Adaptive Non-Linear Filter for Aircraft Pilot Induced Oscillations

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Solution Overview

Problem

Modern aircraft experience induced pilot oscillations (PIO) due to a phase shift between pilot control inputs and the response of movable aerodynamic surfaces, leading to decreased piloting accuracy and increased costs and weight with existing solutions like larger actuators and non-linear filters that also attenuate non-PIO orders.

Innovation Solution

A piloting system that uses a non-linear filter with an adaptation loop to estimate and match the actual maximum speed of control orders to a reference speed, adjusting filtering parameters to eliminate PIO oscillations while maintaining accurate control of amplitude variation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If non-linear filters are used to eliminate PIO oscillations, then piloting accuracy is improved, but useful piloting orders are attenuated and control precision deteriorates

Engineering Contradiction:

Improvepiloting accuracyVSAvoidcontrol precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The filter characteristics are made dynamic and adaptive rather than fixed. The filtering parameter is continuously adjusted based on real-time monitoring of control order characteristics, allowing the filter to adapt its behavior to match the actual piloting situation. This resolves the contradiction by making the filter selective rather than uniformly attenuating all signals.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the filtering parameter dynamically based on the characteristics of the control orders. By monitoring parameters such as amplitude and frequency of control inputs, the system adjusts the filtering parameter to eliminate PIO oscillations while preserving useful piloting orders, thus maintaining both piloting accuracy and control precision.

Inventive Principle:

Principle #35Parameter changes

2Speed

If larger actuators and power supplies are used to reduce phase shift, then response speed is improved, but aircraft weight and cost increase

Engineering Contradiction:

Improveresponse speedVSAvoidaircraft weight

Core Design Contradiction:

SpeedVSWeight of moving object

Solution Approach 1:

The invention replaces the mechanical solution (larger actuators with more power) with a control system solution (adaptive filtering). Instead of increasing physical actuator capacity to reduce phase shift, the system uses signal processing to compensate for the delay and eliminate PIO oscillations, thereby maintaining response speed without increasing weight.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If non-linear filters are used to eliminate PIO oscillations, then oscillation attenuation is improved, but speed control of amplitude variation deteriorates

Engineering Contradiction:

Improveoscillation attenuationVSAvoidspeed of amplitude variation

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The system implements feedback by continuously monitoring the control orders and their characteristics, then using this information to adjust the filtering parameter. This closed-loop approach allows the filter to attenuate PIO oscillations while simultaneously maintaining proper control over the speed of amplitude variation, as the filtering parameter is adjusted based on real-time system state.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8095252B2Piloting method and device avoiding the pilot induced oscillations

Publication Date: 2012.01.10 AIRBUS OPERATIONS (SAS)

AI summary

A piloting method and device for avoiding pilot induced oscillations filters a piloting order with a non-linear filtering function that is controlled by speed comparison information.