3D Probe Controller Contact Point Feedback for Measurement Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional 3D shape measuring apparatuses fail to accurately measure the shape of objects by securely contacting the gauge head on the intended point due to incorrect generation of speed vectors related to the height direction, leading to measurement inaccuracies, especially when the object's surface is inclined or not aligned with the Z-axis.
Innovation Solution
A shape measuring apparatus with a probe, motion mechanism, and controller that includes a contact point obtainer to determine the precise location of the contact point on the object's surface and a motion commander to calculate location commands for the motion mechanism, ensuring the gauge head is securely positioned on the object, using equations to generate speed vectors that account for the object's geometry and gauge head's central location, radius, and normal direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the speed vector VH related to the height direction is generated based on the difference between Zh (target value) and Ch (central location of gauge head), then the gauge head can be moved along the surface of the measured object, but the contact point location does not exist on the constraint plane S, leading to measurement inaccuracies
Solution Approach 1:
The invention introduces a feedback mechanism where the actual contact point location is detected and fed back to the controller. The controller then adjusts the speed vector VH based on the difference between the target height Zh and the actual contact point height, ensuring the gauge head accurately reaches the intended contact point on the constraint plane S.
Solution Approach 2:
The invention replaces the purely mechanical movement system with a controlled system that uses computational geometry. Instead of relying solely on mechanical positioning, the system uses vector calculations and coordinate transformations to determine the precise contact point location and adjust the movement accordingly, substituting mechanical precision with computational control.
2Productivity
If the gauge head is moved along the surface of the measured object using conventional speed vectors, then the measurement process can be completed, but post-measurement corrections are needed, increasing the overall measurement time
Solution Approach 1:
The invention performs preliminary calculations of the contact point location and adjusts the speed vector VH in advance before the actual measurement takes place. By pre-calculating the correct contact point coordinates and preparing the appropriate speed vectors, the system eliminates the need for post-measurement corrections, thereby reducing the overall measurement time while maintaining accuracy.
3Measurement precision
If the gauge head is pressed against the measured object to measure the shape, then the measurement can be performed, but the gauge head may not securely contact the intended point on inclined or misaligned surfaces
Solution Approach 1:
The invention makes the contact point location dynamic rather than fixed. The controller continuously adjusts the speed vector VH based on the actual contact point location detected during the measurement process. This dynamic adjustment allows the gauge head to adapt to inclined or misaligned surfaces and securely contact the intended point, improving both precision and operational ease.
Data Source
AI summary
A 3D measuring apparatus includes a probe that has a spherical gauge head for measuring a measured object; a motion mechanism that holds and moves the probe; and a motion controller that controls the motion mechanism. The controller includes a contact point obtainer that obtains a contact point location of a surface of the measured object and the gauge head based on a central location of the gauge head; a radius of the gauge head; and a swing amount of the gauge head. The controller also includes a motion commander that calculates a location command value causing the motion mechanism to move the probe, based on the contact point location obtained by the contact point obtainer.