tempMeasurement#

Executive Summary#

Models the addition of noise, bias, and faults to temperature measurements.

Message Connection Descriptions#

The following table lists all module input and output messages. The module msg connection is set by the user from python. The msg type contains a link to the message structure definition, while the description provides information on what this message is used for.

Module I/O Messages#
Msg Variable Name	Msg Type	Description
tempInMsg	TemperatureMsgPayload	True temperature measurement
tempOutMsg	TemperatureMsgPayload	Sensed temperature measurement with corruptions

Detailed Module Description#

This module simulates the corruption of a true thermal measurement by noise, bias, and three faults:

TEMP_FAULT_STUCK_VALUE is faulty behavior where the measurement sticks to a specific value
TEMP_FAULT_STUCK_CURRENT fixes the measurement to the value
TEMP_FAULT_SPIKING is faulty behavior where the measurement spikes to a specified multiplier times the actual value, with a given probability
TEMP_FAULT_NOMINAL has no faulty behavior but may still have noise and bias

User Guide#

Fault Parameters#

This module has several parameters that are set to default values:

Default Module Parameters#
Parameter	Description	Default Value
faultState	Sets the fault status.	`TEMP_FAULT_NOMINAL`
senBias	Sets the bias value.	0.0
senNoiseStd	Sets the standard deviation for sensor noise.	0.0
walkBounds	Sets the random walk bounds for sensor noise.	1E-15
stuckValue	Temperature at which the reading is stuck for fault mode `TEMP_FAULT_STUCK_VALUE`.	0.0
spikeProbability	Probability of a spike when in fault mode `TEMP_FAULT_SPIKING`. Between 0 and 1.	0.1
spikeAmount	Sensed temperature multiplier when spiking for fault mode `TEMP_FAULT_SPIKING`.	2.0

Module Setup#

The module is created in python using, for example:

tempMeasurementModel = tempMeasurement.TempMeasurement()
tempMeasurementModel.modelTag = 'tempMeasModel'

A sample setup is done using:

tempMeasurementModel.senBias = 1.0  # [C] bias amount
tempMeasurementModel.senNoiseStd = 5.0  # [C] noise standard devation
tempMeasurementModel.walkBounds = 2.0  #
tempMeasurementModel.stuckValue = 10.0  # [C] if the sensor gets stuck, stuck at 10 degrees C
tempMeasurementModel.spikeProbability = 0.3  # [-] 30% chance of spiking at each time step
tempMeasurementModel.spikeAmount = 10.0  # [-] 10x the actual sensed value if the spike happens

The incomping temperature message must be connected to the module:

tempMeasurementModel.tempInMsg.subscribeTo(sensorThermalModel.temperatureOutMsg)

The fault state is changed by the user to spiking, for example, by setting:

tempMeasurementModel.faultState = tempMeasurement.TEMP_FAULT_SPIKING

Class TempMeasurement#

class TempMeasurement : public SysModel#

Models a sensor to add noise, bias, and faults to temperature measurements.

Public Functions

TempMeasurement()#: This is the constructor for the module class. It sets default variable values and initializes the various parts of the model. Don’t allow random walk by default.

void reset(uint64_t currentSimNanos)#

This method is used to reset the module and checks that required input messages are connected.

Returns:: void

void updateState(uint64_t currentSimNanos)#

This is the main method that gets called every time the module is updated.

Returns:: void

Public Members

ReadFunctor<TemperatureMsgPayload> tempInMsg#: True temperature measurement.

Message<TemperatureMsgPayload> tempOutMsg#: Sensed temperature measurement.

BSKLogger bskLogger#: — BSK Logging

TempFaultState_t faultState#: [-] Fault status variable

double senBias = {}#: [-] Sensor bias value

double senNoiseStd = {}#: [-] Sensor noise value

double walkBounds#: [-] Gauss Markov walk bounds

double stuckValue = {}#: [C] Value for temp sensor to get stuck at

double spikeProbability#: [-] Probability of spiking at each time step (between 0 and 1)

double spikeAmount#: [-] Spike multiplier