Universal Serial Bus Technology In Digital Motion Control Study

With the development of science and technology, NC(Numerical Control) technology gradually develops. Motion control is the core of NC systems. This project deals with the application of USB (Universal Serial Bus) in numerical motion control and designs servo controller with USB interface. This research has important theory significance and actual value.The status and perspective of NC systems, servo systems, their communication interfaces and serial buses are discussed. Then the significance and contents of the project are indicated. CNC (Computer Numerical Control) host computer and servo systems are the key parts of motion control systems. With the rapid development of Open CNC based on PC (Personal Computer) and digital servo systems, their traditional communication interfaces can't meet our needs. So the high-speed serial communication interface is proposed for digital motion control systems.First, based on the general RS-232C/422/485 serial interfaces and the ISO communication protocol SERCOS specially designed for digital servo and CNC, the application of USB in digital motion control is probed, which provides solid base for the realization of real-time communication between digital servo systems and CNC host computer. A novel network implementation approach for open motion control systems is proposed. So the motion control board of the medium and high grade NC systems can be omitted.Next, we design servo controller with USB interface. After studying the world DSP market, we chose TMS320F243 made by TI as the main processor of the servo controllers. This chip is specially designed for digital motion control and motor control. And we chose EZ-USB made by Cypress to implement the interface of the servo controller. The hardware of USB, DSP and the interfaces between them also have been developed successfully. Finally, we analyse and design the software of digital motion control systems based on USB, including the firmware of USB device, the drivers of USB device. The serial communication software of CNC host computer and servo systems has been developed by means of Visual C++, including USB interface communication experimental program and PC monitor for DSP motion control. Some key experimental results are given. In PC monitor for DSP motion control, the commands, parameters, state variables can be set anddisplayed by PC.