CMM Error Compensation via Integral Sensor-Packages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Coordinate measuring machines (CMMs) face errors due to lack of straightness and orthogonality in movement axes, angular rotations, and dynamic deflections, which are challenging to correct, especially at high speeds, leading to inaccurate measurements and reduced productivity.
Innovation Solution
The implementation of a modular pre-calibrated integral sensor-package with multiple displacement sensors that measure translational and rotational displacements, allowing for precise determination and correction of space coordinates, independent of carriage weaknesses, and capable of compensating for dynamic and static errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If measurements are taken at high accelerations to increase productivity, then throughput and inspection speed are improved, but dynamic deflections of the coordinate measuring machine cause measurement errors
Solution Approach 1:
Accelerometers mounted on the probe head provide real-time feedback on the acceleration and dynamic conditions during measurement. This feedback is used to calculate compensation values that correct the measured coordinates, allowing high-speed measurements while maintaining accuracy through active error compensation rather than passive restriction of measurement speed
Solution Approach 2:
The patent replaces reliance on mechanical stiffness and low-speed operation with an electronic/computational compensation system. Instead of mechanically minimizing dynamic deflections by operating slowly, the system uses accelerometers and computer calculations to measure and correct dynamic errors, enabling high-speed operation without sacrificing precision
2Measurement precision
If calibration is performed to correct repeatable errors, then measurement accuracy is improved for stable conditions, but recalibration is required when operating conditions change such as running speed
Solution Approach 1:
The patent transitions from static calibration (fixed reference measurements) to dynamic compensation (real-time error correction during operation). Accelerometers continuously measure dynamic conditions during measurement, and compensation values are calculated and applied in real-time, allowing the system to adapt to changing speeds and conditions without requiring recalibration
Solution Approach 2:
The system changes the parameter being measured from static position only to position plus dynamic acceleration effects. By incorporating accelerometer data into the measurement model, the system accounts for dynamic parameter changes during operation, eliminating the need to recalibrate when speed parameters change
3Measurement precision
If structural stiffness is increased to reduce dynamic deflections, then measurement accuracy at high speed is improved, but machine complexity and cost increase
Solution Approach 1:
The patent introduces accelerometers as intermediary sensors that measure dynamic conditions and enable computational compensation. Rather than directly increasing structural stiffness to reduce deflections, the system uses these intermediary devices to detect and correct dynamic errors, achieving the same goal through measurement and correction rather than structural reinforcement
Solution Approach 2:
The patent substitutes mechanical stiffness enhancement with an electronic compensation system. Instead of making the structure mechanically stiffer and more complex, the system uses accelerometers and computer algorithms to compensate for dynamic deflections, achieving improved accuracy through software-based correction rather than hardware-based structural changes
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention relates to a coordinate measuring machine (1) comprising a stationary base (3), a probe head (6), at least one linear drive mechanism (2X,2Y,2Z) for moving in a first direction, the linear drive mechanism (2X,2Y,2Z) having a linear guide (4X.4Y) and a movable member (5X.5Y) being supported for movement along the guide by bearings [71X, 72X, 73X, 74X,71Y, 72Y, 73Y, 74Y). The linear drive mechanism (2X,2Y,2Z) further comprises at least a first pre-calibrated integral sensor-package (101X,102X, 101Y,102Y) having at least two displacement sensors (91X,92X, 93X, 94X, 95X, 91Y, 92Y, 93Y, 94Y, 95Y) each for measuring a distance from the movable member (5X,5Y) to the guide (4X,4Y) in a direction being non-parallel with respect to the first direction (X, Y, Z), wherein the sensed distances indicate a translational displacement of the movable member (5X,5Y) from an ordinary bearing position in a direction perpendicular to the first direction (X. Y. Z) and a rotational displacement of the movable member (5X,5Y).