Adaptive Rotorcraft Control Law for Pilot Sensitivity

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Solution Overview

Problem

Conventional rotorcraft control systems face challenges in maintaining precise control near the limitations of control movements, requiring significant pilot effort and lacking clear indication of control margin limitations, which affects piloting comfort and sensitivity.

Innovation Solution

A control system that modifies the piloting law by adjusting the sensitivity of servo-controls and introduces a 'dead zone' when the control margin approaches its threshold, along with alert signals to inform the pilot, ensuring precise and comfortable control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional control system with long lever arms and significant travel is used, then the control range is covered and optimal sensitivity is achieved, but the control stick travel becomes very long exceeding several tens of centimeters

Engineering Contradiction:
Improvecontrol sensitivityVSAvoidcontrol stick travel
Core Design Contradiction:
Measurement precisionVSLength of moving object

Solution Approach 1:

The patent applies dynamics by making the control law adaptive rather than fixed. The control law automatically modifies its sensitivity based on the current control margin, transitioning between different sensitivity levels as the control element approaches its limits. This dynamic adaptation allows the system to maintain optimal sensitivity throughout the entire control range without requiring excessive physical travel.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of control law sensitivity dynamically. By monitoring the control margin and automatically adjusting the sensitivity parameter, the system optimizes the relationship between control element position and servo control output. This parameter change allows the same physical control travel to achieve different levels of control authority depending on the operating point.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If a passive control device like a joystick is used, then equipment is simplified, but it becomes difficult for the pilot to know if the current position is close to the limit of control range

Engineering Contradiction:
Improvecontrol device structureVSAvoidcontrol margin information
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The patent implements feedback by continuously monitoring the control margin (the difference between current control position and limit) and using this information to automatically adjust the control law sensitivity. This closed-loop feedback mechanism provides the pilot with implicit information about control margin through the system's automatic response, eliminating the need for additional complex indicators while maintaining awareness of control limits.

Inventive Principle:
Principle #23Feedback

3Device complexity

If the control law sensitivity remains constant, then the control system is simple, but piloting sensitivity is reduced near the limitations of control movements

Engineering Contradiction:
Improvecontrol lawVSAvoidpiloting sensitivity near limits
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The control law transitions from a static to a dynamic system that automatically adapts its sensitivity based on the control margin. When approaching control limits, the system dynamically increases sensitivity to maintain effective piloting control. This dynamic behavior ensures optimal sensitivity throughout the entire control range without requiring complex manual adjustment mechanisms.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system performs self-service by automatically monitoring its own control margin and adjusting its sensitivity parameter without external intervention. The system serves itself by detecting when it approaches limits and autonomously modifying its control law to maintain optimal performance, eliminating the need for pilot awareness or manual recalibration.

Inventive Principle:
Principle #25Self-service

4Device complexity

If a single proportional control lever is used, then the control system is mechanically simple, but maintaining the control stick in a specific position becomes difficult or uncomfortable

Engineering Contradiction:
Improvecontrol system structureVSAvoidcontrol stick positioning
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The patent replaces the mechanical control system with an electrical or optical control system using servo controls. This substitution eliminates the need for long mechanical lever arms and complex linkages, allowing precise control stick positioning without excessive physical effort. The servo controls provide electronic assistance that maintains the control element in desired positions, improving ease of operation while reducing mechanical complexity.

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

Data Source

PatentEP3159258B1A system for controlling a rotorcraft rotor, a rotorcraft fitted with such a system, and an associated control method
Publication Date: 2019.06.05 EUROCOPTER FRANCE SA
  • EP3159258B1 patent drawingFigure 1~3

AI summary

The present invention relates to a control system (1) for controlling at least one rotor (2, 22) of a rotorcraft (20), this control system (1) comprising at least one piloting element (3) capable of piloting at least one control (4) of the movements of the rotor(s) (2, 22).Such a control system (1) comprises: • at least one memory (5) for storing information representative of a predetermined control margin threshold, • calculation means (6) for calculating a current control margin defined as the difference between a current position and a limitation of the control (4) of the movements of the rotor(s) (2, 22), • comparison means (7) for comparing the current control margin with the predetermined control margin threshold, • a control unit (8) for modifying a control law for the control (4) of the movements of the rotor(s) (2, 22) when the current control margin is less than or equal to the predetermined control margin threshold.