Design Of A FPGA-Based Multi-Axis Motion Controller

With the rapid development of manufacturing industry, the modern numerical control (NC) technology attracts more and more attention as a key technology in the field of advanced manufacturing. Leading an important trend in numerical control technology, the multi-axis linkage plays an essential role in shaping the future of numerical control technology. Meanwhile the motion controller works as the core control unit of the NC system. Therfore the studying the multi-axis motion controller stands as the key block in the development of numerical control technology.While the earlier multi-axis motion controller is known for its drawbacks in its low speed, oversimplified control algorithm, and the relative low precision, the emergence of FPGA technology addresses all the above issues by enhancing the flexibility of the multi-axis motion controller, reducing the control difficulty, and upgrading the control precision. Additionally, The System On a Programmable Chip (SOPC), which integrates the processor, memory, bus, bus control, parallel I/O port, DSP and phase-locked loop into a single piece of FPGA, allows the system hardware programming to be tailorable, extensible, and scalable.Using the reusable IP core of SOPC and the integrated embedded soft core processor NIOS Ⅱ, this paper designs and implements a FPGA-based multi-axis motion controller. The main contributions of this are as follows:1. The proper acceleration and deceleration algorithm is chosen after investigation and analysis. First the principles of stepper motor, control mode, drive mode are studied and one kind of stepping motor and its driver is selected for the experiment. Then the performance of three main-stream acceleration and deceleration algorithm are analyzed and compared and the S acceleration and deceleration algorithm is implemented for the motor speed control.2. The hardware of multi axis motion controller is designed. First the overall design of the hardware system is proposed and then the function and customization of each module are introduced in detail; finally the hardware of system is configured, compiled and downloaded, which provides a hardware foundation for the later software design.3. The software of multi axis motion controller is designed and implemented. First all the software modules are designed according to the system functions, including the initialization, interrupt, exception handling, motor control, user interaction, and other functional modules. Then the operation process of each module is analyzed; finally each module is implemented by invoking the HAL (hardware abstraction layer) system library.4. An analysis method of3P-6SS with simplified translation of the structure diagram is proposed. The inverse solution of the mechanism is provided. By analyzing the synchronous motor control principle, a uniform interpolation algorithm is presented. Finally the multi axis motion control system is applied to the3P-3SS mechanism, which verifies its feasibility.