Magnetic Reluctance Position Sensor for Compact Actuators
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Solution Overview
Problem
Conventional position sensing systems for electromechanical actuators, such as RVDTs and encoders, are either too large and expensive or require initial motion to determine position, posing challenges in compact flight control systems with limited space and high cost, especially in thin-wing aircraft applications.
Innovation Solution
A magnetic reluctance-based position sensing system using a hall effect sensor and geometric variations on the actuator's surface, such as a progressively widening or deepening groove or pattern of holes, to determine the angular position of the actuator without the need for initial motion, allowing for compact and cost-effective position sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional position sensing systems (RVDT or encoder) are used, then position sensing capability is provided, but the actuator size and cost increase significantly
Solution Approach 1:
The patent replaces conventional mechanical position sensing systems (RVDT or encoder) with a magnetic field-based sensing system using a magnet and Hall effect sensor. This substitution eliminates complex mechanical components, significantly reducing actuator size while maintaining position sensing capability. The magnetic field interacts with geometric variations on the output arm to provide position information without requiring bulky mechanical sensing apparatus.
Solution Approach 2:
The patent creates geometric variations (grooves or holes) on the output arm surface that modify magnetic field parameters (reluctance). These geometric features cause measurable changes in magnetic field strength as the output arm rotates, enabling position detection through magnetic field parameter changes rather than mechanical sensing. This approach allows compact sensing while maintaining measurement precision.
2Measurement precision
If conventional position sensing systems (RVDT or encoder) are used, then position sensing capability is provided, but the actuator cost increases significantly
Solution Approach 1:
The patent replaces expensive conventional mechanical position sensing systems with a cost-effective magnetic field-based system. The magnet and Hall effect sensor combination, along with simple geometric variations (grooves or holes) on the output arm, provides position sensing capability at a fraction of the cost of RVDT or encoder systems, making the actuator more economically viable.
Solution Approach 2:
The patent uses inexpensive components (magnet, Hall effect sensor, and simple geometric features) to create a position sensing system that is far more cost-effective than conventional mechanical sensing systems. The geometric variations are simply machined into the output arm rather than requiring expensive specialized components, reducing manufacturing costs significantly.
3Volume of moving object
If encoders are used for position sensing, then size and cost are reduced compared to RVDT, but initial motion is required to determine position
Solution Approach 1:
The patent incorporates geometric variations (grooves or holes) pre-machined into the output arm surface that create distinct magnetic field patterns at different angular positions. These pre-configured geometric features enable the Hall effect sensor to determine absolute position immediately upon startup without requiring initial motion, as each angular position produces a unique magnetic field signature that can be directly measured.
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 and immediate angular position sensing upon powering up, reducing the size and cost of the position sensing system while fitting within the limited space constraints of thin-wing aircraft, improving the efficiency and effectiveness of electromechanical actuators.
Implementation Method 1
The position sensor is configured to sense magnetic reluctance. The sensed portion includes a geometric variation in an output arm surface configured to vary a magnetic reluctance sensed at the position sensor as a function of angular position of the output arm relative to the ground arm.
Implementation Method 2
the position sensor includes a magnet fixed at the ground arm to generate a magnetic field, and a hall effect sensor to detect variation in the magnetic field as the output arm is rotated about the axis of rotation relative to the ground arm
Data Source
AI summary
An electromechanical actuator includes a ground arm, an output arm rotatable about an axis of rotation relative to the ground arm and a position sensing arrangement to determine an angular position of the output arm relative to the ground arm. The position sensing arrangement includes a position sensor fixed at the ground arm. The position sensor is configured to sense magnetic reluctance. A sensed portion is located at the output arm proximate to the position sensor. The sensed portion includes a geometric variation in an output arm surface configured to vary a magnetic reluctance sensed at the position sensor as a function of angular position of the output arm relative to the ground arm.