Design And Implementation Of On-line Tuning System For CNC Performance Based On Virtual Instruments

In recent years, the high-precision and high-speed processes is the main direction of the development of CNC. Control arithmetic and control parameters can influence this performance of CNC. During the high-precision and high-speed processes, how to analyze the performance of CNC and tune parameters of servo is very important. There are a lot of control parameters during the modern numerically controlled process. At present the engineers usually adopt the test method based on their own experience. This method can confirm the control parameters quickly. However, it has some disadvantages. In order to solve this problem, the performance parameters must be analyzed quantificationally. Siemens and FANUC provide these tools in their products. But as a appropriative system, their price is very high, so it is not applied for LT-CNC. Virtual Instrument's core is that an instrument is software, which means the software can do everything that the hardware instrument does. Based on this method, this paper designs and implements a performance evaluation system to tune the control parameters and analyze the CNC performance. And the open structures of CNC makes it to be true.In order to supply a means to evaluate the CNC's performance, this paper designs and implements an on-line parameters co-tuning system for CNC based on virtual instruments. It adopts time domain analysis and frequency domain analysis to get the performance index of CNC. At the same time, users can change these indexes through GUI and control CNC to run.This paper also proposes a parameters tuning arithmetic. It can tune the parameters of speed loop by Z-N method which can tune parameters rapidly. In order to get the optimal parameters, a fuzzy PID controller is used in this arithmetic. The controller learns the optimal parameters during a test programme running. At last, the optimal parameters are written in configuration files and work at next start-up. The testing on NC200 indicates that the performance evaluation system for CNC could co-modulate the parameters rapidly and accurately. It also has the ability of computing performance index of CNC. At the same time, the user can adjust the CNC by this virtual performance evaluating system.