Sidestick Grip Geometry for Minimal Cross-Axis Control Coupling
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Solution Overview
Problem
Existing sidestick grips for aircraft with three or more axes suffer from cross-axis control coupling, where input on one axis unintentionally activates other axes, particularly due to the mismatch between the Grip Reference Point (GRP) and the yaw axis of rotation.
Innovation Solution
The sidestick grip design aligns the Grip Reference Point (GRP) substantially with the yaw axis of rotation, minimizing unintentional yaw torque when controlling pitch and roll axes, and incorporating ergonomic cants and contoured surfaces for pilot comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the Grip Reference Point (GRP) is located far from the yaw axis of rotation, then pitch and roll control forces are applied effectively, but significant unintentional yaw movement occurs when force is applied to pitch and roll axes
Solution Approach 1:
The patent repositions the GRP from a location far from the yaw axis to a location substantially coincident with the yaw axis of rotation. This dimensional repositioning in the longitudinal direction eliminates the moment arm that causes cross-axis coupling, allowing pitch and roll forces to be applied effectively without generating unintentional yaw torque.
2Object-generated harmful factors
If the yaw breakout force is increased to counteract cross-axis coupling, then unintentional yaw movement is reduced, but control difficulty increases when small directional inputs are desired
Solution Approach 1:
The patent preemptively positions the GRP coincident with the yaw axis before any control input is applied. This preliminary geometric configuration prevents the generation of coupling torque in the first place, eliminating the need for high yaw breakout forces and preserving the ability to make small directional inputs without excessive control force requirements.
3Object-generated harmful factors
If an almost vertical grip design is used, then cross-axis control coupling is reduced, but aircraft ergonomics are compromised
Solution Approach 1:
The patent employs asymmetric cant angles for the sidestick grip, positioning it at 10° to 17° forward of vertical and 8° to 12° inboard of vertical. This asymmetric configuration maintains ergonomic comfort for the pilot while the GRP is positioned coincident with the yaw axis to minimize cross-axis coupling, resolving the contradiction between ergonomics and control precision.
Data Source
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AI summary
Sidestick grips are disclosed which minimize cross-axis control coupling about three or more control axes, wherein one of the control axes provides directional (yaw) input by twisting the grip in clockwise/counterclockwise directions. Minimizing cross-axis control according to the embodiments disclosed herein is accomplished principally by having the Grip Reference Point (GRP) (i.e., the theoretical point of application of pitch and roll forces) of the sidestick grip to be substantially coincident with the yaw axis of rotation. By providing the GRP substantially coincident with the yaw axis of rotation, unintentional yaw torque is minimized when control input is exerted on the sidestick in the pitch and roll axes.