Sinusoidal Harmonic Nulling by Phase-Adjusted Signal Sampling

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Solution Overview

Problem

Aircraft sensors generate sinusoidal signals with undesirable harmonic content, leading to increased sensor errors due to non-linear behavior at harmonic frequencies, which existing systems attempt to mitigate through aggressive filtering of the excitation source.

Innovation Solution

Oversampling sinusoidal signals at a specific rate and adjusting the sampling phase offset to null the harmonic signal, allowing for precise measurement of the fundamental sinusoid and reducing the need for costly excitation circuitry with aggressive filtering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If aggressive filtering of the excitation source is used to mitigate harmonic content, then sensor measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improvesensor measurement precisionVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary action by calculating correction values for harmonic distortion before the actual measurement process. The microcontroller computes third harmonic correction values and applies them to nullify harmonic effects on the sinusoidal output signal, thereby eliminating the need for complex aggressive filtering hardware while maintaining measurement precision.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If aggressive filtering of the excitation source is used to mitigate harmonic content, then sensor measurement precision is improved, but system cost increases

Engineering Contradiction:

Improvesensor measurement precisionVSAvoidsystem cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The invention replaces the mechanical/electrical filtering system with a computational approach. Instead of using complex analog filters to remove harmonic content, the system uses a microcontroller to calculate and apply digital correction values that nullify third harmonic distortion, thereby reducing hardware complexity and system cost while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If excitation circuitry with aggressive filtering is used to reduce harmonic distortion, then total harmonic distortion is reduced, but device complexity increases

Engineering Contradiction:

Improvetotal harmonic distortionVSAvoiddevice complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The system changes the parameter approach by shifting from physical filtering parameters to computational correction parameters. The microcontroller dynamically calculates correction values based on the excitation frequency and applies them to nullify third harmonic distortion, achieving low total harmonic distortion without requiring complex filtering circuitry.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3839439B1Sinusoidal harmonic nulling by filtering of the harmonic

Publication Date: 2023.04.05 HAMILTON SUNDSTRAND CORP

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Figure 3A~3B

AI summary

Systems (200), methods (400), and computer program products for sinusoidal nulling are provided. Aspects include transmitting (402), by a controller (202), an excitation signal to a first sensor, determining (404), by the controller, a target harmonic based at least on one or more characteristics of the excitation signal, receiving (406) a return signal from the first sensor, sampling (408) the return signal at a first sample rate based on the target harmonic, and adjusting (410) a phase of the sampled return signal to null the target harmonic amplitude to form an adjusted return signal.