Magnetic Angular Sensing for Precise Multi-Turn Power-Off Tracking
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Solution Overview
Problem
Current angular measurement systems face challenges in achieving high precision and power-off capabilities, with existing solutions being bulky, inaccurate, or requiring re-initialization after power failures, which can lead to scrap products and inefficiencies in automated systems.
Innovation Solution
A magnetic sensor system comprising a magnet mounted on a rotatable shaft with integrated angle and multi-turn sensors, utilizing magnetoresistive elements and a shield to detect magnetic fields, and a second magnetic sensing device with incremental sensors to enhance precision and redundancy, allowing power-off operation and accurate angular position measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic multi-turn sensors and single turn sensors are used to measure angular position and number of turns, then measurement capability is provided, but the system requires power to maintain measurement and re-initialization after power failure
Solution Approach 1:
The patent applies preliminary action by pre-storing the absolute angular position information in the magnetoresistive elements during normal operation. When power is restored after a failure, this pre-stored information is immediately available without requiring re-initialization or re-homing procedures, thus eliminating time loss and improving reliability.
2Measurement precision
If gear boxes are used to transfer multiple rotations into one rotation for measurement, then multi-rotation measurement is achieved, but the system becomes big and bulky
Solution Approach 1:
The patent replaces the mechanical gearbox system with a magnetic field-based sensing system. The magnetoresistive elements directly sense the magnetic field variations caused by rotor rotation, eliminating the need for mechanical gear reduction mechanisms. This substitution dramatically reduces system size while maintaining multi-rotation measurement capability through electronic counting of magnetic field cycles.
3Reliability
If battery powered single turn sensors are used to count turns, then turn counting is provided, but the system is not a true powerless solution and requires battery maintenance
Solution Approach 1:
The patent applies self-service by using the magnetic field itself as the storage medium for position information. The magnetoresistive elements passively retain the absolute position data without requiring any external power source, battery, or active maintenance. The system serves itself by utilizing the inherent magnetic properties of the materials to preserve measurement data through power cycles.
4Measurement precision
If magnetoresistive elements are used to detect magnetic field variations, then angular position and turn counting are achieved, but measurement accuracy is limited without additional sensing devices
Solution Approach 1:
The patent merges multiple sensing functions into a single integrated magnetic sensing system. The same magnetoresistive elements that detect absolute position are used to count rotations by detecting magnetic field cycle variations. This combining of absolute position sensing and rotation counting into one system improves measurement precision while avoiding the complexity of separate sensing systems.
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 system provides high precision angular measurements with power-off capability, eliminating the need for re-initialization and ensuring accurate tracking of angular position and number of turns without power interruptions.
Implementation Method 1
Magnetic multi-turn sensors and single turn sensors typically use magnetoresistive elements that are sensitive to an applied external magnetic field. The resistance of the magnetoresistive elements in multi-turn sensors can be changed by rotating a magnetic field within the vicinity of the sensor.
Implementation Method 2
A magnet mounted on a rotatable shaft with integrated angle and multi-turn sensors, utilizing magnetoresistive elements and a shield to detect magnetic fields
Data Source
AI summary
A measurement system and method of manufacture can include: a magnet mounted on a rotatable shaft; a first magnetic sensing device for detecting a first magnetic field from the magnet, the first magnetic sensing device comprising: an angle sensor configured to detect an orientation of the first magnetic field and a magnetic multi-turn sensor configured to detect a number of turns of the first magnetic field; and a second magnetic sensing device comprising a magnetic target mounted on the rotatable shaft and an incremental sensor configured to detect a second magnetic field, the magnetic target comprises a track for inducing a change in the second magnetic field.