SensorFault Module Documentation

Toolbox: RflySim PHM

Introduction

One-sentence description: This module provides multi-type sensor fault injection capabilities for UAV PHM (Prognostics and Health Management) simulation, enabling the addition of specified fault effects to raw sensor measurements based on input fault configuration.

This module belongs to the RflySim PHM toolchain and is primarily used for semi-physical simulation validation of UAV fault diagnosis and sensor health management algorithms. It supports injecting various fault types—including offset, stuck, and gain deviation faults—into commonly used UAV flight control sensors such as barometers, GPS receivers, gyroscopes, and accelerometers. The module receives raw ideal sensor measurement data output from the PX4 flight controller, as well as external input specifying fault types and fault parameters, and outputs sensor data with injected faults for subsequent processing by flight control or PHM algorithms.

Within the RflySim simulation chain, this module resides at the downstream end of the sensor simulation chain and can interact with CopterSim’s dynamics simulation and RflySim3D’s visualization environment, providing a controllable and reproducible sensor fault simulation environment for PHM algorithm development—without requiring physical hardware to validate various sensor fault scenarios.

Port Descriptions

Input Ports (Inputs)

Port Name	Data Type	Dimension	Description
pressure	double	1×1	Raw atmospheric pressure input
windB	double	1×3	Wind velocity input in body-fixed coordinate frame
rho	double	1×1	Air density input
TempC	double	1×1	Atmospheric temperature input, in degrees Celsius
GPSPos	double	1×3	Raw GPS position input
Ab	double	1×3	Actual body-axis acceleration input, in units consistent with configured units
wb	double	1×3	Body-axis angular rate input, in radians/second
dwt	double	1×3	Body-axis angular acceleration input, in radians/second²
DCMbe	double	3×3	Direction cosine matrix for transforming forces due to payload motion into the UAV coordinate frame
Gravity	double	1×1	Gravitational acceleration input
FaultIn	double	Arbitrary	Fault input containing fault type and fault parameter information

Output Ports (Outputs)

Port Name	Data Type	Dimension	Description
Sensorout	Bus	-	Sensor output bus after fault injection, encapsulating UAV acceleration, angular rate, barometric pressure, GPS, and other sensor data

Parameter Configuration (Parameters)

This module has no configurable parameters [To be confirmed].

Parameter Setting Instructions

None.

Module Characteristics (Block Characteristics)

Characteristic	Value
Supported Data Types	double, single
Direct Feedthrough	Yes
Sample Time	Inherited
Code Generation Support	No

Data Communication Protocol

This module does not involve network communication.

Related Modules

Module Name	Description
ActuatorFault	PHM module for generating UAV actuator fault signals
PropellerFault	PHM module for generating UAV propeller fault signals
VehicleFaultInjector	PHM module for unified management of multi-fault injection in UAVs

Notes and Common Issues

• Initialization Order: This module relies on upstream raw sensor signals that have already undergone coordinate transformation and unit conversion. It must be updated only after the aircraft dynamics model and coordinate transformation modules have completed initialization; otherwise, abnormal output values may occur.
• Fault Parameter Format Matching: The fault input FaultIn must strictly match the format required by the module. The positions of parameters corresponding to different sensor faults must align with their definitions—for example, the fault value for barometer faults must be placed as the first element of the parameter vector; otherwise, the injected fault results will not match expectations.
• Sample Time Matching: This module must maintain consistent sample time with upstream sensor input modules. When configured for fixed-step simulation, the module’s sample time must be an integer multiple of the simulation step size to avoid timing misalignment in fault injection.
• Bus Output Matching: The output Sensorout is in Bus format. Downstream connected modules must use the corresponding Bus object definition. If signals are directly split, the port order must match the signal order of this module’s output bus; otherwise, incorrect sensor data may be read.
• Validity of Direction Cosine Matrix: The input DCMbe must be a valid, orthogonal, normalized direction cosine matrix. Passing a singular matrix will result in incorrect sensor output calculations after fault injection.

Changelog

• v4.10 (2024-07-25): Initial release of the SensorFault module, supporting common sensor fault injection functionality, including inner modules NoiseFun and FaultParamsExtract.