INAV blackbox variables

Overview

Blackbox is a valuable tool for analyzing the flight dynamics of our airborne vehicles and as such it can be useful for troubleshooting and debugging purposes.

In INAV we use a set of specific variables, each variable may contain multiple arrays, for example - navPos[0-2].

navPos, navVel, navTgtPos and navTgtVel each hold arrays [0-2], which represent distances due North [0], due East [1] and straight Up [2], all relative to the "point of origin". North and East are fused from accelerometer and GPS data, while Up is fused from accelerometer + barometer for multicopters and accelerometer + gps for airplanes if no barometer is available. Read the Inertial position estimator page for detailed explanation.

"Point of origin" might be different from "Home". "Home" is defined as position at the time of arming. While "Point of origin" is recorded after a valid GPS fix is aquired.

For further information about the coordinate system used please read the Coordinate systems page.

#INAV Variables

Variables listed below with a short description of each:

• navMode (navState in newer code): current mode of operation from INAV's point of view. Might be different from flight mode. Meaning vary by version, but navMode=0 and navState=1 means idle.

• navFlags: binary flags of INAV internal state: new data availability for altitude, position and heading, validity of altitude, surface distance and position, flags to indicate if pilot is adjusting altitude and position via rc input.

• navTgtPos: represents the desired position as used/calculated by INAV. When you are in PH, navTgtPos will be set to hold position coordinates.

• navPos: array of latest NEU coordinates as provided by inertial estimator. Will be slightly different from GPS/baro readings for 99% of time. Units - cm.

• navVel: same as navPos, but for estimated velocity. Units - cm/s

• navTgtVel: represents the desired velocity as used/calculated by INAV. When you are in PH, navTgtVel will be set to calculated desired velocity to reach the target position.

• navDebug: as the name suggests it is used for debugging. Meaning of these values differ all the time depending on what part of the code is currently being debugged.

Blackbox can log data either via serial port or into internal dataflash. In order to log the data into the internal flash at the moment is possible via CLI: set blackbox_device = SPIFLASH # instead of SERIAL set blackbox_rate_num = 1 set blackbox_rate_denom = 2 This will make it work and store every second value.

INAV Logging Intervals

Blackbox logs several types of frames - flight behaviour is written using I- and P-frames. I-frames are fairly big and contain absolute values, P-frames are delta-encoded to save space. Blackbox denominator only reduces P-frame rate, the I-frame rate is constant.

Originally I-frames were logged every 32 iterations, P-frame is logged every blackbox_rate_denom after I-frame. This doesn't give you exactly 1 / blackbox_rate_denom rate, i.e. for 1/16 - 1/31 rates it's going to be c. 16 iterations between frames on average.

For INAV 1.6 and later, the I-frame interval is set dynamically at 1/32, 1/64, 1/128 and 1/256 based on the blackbox_rate_denom chosen.

For example, if a blackbox_rate_denom of 50 is used, INav will select 64 as the I-frame interval, meaning c. 1/32 actual logging rate.

Explanation of all the parameters

Name of field in txt file	Name in Blackbox Log Viewer	Explanation	.	..
loopIteration	not used	counter from main loop
time (us)	x-axis of diagram	real time in micoseconds
axisRate[0]	gyros[roll] (.. deg/s)	rotation rate	roll	deg/sec
axisRate[1]	gyros[pitch] (.. deg/s)	rotation rate	pitch	deg/sec
axisRate[2]	gyros[yaw] (.. deg/s)	rotation rate	yaw	deg/sec
axisP[0]	PID_P[roll]	PID controller	roll	P
axisP[1]	PID_P[pitch]	PID controller	pitch	P
axisP[2]	PID_P[yaw]	PID controller	yaw	P
axisI[0]	PID_I[roll]	PID controller	roll	I
axisI[1]	PID_I[pitch]	PID controller	pitch	I
axisI[2]	PID_I[yaw]	PID controller	yaw	I
axisD[0]	PID_D[roll]	PID controller	roll	D
axisD[1]	PID_D[pitch]	PID controller	pitch	D
axisD[2]	PID_D[yaw]	PID controller	yaw	D
mcPosAxisP[0]	mcPosAxisP[0]	multicopter position	north	cm
mcPosAxisP[1]	mcPosAxisP[1]	multicopter position	east	cm
mcPosAxisP[2]	mcPosAxisP[2]	multicopter position	vertical	cm
mcVelAxisP[0]	mcVelAxisP[0]	multicopter velocity	north	cm/sec
mcVelAxisP[1]	mcVelAxisP[1]	multicopter velocity	east	cm/sec
mcVelAxisP[2]	mcVelAxisP[2]	multicopter velocity	vertical	cm/sec
mcVelAxisI[0]	mcVelAxisI[0]	multicopter velocity	north	cm/sec
mcVelAxisI[1]	mcVelAxisI[1]	multicopter velocity	east	cm/sec
mcVelAxisI[2]	mcVelAxisI[2]	multicopter velocity	vertical	cm/sec
mcVelAxisD[0]	mcVelAxisD[0]	multicopter velocity	north	cm/sec
mcVelAxisD[1]	mcVelAxisD[1]	multicopter velocity	east	cm/sec
mcVelAxisD[2]	mcVelAxisD[2]	multicopter velocity	vertical	cm/sec
mcVelAxisOut[0]	mcVelAxisOut[0]	multicopter velocity	north	cm/sec
mcVelAxisOut[1]	mcVelAxisOut[1]	multicopter velocity	east	cm/sec
mcVelAxisOut[2]	mcVelAxisOut[2]	multicopter velocity	vertical	cm/sec
mcSurfaceP	mcSurfaceP	multicopter surface mode		P
mcSurfaceI	mcSurfaceI	multicopter surface mode		I
mcSurfaceD	mcSurfaceD	multicopter surface mode		D
mcSurfaceOut	mcSurfaceOut	multicopter surface mode
rcData[0]	rcData[0]	received rc signal	roll	1000-2000 µs
rcData[1]	rcData[1]	received rc signal	pitch	1000-2000 µs
rcData[2]	rcData[2]	received rc signal	yaw	1000-2000 µs
rcData[3]	rcData[3]	received rc signal	throttle	1000-2000 µs
rcCommand[0]	rcCommand[0]	stabilized control command	roll	1000-2000 µs
rcCommand[1]	rcCommand[1]	stabilized control command	pitch	1000-2000 µs
rcCommand[2]	rcCommand[2]	stabilized control command	yaw	1000-2000 µs
rcCommand[3]	rcCommand[3]	stabilized control command	throttle	1000-2000 µs
vbat	vbat	voltage of flight battery		volts
amperage		system current drain		amps
magADC[0]	magADC[0]	compass	roll
magADC[1]	magADC[1]	compass	pitch
magADC[2]	magADC[2]	compass	yaw
BaroAlt (cm)	BaroAlt (cm)	altitude(barometer)		cm
gyroADC[0]	gyroADC[0]	rotation(gyro)	roll	deg/sec
gyroADC[1]	gyroADC[1]	rotation(gyro)	pitch	deg/sec
gyroADC[2]	gyroADC[2]	rotation(gyro)	yaw	deg/sec
accSmooth[0]	acc[x]	acceleration	north	ADC * normalised 1g
accSmooth[1]	acc[y]	acceleration	east	ADC * normalised 1g
accSmooth[2]	acc[z]	acceleration	vertical	ADC * normalised 1g
attitude[0]	attitude[0]	heading	roll	0-3600 deg/10
attitude[1]	attitude[1]	heading	pitch	0-3600 deg/10
attitude[2]	attitude[2]	heading	yaw	0-3600 deg/10
motor[0]	motor[0]	output to motor ESC	0	1000-2000 µs
motor[1]	motor[1]	output to motor ESC	1	1000-2000 µs
motor[2]	motor[2]	output to motor ESC	2	1000-2000 µs
motor[3]	motor[3]	output to motor ESC	3	1000-2000 µs
navState		navigation control state
navFlags		navigation data trusted
navEPH		Std deviation horizontal position error		meters
navEPV		Std deviation of vertical position error		meters
navPos[0]	navPos[0]	position of copter	north	cm
navPos[1]	navPos[1]	position of copter	east	cm
navPos[2]	navPos[2]	position of copter	vertical	cm
navVel[0]	navVel[0]	velocity of copter	north	cm/s
navVel[1]	navVel[1]	velocity of copter	east	cm/s
navVel[2]	navVel[2]	velocity of copter	vertical	cm/s
navAcc[0]	navAcc[0]	acceleration of copter	north	cm/s/s
navAcc[1]	navAcc[1]	acceleration of copter	east	cm/s/s
navAcc[2]	navAcc[2]	acceleration of copter	vertical	cm/s/s
navTgtVel[0]	navTgtVel[0]	target value: velocity	north	cm/s
navTgtVel[1]	navTgtVel[1]	target value: velocity	east	cm/s
navTgtVel[2]	navTgtVel[2]	target value: velocity	vertical	cm/s
navTgtPos[0]	navTgtPos[0]	target value: position	north	cm
navTgtPos[1]	navTgtPos[1]	target value: position	east	cm
navTgtPos[2]	navTgtPos[2]	target value: position	vertical	cm
navTgtHdg		active heading computation	horizontal
navSurf[0]	navSurf[0]
flightModeFlags (flags)		active modes
stateFlags (flags)		active control states
failsafePhase (flags)
rxSignalReceived
rxFlightChannelsValid
hwHealthStatus		active sensor communication
powerSupplyImpedance		flight battery internal resistance		mΩ
sagCompensatedVBat		load compensated battery voltage		volts
wind[0]		wind force X axis	north	m/s
wind[1]		wind force Y axis	east	m/s
wind[2]		wind force Z axis	vertical	m/s
windHeading				degrees
windVelocity				m/s
GPS_home[0]		latitude		degrees
GPS_home[1]		longitude		degrees
GPS_fixType		GPS_fixType
GPS_numSat		number of sats
GPS_coord[0]		latitude		degrees
GPS_coord[1]		longitude		degrees
GPS_altitude		GPS_altitude		m
GPS_speed		velocity		m/s
GPS ground course		ground course heading		degrees
GPS_hdop		quality of GPS fix