Coordinate Measuring Machine With Decoupled Imaging Detectors
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Solution Overview
Problem
Conventional coordinate measuring machines face accuracy issues due to mechanical imperfections, vibrations, and temperature drifts, which impact measurement precision and require complex calibration and high-quality, expensive mechanics to compensate.
Innovation Solution
A coordinate measuring machine with a Delta robot structure and multiple imaging detectors mounted on a stationary metrology table, allowing for precise position determination of the end-effector in six degrees of freedom, including mechanical decoupling and synchronized image acquisition to minimize the impact of mechanical instabilities and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frame structure is made of stone or stiff materials to achieve high static stiffness and measurement precision, then measurement precision is improved, but the machine and movable frame elements become quite heavy
Solution Approach 1:
The patent replaces the traditional mechanical frame structure made of stone or stiff materials with a parallel kinematic mechanism (PKM) consisting of lightweight robotic arms. The mechanical stability and measurement precision are achieved not through heavy materials but through the geometric configuration and control system of the parallel mechanism, which compensates for mechanical imperfections via software-based error correction
Solution Approach 2:
The patent changes the fundamental parameters of the measurement system by transitioning from a rigid mechanical structure to a controlled dynamic system. The measurement precision is maintained through real-time calibration and error compensation algorithms that adjust for variations in the lightweight structure's position and orientation, rather than relying on the inherent stiffness of heavy materials
2Productivity
If the machine components are built with less weight to achieve faster positioning and reduce forces, then productivity is improved, but machine vibrations and torsions increase due to reduced stiffness
Solution Approach 1:
The patent substitutes the mechanical stability provided by heavy materials with a controlled dynamic system using parallel kinematic mechanisms. The lightweight robotic arms enable fast positioning and high productivity, while the stability is maintained through real-time error compensation and calibration that corrects for vibrations and torsions through software rather than relying on mechanical rigidity
Solution Approach 2:
The patent implements continuous feedback through calibration procedures and error compensation algorithms that monitor and correct for mechanical imperfections, vibrations, and torsions in real-time. This feedback mechanism allows the lightweight structure to maintain measurement accuracy despite dynamic movements and environmental variations
3Measurement precision
If conventional calibration procedures are used to compensate for mechanical imperfections, then measurement precision is maintained, but the calibration process is complex and time-consuming
Solution Approach 1:
The patent replaces complex mechanical calibration procedures with a simplified software-based error compensation system. The parallel kinematic mechanism's geometric model is used to calculate and correct for mechanical imperfections through computational algorithms, eliminating the need for complex physical calibration fixtures and procedures
Solution Approach 2:
The patent enables the measurement system to self-correct for mechanical imperfections through automated error compensation algorithms. The system uses its own geometric model and sensor data to identify and correct calibration errors without requiring external calibration equipment or complex manual procedures, making the calibration process simpler and more self-contained
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate and efficient measurement by directly accounting for geometrical imperfections and thermal expansions, reducing the importance of mechanical stability and allowing for faster measurement times with improved precision and reduced calibration needs.
Implementation Method 1
an analysing unit for processing electronic signals and/or data delivered by the imaging detectors... determining a position of the end-effector in six degrees of freedom by receiving image data representing an image covering at least a part of the end-effector, determining image-positions of reference points related to the end-effector in the image by image processing
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~5b
AI summary
The present invention relates to a coordinate measuring machine CMM (22), comprising a carrier (12, 30, 31) as a support and positioning structure for an end-effector (40) as a target, the end-effector (40) being movable in at least three degrees of freedom and positionable by the carrier (12, 30, 31), a stationary metrology table (35) as a support for a possible target object, and a control unit controlling the moving of the end-effector (40) by the carrier (12, 30, 31). The CMM further comprises at least one, in particular at least two, imaging detectors (33) for measuring and determining in six degrees of freedom a position of the possible target object, and an analysing unit for processing electronic signals and/or data delivered by the imaging detectors (33). According to the invention, the imaging detectors (33) are firmly mounted to the metrology table (35), mechanically de-coupled from the carrier (12, 30, 31).