Redundant Inductive Angular Position Sensor with Sector Apertures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing non-contact position sensors, particularly inductive position sensors, lack redundancy and noise immunity, which is critical for safety applications like automotive systems, where failure of one sensor can lead to system failure without a redundant solution.
Innovation Solution
A redundant angular position sensor system is designed with two independent inductive position sensors, each with its own excitation and sensing coils, and a rotatable inductive coupling element with sector apertures, providing redundancy and improved noise immunity by using separate voltage supplies and ground nodes, allowing continued operation even if one sensor fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single non-contact inductive position sensor is used, then the device complexity is reduced, but the reliability is insufficient for safety-critical applications
Solution Approach 1:
The sensor system is divided into two independent sensor channels, each with its own excitation coil and sensing coils. This segmentation allows each channel to operate independently, providing redundancy while maintaining manageable complexity through modular design. The rotatable target is also segmented with multiple conductive sectors that interact with both channels.
Solution Approach 2:
Two independent sensor channels are merged into a single integrated system sharing common components such as the rotatable target, signal processing circuitry, and housing. This merging provides redundancy for safety-critical applications while reducing overall system complexity compared to having completely separate sensor systems.
2Reliability
If two independent sensors are used for redundancy, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The rotatable target serves multiple functions: it is simultaneously used by both sensor channels for position measurement, and its conductive sectors modulate the magnetic field for both excitation coils. This multi-functionality reduces the need for separate components, thereby reducing complexity while maintaining redundancy.
Solution Approach 2:
The patent uses planar coils formed on printed circuit boards instead of traditional three-dimensional wound coils. This dimensional change from 3D to 2D coil construction simplifies manufacturing, reduces assembly complexity, and enables easier integration of multiple coils in a compact planar arrangement.
3Ease of manufacture
If planar coils on PCB are used, then the ease of manufacture is improved, but the noise immunity deteriorates
Solution Approach 1:
The sensing coils are designed with different winding directions (clockwise and counter-clockwise) to create local differences in their electromagnetic characteristics. This allows the system to differentiate between actual position signals and noise by comparing the responses of coils with opposite winding senses, thereby improving noise immunity while maintaining planar PCB construction.
Solution Approach 2:
The system uses differential measurement techniques where the outputs of sensing coils with opposite winding directions are compared. This feedback mechanism allows the system to detect and reject common-mode noise while preserving the differential position signal, improving noise immunity in the planar coil configuration.
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 redundant system ensures continued accurate angular position sensing even if one sensor fails, meeting stringent reliability and safety requirements by minimizing mutual coupling effects and providing independent operation of the sensors.
Implementation Method 1
an alternating current (AC) is injected into the excitation coil(s) which results in the generation of a time varying magnetic field in the vicinity of the excitation coil(s). The time varying magnetic field is sufficient to induce a time varying voltage in the sensing coils as a result of the mutual magnetic coupling between the excitation coil and the sensing coils.
Implementation Method 2
The presence of the rotatable target within the time varying magnetic field changes the mutual magnetic coupling between the excitation coil and the sensing coils, relative to the position of the rotatable target. The change in mutual coupling between the excitation coil and the sensing coils alters the time varying voltage induced in the sensing coils.
Data Source
AI summary
A redundant angular position sensor comprising a first angular position sensor including a first excitation coil, a first sensing coil and a second sensing coil and a second angular position sensor. The second angular position sensor including a second excitation coil, a third sensing coil and a fourth sensing coil. Each of the first, second, third and fourth sensing coils comprising a respective clockwise winding portion and a respective counter-clockwise winding portion. The redundant angular position sensor further comprises a rotatable inductive coupling element positioned in overlying relation to the sensing coils and separated from the sensing coils by a gap, wherein the rotatable inductive coupling element comprises four, substantially evenly radially spaced, sector apertures.