Multi-Turn Absolute Angular Position Sensor System
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Solution Overview
Problem
Traditional Hall effect sensors cannot accurately determine the absolute angular position of a rotating member beyond a single turn, as they lack the capability to count multiple rotations and are prone to interference from rotating magnets.
Innovation Solution
A sensor system comprising multiple linear Hall effect sensors and a processor that uses a complementary retaining pair to track axial movement of a sleeve along a shaft, coupled with a printed circuit board configuration to eliminate interference and calculate the absolute angular position based on outputs from multiple transducers, including a method to select the most relevant sensor and calculate turn values.
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 provide angular position output (0-360 degrees), but the sensor cannot accurately determine absolute angular position beyond a single turn and is prone to interference from rotating magnets
Solution Approach 1:
The sensor system is divided into multiple independent Hall effect sensors (at least two sensors) positioned at different angular locations around the rotating member. Each sensor independently measures the magnetic field at its specific position, and the processor combines these segmented measurements to determine the absolute angular position and track multiple rotations accurately.
Solution Approach 2:
The system transitions from a single angular measurement dimension to a multi-dimensional measurement approach by using multiple sensors positioned at different angular positions. This dimensional expansion allows the system to distinguish between multiple rotations and determine absolute angular position beyond a single 0-360 degree cycle.
2Measurement precision
If multiple linear Hall effect sensors and a processor are used to track axial movement and calculate absolute angular position, then accurate determination of absolute angular position over multiple turns is enabled, but the device complexity increases
Solution Approach 1:
The processor performs multiple functions: it processes outputs from multiple Hall effect sensors, eliminates interference from rotating magnets, tracks axial movement of the sleeve, counts rotations, and calculates absolute angular position. This multi-functionality consolidates what could be separate components into a single processing unit, managing complexity while achieving high measurement precision.
Solution Approach 2:
The system combines multiple Hall effect sensors and the processing unit into an integrated sensor system. The processors combines the outputs from multiple sensors to achieve interference elimination and accurate multi-turn tracking, merging the functionality of multiple components into a coordinated system that achieves high precision without proportionally increasing 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 by reducing interference and enhancing the resolution of angular position measurement, allowing for precise tracking of rotating members.
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.
Data Source
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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.