Indexed Articulated Joint Verification for Repeatable Metrology Locking
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Solution Overview
Problem
Existing articulated heads in coordinate measuring machines lack a reliable mechanism to verify the proper locking and repeatability of indexed positions, leading to potential misalignment and inaccuracies in measurement operations.
Innovation Solution
An indexed articulated joint with a verification sensor that measures and compares the relative spatial configuration of engaged bodies to calibration information, ensuring proper locking and repeatability by reacting to misalignments and providing error feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an indexed articulated joint with engagement elements is used to provide multiple angular positions, then the versatility and positioning capability are improved, but the reliability of locking and repeatability deteriorates without verification
Solution Approach 1:
The patent implements a verification sensor that measures the relative spatial configuration of the first and second bodies when locked, and compares this measurement to calibration information stored in memory. This feedback mechanism detects whether the bodies are properly locked at the intended indexed position, and can trigger corrective actions such as unlocking and relocking the joint to achieve proper engagement, thereby ensuring reliable and repeatable positioning
Solution Approach 2:
The patent replaces purely mechanical locking verification with an optical/electronic measurement system. Instead of relying solely on mechanical engagement elements, the system uses verification sensors (such as optical encoders or capacitive sensors) to detect the spatial configuration and verify proper locking, substituting mechanical sensing with more precise electronic measurement and comparison against stored calibration data
2Reliability
If verification sensors and calibration mechanisms are added to ensure proper locking, then the reliability and measurement precision are improved, but the device complexity increases
Solution Approach 1:
The patent integrates the verification sensor into the existing articulated joint structure, allowing the same sensor system to serve multiple functions: measuring the relative spatial configuration for verification purposes, providing feedback for corrective actions, and potentially serving as part of the overall measurement system. The calibration information is stored in memory and can be reused across multiple indexing operations, making the verification system efficient and reducing the need for separate dedicated verification mechanisms
3Measurement precision
If the apparatus reacts to misalignment by unlocking and relocking, then the measurement precision is improved, but the time required for positioning increases
Solution Approach 1:
The patent implements a verification and correction mechanism that may occasionally require unlocking and relocking the articulated joint to achieve proper alignment. While this corrective action increases positioning time in some cases, it ensures high measurement precision by verifying proper locking at each indexed position. The system uses verification sensors to detect misalignment and triggers corrective actions only when necessary, balancing the trade-off between precision and time efficiency
Data Source
AI summary
A metrology apparatus includes an indexed articulated joint including: first and second relatively reorientable bodies, respectively having mutually engageable engagement elements, which can be locked together in different angular orientations about a first axis to provide a plurality of angularly indexed positions of the bodies; at least one verification sensor configured to provide a measure of the relative spatial configuration of bodies when in their locked state; and wherein the apparatus is configured such that when the bodies lock together at an indexed position, the sensor measures the relative spatial configuration of the bodies, and wherein information obtained from the measure is compared to calibration information obtained from at least one other measure of the relative spatial configuration of the bodies when the bodies were locked at said indexed position at an earlier point in time, in order to establish information about the state of engagement of the bodies.