increase the robustness of the system and improve theperformance of single axis servo motor.The third aspect is the study of how to synchronize two motors of Y axis. Keepingtwo motors synchronization is the basis of guaranteing the normal work of theplacement machine. In this paper, the author comes up with using cross-couplingcontroller to solve synchronization problems. Cross-coupling controller is easy todesign, this paper adopt PD controller instead of traditional cross-coupling controller.The simulation results show that PD controller of synchronous effect is significant,which can meet the needs of the actual control.Finally the paper complete the hardware design of a control board. The function ofthe control board mainly includes two parts, motion control and synchronization control.Control board adopts traditional DSP+CPLD structure, DSP is used as processing unit,CPLD is used as decoding tool, PCI bus is used as the communication protocol. Theboard design each unit modular separately. DSP adopts faster TMS320F28335tocomplete Motion control, synchronization control, T velocity planning and so on. CPLD need to finish the PCI protocol parsing, read signal of ruler, access data of SRAM. Atthe same time, the board reserve the CAN bus, AD sampling, serial port communication,PWM output as function extension for future. |
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