Rotary Position Sensor Misalignment Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing position sensing technologies face challenges in accurately measuring the angle of a rotating shaft when the shaft passes through the sensor, particularly in scenarios where lateral and angular misalignments occur, and they often require complex resonator designs that limit signal quality and flexibility.
Innovation Solution
A rotary position sensor design featuring coils arranged between inner and outer radii and a target with asymmetric portions that magnetically couple to generate signals dependent on rotational position, compensating for misalignments and allowing for sinusoidal signal variation, enabling accurate angle measurement even with shafts passing through the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resonator with high Q-factor is used to provide large signal levels, then signal quality is improved, but the system becomes inappropriate for through-shaft operation
Solution Approach 1:
The target is divided into multiple portions (first portion between inner and outer radii, second and third portions at inner or outer radius) that can be independently positioned. This segmentation allows the target to function in through-shaft configurations while maintaining signal quality through the combined magnetic coupling of all portions.
Solution Approach 2:
The second and third portions of the target are positioned asymmetrically on either side of the target axis to compensate for misalignments between target axis and sensor axis. This asymmetric arrangement provides immunity to lateral misalignments while enabling flexible mounting configurations including side mounting for through-shaft operations.
2Measurement precision
If the target is positioned across the sensor axis, then signal levels are large, but the system cannot accommodate through-shaft operation
Solution Approach 1:
The target portions are arranged in multiple radial dimensions (between inner-outer radii and at inner/outer radii), allowing the target to maintain effective magnetic coupling with the sensor coils while accommodating shaft passage through the center. This multi-dimensional arrangement enables both high signal levels and through-shaft operation.
3Measurement precision
If lateral misalignment occurs between target and sensor, then measurement accuracy deteriorates, but asymmetric target positioning can compensate
Solution Approach 1:
The asymmetric positioning of the second and third target portions on either side of the target axis creates a compensatory mechanism that preemptively counteracts the effects of lateral misalignment. The geometric arrangement ensures that misalignment-induced errors in one portion are compensated by opposite effects from other portions, maintaining measurement accuracy despite manufacturing tolerances.
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 provides immunity to lateral and angular misalignments, maintains high signal levels, and allows for flexible mounting configurations, including side mounting, while ensuring accurate angle determination over 360° rotation with reduced complexity in sensor design.
Implementation Method 1
wherein said target is arranged to magnetically couple with said coils so that signals are generated that depend on the relative rotational position of the target and the one or more coils
Implementation Method 2
wherein said second and third portions of the target are arranged on either side of the target axis to compensate for misalignments between the target axis and the sensor axis
Data Source
AI summary
A number of position sensors inductively sense a target's position relative to a number of sensor coils. The target is magnetically coupled with first and second coils so that signals are generated that depend on the relative position of the target and the first and second coils. Substantially all of the target overlaps with loops of the first coil and so that when a first end of the target is adjacent a first loop of the first coil, a second end of the target is adjacent a second loop of the first coil that has an opposite winding direction to that of the first loop. The second coil is arranged relative to the target such that the magnetic coupling between the second coil and the first end of the target is opposite to the magnetic coupling between the second coil and the second end of the target.