Rotational Position Sensor Loop Correction for Angular Accuracy
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Solution Overview
Problem
Existing sensor devices for measuring the rotational position of an element are imprecise due to angular errors caused by varying magnetic flux at the ends and central parts of the sensor, which change with the air gap between the stator and rotor.
Innovation Solution
The sensor device includes a sender member emitting a magnetic field and two receiving members formed by conductors arranged in an annular ring segment, where the shape of some loops deviates from a base function by a correction function to compensate for errors, allowing precise angle determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an annular ring segment is used to save costs and assembly space, then assembly space and cost are reduced, but measurement precision deteriorates due to angular errors caused by varying magnetic flux at the ends and central parts
Solution Approach 1:
The patent applies local quality by differentiating the loop shapes within the annular ring segment. Specifically, loops at the ends of the segment have different shapes than loops at the central part. This local differentiation compensates for the varying magnetic flux conditions at different positions, maintaining measurement precision while using a compact annular ring segment structure.
Solution Approach 2:
The patent changes the geometric parameters of the loops based on their position within the annular ring segment. By adjusting the loop shapes (a geometric parameter) according to their location (end vs. central), the system compensates for position-dependent magnetic flux variations, thereby maintaining angular resolution precision in the reduced-size sensor device.
2Volume of moving object
If the sensor device is made compact with an annular ring segment, then device size is reduced, but angular errors increase due to magnetic flux variations at different positions
Solution Approach 1:
The patent implements local quality by making loops at the ends of the annular ring segment have different shapes from loops at the central part. This local differentiation addresses the position-dependent magnetic flux variations that cause angular errors, allowing the compact device to maintain measurement precision despite its reduced size.
Solution Approach 2:
The patent replaces uniform mechanical loop structures with position-dependent varied loop structures. Instead of using identical loops throughout the annular ring segment, the system uses loops with shapes tailored to their specific positions, compensating for magnetic flux variations and reducing angular errors in the compact device.
3Ease of manufacture
If uniform loop shapes are used in the annular ring segment, then manufacturing is simplified, but measurement precision deteriorates due to harmonics in angular error
Solution Approach 1:
The patent applies local quality by differentiating loop shapes based on their position within the annular ring segment. Loops at the ends have different shapes from loops at the central part, which compensates for position-dependent magnetic flux variations and reduces angular error harmonics, while still maintaining relatively simple manufacturing processes.
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 precision of rotational position measurement by correcting for errors caused by magnetic field variations at the ends and central parts of the sensor, optimizing angular resolution and reducing assembly space.
Implementation Method 1
a sender member (110) for emitting a magnetic field
Implementation Method 2
a first receiving member (120) formed by a first conductor for receiving the magnetic field, and a second receiving member (130) formed by a second conductor for receiving the magnetic field
Data Source
AI summary
A sensor device for measuring a rotational position of an element that is rotatable about an axis of rotation includes a sender member emitting a magnetic field, a first receiving member formed by a first conductor and receiving the magnetic field, and a second receiving member formed by a second conductor and receiving the magnetic field. The first receiving member and the second receiving member are arranged within an annular ring segment having a period along a circumferential direction about the axis of rotation. The first conductor and the second conductor each define a plurality of loops. A shape of each of the loops follows in the circumferential direction a base function with half the period, the shape of only some of the loops deviates from the base function by a correction function.