Coordinate Measuring Machine Dual Inclination Sensor Self-Calibration
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Solution Overview
Problem
Existing coordinate measuring machines, such as laser trackers, face inaccuracies and reliability issues in determining the inclination of the beam steering unit, especially during high-precision measurements, due to limitations in inclination sensing, particularly when slight deviations occur between the stationary base and rotatable support.
Innovation Solution
The implementation of two inclination sensors, one in the stationary base and another in the rotatable support, allows for precise and reliable determination of inclination in multiple directions, enabling continuous monitoring and self-calibration of the measurement system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single inclination sensor is used in the beam guidance unit, then the device complexity is reduced, but the measurement precision and reliability of inclination determination deteriorates due to inability to detect deviations between base and support
Solution Approach 1:
The inclination sensing function is segmented into two separate sensors: one mounted on the stationary base and another on the rotatable support. This segmentation allows each sensor to independently measure inclination from its respective reference frame, enabling detection of relative deviations between base and support while maintaining manageable system complexity.
Solution Approach 2:
The control unit acts as an intermediary that receives inclination data from both sensors, processes the information to determine relative positioning deviations, and generates correction signals. This intermediary processing layer resolves the contradiction by intelligently combining data from multiple sensors to achieve high measurement precision without proportionally increasing overall system complexity.
2Reliability
If two inclination sensors are implemented (one in base, one in support), then the reliability of inclination detection is improved, but the device complexity increases
Solution Approach 1:
The system implements feedback by continuously monitoring inclination from both sensors and using the control unit to compare measurements. When deviations between base and support are detected, the system generates corrective signals to realign the beam guidance unit, thereby maintaining measurement reliability despite the increased sensor configuration complexity.
Solution Approach 2:
The dual-sensor configuration enables self-service functionality where the system automatically detects and corrects its own alignment deviations. The control unit processes data from both sensors and autonomously generates correction signals, allowing the system to self-monitor and self-calibrate without external intervention, thus improving reliability while managing complexity through automation.
3Measurement precision
If inclination deviations between base and support are not monitored, then the device complexity is reduced, but the measurement precision deteriorates during rotations
Solution Approach 1:
The system replaces complex mechanical alignment mechanisms with an electronic monitoring and correction system. Two inclination sensors and a control unit electronically detect and correct alignment deviations, substituting what would otherwise require complex mechanical adjustment mechanisms during rotations, thereby maintaining measurement precision while managing overall system complexity through electronic control.
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 configuration enhances the accuracy and reliability of measurement results by providing more accurate inclination data, allowing for real-time self-monitoring and self-calibration, thereby reducing errors and maintaining measurement precision even during rotations.
Implementation Method 1
a first tilt sensor is provided at the base, and a second tilt sensor is provided at the support, wherein the first tilt sensor and the second tilt sensor are each configured to detect an inclination in at least two substantially orthogonal directions with respect to the direction of gravity
Implementation Method 2
at least one distance meter for measuring the distance to the measuring aid by means of a measuring beam
Implementation Method 3
which is targeted by an optical measuring beam from the measuring device, in particular a laser beam. The laser beam is reflected parallel back to the measuring device, and the reflected beam is detected by a detection unit of the device
Implementation Method 4
The direction of beam reception is determined, for example, by means of angle sensors assigned to a deflection mirror or a targeting unit of the system
Implementation Method 5
The interferometers used for distance measurement in this context primarily employ HeNe gas lasers as light sources due to their long coherence length and the resulting measurement range. The coherence length of the HeNe laser can reach several hundred meters
Implementation Method 6
Since such distance measuring units can only measure relative distance changes, modern laser trackers incorporate so-called absolute distance sensors in addition to interferometers
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
Coordinate measuring machine (1), with laser tracker, comprising at least one support (20) rotatably mounted on a base (40) about a first axis of rotation (9), wherein a first inclination sensor (49) is provided on the base (40), characterized by a second inclination sensor (29) on the support (20), wherein the first inclination sensor (49) and the second inclination sensor (29) are each configured to detect an inclination in at least two substantially orthogonal directions with respect to the direction of gravity, and to output inclination data, and an evaluation and control unit (27) configured for the purpose of self-monitoring and/or self-calibration of the coordinate measuring machine (1) for acquiring and evaluating the inclination data of the two inclination sensors (29, 49).