Numerical Controller Interference Check with Feedrate Override
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Solution Overview
Problem
Existing numerical controllers fail to safely stop movable parts when feedrate variations occur, leading to potential collisions due to incomplete interference checks before feedrate changes are accounted for.
Innovation Solution
A numerical controller that performs interference checks based on surplus look-ahead positions calculated considering feedrate variations, incorporating a feedrate override changing unit to limit override value changes and ensure safe stopping, even when feedrates change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the look-ahead period is set to TP1+TP2+TP3+α to ensure safe stopping, then the interference check reliability is improved, but when feedrate override changes occur, the current position may surpass the look-ahead position before interference check completion, causing the movable part to cannot be stopped safely
Solution Approach 1:
The patent performs interference checks at multiple surplus look-ahead positions (first, second, and third positions) before the feedrate override takes effect. By checking interference at these preliminary positions corresponding to different feedrates, the system ensures that interference is detected even when feedrate changes occur during the look-ahead period, allowing safe stopping to be achieved regardless of feedrate variations.
2Productivity
If interference check is performed based on current feedrate, then the check speed is maintained, but when feedrate override is changed, the interference check cannot account for the new feedrate, leading to potential collisions
Solution Approach 1:
The patent performs interference checks at multiple surplus look-ahead positions beyond the single standard look-ahead position. By checking at the first surplus look-ahead position (corresponding to current feedrate), second surplus look-ahead position (corresponding to overridden feedrate), and third surplus look-ahead position (intermediate feedrate), the system conducts excessive checks to ensure that interference is detected under all possible feedrate conditions, not just the current one.
3Ease of operation
If the look-ahead position is recalculated after feedrate change, then the check reflects current conditions, but the interference may have already occurred when the check is completed
Solution Approach 1:
The patent performs interference checks at multiple surplus look-ahead positions before the feedrate override takes effect. By checking interference at these preliminary positions corresponding to different feedrates, the system ensures that interference is detected even when feedrate changes occur during the look-ahead period, allowing safe stopping to be achieved regardless of feedrate variations.
Data Source
AI summary
An object of the present invention is to provide a numerical controller that performs interference check based on a look-ahead position before a feedrate varies by taking the variation in the feedrate into consideration and controls the change of an override safely. To achieve this object, the numerical controller is configured such that, when calculating a coordinate value of a look-ahead position which a movable part subjected to interference check reaches after a look-ahead period elapses from a current position at a current time, the numerical controller calculates the look-ahead position assuming that the movable part moves at a predetermined feedrate of which the upper limit is the maximum feedrate.