Coordinate Measuring Machine Feedback Control for Deformation Compensation
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Solution Overview
Problem
Coordinate measuring machines face challenges in maintaining precise positioning due to dynamic deformations, which can exceed the measuring range of probes, leading to inaccurate scanning and measurement errors, especially at increased speeds and in lightweight designs.
Innovation Solution
A method that involves measuring and compensating for deformations in real-time during the measurement process using a geometric model, allowing the drive of the coordinate measuring machine's axes to adjust and maintain the target position of the probe, even under dynamic conditions, thereby ensuring precise positioning and avoiding collisions or loss of contact with the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the coordinate measuring machine uses lightweight construction to reduce mass, then the inertia is reduced and scanning speed can be increased, but dynamic deformations increase and exceed the measuring range of probes
Solution Approach 1:
The patent implements a feedback mechanism where sensors continuously monitor the actual position of the probe head and this information is fed back to the control unit. The control unit compares the actual position with the target position and dynamically adjusts the drive commands to compensate for deviations caused by dynamic deformations, enabling high-speed scanning while maintaining positioning precision
Solution Approach 2:
The patent replaces purely mechanical positioning with a hybrid system that combines mechanical drives with active sensor-based compensation. Instead of relying solely on mechanical rigidity to maintain precision at high speeds, the system uses optical or other non-contact sensors to detect position deviations and compensates for them through software control, effectively substituting mechanical precision requirements with sensor-based measurement and control
2Productivity
If the probe is moved at higher speed along a predetermined path, then the scanning efficiency is improved, but the probe may lift off the workpiece surface or exceed the measuring range due to dynamic deformations
Solution Approach 1:
The control unit receives real-time feedback on the actual probe position and workpiece surface position, continuously monitoring whether the probe remains within the valid measuring range. When deviations approach critical thresholds, the system dynamically adjusts scanning parameters or pauses measurement to prevent probe lift-off or excessive deformation, maintaining measurement reliability at high scanning speeds
Solution Approach 2:
The patent implements dynamic adjustment of scanning parameters based on real-time conditions. The system adapts the scanning speed, path, and probe engagement depth according to the measured dynamic deformations and workpiece geometry, allowing high-speed scanning in stable conditions while automatically reducing speed or adjusting parameters when deformation risks exceed measurement reliability thresholds
3Ease of operation
If the probe head position is adjusted to reach target position based on encoder signals, then the positioning is simplified, but dynamic deformations cause the actual position to deviate from the target position
Solution Approach 1:
The system uses encoder signals for basic positioning control (maintaining simplicity) but adds a feedback layer where sensors measure the actual probe head position and feed this information back to the control unit. The control unit calculates the deviation between actual and target positions and applies corrective commands to the drives, preserving ease of operation while achieving high measurement precision through active compensation
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method for controlling a co-ordinate measuring device (1) comprising a plurality of motor-driven axes for positioning a scanner head (50). In said method, the co-ordinate measuring device is moved along at least one axis in order to position the scanner head (50) in relation to a workpiece (3) to be measured, a deformation of the co-ordinate measuring device is measured, a deviation of an actual position from a target position, caused by said deformation, is determined and a drive of the at least one axis of the co-ordinate measuring device is controlled in order to compensate for the deviation. The invention also relates to a co-ordinate measuring device for carrying out said method.