Development And Application Research On USB3.0 And FPGA –based Multi-Axis Motion Controller

Currently, most open motion control systems adopt the architecture of “PC + motion controller” and the common used communication bus of this motion controller is PCI(Peripheral Component Interconnect). However, due to the inconvenience of PCI devices and unavailable interface of PCI bus in portable PC, a new high-speed communication interface is needed to replace PCI bus. At the end of 2008, the new USB3.0 protocol has implemented the speed of 5Gbps. In addition, portable PC with USB3.0 is gradually occupying the PC market. All of these pave the way for the development of low cost, high performance and portable motion controller by means of USB bus. Therefore, after deep studying on the motion control technology, a USB3.0-based open architectures motion controller is developed using FPGA(Field Programmable Gate Array) as the main control chip. On the basis of that, the application research and function test are carried out according to the servo control requirements of WEDM(Wire-cut Electrical Discharge Machining) machine tools. The specific work is as follows:(1)On the basis of analyzing the function and performance requirements of traditional motion control system, the general hardware and software design scheme for the motion controller is put forward which based on USB3.0, FPGA and uses rough and fine two-level interpolation.(2) Key integrated circuit chips of the motion controller are selected and then the schematic diagram of motion control peripheral interface modules are designed using Altium Designer, including FPGA minimum system, CYUSB3014 minimum system, motor driver interface, encoder feedback signal processing interface module. In addition, the PCB production, components welding and circuit test of motion controller is completed.(3) In view of system integration, circuit modules in the FPGA chip EP3C40F484 such as DDA interpolation, encoder signal frequency doubling and direction discrimination and dual port RAM are programmed respectively and integrated through SOPC(System on Programmable Chip) technology.(4) A kind of hard real-time motion control protocol of data transmission error control and bidirectional data transmission function is developed based on the features of the CYUSB3014 and USB3.0 communication protocol. Design the UART of CYUSB3014 channel to transfer the direction commands. In addition, USB3.0 driver, the rough interpolation algorithm, main motion control function and the improved PID algorithm are programmed as well.(5) The application of motion controller is researched according to the WEDM servo control requirements including the design of development process, hardware wiring and software framework, and the setup of WEDM servo control prototype system. A wire-cut machining control experiment which generates the profile of a piece of three-order B spline curve is completed and the experimental results verifies the designed motion control modules such as the encoder interface circuit, digital IO, analog input, multi-axis interpolation, etc.