Spline Interpolation Algorithm Of Adaptive Feed-rate Based On S Curve In The CNC System

Interpolation technology is the basis how to achieve trajectory control and the key which isurgently needed to improve and perfect for the CNC system. Interpolation algorithm of the CNCsystem will directly affect the performance. Spline interpolation technique is the key which is toachieve high-speed, high-precision for CNC machining. Therefore, the B-spline curveinterpolation algorithm of CNC system is studied in this paper, including the following:In the second Chapter, the article introduces some splines which are used in the numericalsystem, the spline including polynomial curve, parametric cubic spline curves, B-spline curvesand NURBS curves. Focuses on the B-spline curve, I give the construction process andrepresentation of the curve.In the third chapter，the article studies the acceleration and deceleration control method ofnumerical control system, introduce the common methods includes the linear acceleration anddeceleration, the index acceleration and deceleration method, the trigonometric accelerationdeceleration method. Focus on the S-type deceleration method, and presented a planning methodwhich is based on three kinds of constraints (constraints displacement, velocity and accelerationconstraints constraints), and improve the performance of the overall planning method bycompensate the loss of precision when discrete the system. On the basis of generally S-shapedramp model, a mathematical model that the start speed and end speed are not zero will be givenby deriving; this model will be applied in the spline interpolation algorithm to controlacceleration and deceleration of the system.In the fourth chapter will studies the spline interpolation algorithm in the CNC system,introduces some existing spline interpolation algorithm, especially the adaptive feed-rate splineinterpolation algorithm. Combining spline theory and S type acceleration and decelerationcontrol method, an adaptive spline interpolation algorithm based on the S-type acceleration anddeceleration control method was give. The algorithm is based on a given precision, maximumfeed speed and maximum acceleration, and considering the chord error and the normal limitunder acceleration, etc., calculate the limit-speed curve, and according to the limit-speed curveand the model which was given in the last chapter to complete the spline interpolation.Finally, the simulation results shows the feasibility and practicality of the interpolationalgorithm, and the algorithm is applied in the CNC motion platform which is independentlydeveloped, performance is good.