Rotorcraft FBW Control State Comparison for Redundant Processors

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Solution Overview

Problem

As rotorcraft become larger and more complex, the differences between flying rotorcraft and fixed-wing aircraft become more pronounced, requiring tightly coupled flight parameters and controls, which existing flight control systems struggle to manage efficiently, especially in varying flight regimes, leading to increased pilot workload and potential stability issues.

Innovation Solution

A rotorcraft system employing redundant control processors with state comparison, where a primary microprocessor and a secondary microprocessor determine desired control law states, matching them for consistent control and maintaining the last known state when they do not match, ensuring stable flight operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If redundant control processors are used to improve reliability, then system reliability is improved, but device complexity increases

Engineering Contradiction:
Improveflight control reliabilityVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system continuously compares the output states from primary and secondary microprocessors through a feedback mechanism. The comparison unit monitors whether both processors produce matching control law states, and this feedback loop ensures that any divergence is detected and handled appropriately, thereby maintaining reliability while managing complexity through automated monitoring.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent applies different processing approaches to different components: the primary microprocessor handles normal control operations, while the secondary microprocessor serves as a redundant backup. The comparison unit selectively activates based on the operational state, applying redundancy only where needed rather than uniformly across all operations, thus balancing reliability improvement with complexity management.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If state comparison between processors is implemented to ensure stability, then flight stability is improved, but processing time increases

Engineering Contradiction:
Improveflight stabilityVSAvoidcontrol processing time
Core Design Contradiction:
Stability of the object's compositionVSLoss of time

Solution Approach 1:

The system performs preliminary comparison of control law states from both processors before final control execution. By comparing states in advance and maintaining a last known good state when mismatches occur, the system prepares for potential failures proactively without disrupting real-time control responsiveness, thus ensuring stability while minimizing processing delays.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If redundant processors with state comparison are used, then control precision is improved, but device complexity increases

Engineering Contradiction:
Improvecontrol law state accuracyVSAvoidprocessor redundancy complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system creates a redundant copy of the control law computation through the secondary microprocessor. Both processors independently calculate the desired control law state from the same input parameters, and the comparison unit verifies consistency between these copies. This copying approach ensures control precision through verification while managing complexity through systematic duplication rather than complex coordination protocols.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP3428758B1FBW rotorcraft control using state comparison calculated by redundant processors
Publication Date: 2023.07.19 TEXTRON INNOVATIONS INC
  • EP3428758B1 patent drawingFigure 1~5
  • EP3428758B1 patent drawingFigure 2
  • EP3428758B1 patent drawingFigure 3

AI summary

A control system and method for providing state comparison of redundant processors used to control a rotorcraft (101). A primary microprocessor (412) is configured to receive input data from a position sensor (207) and a flight condition sensor (207) and to determine therefrom a first desired control law state, and a secondary microprocessor (414) is configured to receive input data from the position sensor (207) and the flight condition sensor (207) and to determine therefrom a second desired control law state. The first desired control law state from the primary microprocessor (412) and the second desired control law state from the secondary microprocessor (414) are compared, and either (a) the first desired control law state is taken into accont when the first desired control law state and the second desired control law state match, or (b) a last known control law state is maintained when the first desired control law state and the second desired control law state do not match.