Rotorcraft Speed Sensor Fault Detection via Shaft-Rotor Comparison
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Solution Overview
Problem
Existing fault detection methods for speed sensors in multi-engine rotorcrafts are inadequate, as they may fail to accurately identify faults when speed sensor readings are erroneous or when engine coupling status is uncertain, potentially leading to incorrect control decisions.
Innovation Solution
A method and system for fault detection in multi-engine rotorcrafts that compare shaft speed and rotor speed, issuing fault signals based on discrepancies, and determine engine coupling status through fuel flow analysis to detect and signal speed sensing system faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing fault detection methods are used, then the system operates with simpler detection logic, but the fault detection accuracy deteriorates when speed sensor readings are erroneous or engine coupling status is uncertain
Solution Approach 1:
The patent introduces an intermediary assessment mechanism that evaluates the plausibility of speed sensor readings by comparing them against expected operational relationships (engine shaft speed vs. rotor speed). This intermediary layer acts as a mediator between raw sensor data and fault detection decisions, resolving contradictions by validating readings through cross-checking with fuel flow data and operational context before declaring faults, thereby improving accuracy without requiring complex additional hardware.
Solution Approach 2:
The system implements feedback by continuously monitoring the relationship between engine shaft speed and rotor speed, and using this feedback to assess the validity of speed sensor readings. When discrepancies are detected (e.g., shaft speed greater than rotor speed when they should be coupled), the system uses this feedback to trigger fault detection or further assessment, creating a closed-loop validation system that improves fault detection accuracy through iterative verification.
2Reliability
If sensor redundancy is increased to improve fault detection reliability, then the reliability improves, but the system cost and complexity increase
Solution Approach 1:
The patent applies self-service by enabling the speed sensing system to validate its own readings through internal cross-checking mechanisms. Instead of relying on redundant sensors, the system uses its existing data (fuel flow measurements, engine shaft speed, rotor speed) to self-assess the plausibility of speed sensor readings. This self-validation approach achieves improved reliability without adding redundant sensors, thereby avoiding increased complexity and cost.
Solution Approach 2:
The system achieves multi-functionality by using existing sensors and data sources for multiple purposes: fuel flow sensors are used not only for engine control but also for assessing engine coupling status and validating speed sensor readings. This universal use of existing components improves fault detection reliability without requiring additional dedicated redundancy sensors, thereby maintaining system simplicity while enhancing reliability.
3Ease of operation
If speed sensor readings are not validated, then the system operates with simpler control logic, but incorrect control decisions may be made leading to operational safety issues
Solution Approach 1:
The patent applies preliminary action by validating speed sensor readings before they are used for control decisions. The system performs preliminary assessments by checking whether shaft speed is greater than rotor speed (when coupled), comparing readings against fuel flow-based coupling status, and evaluating the plausibility of readings before they influence control logic. This preliminary validation prevents incorrect control decisions while maintaining relatively simple control logic by filtering out erroneous readings in advance.
Data Source
AI summary
The present disclosure provides methods and systems for fault detection for a speed sensing system of a multi-engine rotorcraft. A shaft speed for a first engine and a rotor speed for at least one rotor of the multi-engine rotorcraft are obtained. The shaft speed is compared to the rotor speed. When the shaft speed is greater than the rotor speed, a first fault in the speed sensing system is detected and a first speed sensing system fault signal is issued. When the shaft speed is less than the rotor speed, a determination is made regarding whether the first engine is coupled the at least one rotor based on a fuel flow to the first engine. A second fault in the speed sensing system is detected and a second speed sensing system fault signal is issued responsive to determining that the first engine is coupled to the at least one rotor.