Surface Absolute Encoding with Nested Code Lines
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Solution Overview
Problem
Existing position determination methods, particularly in industrial applications, are imprecise and error-prone, especially when trying to determine absolute positions in two or more degrees of freedom using incremental sensors, which often require large code areas and complex decoding processes.
Innovation Solution
A surface position code pattern with a matrix sensor that uses overlapping absolute code sequences with different primary period lengths, allowing for precise determination of positions and orientations in two or more degrees of freedom using a smaller sensor area, and an associated method for evaluating the code marks based on their centers of gravity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If incremental position determination methods are used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The code pattern is segmented into multiple code lines with different primary period lengths (first code line with period L1, second code line with period L2). Each code line provides partial position information, and the combination of these segmented codes enables absolute position determination without requiring complex incremental counting mechanisms, thus resolving the contradiction between device simplicity and measurement precision.
Solution Approach 2:
The invention transitions from one-dimensional incremental encoding to two-dimensional absolute encoding by introducing multiple code lines with different spatial periods arranged in a grid pattern. This dimensional expansion allows the system to determine absolute position directly through pattern recognition rather than relative counting, achieving high precision while maintaining system simplicity.
2Measurement precision
If large code areas are used to encode positions in two or more degrees of freedom, then measurement range is improved, but area of moving object increases
Solution Approach 1:
The code pattern employs a nested structure where code marks are arranged in a basic grid pattern, and multiple code lines with different primary periods are superimposed on the same spatial area. This nesting allows multiple degrees of freedom to be encoded within a compact region, enabling absolute position determination in two or more dimensions without proportionally increasing the required sensor area.
Solution Approach 2:
By introducing multiple code lines with different spatial periods arranged in a two-dimensional grid, the system encodes multiple degrees of freedom within a compact area. The different primary periods (L1, L2, L3, L4) allow simultaneous determination of position in multiple directions without requiring a large linear code area, thus resolving the contradiction between measurement range and sensor size.
3Measurement precision
If complex decoding processes are used to determine absolute position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The code pattern is pre-configured with multiple code lines having different primary periods and specific phase relationships during the encoding stage. This preliminary structuring of the code allows the decoding process to simply recognize the pre-defined patterns and calculate position through straightforward correlation or pattern matching, rather than requiring complex real-time decoding algorithms, thus achieving high precision with minimal decoding complexity.
Data Source
Figure 1a~1g
Figure 2~3
Figure 4a~5d
AI summary
The invention relates to an area position code pattern for an area to be absolutely coded, comprising an arrangement of code markers in a basic grid. At least a portion of this position code pattern can be read by a matrix sensor for position determination. According to the invention, the position code pattern is formed as the first row on the area to be coded, comprising a first absolute code sequence in a sequence of code markers in a first row direction of the basic grid. Along a second row following the first row in the same row direction, the code markers are encoded with a second absolute code sequence. The first and second rows form a row pair, and in a subsequent row pair, the two absolute code sequences are arranged offset in the first direction within the basic grid.The invention also includes the associated methods, an associated area sensor for evaluating the position code pattern, and a position transmitter with these.