[[searchwing-ardupilot-parameters]]

Ardupilot Parameter Setup

Parametername Value Description Remark
BRD_SAFETYENABLE 0 Disable the safety switch Safety switch is not accessible, because it is inside the fuselage
ARMING_RUDDER 2 Arm and Disarm with rudder Default is that you can only arm but not disarm with rudder
BRD_SAFETY_MASK 27 Servo 1,2,4,5 enabled These servos can move also in safe state - NOT REQUIRED???
INS_GYRO_CAL 0 Disable Gyro Calibration at startup This prevents INS calibration at startup
ARSPD_TYPE 0 No Airspeed Pitot Tube Disable the Pitottube airspeed sensor (we don't have one)
COMPASS_USE2 0 Disable PixRacer compass Disable the PixRacer internal compass
COMPASS_USE3 0 Disable PixRacer compass Disable the PixRacer internal compass

Is the safety_mask maybe not required because the pixracer is always in safe state? Safe and disarmed is different?

Parametername Value Description Remark
SERVO1_FUNCTION 4 Aileron left
SERVO1_REVERSED 1 Reverse the servo
SERVO2_FUNCTION 79 VTAIL left
SERVO2_REVERSED 0 Normal
SERVO3_FUNCTION 70 Throttle
SERVO3_REVERSED 0 Reverse the servo
SERVO4_FUNCTION 80 VTAIL right
SERVO4_REVERSED 1 Reverse servo
SERVO5_FUNCTION 4 Aileron right
SERVO5_REVERSED 1 Reversed
Servo ranges for servo 1,2,4,5 (aileron and vtail)
SERVOx_MIN 1000 Minimum servo value Default is 1100 - too high
SERVOx_MAX 2000 Maximum servo value Default is 1900 - too low
SERVOx_TRIM 1500 Default value Leitwerk mitte
Servo ranges for throttle
SERVO3_MIN 900 Minimum servo value CHECK THIS!!! Maybe 950 to be able to arm
SERVO3_MAX 2000 Maximum servo value Default is 1900 - too low
SERVO3_TRIM 900 Default value zero throttle
Parametername Value Description Remark
MIXING_GAIN 0.75 Mixing of pitch and rudder to vtail Default is 0.5 - full pitch will yield only 50 percent of vtail servo output
Parametername Value Description Remark
SERIAL4_BAUD 57 57600 Baud
SERIAL4_PROTOCOL 10 FrSky SPort Passthrough (OpenTX) Format for the FrSyk Telemetry

Aktiviert die FrSky Telemetrie auf dem FrSky Port des Pixracers

Metadata consist of GPS / Timestamp

Parametername Value Description Remark
SERIAL2_BAUD 9 9600 Baud reduced to 9600 as otherwise no wifi with MAVESP connection possible
SERIAL2_PROTOCOL 2 MAVLink2 Mavlink2 needed for PLAY_TUNE
SR2_RAW_SENS 0 0 Hz no raw data needed
SR2_EXT_STAT 1 1 Hz
SR2_RC_CHAN 0 0 Hz
SR2_RAW_CTRL 0 0 Hz
SR2_POSITION 5 5 Hz Contains GLOBAL_POSITION_INT, LOCAL_POSITION_NED messages
SR2_EXTRA1 5 5 Hz Contains ATTITUDE message
SR2_EXTRA2 0 0 Hz
SR2_EXTRA3 1 1 Hz Contains SYSTEM_TIME message
SR2_PARAMS 0 0 Hz
SR2_ADSB 0 0 Hz

Several bits can be set for logging of different informations: Log Bitmask Description

Enabled all (==65535) results in following per message data sum in bytes for a 20 minute flight:

  • The PID, NKF(EKF) and IMU take a lot of space.
  • The PID and EKF is saved using the “attitude” bit in the logging parameter setting (see Code). For the attitude two settings are available: Fast (50Hz), Medium(10Hz) according to LINK. I think 10Hz could be enough for us. But in the Code actually the Logging is done with 25Hz (see Code)
  • IMU logging could be disabled, as its already triggerd by attitude logging anyway (see Code), but with less data amount. UPDATE: Actually IMU also loggs the BARO, so it should not be disabled (see INFO.
  • TECS (Total Energy Control System) controls altitude vs speed and is important and should be enabled.
  • CTUN Logs contain baro and should be enabled.
  • NTUN Logs navigation tuning info at 10 Hz and should be enabled.

This results in the following Table (according to Log Bitmask Description):

Bit Meaning Enabled
0 ATTITUDE_FAST(50Hz) OFF
1 ATTITUDE_MED(10Hz) ON
2 GPS ON
3 PM ON
4 CTUN ON
5 NTUN ON
6 MODE ON
7 IMU ON
8 CMD ON
9 CURRENT ON
10 COMPASS ON
11 TECS ON
12 CAMERA OFF
13 RC ON
14 SONAR OFF
15 ARM/DISARM ON
19 IMU_RAW OFF
20 ATTITUDE_FULLRATE OFF

This results into the following parameter values. In the remarks you can see empirical Results for some settings from ArduPlane Simulator.

Parametername Value Description Remark
LOG_BITMASK 65535 Log all ~3.04 MB/Min Log
LOG_BITMASK 45054 Log from table above (IMU disabled) TODO
LOG_BITMASK TODO Log from table above (IMU enabled) TODO
LOG_BITMASK 2 Log only attitude Medium ~1.75 MB/Min Log
Parametername Value Description Remark
SERIAL5_BAUD 921 921600 Baud
SERIAL5_PROTOCOL 2 MAVLink2
  1	1	BATT_AMP_PERVLT	24.0	9
  1	1	BATT_AMP_OFFSET	-0.07	9
  1	1	BATT_CURR_PIN	3	2
  1	1	BATT_MONITOR	4	2
  1	1	BATT_SERIAL_NUM	-1	6
  1	1	BATT_VOLT_MULT	10.213	9
  1	1	BATT_VOLT_PIN	2	2
  1	1	BATT_WATT_MAX	0	4
  
  

To measure the RPM of the motor we can use a BACK-EMF Measurement from 2 of the 3 motorcables. For more info check out the page:

https://www.hobbywingdirect.com/products/rpm-sensor

We connected the output pins to a AUX pin of the FC. Check out the info from Ardupilot for some info regarding the following config:

https://ardupilot.org/copter/docs/common-rpm.html

Parametername Value Description Remark
RPM_MAX 100000.000000000000000000
RPM_MIN 10.000000000000000000
RPM_MIN_QUAL 0.100000001490116119
RPM_PIN Pin PIN depending on FC
RPM_SCALING 0.143 check the hints below for this setting
RPM_TYPE 2 AUX Type needs to be AUX to calc using the given sensor

The RPM in general can be calculated using the formula from https://www.radiocontrolinfo.com/brushless-motor-efficiency/measuring-motor-rpm/ :

RPM = ( 120 x Frequency ) / # of Motor Poles

Thats because:

The AC current that is produced alternates each time 2 magnetic poles pass by a winding in the stator.

As Ardupilot measures the periode duration dt_avg of the sensor rectangular signal, and calculates the RPM using

float rpm = scaling * (1.0e6 / dt_avg) * 60;

the scaling needs to correct this using

SCALING = ( 1 / # of Motor Poles ) * 2

For the Extron 800KV Motor , we have 14 Poles.

(David, Mülli, Simon)

  1	1	ARSPD_FBW_MAX	28	4
  1	1	ARSPD_FBW_MIN	12	4

Min and max airspeed - default 22 / 9

  1	1	LIM_PITCH_MAX	3000	4
  1	1	LIM_PITCH_MIN	-2000	4

default 2000, -2500

  1	1	MIN_GNDSPD_CM	800	6

If min groundspeed is net met, plane increases throttle

  1	1	NAVL1_DAMPING	0.800000023841857910	9	
  1	1	NAVL1_PERIOD	17.000000000000000000	9

This is the default value for NAVL1 (Beck, 27.2.20)

  1	1	PTCH2SRV_RLL	1.299999952316284180	9

This parameter controls how much elevator to add in turns to keep the nose level. Many aircraft require a small change to this parameter from the default of 1.0. (autotune)

  1	1	TECS_CLMB_MAX	6.500000000000000000	9
  1	1	TECS_SINK_MAX	5.000000000000000000	9
  1	1	WP_LOITER_RAD	60	4	
  1	1	WP_RADIUS	90	4

WP settings are set to default (Beck, 27.2.20)

# Modes Setup (Special Switches)

to be done.

  • searchwing-ardupilot-parameters.txt
  • Last modified: 2021/11/30 19:21
  • by wf68spef