Adaptive Optronic Sight Control for Variable-Frequency Vibration

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Solution Overview

Problem

Current optronic viewfinders for motorized vehicles, such as helicopters and propeller-driven aircraft, struggle to stabilize the line of sight due to vibrational disturbances caused by engine speed variations and non-infinitely rigid mechanics, leading to image blurring, as existing correctors are ineffective in compensating for angular movements with variable vibration frequencies.

Innovation Solution

An adaptive control loop that continuously measures acceleration in three orthogonal directions, detects the fundamental frequency of vibratory disturbances, and uses an adaptive corrector to output a displacement setpoint, allowing the system to automatically adjust filter frequencies in real time to eliminate vibrations, ensuring robust inertial stabilization and image clarity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional control loop with fixed filters is used to stabilize the line of sight, then the system can reject vibration disturbances at fixed frequencies, but it fails to compensate for angular movements when vibration frequencies vary with engine speed

Engineering Contradiction:
Improvestabilization performanceVSAvoidadaptability to variable frequencies
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by transforming the static filter frequencies into dynamic variables that adapt in real-time to changing engine speeds. The filter frequencies are continuously updated based on the detected fundamental frequency of vibrations, allowing the control loop to maintain effectiveness across varying operational conditions without manual intervention.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by automatically adjusting the filter frequencies as key parameters of the control system. These parameters are modified in response to detected changes in vibration characteristics, enabling the system to adapt to different engine speeds and vibration patterns while maintaining stable line of sight control.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the engine speed varies, then the power and productivity of the vehicle improve, but the vibration frequency varies causing image blurring and destabilization

Engineering Contradiction:
Improvevehicle operational capabilityVSAvoidimage stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies feedback by continuously monitoring the fundamental frequency of vibrations and using this information to adjust the filter frequencies in the control loop. This closed-loop approach ensures that the system automatically compensates for frequency variations caused by changing engine speeds, maintaining image stability without sacrificing operational flexibility.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent implements preliminary action by proactively adjusting the filter frequencies before significant destabilization occurs. The system detects changes in vibration characteristics and preemptively modifies the control parameters to prevent image blurring, rather than reacting after degradation has already occurred.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If manual adjustment of correctors is performed to adapt to frequency changes, then compensation accuracy can be improved, but the complexity of operation and time required increase

Engineering Contradiction:
Improvecompensation accuracyVSAvoidoperational simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent applies self-service by enabling the control system to automatically detect vibration frequencies and adjust filter parameters without requiring manual intervention. The system serves itself by continuously adapting to changing conditions, eliminating the need for operators to manually tune correctors while maintaining high compensation accuracy.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical adjustment with an automated electronic control system. The mechanical operation of manually tuning correctors is substituted by an electronic algorithm that automatically detects vibration characteristics and adjusts filter frequencies, thereby improving both accuracy and ease of operation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 solution provides robust inertial stabilization, maintains performance, and offers robustness margins by automatically adapting to variable vibration frequencies, reducing the need for additional adjustments and ensuring the optronic viewfinder maintains stability and clarity even with varying engine speeds.

Implementation Method 1

means for continuously measuring the acceleration of the sighting module in three orthogonal directions in space

Methodology Applied
Scientific EffectAcceleration measurement: Accelerometer

Implementation Method 2

means for detecting at least one fundamental frequency of the vibratory disturbances generated by the operation of the motorized vehicle, this frequency being obtained from the output data of said acceleration measuring means

Methodology Applied
Scientific EffectFrequency detection:

Implementation Method 3

an adaptive corrector configured to continuously receive as input said fundamental frequency, a difference between an angular setpoint value and said angular data, and to provide as output a displacement setpoint value to the displacement means

Methodology Applied
Scientific EffectFeedback control: Feedback

Data Source

PatentEP4217790B1Adaptive feedback control of an optronic sight
Publication Date: 2024.10.30 SAFRAN ELECTRONICS & DEFENSE (FR)
  • EP4217790B1 patent drawingFigure 1~2
  • EP4217790B1 patent drawingFigure 3~4
  • EP4217790B1 patent drawing

AI summary

The invention relates to an optronic sight (2) for motorized vehicles such as an aerial or marine vehicle propelled by a propeller or airscrew, or a tracked land vehicle comprising a sight module (4), movement means (17a, 17b) for moving the sight module about the first (8A) and the second (10) axis, measurement means (14) for continuously measuring angular data, characterized in that it comprises a feedback control loop comprising means (28) for continuously measuring the acceleration of the sight module (4) in three orthogonal directions (8a, 8b, 8c) of space, detection means (32) for detecting at least one fundamental frequency of vibrational disturbances, an adaptive corrector (26) configured to continuously receive as input said fundamental frequency and a difference between an angular setpoint value and said angular data, and to supply as output to the movement means (17a, 17b) a movement setpoint value.