Sensor Voltage Correction via Dual Bias Resistance Evaluation
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Solution Overview
Problem
Measurement errors due to output impedance variations in sensors connected to digital computers are significant and difficult to compensate for, especially when the impedance ratio is non-negligible, leading to inaccuracies in the acquisition chain, particularly in the aeronautical field.
Innovation Solution
A method involving the application of two different bias voltages across pull-up/down resistors connected to the sensor to evaluate and correct the series resistance, allowing for precise compensation of measurement errors by determining a compensation value based on the series resistance and the voltage to be corrected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is connected to a digital computer with finite input impedance, then the measurement system can process data, but a measurement error occurs due to the non-negligible ratio between output impedance of the sensor and input impedance of the computer
Solution Approach 1:
The invention changes the electrical parameters (bias voltages) applied to the pull-up/down resistors to evaluate the series resistance at different operating points. By applying first and second different bias voltages and measuring the corresponding output voltages, the method determines the series resistance value that varies with the measurement point, thereby compensating for impedance-related measurement errors dynamically.
Solution Approach 2:
The invention implements a feedback mechanism where the measured output voltages under different bias conditions are used to calculate the series resistance, which then feeds back into the correction algorithm. This closed-loop approach allows the system to automatically compensate for impedance variations and improve measurement accuracy continuously.
2Measurement precision
If the equivalent series impedance of the sensor varies due to production variations, then different sensors cannot be compensated uniformly, but compensating for each variation complicates the algorithm
Solution Approach 1:
The invention enables the sensor system to self-evaluate its own series resistance by measuring its own output voltages under different bias conditions. Each sensor automatically determines its own impedance characteristics without requiring external calibration equipment or complex manual adjustment, simplifying the overall system while maintaining high compensation accuracy.
Solution Approach 2:
The invention performs preliminary evaluation of the series resistance by measuring voltages under different bias voltages before final measurement correction. This preliminary characterization of the sensor's impedance properties allows the system to prepare correction factors in advance, simplifying the main measurement algorithm while achieving accurate compensation.
3Measurement precision
If the measurement point of the sensor changes, then the equivalent series impedance varies non-linearly, but compensating for this non-linear error requires complex approximation functions
Solution Approach 1:
The invention adopts a dynamic approach by evaluating the series resistance at the actual measurement point rather than using a fixed nominal value. By applying different bias voltages corresponding to different measurement points and determining the impedance at each point, the system adapts to non-linear variations dynamically, avoiding the need for complex pre-defined approximation functions.
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
This method effectively compensates for measurement errors caused by output impedance, improving the accuracy of sensor measurements by inferring the corresponding voltage generated by the sensor, even when the sensor's output impedance is unknown, thus enhancing the reliability of the acquisition chain.
Implementation Method 1
each of the output terminals being respectively connected to a pull-up/down (i.e. pull-up or pull-down) resistor, the method comprising: when the generator generates a determined voltage, a preliminary step for evaluating the series resistance of the sensor, the preliminary step comprising: the measurement of a first voltage across the output terminals when a first bias voltage is applied on each pull-up/down resistor; the measurement of a second voltage across the output terminals when a second bias voltage different from the first bias voltage is applied on the pull-up/down resistors
Data Source
AI summary
A method for correcting measurement of a voltage across output terminals of a sensor, the sensor configured to be assimilated with an assembly including a generator and a series resistance, each of the output terminals being respectively connected to a pull up/down resistor. The method includes: evaluating the series resistance of the sensor, including measuring first and second voltages across the output terminals when first and second bias voltages are applied on each pull up/down resistor; evaluating the series resistance from the first and second voltages; and correcting, from the series resistance, a voltage measured across the output terminals of the sensor to infer therefrom a corresponding voltage generated by the generator.