Research On Interpolation Algorithm And Acceleration-Deceleration Controller In CNC System

It is important for CNC system to control the precision and speed of interpolatorand Acceleration and deceleration, which decide the character of CNC system. Theresearch to this two aspects is done deeply in this paper. In order to research and develop economic-type CNC system, Minimumdeviation interpolator and feed-control method are studied, which possesses higherprecision and benefit for motor. On the basis of improved original interpolator, onesof line and circle not to go through the initial point are solved, interpolation precisionin special cases is proved, three-dimensional line one is deduced. Analysis is takenstep firstly to prove the precision of three-dimensional line interpolator. The endpoint criterion is discussed in detail so that no-stop caused by error end is solved. It iscombined between Bresenham algorithm in computer graphic area and Minimumdeviation interpolator to establish the bridge between them. The real-timeAcceleration-Deceleration control algorithm to stepper motor is put forward, whichbreaks away form traditional look-up table and uses real-time calculating way. Butthis method has its disadvantage that calculating speed is slower. For this reason,multiform means, for example, decreasing static variables, decreasing parametertransfer, decreasing long jump and simplified multiplication-division operation, areused to deal with its disadvantage in practice and take effective. The fastest feedreaches 2500 mm /min. The engineer may change flexibly highest frequency,acceleration and so on according to loading, without renewing chart.Above all, a complete minimum deviation interpolator and feed-control method isshowed, which meet the need of economic-type CNC system and benefit forindustrializationIn order to improve present level of CNC system, the Nurbs curve,multi-coordinates parameter surface interpolator and adaptive-feed control methodare discussed. In order to improve the precision and rate of interpolator, advancedtrial-amendment method is adopted. S shape Acceleration-Deceleration methodforehand Nurbs interpolator is adopted, taking chord error and jerk into consideration,proposing time-progressive-last and Acce-Dece-symmetry method, which not onlymake good use of higher position in Acce-Dece control of forehand interpolator, butalso solving rationally difficulty in the predetermination Deceleration-point. In which,the accuracy of the calculation of arc is better than the one in CAD/CAM software.This method is a higher position, no impact and adaptive one. It also may become theassistant to the programmer, helping them to select optimizing parameter, forexample, feed, acceleration and jerk as well through the simulation so as to improveprecision and efficiency of machining. Above all, the Nurbs curve interpolator andparametrical surface interpolators are realized, which can support strongly the higheraccuracy and higher speed machining, avoid the disadvantage of transfer curve andsurface into line or circle and will promote the level of Chinese CNC system.