| Numerical Control System is the brain of NC machine tools and the core of CNCtechnology. The performance of NC system will directly affect the quality of themachine tools. The NC System was composed by hardware circuit in the early stages.With the rapid development of computer technology and the micro-electronicstechnology, embedded technology has affected all aspects of society as an importantfield of computer application, and is used more and more widely in the numericalcontrol (NC) system.Interpolation precision decides the performance and function of CNC system.Traditional methods are about linear and/or circular interpolation. Though a fewresearches involved in the interpolation of complicated curves, the unified algorithmhas not been gained.NC systems are most based on DOS or Window/NT in the markets. But thereal-time character, stability and machining precision obstruct the development of theNC system. The NC system is facing a new round of reform. In this thesis, the generalinterpolation algorithm of complicated curves based on RTAI/Linux is researched. Itsmain contents include:(1) Firstly the current situation of NC systems was introduced then the NCSystems were compared under different platforms of DOS, Windows and Linux, whichshowed the best choice is the RTAI/Linux operating system.(2) The Real-time modification scheme about Linux is put forward. And the dualcore mechanism about RTAI/Linux is deeply studied. Then the RTAI realizationmechanism and implementation principle are mainly analyzed. Meanwhile thereformed Real-time kernel is configured and tested. The results show that theperformance of real-time meet NC System needs completely.(3) The parallel port is chose as the interface of NC system. Then the driver ofparallel port in Linux is installed and configured. The stepping motor is controlled bypulse mode in Qt Creator which effectively improves the machining accuracy.(4) The difference of interpolation algorithm is given in this thesis, and theprinciple of algorithm is described in detail. The post-quadrant problem is resolved bythe alteration of the parameters in relative coordinate system. The simulation of arc,ellipse, hyperbola and other curves is achieved by the difference interpolationalgorithm. The NC machining path can be obtained by Qpainter function in Qt Creator. Experiment shows that the NC system which based on RTAI/Linux in this paperhas higher stability and openness, and accuracy of the difference interpolationalgorithm is quite high. |
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