6.9 KiB
+++ title = "Ardupilot setup checklist" weight = 2 sort_by = "weight" insert_anchor_links = "right" +++ This is a short guide for setting up ArduPilot on a flying wing. I use an Omnibus F4 that was previously set up for INAV (so motor on 1, elevons on 3/4), so most of this guide will be geared to that. If you use a different controller, your mileage may vary.
You should keep the full list of ArduPilot parameters open, for your reference while tuning.
Hardware setup
The values in this section are specific to the Omnibus F4, but the settings aren't, so you'll usually need to adjust your outputs to your specific configuration but you probably won't need to skip many of the steps here.
- Connect GPS to UART 6 (SERIAL4). You don't need to do anything else for GPS, it should work out of the box.
- Connect Fport to a UART. I chose UART 3 (SERIAL2). If you want to use UART 1, you should set the RC input jumper to PPM on the F4 to disconnect the SBUS inverter from the pin.
- To get Fport working with UART 3, you need to set
BRD_ALT_CONFIG=1
, to get UART 3 to act like a UART instead of I2C on the Omnibus F4. - Change the board orientation with
AHRS_ORIENTATION
. - Set the following for Fport on UART 3:
SERIAL2_PROTOCOL = 23 (RCIN) SERIAL2_BAUD=115 SERIAL2_OPTION=4
- Once Fport works, reverse the elevator with
RC2_REVERSED=1
. - Set up your servo functions and trims:
All these values are necessary, because usually theSERVO1_FUNCTION=70 SERVO1_MIN=1000 SERVO1_MAX=2000 SERVO1_TRIM=1000 SERVO3_FUNCTION=77 SERVO3_MIN=1000 SERVO3_MAX=2000 SERVO3_TRIM=1500 SERVO4_FUNCTION=78 SERVO4_MIN=1000 SERVO4_MAX=2000 SERVO4_TRIM=1500
SERVOn_TRIM
won't be at 1500. - Set
SERVO_BLH_OTYPE=4
for DShot150 andSERVO_BLH_MASK=1
to enable it for the motor. - Set
COMPASS_ENABLE=0
if you don't have a compass, otherwise calibrate it (not detailed here). - Set
TERRAIN_ENABLE=0
to get rid of the terrain warning. - Set the board orientation with
AHRS_TRIM_Y
and check that FBWA mode flies level. - If you don't use logging, set
LOG_BACKEND_TYPE=0
. - Check the preflight errors to warn on, though usually leaving it set to "all" is fine.
- Set up the OSD (Mission Planner has a very nice UI for that). Keep in mind that ArduPilot's airspeed and windspeed estimation are quite good, so you may want to add those even if you don't have an airspeed sensor. You may also want to set up multiple screens, I use a potentiometer to switch between the four different screens of the OSD:
- One with everything on (for debugging), which is also set as the
OSD_ARM_SCR
/OSD_DSARM_SCR
. - One with the artificial horizon, system messages and some basic info like RSSI, battery, ground speed and altitude.
- A minimal screen with just system messages and battery/RSSI/speed/altitude.
- A screen with just system messages, for when I want to enjoy the scenery.
- One with everything on (for debugging), which is also set as the
Radio-related
- Set your radio channels to AETR and run the radio calibration in the calibration section of ArduPilot.
- Add arming switch with
RCn_OPTION=41
(on whatever channel you want). - Set up modes, possibly having switches override the mode channel to the mode you want.
What I do is set a given channel as the mode channel, and make that channel always output -100% on the radio. Then, I set up channel overrides for each switch, keeping in mind that overrides in OpenTX are executed in order (so the bottom override has the highest priority).
That way, I set MANUAL/ACRO/FBWA to be lowest priority (on the same switch), then CRUISE to override those, then LOITER, AUTO, AUTOTUNE in that order.
Finally, I add RTL to a switch on its own channel, with the highest priority of all overrides. I also add an override for that switch to the mode channel to -100%, so moving any other stick won't exit RTL mode as long as RTL is enabled.
Auto modes
- Set
SERVO_AUTO_TRIM=1
so the aircraft trims itself while flying. - Set
FS_SHORT_ACTN
/FS_SHORT_TIMEOUT
/FS_LONG_ACTN
/FS_LONG_TIMEOUT
. I tend to disable the short action and set long to RTL. - Set
RTL_CLIMB_MIN=30
so the aircraft climbs first before starting to return to home. - Set
ACRO_LOCKING=1
to avoid drifting when you aren't moving the sticks. - Change
AUTOTUNE_LEVEL
according to how aggressive you want the tune. - Set
ACRO_PITCH_RATE
/ACRO_ROLL_RATE
according to your craft. - Set
THR_PASS_STAB=1
so you have total throttle control in ACRO/FBWA/STABILIZE. - Set
ARSPD_FBW_MIN
/ARSPD_FBW_MAX
to the minimum and maximum airspeed you want auto modes to fly.
Auto takeoff
- Change
TKOFF_THR_MAX
to the desired max takeoff throttle. - Change
TKOFF_ALT
to the altitude you want takeoff to reach. - Set
TRH_SUPP_MAN=1
so you can manually set the autolaunch "idle" throttle (before the throw). - Set
TKOFF_THR_MINACC=18
for the takeoff throw to activate takeoff with a minimum of 2g. - set
TKOFF_LVL_PITCH
to your desired angle (20 is a good value). - Set
TKOFF_THR_DELAY
to the number of deciseconds that you want the motor to wait before it starts up. - Potentially set
TKOFF_THR_SLEW=127
to make the throttle spin up to full faster (within 0.8 sec).
Tuning the TECS
To tune the TECS, follow this procedure:
- Set
THR_MAX
to the max throttle you want the system to use in altitude controlled modes. - Set
TRIM_ARSPD_CM
to the desired cruise air speed. - Set
TRIM_THROTTLE
to fly atTRIM_ARSPD_CM
while level. - Set
TECS_PITCH_MAX
to the maximum angle that can achieveTRIM_ARSPD_CM
atTHR_MAX
, and setTECS_CLMB_MAX
to the maximum climb rate. - Set
TECS_PITCH_MIN
andTECS_SINK_MAX
.
In the field
- Run an autotune.
- Note a comfortable airspeed so you can tune
TRIM_ARSPD_CM
later. - Note your stall airspeed so you can set
ARSPD_FBW_MIN
later. - Note your maximum airspeed at
THR_MAX
so you can setARSPD_FBW_MAX
later. - Fly and check at what max pitch angle up you can achieve
TRIM_ARSPD_CM
with throttle atTHR_MAX
. - Fly and check at what max pitch angle down you can achieve
TRIM_ARSPD_CM
with throttle at 0, so you can setTECS_PITCH_MIN
. - Note the throttle percentage that will fly at
TRIM_ARSPD_CM
while level (so you can tuneTRIM_THROTTLE
later). - Fly in FBWA and see if you're gaining/losing altitude. Pitch up/down to fly level, check the pitch on the OSD, and use the formula
old_value+pitch*π/180
to get the new value (in radians).
(Many thanks to Michel Pastor for his help with everything in this note.)
Last updated on January 08, 2021. For any questions/feedback, email me at hi@stavros.io.