Domain-Wall Position Measurement for Multi-Turn Absolute Sensing
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Solution Overview
Problem
Existing position measuring devices, particularly multi-turn angular and linear measuring devices, face challenges in achieving precise absolute position determination over large measurement lengths, especially in electrical drives, and require efficient storage of revolution or position information in a non-volatile manner.
Innovation Solution
A position measuring device utilizing a domain-wall memory with a first and second component group, where the second group includes a scale and a magnet to displace domain walls in a domain-wall conductor, enabling precise relative position determination through an inductive measurement principle, with a compact and efficient design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If multiple linear or identical scales are mounted end to end to increase measurement length, then the measurement length is improved, but the device complexity increases
Solution Approach 1:
The measuring device is divided into two functional component groups: a first component group containing the detector and domain-wall conductor on separate printed circuit boards, and a second component group containing the scale and magnet. This segmentation allows the measurement function to be distributed across modular units that can be extended by adding more scales end-to-end without proportionally increasing overall system complexity
Solution Approach 2:
The domain-wall conductor serves multiple functions: it acts as both the measurement scale reference and the non-volatile memory storage medium. The magnet serves dual purposes by both generating the magnetic field for domain wall displacement and providing the reading signal for position detection. This multi-functionality reduces the number of separate components needed, allowing measurement length extension without proportional complexity increase
2Reliability
If domain-wall memory is implemented for non-volatile storage, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the non-volatile memory function with the existing domain-wall conductor structure used for measurement. The same conductor that defines the measurement scale also stores the revolution count information through domain wall positions. This integration eliminates the need for separate memory components, achieving reliable non-volatile storage without proportionally increasing device complexity
Solution Approach 2:
The measuring device uses its own magnetic field generation capability to both read the scale position and write/update the domain wall positions in the memory function. The magnet that generates the reading signal also serves to displace domain walls for storage operations. This self-service approach eliminates the need for separate write head components, reducing complexity while maintaining reliability
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 device achieves precise and reliable absolute position measurement over multiple revolutions with non-volatile storage of position information, even in power-outage conditions, using a domain-wall conductor and magnet arrangement for efficient domain wall displacement.
Implementation Method 1
The magnet is configured and arranged such that the magnet generates a displacement of a domain wall in the domain-wall conductor when the magnet travels past domain-wall conductor
Implementation Method 2
The scale is configured to be read by the detector to determine a relative position in the measurement direction
Data Source
AI summary
A position measuring device including a first component group and a second component group. The component groups are arranged so as to be movable relative to one another in a measurement direction. The first component group includes a first printed circuit board, which includes a detector and a second printed circuit board, which includes a domain-wall conductor. The first printed circuit board is arranged offset from the second printed circuit board in the measurement direction. The second component group includes a scale and a magnet. The scale is arranged between the magnet and the second printed circuit board. The scale is configured to be read by the detector to determine a relative position in the measurement direction. The magnet is configured and arranged such that the magnet generates a displacement of a domain wall in the domain-wall conductor when the magnet travels past domain-wall conductor.