A Study On FPGA-Based Four-Axis Motion Controller

Motion control is a comprehensive, interdisciplinary technology, which is the key technology to promote the new industrial revolution and plays an important role in the modern manufacturing industry. It has extensive applications and has been used to many kinds of complex tasks. Along with the growing demand of Montion-Control product, Motion-Control technology is developing very fast, and its categories and application scopes are also expanded constantly. Recently, the developments of electronic information and some other high-tech technologies provide a larger development space and a broader market for the products of motion control.In this thesis, the background of motion control is introduced, and then the Numerical Control systems and the current development status of motion-controller is studied, some critical key technology and its development trend are carefully analyzed. By studying the montion control technology deeply and considering the requirement of system and performance indexes, a powerful 4-axis motion-controller's design scheme with more flexibility is proposed by us, in which FPGA is used as its core processor. This thesis is organized as follows:Firstly, according to the functional requirement and performance indexes of motion controller, a reasonable hardware structure of the system is put forward, which uses Microprogrammed Control Unit(MCU) and Field Programmable Gata Array (FPGA) as the overall scheme. And then the internal structure design of the Motion-Control chip based on FPGA is detailed. As the main processor, FPGA integrates all the main algorithms of the motion controller, including interpolation algorithm, acceleration/deceleration algorithm and motor sequential-control algorithm, etc. We choose MCU as upper computer, which is used to schedule task and monitor the status, etc.Secondly, in this thesis, the whole system is designed mainly from two aspects: one is to design the Motion-Control chip, which is based on FPGA and works as the core processor of this system. The other is to design a interface to the upper computer and a minimum system based on this Motion-Control chip. By further analysis of the FPGA chip EP1C6Q240C8N, which comes from Altera Company, is chosen. As to the USB interface chip, CY7C68013-128AXC, a product of Cypress Company is our choice.Thirdly, the interpolation algorithm for motion controller and the velocity control algorithm are further studied, then their basic principles are briefly expatiated and advantages and disadvantages are compared. Finally a Digital Differential Analyzer (DDA) digital integral method is used to realize the main interpolation algorithm. And, in Very High Speed Integrated Circuits Hardware Description Language (VHDL), the velocity control algorithms of ladder and exponential are design respectively. Then, by analyzing the drawback of index curve alogorithm, an improved approach is proposed, in which inverse index curve is applied to deceleration part, therefore, the whole system performance is improved.Fourthly, the basic principle of other function modules in FPGA are elaborated, then the logic structure of each function module, including location management module, interrupt management module, encoder modules and motor sequential control module and interface module, etc, is further designed. At last, simulations are used to demonstrate the feasibility of above modules on Quartusâ…¡platform in VHDL language.