Aircraft Control Stick Force Feedback With Mechanical Backup
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Solution Overview
Problem
Current aircraft side-stick force feedback systems are prone to failure due to electrical or mechanical faults, leading to a loss of feedback, increased mass, space requirements, and power consumption, and compromise ergonomics and reliability.
Innovation Solution
A mechanical backup channel is integrated into the side-stick using an electromagnet, actuator, and coupling device with a pre-stressed fastening part to provide a return force in case of electrical failure, ensuring the lever remains immobilized and force feedback is maintained through sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active electromechanical force feedback systems are used, then force feedback is provided to the pilot, but the system becomes bulky, expensive, and complex with multiple components including motors, clutches, torque limiters, and gears
Solution Approach 1:
The patent extracts and eliminates unnecessary intermediate components (clutches, torque limiters, gears) from the force feedback system, creating a direct mechanical linkage between the control lever and the feedback mechanism. This simplification maintains force feedback functionality while reducing component count and system complexity.
Solution Approach 2:
The control lever serves multiple functions: it acts as both the control input device and the feedback transmission element. The mechanical linkage integrates position sensing and force feedback delivery into a single unified structure, eliminating the need for separate components for each function.
2Force
If gears are introduced in the force feedback system, then force transmission is achieved, but the dynamic performance is reduced due to increased inertia and the pilot feels torque variations
Solution Approach 1:
The patent replaces the gear-based mechanical transmission system with a direct mechanical linkage. This substitution eliminates the intermediate gear stages that cause inertia increases and torque variations, providing smooth force transmission while maintaining excellent dynamic performance and pilot ergonomics.
3Ease of manufacture
If passive mechanical spring systems are used, then force feedback is provided, but the system lacks adaptability and cannot provide active force law control
Solution Approach 1:
The patent creates a dynamic force feedback system where the mechanical linkage can adapt its characteristics based on pilot input. The system transitions from a static spring-based approach to a dynamic mechanism that provides active force law control, allowing the feedback force to vary adaptively with control lever position and pilot applied force.
Solution Approach 2:
The system incorporates feedback mechanisms that sense pilot input forces and lever position, then actively adjust the feedback force accordingly. This closed-loop feedback enables adaptive force law control while maintaining the mechanical simplicity of a direct linkage system.
4Reliability
If active force feedback motors are used, then force feedback is maintained, but power consumption and mass increase
Solution Approach 1:
The patent replaces electric motors with a purely mechanical force feedback mechanism using direct linkage and spring elements. This substitution eliminates the need for heavy motor assemblies, power electronics, and associated cooling systems, significantly reducing system mass while maintaining continuous force feedback through mechanical means.
Solution Approach 2:
The mechanical spring-based system is self-powered, using the pilot's own input forces and the spring's elastic energy to generate feedback. This self-service mechanism eliminates the need for external power sources, reducing both mass and power consumption while maintaining force feedback continuity.
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 prevents free rotation of the lever during faults, maintains pilot feedback, reduces system mass and power consumption, and enhances ergonomics and reliability by ensuring continuous force feedback even in degraded modes.
Implementation Method 1
an electromagnet (22), mounted on the casing (24)
Implementation Method 2
The fastening part is pre-stressed and applies a force on the actuator and on the output mesh, so that when the electromagnet is not supplied, the fastening part exerts a return force on the actuator and on the output mesh in the direction of the input mesh
Data Source
AI summary
The invention relates to a force application device for an aircraft control stick comprising: —a casing (24), —an electromagnet (22) mounted on the casing (24), —an actuator (30) mounted on the shaft (13), the actuator (30) being mobile in translation in relation to the shaft (13) along the axis (A), the actuator (30) comprising a magnetic material, and —a coupling device comprising an input gear (40) that is mounted so as to be stationary in relation to the casing (24) and an output gear (50) connected to the actuator (30) by means of an attachment part (60), the attachment part (60) being configured so as to allow a limited angular displacement between the output gear (50) and the shaft (13) around the axis (A) and to allow the actuator (30) of the output gear (50) to translate along the axis (A).