Speed Panning Of CNC And Research On NURBS Curve Fitting

With the development of automatic control,electric electronic and mechanical manufacturing,great changes have taken place in the field of CNC.The traditional numerical control system that takes the straight line and circular arc as its main function has been difficult to meet the higher and higher processing requirements of the current industry.In order to adapt to the requirements of modern numerical control technology,It is a high time to study new curve interpolation techniques to improve the efficiency and machining accuracy in CNC systems.Non-Uniform Rational B-Spline(NURBS)has been better applied in the CAD/CAM field because of its mathematical characteristics.Therefore,NURBS has become an inevitable choice to study free-form curve and surface interpolation.Firstly,this paper studies the mathematical principles and properties of NURBS and introduces a simplified calculation algorithm for basic functions in programming.The latter can effectively reduce the amount of calculation of basic functions in program design.Secondly,the common acceleration and deceleration control algorithms in the numerical control system are studied.Acceleration and deceleration control rules affect the accuracy and stability of CNC machine tools.After in-depth study of the most commonly used S-type acceleration and deceleration rules,it is pointed out that the S-type acceleration and deceleration algorithm is prone to overspeeding at the extreme points of curvature.Then an adaptive S-type acceleration and deceleration planning algorithm based on curvature constraint is proposed.Thirdly,this paper proposes a node optimization combination strategy based on genetic algorithm.For the data points to be fitted,a NURBS curve fitting optimization mathematical model is established under various constraints.It will get the optimal node vector combination by continuous iteration through genetic algorithm.Finally,this paper will use curve fitting and speed planning simulation in Matlab.Simulation results show that using this strategy has a very high approximation accuracy in curve fitting.Then,it is verified that the improved S-type acceleration and deceleration planning algorithm is smoother than the traditional S-type algorithm.Especially at the extreme point of curvature,there is a more stable speed,which has important significance for improving the accuracy of interpolation.