Half-Bridge VDT Position Sensor Wiring Reduction
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Solution Overview
Problem
Conventional position sensors in aerospace applications, such as LVDT and RVDT, face challenges with complex system wiring and increased weight due to multiple wires, as well as temperature and non-linearity issues that require user correction, often compromising reliability and accuracy.
Innovation Solution
A half-bridge variable differential transformer position sensing system using a transducer with a stator and magnetically permeable core, operated with no more than three electrical wires, and equipped with a microcontroller for temperature correction and non-linearity compensation, along with signal conditioning circuitry for analog-to-digital conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LVDT and RVDT sensors are used with multiple wires for excitation and output, then the sensors can provide high reliability and accuracy, but the number and length of wires increase system wiring complexity and overall weight
Solution Approach 1:
The patent combines multiple wire functions into a single differential output wire. The primary coil excitation and secondary coil output are merged into one signal transmission path, eliminating the need for separate excitation and output wires. This reduces the wire count from four to three wires per sensor, directly addressing the wiring complexity issue while maintaining sensor functionality and reliability
2Measurement precision
If conventional LVDT and RVDT sensors use five wires for excitation and output, then the sensors can operate with high accuracy, but the weight of wires and connections increases
Solution Approach 1:
The patent merges multiple wire functions into a single differential output wire, reducing the total wire count from five to three wires per sensor. This reduction directly decreases the weight of wires and connections in the sensor system, addressing the weight issue while maintaining measurement precision through the differential signaling approach
3Reliability
If more sensors are used for redundancy, then the system can improve reliability, but the number and length of wires connecting signals to electronics increases
Solution Approach 1:
The patent applies the merging principle at the sensor level, reducing each sensor's wire count from four to three wires. When multiple sensors are deployed for redundancy, this per-sensor reduction accumulates to significant system-wide wiring simplification. For example, three sensors would require 9 wires total under the invention versus 12 wires with conventional designs, directly reducing system wiring complexity while maintaining redundancy-based reliability
4Measurement precision
If conventional sensors are used, then the transducer output can be obtained, but temperature variations cause nonlinear changes in output voltage that require user correction
Solution Approach 1:
The patent implements self-service by embedding temperature compensation functionality within the sensor system itself. The microcontroller automatically monitors temperature and adjusts the output signal to compensate for temperature-induced nonlinearities, eliminating the need for external manual correction. This transforms the system from requiring user intervention to automatically maintaining measurement precision across temperature variations
5Measurement precision
If conventional sensors are used, then position data can be obtained, but nonlinearity of the transducer output with respect to position requires user correction
Solution Approach 1:
The patent implements self-service by embedding non-linearity compensation functionality within the sensor system itself. The microcontroller automatically monitors the transducer output and applies correction algorithms to compensate for nonlinearities, eliminating the need for external manual correction. This transforms the system from requiring user intervention to automatically maintaining measurement precision across the full range of motion
6Device complexity
If the number of wires is reduced to three or fewer, then wiring complexity and weight are minimized, but the system must achieve accurate position sensing with reduced electrical interface
Solution Approach 1:
The patent replaces the conventional mechanical/electrical approach of using separate excitation and output wires with a differential signaling approach. The microcontroller generates the excitation signal and processes the output signal internally, replacing external wiring with integrated electronic functionality. This substitution enables accurate position sensing with only three wires while minimizing wiring 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
The system reduces wiring complexity, minimizes weight, and enhances reliability by automatically correcting for temperature and non-linear effects, providing accurate positional data with reduced user burden.
Implementation Method 1
a transducer having a stator with an inductive coil having a center tap configured to provide an output signal. The transducer also has an armature with a magnetically permeable core configured to move within the inductive coil, such that movement of the magnetically permeable core causes a change in the output signal
Data Source
AI summary
A half-bridge variable differential transformer position sensing system that includes a transducer having a stator with an inductive coil having a center tap configured to provide an output signal. The transducer also has an armature with a magnetically permeable core configured to move within the inductive coil, such that movement of the magnetically permeable core causes a change in the output signal. The position sensing system includes a first circuit configured to provide an excitation signal at one terminal of the inductive coil. The system includes no more than three electrical interface wires, and a microcontroller configured to calculate the degree of change in the position of the magnetically permeable core, and is configured to correct for variations in the voltage of the output signal due to the temperature of the transducer and due to non-linear effects on the output signal caused by movement of the magnetically permeable core.