Absolute Angular Position Sensor Using Magnetic Coupling
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Solution Overview
Problem
Traditional Hall effect sensors can determine angular rotation but fail to accurately track multiple turns of a rotating member, limiting their application in systems requiring absolute angular position measurement.
Innovation Solution
A sensor system comprising a rotating member with a magnet and a sleeve, where the sleeve travels axially along the shaft as the sensor rotor rotates, utilizing multiple transducers to sense the magnet's orientation and location, and a processor to convert these signals into an absolute angular position representation, allowing for precise tracking of multiple turns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional Hall effect sensor is used to determine angular position, then the sensor can detect single-turn rotation, but it fails to accurately track multiple turns of the rotating member
Solution Approach 1:
The measurement function is segmented between two components: a rotary sensor for angular position detection and a linear sensor for turn counting. The sleeve with linear magnet and transducer arrangement divides the multi-turn measurement task into discrete segments, where each segment corresponds to one full rotation, enabling accurate tracking of multiple turns while maintaining single-turn angular precision.
Solution Approach 2:
A magnetic coupling mechanism acts as an intermediary between the rotary sensor rotor and the linear sensor sleeve. The first magnet on the rotor and second magnet on the sleeve create a magnetic field connection that transmits rotational information to the linear transducer without mechanical contact, enabling non-contact turn counting while preserving measurement accuracy.
2Measurement precision
If multiple transducers are added to enable multi-turn tracking, then the sensor can determine absolute angular position over multiple turns, but the device complexity increases
Solution Approach 1:
The rotary and linear sensing functions are merged into a single integrated sensor assembly. The first and second transducers are positioned in close proximity, sharing common structural elements such as the housing and magnetic coupling mechanism. This merging reduces overall system complexity compared to using separate rotary and linear sensors, while achieving multi-turn measurement capability.
Solution Approach 2:
The magnetic coupling mechanism serves multiple functions simultaneously: it transmits rotational information from the rotor to the sleeve, provides non-contact coupling to eliminate mechanical wear, and enables both angular position and turn counting operations. This multi-functionality reduces the need for additional separate components, thereby managing device complexity.
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
Enables accurate determination of absolute angular position over multiple turns, enhancing the sensor's capability beyond single-turn detection and improving its applicability in various rotational measurement scenarios.
Implementation Method 1
A Hall effect sensor is a sensor that varies its output in response to a magnetic field. A Hall effect sensor can be used to determine an angular position of a rotating member.
Implementation Method 2
The first transducer or the second transducer can be a Hall effect transducer, an optical transducer, a resistive transducer, or an inductive transducer.
Implementation Method 3
the sensor can further include a magnetic shield positioned between the first magnet and the second magnet.
Data Source
AI summary
A sensor system determines an absolute angular position of a to-be-sensed rotating member. The sensor system may include a rotor with a first magnet coupled to the rotor and a shaft having threads thereon. The sensor system may further include a sleeve with a second magnet and threads complementary to the threads of a shaft. The sleeve may be configured to travel axially along the shaft as a function of rotation of the rotor. The sensor system may also include a first transducer configured to sense orientation of the first magnet and at least one second transducer configured to sense a location of the second magnet along the shaft. Through use of the sensor system, an absolute number of turns and, consequently absolute angular position, of the rotating member can be determined.