Flexible Command Model Blending Aircraft Control Responses
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Solution Overview
Problem
Existing fly-by-wire aircraft control systems often compromise either stability or maneuverability, as they typically utilize a single response type, and switching between multiple modes is complex, costly, and confusing for pilots.
Innovation Solution
A flexible command model that blends rate and attitude command modes based on pilot stick amplitude and airspeed, using time-varying coefficients and non-linearities to transition between response types, allowing for continuous blending and explicit angular acceleration limits, either through a single integrated command model or multiple parallel models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single response type is used in the command model, then the control system is simple, but the aircraft must compromise on either stability or maneuverability
Solution Approach 1:
The command model dynamically adjusts the response type based on the magnitude of pilot stick input. For small stick inputs, the system uses attitude command response type to provide stability, while for large stick inputs, it switches to rate command response type to provide maneuverability. This dynamic adaptation resolves the contradiction by making the control system behavior context-dependent rather than fixed.
Solution Approach 2:
The system changes the parameter of response type selection based on the magnitude of stick input. By monitoring the stick input magnitude and adjusting the response type parameter accordingly, the system achieves both stability (when stick input is small) and maneuverability (when stick input is large) without requiring multiple separate control systems.
2Adaptability or versatility
If multiple pilot selectable response types are utilized, then maneuverability and stability can be optimized, but software complexity and test cost increase
Solution Approach 1:
The patent merges multiple response types (attitude command and rate command) into a single unified command model. Instead of implementing separate software modules for each response type that require switching logic, the system combines them into one model that automatically selects the appropriate response type based on stick input magnitude, thereby reducing software complexity while maintaining the benefits of multiple response types.
Solution Approach 2:
The single command model serves multiple functions by being capable of operating in both attitude command and rate command modes. This multi-functional design eliminates the need for separate dedicated software for each response type, reducing overall system complexity while providing the adaptability of multiple response types through a universal control architecture.
3Adaptability or versatility
If frequency splitting of pilot stick command is used to combine response types, then some maneuverability and stability are achieved, but the approach is complex
Solution Approach 1:
The system applies different response type characteristics to different ranges of stick input magnitude. For small magnitude inputs (local region), attitude command response is applied to provide stability. For large magnitude inputs (another local region), rate command response is applied to provide maneuverability. This localized application of different control characteristics simplifies the overall model compared to frequency splitting while achieving similar benefits.
Data Source
AI summary
Two methods of combining multiple response types into a single flexible command model are provided and include receiving a pilot stick input, generating an aircraft response to the pilot stick input that is a continuous blend of response types by including calculable time-varying coefficients set as a function of a magnitude of the pilot stick input and other aircraft states such as airspeed, imposing at least an angular acceleration command limit and using other non-linear elements to optimize the aircraft response to the pilot stick input.