Actuator Controller Redundancy for Common-Mode Failure Resistance

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Solution Overview

Problem

Existing aircraft actuation systems with electromechanical actuators (EMAs) face challenges in achieving high integrity control while minimizing weight, complexity, and cost, as they require redundant systems and complex design features to prevent common mode failures, which are costly and inefficient.

Innovation Solution

A high-integrity electromechanical actuator control system with redundant control channels, including primary and backup channels, implements a command voting scheme and duty cycle computation to verify actuator control command integrity, using dissimilar microcontrollers and simplified COM-COM architecture to generate PWM commutation control signals, ensuring reliable actuation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If redundant control systems and complex design features are implemented to prevent common mode failures, then system reliability is improved, but system weight, complexity, and cost increase

Engineering Contradiction:

Improvesystem reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control system is segmented into multiple independent control channels (primary and secondary), each capable of independently controlling the actuator. This segmentation allows the system to maintain reliability through redundancy while managing complexity by dividing functions into separate, modular channels rather than requiring a single complex redundant system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each control channel is designed to be universal and multi-functional, capable of performing the complete control function independently. The primary and secondary channels can both fully control the actuator, allowing either channel to take over in case of failure, thus improving reliability without requiring specialized backup systems that会增加 complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If redundant control systems and complex design features are implemented to prevent common mode failures, then system reliability is improved, but system weight increases

Engineering Contradiction:

Improvesystem reliabilityVSAvoidsystem weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent merges the redundancy function into the existing control channel architecture rather than adding separate physical backup systems. By combining the primary and secondary control channels into a unified system where both share the same actuator and control bus, the weight penalty is reduced compared to fully independent redundant systems, while still achieving the required reliability through functional redundancy.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If redundant control systems and complex design features are implemented to prevent common mode failures, then system reliability is improved, but system cost increases

Engineering Contradiction:

Improvesystem reliabilityVSAvoidsystem cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The system uses copying by implementing a secondary control channel that replicates the primary channel's functionality. Rather than designing and manufacturing entirely separate backup systems, the secondary channel copies the primary channel's control logic and interface, reducing development and manufacturing costs while maintaining reliability through redundancy.

Inventive Principle:

Principle #26Copying

4Reliability

If dissimilar microcontrollers are used in primary and backup channels, then common mode failure resistance is improved, but device complexity increases

Engineering Contradiction:

Improvecommon mode failure resistanceVSAvoidcontroller complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by using dissimilar microcontrollers (different manufacturers or models) in the primary and secondary control channels. This asymmetric design prevents common mode failures that could affect identical components simultaneously, improving reliability. The complexity increase is managed by maintaining similar control logic and interfaces despite hardware differences.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS12470157B2High-integrity actuator controller and control systems

Publication Date: 2025.11.11 HONEYWELL INTERNATIONAL INC

AI summary

A high-integrity electromechanical actuator control system includes a system function controller, a plurality of actuator controllers, and at least one electromechanical actuator. Each actuator controller includes a primary channel having a first controller, a second controller, and a duty cycle computation circuit, and includes a backup channel having a backup controller. The first controller receives digital actuator control commands from two functional control channels and supplies first digital duty cycle commands. The second controller receives digital actuator control commands from two functional control channels and supplies second digital duty cycle commands. The duty cycle computation circuit computes an average of the first and second duty cycle commands and generates pulse width modulated (PWM) commutation control signals based on the computed average. The backup controller receives digital actuator control commands from two different functional control channels and generates and supplies backup PWM commutation control signals.