Adaptive Position Measuring Device for Misalignment Resilience
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Solution Overview
Problem
Absolute position measuring devices with pseudo-random code tracks face reliability issues due to the dependency on precise alignment of the light source, code track, and detector elements, leading to undefined states and incorrect position values when misalignment occurs.
Innovation Solution
A position measuring device with a scanning unit that includes an illumination unit, a detector unit, and an evaluation unit, where the detector signals are selected based on the mapping of code elements onto the detector unit, using Manchester coding and incremental tracks to enhance reliability and operational safety by optimizing the selection of detector pairs for accurate position determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical scanning with fixed detector array is used, then position measurement can be performed, but reliability deteriorates due to misalignment between light source, code track, and detector elements
Solution Approach 1:
The patent applies dynamics by making the detector element selection adaptive rather than fixed. The evaluation unit dynamically selects which detector elements to use based on real-time assessment of signal quality and mapping accuracy, allowing the system to adapt to misalignment conditions and maintain reliable measurements despite geometric deviations.
Solution Approach 2:
The system changes the parameter of detector element selection based on mapping quality assessment. By evaluating the actual mapping of code elements to detector elements and selecting only those with adequate signal quality, the system adjusts its operational parameters to compensate for misalignment and maintain measurement accuracy.
2Measurement precision
If multiple detector elements are used per code element, then measurement resolution is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the detector array into multiple detector elements that can be independently evaluated and selected. Each code element is mapped to multiple detector elements, and the evaluation unit selectively uses only those detector elements that provide adequate signal quality, effectively segmenting the detector array into functional and non-functional portions based on real-time conditions.
3Adaptability or versatility
If fixed detector element selection is used, then device complexity is reduced, but adaptability to misalignment conditions deteriorates
Solution Approach 1:
The patent implements feedback by having the evaluation unit assess the mapping quality between code elements and detector elements in real-time, then use this feedback information to selectively determine which detector elements to use for position measurement. This closed-loop approach allows the system to adapt to misalignment conditions while maintaining a relatively simple hardware configuration.
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
The solution improves the reliability and accuracy of position measurement by adaptively selecting detector signals, reducing the impact of misalignment and enhancing the resolution of the position-measuring device through advanced signal processing and interpolation techniques.
Implementation Method 1
a measuring scale, which is applied to a scale, is imaged onto a number of photodetectors with directed light emitted by a light source
Implementation Method 2
The scale is movably arranged in the beam path of the light and modulates the light when the measuring graduation is moved relative to the light source and the photodetectors
Implementation Method 3
a number of photodetectors with directed light emitted by a light source
Data Source
Figure 1a
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Figure 2
AI summary
A position measuring device is proposed, comprising a code (10) and a scanning unit (20). The code (10) consists of a sequence of code elements (C, CL, CR, CM) arranged one after the other in a measuring direction (X), wherein at least two consecutive code elements (C, CL, CR, CM) each form a codeword (CW) containing position information. The scanning unit (20) comprises an illumination unit (30) for emitting directed light in the direction of the code (10) to map at least the codeword (CW) forming code elements (C, CL, CR, CM) onto a detector unit (40), wherein the detector unit (40) has at least two detector elements (D, DL, DR, DM) in the measuring direction (X) for each codeword (CW) forming code element (C, CL, CR, CM), and an evaluation unit (50) in which the codeword (CW) with the current position information can be determined from the detector signals (S) of the detector elements (D; DL1-DL6; DR1-DR6; DM1-DM6).The scanning unit (20) and the code (10) are arranged to be movable relative to each other in the measuring direction (X). The invention is characterized in that the detector signals (S) to be evaluated for the formation of the codeword (CW) can be selected in the evaluation unit (50) depending on the mapping of the code elements (C, CL, CR, CM) forming the codeword (CW) onto the detector unit (40).