CMM Probe Scan Path Planning for Faster Precision Measurement

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Solution Overview

Problem

Coordinate measuring machines (CMMs) face inefficiencies when measuring objects with complex geometries, requiring excessively long measurement times due to the need for slow, on-the-fly path generation, often taking three to five times longer than the object's manufacturing time.

Innovation Solution

A method and apparatus that utilize a CMM to conduct an initial set-up measurement based on nominal geometry data to generate a more accurate scan path, allowing the probe to move rapidly along this path during a subsequent fine measurement, potentially including multiple revolutions and varying measurement resolutions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the CMM probe moves slowly along the object to ensure accurate measurements, then measurement precision is improved, but measurement time increases significantly

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs a preliminary setup measurement to generate a scan path before conducting the actual fine measurement. This preliminary action creates a roadmap that enables faster subsequent measurements while maintaining accuracy, as the probe follows the pre-planned path rather than generating it in real-time during measurement.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The measurement process is divided into two distinct phases: a setup measurement phase that generates the scan path, and a fine measurement phase that follows the generated path. This segmentation allows each phase to be optimized independently - the setup phase focuses on path generation while the fine measurement phase focuses on high-precision data collection along the predetermined trajectory.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If the CMM probe traverses slowly about the object to ensure accurate measurements, then measurement precision is improved, but productivity deteriorates

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmanufacturing throughput
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The scan path is generated in advance during a setup measurement phase, allowing the subsequent fine measurement to proceed rapidly along the predetermined path. This preliminary path generation action enables high-speed measurement execution while maintaining precision, thereby improving overall productivity and manufacturing throughput.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts measurement speed based on the measurement phase. During setup measurement, the probe moves at a moderate speed to gather data for path generation. During fine measurement along the generated scan path, the probe can move faster since the path is already optimized, thus increasing productivity without sacrificing measurement accuracy.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If the CMM generates the scan path on-the-fly during measurement, then adaptability is improved, but measurement time increases

Engineering Contradiction:
Improvepath generation flexibilityVSAvoidmeasurement time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The scan path is generated in advance during a dedicated setup measurement phase rather than in real-time during the fine measurement. This preliminary path generation separates the computationally intensive path planning from the actual measurement execution, allowing the fine measurement to proceed rapidly while still benefiting from adaptive path optimization based on the setup data.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3283840B1CMM probe path controller and method
Publication Date: 2023.06.07 HEXAGON METROLOGY INC
  • EP3283840B1 patent drawingFigure 1A
  • EP3283840B1 patent drawingFigure 1B
  • EP3283840B1 patent drawingFigure 2

AI summary

A method and apparatus for measuring an object using a CMM receives nominal geometry data relating to the object, and produces a set-up path based on the received nominal geometry data. The method also conducts a set-up measurement of the object using a CMM probe. The CMM probe conducts the set-up measurement by following the set-up path, and the set-up measurement of the object produces scan path information. The method generates a scan path using the scan path information, and controls the CMM probe to conduct a fine measurement of the object by causing the CMM probe to move along the generated scan path.