Single-Track Absolute Angle Coding With Simpler Decoding
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Solution Overview
Problem
Existing angle measuring devices face challenges in achieving high resolution with serial coding, as they require a large number of code words and decoding tables, leading to complex decoding processes and limited absolute positions that can be coded over 360°, and parallel arrangements suffer from moiré sensitivity and limited codable positions.
Innovation Solution
The use of multiple code sequences with different lengths arranged alternately in a common track, where one code sequence is repeated more times than the other, allowing for the generation of a large number of positions over 360° with simplified decoding by utilizing two sets of values in a decoding device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single code track with pseudo-random distributed code elements is used to achieve space-saving coding, then the space efficiency is improved, but the decoding complexity increases significantly due to the large number of code words that must be generated and decoded to achieve high resolution
Solution Approach 1:
The patent divides the single code track into multiple code sequences (first code sequence and second code sequence) with different lengths. Each code sequence is arranged a different number of times over 360°, creating distinct code words that are easier to decode. This segmentation reduces the decoding complexity while maintaining space efficiency by keeping all sequences within a single track structure.
Solution Approach 2:
The patent introduces a new dimension of differentiation by arranging code sequences with different lengths (LA and LB) and different repetition counts (NA and NB) within the same track. This dimensional variation in code sequence parameters enables the system to generate sufficient code words for high resolution without requiring an excessively large decoding table, thus reducing decoding complexity while maintaining compact space utilization.
2Device complexity
If multiple code sequences are arranged in parallel tracks to reduce decoding effort, then the decoding complexity is reduced, but moiré sensitivity increases and the number of absolute positions that can be coded over 360° is limited
Solution Approach 1:
The patent merges multiple code sequences into a single common track rather than using parallel tracks. The first code sequence and second code sequence are interleaved within the same track, with code elements from different sequences alternating in the radial direction. This merging eliminates the moiré sensitivity problem associated with parallel track arrangements while still maintaining the benefit of reduced decoding complexity through the use of multiple sequences with different parameters.
3Quantity of substance
If code sequences with different lengths and repetition counts are arranged alternately in a common track, then the number of codable positions over 360° is increased and decoding complexity is reduced, but the arrangement complexity of the code elements increases
Solution Approach 1:
The patent applies local quality by assigning different properties to different regions of the code track. The first code sequence and second code sequence have different lengths and repetition counts, creating locally distinct code patterns. This local differentiation enables the system to encode more positions over 360° while maintaining a systematic arrangement that doesn't excessively increase overall complexity, as each local region follows its own consistent pattern.
Data Source
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AI summary
An absolute angle code (1) is designed as a single-track code. A part of a first code sequence (A) and a part of a second code sequence (B) are arranged in said track in an alternating manner. The code sequences (A, B) have different lengths, the lengths of both code sequences (A, B) preferably differing by 1. In order to determine an unambiguous absolute position (POS) during a rotation of the angle code (1), a decoding device (3) is provided which has its proper table (TA, TB) for each of the two code sequences (A, B) for decoding. The absolute position (POS) is determined from the obtained partial positions (xA, xB).