Induction Rotary Encoder Multi-Track Absolute Positioning
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Solution Overview
Problem
Existing induction detecting rotary encoders face challenges in achieving high accuracy and precise absolute position measurement due to limitations in pitch reduction and tolerance for absolute position measurement over a wide range, particularly in downsized applications like micrometers.
Innovation Solution
The design incorporates multiple concentric transmitting and receiving windings with distinct flux coupling bodies on a stator and two rotors, allowing for multiple angle detection tracks with different cyclic changes per rotation, enabling accurate absolute position measurement by synchronizing the rotation of the first and second rotors through a relay gear system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pitch of the receiving windings is reduced to achieve high accuracy, then measurement precision is improved, but device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The encoder is divided into multiple independent angle detection tracks (first track with N1 cycles, second track with N2 cycles, third track with N3 cycles), where each track uses flux coupling bodies with different numbers of protrusions. This segmentation allows each track to operate independently with optimized pitch requirements, achieving high overall accuracy without requiring uniform pitch reduction across all windings.
Solution Approach 2:
The invention transitions from a single-track detection system to a multi-dimensional detection system by adding radial dimension (multiple concentric tracks with different radii) and numerical dimension (different cycle counts N1, N2, N3). This dimensional expansion allows the system to achieve high accuracy through multi-track integration rather than relying solely on pitch reduction in a single track.
2Measurement precision
If two tracks are used for absolute position measurement, then measurement range is improved, but accuracy is deteriorated due to limited tolerance
Solution Approach 1:
Each angle detection track is assigned different local characteristics: the first and second tracks (with N1 and N2 cycles) provide high-resolution local measurement, while the third track (with N3 cycles, where N3 < N1 and N3 < N2) provides coarse absolute position reference. This local quality differentiation allows each track to contribute optimally to the overall measurement system without requiring uniform high precision across all tracks.
Solution Approach 2:
The third flux coupling body with fewer protrusions (N3 cycles) acts as an intermediary that provides a coarse absolute position reference, which helps resolve the ambiguity in absolute position measurement. This intermediary track with relaxed tolerance requirements enables the high-precision first and second tracks to achieve accurate absolute position measurement without being constrained by tight tolerance requirements across all tracks.
3Measurement precision
If multiple concentric windings and flux coupling bodies are added to create multiple angle detection tracks, then measurement precision is improved, but device complexity and assembly difficulty increase
Solution Approach 1:
The flux coupling bodies are arranged in a nested concentric configuration where the first flux coupling body (with N1 protrusions), second flux coupling body (with N2 protrusions), and third flux coupling body (with N3 protrusions) are positioned at different radial distances from the rotation axis. This nesting approach allows multiple detection tracks to share the same axial space, reducing the overall device length and simplifying assembly compared to stacked configurations.
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 configuration enhances the accuracy of absolute position measurement over a long range while reducing the stator's space requirements and assembly complexity, achieving high precision and efficient detection of absolute angles.
Implementation Method 1
an induction detecting rotary encoder includes a stator 41; a first rotor 42 engaged with a rotatable shaft 3, rotated along with the rotating shaft 3, and provided axially opposite to the stator 41
Implementation Method 2
a first flux coupling body and a second flux coupling body provided in order from inside concentrically to the rotating shaft 3, on the surface opposite to the stator 41 of the first rotor 42, the first flux coupling body flux-coupling with the first transmitting winding 411 and the first receiving winding 414, the second flux coupling body flux-coupling with the second transmitting winding 412 and the second receiving winding 415
Data Source
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AI summary
An induction detecting rotary encoder has first to third transmitting windings, first to third receiving windings, and first to third flux coupling winding. The first transmitting winding, the first receiving winding, and the first flux coupling body constitute a first angle detection track generating a cyclic change for N1 times per single rotation of the first rotor. The second transmitting winding, the second receiving winding, and the second flux coupling body constitute a second angle detection track generating a cyclic change for N2 times per single rotation of the first rotor. The third transmitting winding, the third receiving winding, and the third flux coupling body constitute a third angle detection track generating a cyclic change for N3 times per single rotation of the second rotor. N1, N2, and N3 are different from one another, and N3 is less than N1 and N2.