Inductive Displacement Sensor Absolute Position Coding
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Solution Overview
Problem
Existing inductive position sensors and encoders face challenges in determining the absolute position of an object relative to another without a predefined reference point, particularly in industrial applications where simplicity and reliability are crucial.
Innovation Solution
The design incorporates a coding device with variable-width measuring sections and distinct physical properties for marking sections, allowing the sensor unit to form identification areas that can be uniquely identified, enabling unambiguous absolute position determination without additional information, using a plurality of inductive sensors arranged at equal distances for non-contact scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a generic incremental encoder with two periodic switching signals is used, then the device complexity is low, but the ability to determine absolute position without a predefined reference point is lost
Solution Approach 1:
The coding device is segmented into multiple marking sections separated by measuring sections with variable widths. Each measuring section has a distinct width that creates a unique identification area when combined with adjacent marking sections. This segmentation allows the sensor unit to determine absolute position by identifying the unique pattern of measuring section widths without requiring a predefined reference point, thereby achieving absolute position determination while maintaining relatively simple device structure.
Solution Approach 2:
The measuring sections are designed with asymmetric variable widths rather than uniform spacing. This asymmetry creates unique identification areas that can be unambiguously recognized by the sensor unit. The non-uniform distribution of measuring section widths provides positional information without requiring a reference point, resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If marking sections are arranged strictly equidistantly, then the device structure is simple, but the ability to determine absolute position is lost
Solution Approach 1:
Instead of uniform equidistant arrangement, the coding device employs local quality variation through measuring sections with different widths at different positions. Each local region (measuring section) has a specific width that encodes positional information. This local differentiation allows the sensor unit to determine absolute position by reading the unique pattern of widths, achieving precise position determination without complex overall structure.
3Reliability
If the sensor unit is made longer and more inductive sensors are added, then identification area determination reliability improves, but the device complexity and cost increase
Solution Approach 1:
The patent determines that a minimum sufficient number of inductive sensors and a minimum sensor unit length are required to reliably determine at least one identification area in every measuring situation. Rather than using excessive sensors, the invention identifies the optimal minimum configuration that provides reliable absolute position determination without unnecessary complexity or cost.
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 approach allows for reliable and simple determination of absolute positions, even in robust industrial environments, without the need for a fixed starting point, and can be adapted for various configurations, including curved paths and incremental encoders.
Implementation Method 1
a sensor unit to be attached to the second object with a plurality of inductive sensors for scanning the encoding device
Data Source
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AI summary
The invention relates to an inductive displacement sensor for determining a position of a first object relative to a second object having a coding device to be attached to the first object, having a sensor unit to be attached to the second object, said sensor unit comprising a plurality of inductive sensors for scanning the coding device. The inductive displacement sensor according to the invention is characterized in that the coding device comprises a plurality of marking sections separated from one another by measurement sections, at least the measurement sections having variable widths, in that the marking sections and the measurement sections have different physical properties to aid differentiation by the sensor unit, in that identification regions are formed by the measurement sections or by the measurement sections along with adjacent marking sections, in that the sensor unit is at least long enough in the extension direction of the coding device and the number of inductive sensors is at least great enough that at least one identification region may be detected in every measurement situation, and in that, in order to distinctly associate an identification region with an absolute position of the sensor unit relative to the coding device, each identification region occurs precisely once on the coding device. The invention further relates to a coding bar and a method for determining a position of a first object relative to a second object.