Curve velocity planning method, device, and numerical control machining route data processing method thereof

A velocity control method based on NURBS (non-uniform rational B-splines) curve interpolation, comprising:

• calculating a curvature 1/ρi of everywhere of the NURBS curve and determining a curve of a maximum allowable velocity based on a constraint condition of a chord height error δmax and a constraint condition of a centripetal acceleration amax;
• calculating an acceleration ai within each parameter step length Δui and determining an end point of the parameter step length Δui corresponding to the acceleration ai with a minimum difference from a maximum allowable acceleration as the acceleration sensitive point when the acceleration ai within the parameter step length Δui is greater than the maximum allowable acceleration and the acceleration ai+n within the parameter step length Δui+n is smaller than the maximum allowable acceleration;
• dividing the curve of the maximum allowable velocity into a plurality of segments at a minimum value, determining a corresponding parameter value umid according to an intermediate point of an acceleration sensitive interval of each of the velocity curve segments, and calculating a velocity value of the intermediate point;
• determining whether a parameter u corresponding to an interpolation point has entered the acceleration sensitive interval;
• and
• accelerating from a side point of the acceleration sensitive interval taken as a start point to the intermediate point, and decelerating from the intermediate point to another side point of the acceleration sensitive interval taken as an end point when the parameter u corresponded by the interpolation point is determined to have entered the acceleration sensitive interval, wherein an acceleration of the intermediate point is 0.

A numerical control machine, comprising a numerical control system, a servo motor, and an execution component, the numerical control system is configured to:

• obtain numerical control machining route data with a NURBS (non-uniform rational B-splines) curve;
• obtain an acceleration ai within a parameter step length Δui on the NURBS curve;
• compare the acceleration ai of everywhere of the NURBS curve with a maximum allowable acceleration to determine an acceleration sensitive point and determine an acceleration sensitive interval based on the determined acceleration sensitive point;
• determine an intermediate point of the acceleration sensitive interval as a demarcation point of the acceleration and the deceleration within the sensitive interval;
• calculate a velocity value of the intermediate point as a target velocity;
• plan acceleration and deceleration of the acceleration sensitive interval based on the target velocity to obtain the numerical control machining route data with the planned NURBS curve;
• and
• receive the numerical control machining route data with the planned NURBS curve and control the execution component to perform numerical control machining according to the received numerical control machining route data through the servo motor.