Aircraft Control Stick Force Feedback via Elastic Return
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Solution Overview
Problem
Aircraft control sticks without mechanical linkage to control surfaces lack resistance feedback, making it difficult for pilots to estimate control surface movements and forces, especially in electric or hydraulic actuation systems, which can be hazardous in case of actuator failure.
Innovation Solution
A device that mechanically connects the control stick to elastic means, using torsion bars to generate variable return forces based on the stick's position, ensuring reliable force feedback through mechanical means, with different intensities on different parts of the trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electric or hydraulic actuators are used to control control surfaces without mechanical linkage to the stick, then the ease of operation is improved, but the reliability deteriorates because the pilot loses force feedback and cannot estimate control surface movements and forces
Solution Approach 1:
The patent introduces an intermediary mechanical linkage system between the control stick and the elastic return means. This intermediary mechanism transmits the return forces generated by elastic elements (torsion bars, springs) to the control stick through a transmission component, providing the pilot with tactile force feedback while maintaining the benefits of electrical/hydraulic actuation for control surface movement. The intermediary mechanical connection restores the sense of connection without requiring direct mechanical linkage to the control surfaces.
2Device complexity
If a single intensity of return force is applied throughout the entire trajectory, then the device complexity is reduced, but the adaptability deteriorates because the return force cannot be optimized for different flight conditions or trajectory segments
Solution Approach 1:
The patent segments the trajectory into multiple zones (first part and second part of the trajectory) and applies different return force intensities to each segment. This is achieved through the mechanical linkage geometry and elastic element configuration, which naturally produce varying force characteristics across different angular positions. The segmentation allows optimized force feedback for different flight phases without requiring complex active control systems.
Solution Approach 2:
The patent implements dynamic return force characteristics by using elastic elements (torsion bars, springs) whose force output naturally varies with displacement. The mechanical linkage system translates the linear or rotational displacement of the elastic elements into position-dependent forces on the control stick. This dynamic force variation adapts to different trajectory positions automatically, providing softer forces near neutral and stronger forces at extremes without electronic intervention.
3Reliability
If mechanical means are used to generate return forces instead of electronic actuators, then the reliability is improved, but the device complexity increases due to the need for mechanical connection means and transmission parts
Solution Approach 1:
The patent employs self-service elastic elements (torsion bars, springs) that automatically generate return forces based on their deformation. These passive mechanical elements require no power supply, control electronics, or active regulation - they simply deform with stick movement and exert restoring forces according to Hooke's law. The mechanical linkage system passively transmits these forces to the stick, creating a reliable, maintenance-free force feedback system that serves itself without external intervention.
Solution Approach 2:
The patent replaces complex electronic actuator systems with a simpler mechanical substitution approach. Instead of using electric motors or hydraulic cylinders to generate return forces, the invention uses purely mechanical elastic elements and linkages. This substitution eliminates electronics, sensors, and control systems while providing reliable tactile feedback through straightforward mechanical force transmission, reducing both complexity and potential failure points.
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
Provides reliable and position-dependent force feedback to the pilot, enhancing control and safety by simulating the resistance felt in mechanical systems without the need for electronic actuators, while limiting vibration modes and allowing for complex force laws without electronic assistance.
Implementation Method 1
The elastic return means comprise at least a first type of elastic return means, each elastic means of the first type comprising first and second torsion bars
Implementation Method 2
each elastic means of the first type comprising first and second torsion bars and means for coupling in rotation of these first and second torsion with the transmission part
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The device (1) has a mechanical connection unit (5) and a resilient return unit (4) that are arranged to produce, over two portions (3a, 3b) of movement trajectories, two intensities of return effort (F). The connection unit includes a transmission part (6) adapted to be mechanically connected to a handle (2) such that any movement of the handle along one of the portions corresponds to rotating movement of the transmission part, and transmitting the return force to the handle when the handle is positioned in the portion.