Optical Position Sensor Cylinder with B-adic Marking
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Solution Overview
Problem
Existing position measurement systems for piston rods face challenges such as long reference runs for incremental measurements and complex setup for absolute coding, and existing solutions do not provide reliable and easy-to-read position information.
Innovation Solution
A cylinder with a piston rod featuring a marking that includes code word pairs with different physical lengths, allowing for reliable optical position detection using b-adic representation, where b is 2 or 3, and a separator to facilitate error correction and easy reading of position information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If incremental position detection is used on the piston rod, then position measurement is possible, but a long reference run is required to detect the reference mark as the starting point
Solution Approach 1:
The marking is pre-configured with code word pairs that encode absolute position information in advance. This allows the optical sensor to immediately determine position without requiring a reference run to establish a starting point, thus eliminating the time loss while maintaining measurement precision.
Solution Approach 2:
Instead of using a single reference mark that requires traversal, the invention uses multiple code word pairs distributed along the piston rod. Each code word pair serves as a local reference that contains encoded position information, allowing the sensor to quickly identify position without traversing a long reference run.
2Measurement precision
If absolute position coding is used on the piston rod, then the absolute position can be determined, but the coding complexity and sensor construction complexity increase
Solution Approach 1:
The absolute position coding is segmented into multiple code word pairs, each encoding a portion of the position information. This segmentation simplifies the coding structure compared to a single complex absolute code, and allows the optical sensor to read position information in discrete, manageable units, reducing sensor construction complexity.
Solution Approach 2:
The invention uses b-adic representation (where b >= 2) to encode position information. By changing the encoding parameter from binary to b-adic with b > 2, the number of code elements required to represent a given position range is reduced, thereby simplifying both the marking construction and the sensor reading process while maintaining absolute position determination capability.
3Loss of information
If code elements with different physical lengths are used for b-adic representation, then position information can be encoded, but the reading process becomes more complex without error checking
Solution Approach 1:
The code word pairs are designed with a predetermined total physical length that serves as a feedback mechanism. When the optical sensor reads the marking, it can verify whether the read code word pair matches the expected total length. This feedback allows for error detection and verification of reading completeness, improving reliability while maintaining efficient position information encoding.
Solution Approach 2:
The predetermined total physical length of code word pairs is established in advance to prevent reading errors. By designing the code structure with built-in length constraints, the system proactively prevents incorrect readings before they can cause problems, rather than attempting to correct errors after detection.
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 enables efficient and accurate position measurement by allowing quick identification of reading errors and initiation of new reading processes, providing clear and reliable position information through the use of code word pairs with the same physical length, enhancing the accuracy and reliability of position detection.
Implementation Method 1
an optical position sensor (5) directed at a marking (5) arranged on the piston rod (3)
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
Cylinder with a piston rod and an optical position sensor directed towards a mark arranged on the piston rod, which has a number of codewords, wherein each codeword consists of two or more code characters and a separator, and each of the two or more code and separator characters consists of a sequence of code elements (h, d) selected from a set of at least two code elements (h, d) readable by the position sensor and applied to the piston rod, wherein - b-different code characters (0, 1, 2,..., b-1) are formed in a b-adic representation from the code elements (h, d), and - two or more of the code characters (0, 1, 2,..., b-1) form a codeword in the b-adic representation.