Aircraft Control Stick Magnetic Brake for Power-Loss Force Feedback

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Solution Overview

Problem

Aircraft control sticks lack a reliable mechanical backup to prevent free rotation of the lever and loss of force feedback in cases of general power unavailability, leading to safety concerns and increased complexity with additional power supplies and bulky mechanical systems.

Innovation Solution

A control stick with a magnetic brake system that uses a rheological fluid with variable shear resistance, actuated by a movable magnetic element, which engages automatically in the event of power failure, providing a resistive force to prevent free rotation without additional power sources or complex mechanical systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional mechanical systems or brakes are added to provide backup in power failure situations, then reliability is improved, but device complexity and bulk increase

Engineering Contradiction:

Improvecontrol stick reliability in power failureVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical backup systems with a magnetic field-based solution. A movable magnetic element generates a magnetic field that interacts with a stationary magnetic element to create a braking force on the shaft, eliminating the need for additional mechanical brakes or locking mechanisms while providing reliable backup in power failure situations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state or properties of materials to achieve the desired function. Specifically, it uses materials with different magnetic permeabilities (movable magnetic element with high permeability vs. stationary magnetic element with low permeability) to create a selective magnetic braking effect that activates only when needed

Inventive Principle:

Principle #35Parameter changes

2Reliability

If additional power supply systems are added to power backup brakes, then reliability is improved, but use of energy and device complexity increase

Engineering Contradiction:

Improvebackup system reliabilityVSAvoidelectrical power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The magnetic backup braking system operates passively without requiring external power input. The movable magnetic element, when displaced from its neutral position, automatically generates a magnetic field that interacts with the stationary magnetic element to create a restoring braking force, eliminating the need for additional power supplies or active control systems

Inventive Principle:

Principle #25Self-service

3Reliability

If mechanical locking systems are added to prevent free rotation, then reliability is improved, but ease of operation and device complexity worsen

Engineering Contradiction:

Improvelever anchoring reliabilityVSAvoidcontrol lever operability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces mechanical locking systems with a magnetic field-based braking system. The interaction between the movable and stationary magnetic elements creates a continuous restoring force that prevents free rotation of the shaft without requiring discrete locking mechanisms, maintaining smooth operability while ensuring reliability

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

The solution ensures continuous haptic feedback and prevents free rotation of the control lever during power failures, enhancing flight safety with reduced mass, bulk, and electrical power consumption, while maintaining high reliability and a satisfactory lifetime.

Implementation Method 1

a volume containing a rheological fluid in contact with the braking part, resistance to shear of the rheological fluid being variable as a function of a magnetic field applied to the rheological fluid

Methodology Applied

Scientific EffectMagnetorheological effect: Magnetorheological Fluid

Implementation Method 2

a movable magnetic element having a position close to the magnetic brake and a position distant from the magnetic brake, the movable magnetic element emitting a magnetic field in the volume in the close position

Methodology Applied

Scientific EffectMagnetic field generation: Magnetic Field

Implementation Method 3

separating means configured to retain the movable magnetic element in the distant position when the separating means are supplied with electrical power by the power source

Methodology Applied

Scientific EffectElectromagnetic force: Electromagnet

Data Source

PatentUS11628925B2Force application device for control stick in a power failure situation

Publication Date: 2023.04.18 SAFRAN ELECTRONICS & DEFENSE (FR)

AI summary

The present invention relates to a force application device for a control stick of an aircraft comprising a shaft and a control lever configured to rotate the shaft about a first axis, the device comprising: a magnetic brake comprising a braking part configured to be connected to the shaft, and a volume containing a rheological fluid in contact with the braking part, of variable shear resistance as a function of a magnetic field applied to the rheological fluid, a force feedback motor configured to exert a resistive force opposing the rotation of the shaft about the first axis, a motor power source, a movable magnetic element biased towards a position close to the magnetic brake, and distancing means configured to maintain the movable magnetic element in a position away from the magnetic brake, when such distancing means are powered by the power source.