Active Inceptor Trim Control Without Buzzing Dynamics

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Solution Overview

Problem

Conventional fly-by-wire aircraft control systems lack feedback on forces acting on the aircraft, leading to an unpleasant 'buzzing' sensation during trim position adjustments in active inceptors.

Innovation Solution

A control system and method that includes a summing circuit, integrator circuits, and a force-position mapping characteristic to allow the control stick to settle to a trim position without applying force, using a trim input signal to modify the mapping characteristic and prevent unwanted dynamics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a servo actuator mechanism with force and position sensors is used to modify the force feel characteristic continuously, then the adaptability of the control stick is improved, but the complexity of the device increases and unwanted dynamics during trim adjustments occur

Engineering Contradiction:

Improveforce feel characteristic modificationVSAvoidservo actuator mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent modifies the force-position mapping characteristic by changing the position values in the mapping table based on trim input signals. This allows continuous adaptation of the force feel characteristic without requiring a complex servo actuator mechanism, thereby resolving the contradiction between adaptability and device complexity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical servo actuator mechanism with a computational approach using a summing circuit and modified force-position mapping. Instead of physically adjusting components, the system uses signal processing to achieve the same effect, reducing mechanical complexity while maintaining adaptability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If the control stick uses conventional fly-by-wire system without force feedback, then the device complexity is reduced, but the stability during trim adjustments deteriorates due to buzzing sensation

Engineering Contradiction:

Improvecontrol system structureVSAvoidcontrol stick stability

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent introduces a feedback mechanism through the summing circuit that receives force feedback signals and subtracts them from the operator input signal. This feedback loop stabilizes the control stick during trim adjustments by compensating for unwanted dynamics, while maintaining a relatively simple control system structure

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses a computational intermediary (the summing circuit and force-position mapping modification) to mediate between the operator input and the control output. This intermediary processes signals to eliminate buzzing sensations without requiring direct mechanical force feedback, thus maintaining system simplicity while improving stability

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11414176B2Control systems

Publication Date: 2022.08.16 BAE SYSTEMS PLC

AI summary

A control system (400) for an active inceptor (103) for a fly by wire aircraft permits a zero force null point to settle to a non-zero displacement trim position. An internal position state of a second order mass spring damper model is moved in conjunction with force-displacement characteristic coordinates. This results in no second order dynamics being superimposed on the feel of the inceptor (103) when dynamically adjusting the trim position, thereby eliminating the possibility of any unpleasant buzzing been felt by the operator of the inceptor during a trimming operation.