Stylus Tip Retraction Control for Shape Measuring Apparatus
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Solution Overview
Problem
Existing shape measuring apparatuses face inefficiencies and errors during retraction due to offsets between design values and actual work pieces, leading to frequent emergency stops and manual intervention, which decreases measurement efficiency and requires specialized skills.
Innovation Solution
A control method for shape measuring apparatuses that detects contact between the stylus tip and the work piece, calculates an offset amount, and adjusts the retraction length dynamically using an error avoidance retraction length, ensuring safe separation and minimizing contact risks by returning the probe to a final positioning point and adjusting retraction distance based on the stylus tip's diameter and sensor data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed retraction length is used, then the retraction process is simple, but the probe may contact the work piece causing measurement errors
Solution Approach 1:
The retraction length is changed from a fixed value to a dynamically adjustable parameter. The control unit calculates an appropriate retraction length based on the actual offset between the work piece and design data, allowing the retraction distance to adapt to different measurement scenarios and prevent probe contact while maintaining operational simplicity
Solution Approach 2:
The system uses feedback from the offset calculation to adjust the retraction length. By continuously monitoring the position deviation between actual measurement points and design data, the control unit dynamically determines the safe retraction distance, ensuring the probe does not contact the work piece while maintaining measurement accuracy
2Reliability
If the designated retraction length is increased to ensure safety, then probe contact is prevented, but measurement efficiency decreases due to excessive retraction distance
Solution Approach 1:
The retraction length is dynamically optimized based on actual measurement conditions. Instead of using a uniformly large safe distance, the system calculates the minimum necessary retraction length based on the measured offset, ensuring safety while minimizing unnecessary probe movement and maintaining high measurement efficiency
Solution Approach 2:
The retraction length parameter is adjusted based on the offset magnitude. When offsets are small, a shorter retraction length suffices; when offsets are larger, the retraction length is increased accordingly. This parameter adaptation ensures both safety and efficiency without unnecessary conservative over-retraction
3Strength
If emergency stop is used when contact occurs, then probe and work piece are protected, but measurement efficiency decreases due to frequent stops and manual intervention
Solution Approach 1:
The system takes preliminary action by calculating the offset and adjusting the retraction length before contact can occur. By proactively determining the safe retraction distance based on position deviations, the system prevents contact situations entirely, eliminating the need for emergency stops and manual intervention while maintaining equipment protection
Solution Approach 2:
The control unit performs preliminary calculations of the offset between actual and design positions, and pre-determines the appropriate retraction length before the retraction operation begins. This advance preparation ensures safe probe withdrawal without contact, preventing the need for protective emergency stops and maintaining continuous measurement efficiency
Data Source
AI summary
During a retraction where a stylus tip separates from a work piece from a state where the stylus tip and the work piece are in contact, whether there is contact between the stylus tip and the work piece is monitored. When the contact between the stylus tip and the work piece is detected during the retraction, a probe is displaced to a position where the stylus tip does not come in contact with the work piece and a recovery process is executed. When a distance between a point on a surface of the work piece at a retraction start point and a contact point between the stylus tip and the work piece is Lm, and a value defined by (Lm−d) multiplied by a coefficient k (0<k<1) is a proper retraction amount Lr in view of a diameter d of the stylus tip.