NURBS Velocity Planning for CNC Interpolation
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Solution Overview
Problem
Existing numerical control machining systems using NURBS curve interpolation struggle with excessive acceleration during deceleration phases, leading to computational intensity and limited real-time interpolation capabilities due to unpredictable velocity changes and inability to control interpolation points effectively.
Innovation Solution
A method and device for planning curve velocity based on NURBS curve interpolation, which predicts acceleration sensitive points and adjusts acceleration and deceleration phases to prevent excessive acceleration, using curvature calculations and maximum allowable velocity constraints to ensure interpolation points are calculated efficiently and accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backtracking method is used to prevent excessive acceleration during deceleration phase, then acceleration limitation is satisfied, but computational complexity increases and real-time interpolation capability is limited
Solution Approach 1:
The patent applies preliminary action by calculating and marking acceleration sensitive points and intervals before interpolation execution. The velocity planning algorithm pre-identifies where acceleration constraints will be violated and prepares correction strategies in advance, avoiding the need for computationally intensive backtracking during real-time operation. This allows the system to satisfy acceleration limitations while maintaining real-time interpolation capability.
2Reliability
If bidirectional acceleration method is used to prevent excessive acceleration, then acceleration limitation is satisfied, but interpolation control becomes complex and real-time performance deteriorates
Solution Approach 1:
The patent segments the NURBS curve into acceleration sensitive intervals based on curvature analysis. By dividing the curve into segments where acceleration constraints are likely to be violated and handling these segments separately with targeted velocity planning, the system satisfies acceleration limitations without requiring complex bidirectional acceleration control across the entire curve, thus maintaining real-time interpolation performance.
3Reliability
If multiple backtracking calculations are performed to obtain velocity curve meeting acceleration requirements, then acceleration limitation is satisfied, but calculation time increases significantly
Solution Approach 1:
The velocity planning algorithm performs preliminary calculations to identify acceleration sensitive points and intervals before generating the final velocity curve. By pre-marking these critical regions and preparing appropriate velocity adjustments in advance, the system avoids multiple iterative backtracking calculations, significantly reducing calculation time while still ensuring acceleration requirements are met.
Data Source
AI summary
A method and a device for curve velocity planning based on NURBS (non-uniform rational B-splines) curve interpolation as well as a numerical control machining route data processing method using NURBS curve interpolation velocity planning are provided. The method includes: obtaining numerical control machining route data with a NURBS curve; obtaining an acceleration within a parameter step length on the NURBS curve; comparing each the acceleration with a maximum allowable acceleration to determine an acceleration sensitive point and an acceleration sensitive interval; determining an intermediate point of the acceleration sensitive interval as a demarcation point of the acceleration and the deceleration; calculating a velocity value of the intermediate point as a target velocity; and planning the 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.