The following items are installed in the plane.
APM APM HKPilot Mega V2.5 flight controller board.
UBLOX GPS module.
3DR 915MHz telemetry transmitter.
Air speed sensor.
FrSky X8R receiver.
FrSky FLVSS battery monitor.
The battery sits in a plastic tray attached to the base of the instrument bay with adhesive backed Velcro. The battery slides into this tray under the component board and is secured with two loops of double sided Velcro.
Arduplane version 3.4.0 is the final version of firmware for the APM 2.5 Flight Controller. Development of the firmware has stopped because the APM board has reached its capacity.
The 3.4.0 release notes are here.
The release note in the arduplane 3.4.0 discussion blog is here.
The arduplane 3.4.0 discussion blog is here
On the Taranis radio, to set up a 6 position switch as a mode switch, refer to Application Note 24.
Refer to Application Note 2 : ‘Timer – Use a Switch to Reset, Pause and Run’.
Refer to Application Note 7: ‘Use a Timer To Record Accumulated Flight Time’.
Refer to Application Note 3: ‘Throttle Disable with Sticky Throttle Option’.
Refer to Application Note 5: ‘Control Audio Volume With A Slider’.
Elevon mixing is done in the transmitter. The left elevon is channel 2 and the right elevon is channel 3.
In the mixer, set the weights and sources as follows.
On the Outputs screen, channel 2 direction is normal and channel 3 direction is reversed.
Elevons must also be selected on the Radio Calibration screen of Mission Planner here.
The rudder channel, channel 4, is used for steering the nose wheel and arming the motor.
This aircraft has no rudder.
Refer to Application Note 19: ‘Voltage Sensor – FLVSS’
On the Taranis radio, switch SC controls the geofence as follows.
Switch SC↑ is geofence off.
Switch SC- is geofence enabled.
Switch SC↓ is geofence enabled and reset.
The geofence enable channel in the Taranis is channel 7.
When channel 7 = -100%, the geofence is disabled. When channel 7 = 0 or +100%, the geofence is enabled.
The mixer controls channel 7 is set as follows.
CV2 is as follows.
The geofence reset channel in the Taranis is channel 6.
When channel 6 = 0 or -100%, the geofence reset is disabled. When channel 6 =+100%, the geofence reset is enabled.
The mixer controls channel 6 as follows.
CV3 is as follows.
Geofence Audio Files
Create these audio files and transfer them to the SD card folder SOUNDS / en.
Use these special functions to play the geofence files. For this example, SF11 through SF13 are used.
Check Geofence Control
In each of the SC positions, check the channel 7 value, the channel 6 value and the audio announcement as described in this table
Mission Planner version 1.3.58 is used in the descriptions below.
On the Taranis radio, select Manual Mode using the 6 position switch.
In Manual Mode, the Taranis channels go straight to the aircraft outputs. In the Taranis radio on the Outputs screen, set normal or reverse for each channel so the throttle, ailerons and rudder/steering move correctly. On the Taranis Outputs screen, I set the channels as follow.
Channel 1 (Throttle) : Normal
Channel 2 (Left Elevon) : Reversed.
Channel 3 (Right elevon) : Normal.
Channel 4 (Rudder/Steering) : Reversed.
The modes programmed into the Taranis radio above must now be set up in the APM. The modes are summarized in this table.
Assigning modes to the mode numbers is done in Mission Planner on the ‘Config/Tuning’ page under ‘Flight Modes’. For each flight mode, select the mode name from the pull down menu. Press ‘Complete’ to write the modes into the APM.
Check that the mode switch selects the correct mode on the ‘Flight Data’ screen. Select each of the 6 switch positions and check the display on the artificial horizon displays the correct mode.
(Refer here for Arduplane documentation on radio calibration.)
Channel Range Calibration
The radio calibration procedure tells the APM what PWM ranges for each channel are sent from the transmitter.
Initially, the Radio Calibration is displayed as follows.
Red range limits lines are displayed on each channel display.
Ensure each of the following channels is moved to their maximum and minimum ranges.
Radio Channel 5 is not used.
Radio Channel 6 : switch SC (Geofence reset).
Radio Channel 7 : switch SC (Geofence enable).
Radio Channel 8 : switch S3 (Mode).
The following message is displayed.
Set the sticks as instructed and click OK.
The status shows Completed, the results are saved and the following window shows the channel ranges.
This completes the calibration procedure.
Stabilisation Control Check
In Mission Planner, connect to the APM. On the Initial Setup Screen select Mandatory Hardware – Radio Calibration.
On the Taranis radio, select Fly By Wire A (FBWA) Mode using the 6 position switch. In FBWA mode, the APM controls the outputs.
On the Radio Calibration screen, tick the Elevons box.
Roll the aircraft. Set the reversing of each elevon so they respond to hold the aircraft level.
Pitch the aircraft. Check that the elevens also respond to hold the aircraft level.
My aircraft is set as follows.
(Refer here for Arduplane documentation on ESC Calibration)
Perform the accelerometer calibration using instructions in the Arduplane documentation.
After each position, click ‘Click When Done’ until ‘Calibration successful’ is displayed.
1. Place the APM on a level surface.
2. Place the APM on its left side.
3. Place the APM on its right side.
4. Place the APM nose down.
5. Place the APM nose up.
6, Place the APM on its back.
(Refer here for Arduplane documentation on compass calibration.)
On the Initial Setup screen, select Mandatory hardware then Compass.
Click OK and the following window is displayed.
(Refer here for Arduplane documentation on plane failsafe.)
I have set the failsafe parameters as described in the following table.
The action chosen in the table above is described as follows.
In stabilisation modes (AUTO, GUIDED or LOITER), if a failsafe event is present for >1.5 seconds, CIRCLE mode is entered.
If the failsafe event is removed, then the previous stabilisation mode is resumed.
If the failsafe event continues for >20 seconds, then RTL mode is entered.
The target altitude used by the ‘RTL’ command is the parameter ALT_HOLD_RTL. Its units are centimetres and its value is 10,000. (100m)
Failsafe states can be entered by the following trigger events.
Transmitter Signal Loss Failsafe is called Throttle Failsafe.
Enable it by setting THR_FAILSAFE = 1. (0=Disabled, 1=Enabled)
Set the Receiver Throttle Failsafe PWM
The receiver must be set up so that when it loses signal, the throttle output PWM is less than the THR_FS_VALUE of 950uS. The following procedure sets the FrSky X8R receiver throttle failsafe PWM as required.
Check Transmitter Signal Loss
Turn on the Transmitter and the aircraft. Connect the GCS and monitor the mode.
With the mode in LOITER, turn off the transmitter. Check the APM mode changes to CIRCLE for 20 seconds, then to RTL.
If the APM stops receiving MAVLink heartbeat messages for more than the FS_SHORT_TIMEOUT and/or the FS_LONG_TIMEOUT, then the FS_SHORT_ACTN and/or the FS_LONG_ACTN action(s) are triggered.
The GCS failsafe is enabled using the FS_GCS_ENABLE parameter. (0 = disabled, 1 = enabled)
If the GPS signal is lost for more than 20 seconds, then Dead Reckoning mode is used until the GPS signal is restored.
If the battery voltage drops below FS_BATT_VOLTAGE, then the APM mode changes to RTL.
If FS_BATT_VOLTAGE = 0, battery voltage failsafe is disabled.
I have set FS_BATT_VOLTAGE = 0. (I use a FrSky FLVSS battery monitor with alarms in the Taranis instead.)
If the battery capacity remaining is less than FS_BATT_MAH, then the APM mode changes to RTL.
If FS_BATT_MAH = 0, battery charge failsafe is disabled.
I have set FS_BATT_MAH = 0.
From the Config/Tuning screen, select Basic Tuning to display the tuning parameters.
These are my current settings.
In Autotune mode, the PID parameters of roll and pitch are set automatically when rapid full manual roll and pitch movements are made. At least 20 movements are required because each parameter is only changed by up to 5% after each movements. Changes are saved every 10 seconds.
AUTOTUNE_LEVEL controls how aggressive the tuning is to be. Default value = 6.
The air speed during autotune must be greater than ARSPD_FBW_MIN, currently set to 9 m/S.(32.4 kph)
Automatic Tuning Procedure
1. Start with NAVL1_PERIOD = 25.
2. From the GCS or the transmitter, select AUTOTUNE mode before taking off or during flight.
3. Roll the plane to the left and right with at least 80% rapid stick movement at least 20 times with about 2 second delay between movements.
4. Pitch the plane up and down with at least 80% rapid stick movement at least 20 times with about 2 second delay between movements.
5. Every 10 seconds, the autotune parameters are saved.
6. Set NAVL1_PERIOD = 18.
7. In AUTO mode, fly a rectangular mission and reduce NAVL1_PERIOD by 1 at a time until the turning rate is optimum.
The PTCH2SRV_RLL parameter determines how much up elevator is added in turns to keep the nose level.
PTCH2SRV_RLL default value is 1.0.
PTCH2SRV_RLL Tuning Procedure
1. In FBWA mode, fly in a tight circle with aileron stick hard over and centred elevator.
2. If the plane gains altitude, reduce PTCH2SRV_RLL by .05 at a time to a minimum of 0.7.
3. If the plane loses altitude, increase PTCH2SRV_RLL by .05 at a time to a maximum of 1.5.
I set PTCH2SRV_RLL = 1.0.
(Refer here for Arduplane documentation on arming.)
Arming parameters are set as follows.
Arming is allowed only in Manual mode and is requested in two ways.
1. Hold rudder to the left for two seconds with throttle at minimum, or
2. Press Arm on the GCS (Ground Control Station).
NOTE: Arming with the rudder requires left rudder because the rudder channel is reversed in the transmitter.
Disarming is allowed only in Manual mode and is requested in two ways.
1. Hold rudder to the right for two seconds with throttle at minimum, or
2. Press Disarm on the GCS (Ground Control Station).
NOTE: Disarming with the rudder requires right rudder because the rudder channel is reversed in the transmitter.
Battery level check is used only if configured.
APM does not have a hardware safety switch and is not required.
(Refer here for Arduplane documentation on sensor testing.)
On the Mission Planner Flight Data screen, any of the data items in the APM can be displayed on graphs in real time.
To display a list of all possible sensor data, double click the left mouse button anywhere on the graph.
Tick the box of the variable to be displayed on the graph.
Magnetic field strength graph of compasses 1 & 2.
Moving a magnet close to the remote compass increases magfield from 500 to over 2000.
Moving a magnet close to the on board compass increases magfield2 from 560 to over 4000.
(Refer here for Arduplane documentation on power module configuration.)
The power module was sourced from UAV Robotics here.
In Mission Planner, select ‘Initial Setup’, ‘Optional Hardware’ then ‘Battery Monitor’ and set up as follows.
(Refer here for Arduplane documentation on Telemetry Radio Configuration.)
The radio Telemetry Kit 915MHz was sourced from Hobby King here.
This is compatible with the 3Drobotics 3DR Radio Set here.
The aircraft was connected according to the Quick Start Guide.
From the Initial Setup screen, select Optional Hardware then Sik Radio.
Disconnect the Mavlink connection. Press Load Settings. After a few seconds, the current configuration values are displayed as follows.
Here is my current configuration.
These parameters are stored in the local radio module and the remote radio module. (They are not stored in the APM.)
Ensure the following parameters are set.
For two radios to communicate, the following must be the same at both ends of the link:
- radio firmware version
- ECC setting
- LBT_RSSI setting
- MAX_WINDOW setting
(Refer here for Arduplane documentation on airspeed sensor.)
The airspeed sensor was sourced from UAV Robotics, here
The airspeed sensor is connected to the A0 port on the APM board.
From the Initial Setup screen, select Optional Hardware then Airspeed.
Configure as follows.
Check operation on the Mission Planner Flight Data screen.
To calibrate the airspeed sensor, in the parameter list set ARSPD_AUTOCAL = 1. The default value = 0.
If this is enabled then the APM automatically adjusts the ARSPD_RATIO parameter during flight, based on an estimation filter using ground speed and true airspeed. The automatic calibration saves the new ratio to EEPROM every 2 minutes if it changes by more than 5%.
During calibration, fly with frequent direction changes as in a loiter or normal circuit pattern. Set ARSPD_AUTOCAL = 0 after calibration
Leave the other parameters with their default values.
NOTE: Cover pitot tube when not in use. Remove cover after the APM has powered up and before flight.
Arduplane version 3.4 does not support camera control. It was removed in a previous version to make space for other features.
(Refer here for Arduplane documentation on steering control.)
Once configured, automatic ground steering is enabled in stabilised modes (like FBWA and Auto) whenever the rudder and aileron sticks are centred and the aircraft is below GROUND_STEER_ALT (set here to 5m). Auto steering relies on a compass heading to determine direction. The compass heading is set when the rudder and aileron sticks are centred. Moving the rudder overrides the auto steering. Alignment of the nose wheel is critical to a straight take off.
Before an auto take off, in manual or FBWA mode taxi to align the aircraft to the take off direction. With the rudder and aileron sticks centred, select Auto mode. The current compass heading is used to steer the aircraft when it throttles up and starts moving until it reaches an altitude of 5m. Be ready to take manual control using the rudder stick if the aircraft veers off course!
Channel 4 is used to control the rudder and steering.
Enable Steering Control
Steering Control is enabled by setting the parameter GROUND_STEER_ALT to a non zero value. Below this altitude, the nose wheel is used for steering. Above this altitude, steering changes from the nose wheel to the rudder. GROUND_STEER_ALT is set to 5m.
The steering servo is connected to output channel RC7. To set the parameters for RC7, in Mission Planner on the Config/Tuning screen, display the Full Parameter Tree. Set RC7 parameters as shown here.
Parameter RC7_FUNCTION is set to 26 meaning ‘ground steering’. Refer to RC Output Mapping for more details.
The steering parameters are shown here. All the values are set to those suggested by the Arduplane documentation except STEER2SRV_P which is set to the turning circle diameter, measured to be 4.3m.
On the Taranis, select Manual Mode. Check that the rudder stick turns the nose wheel in the correct direction. If not, reverse channel 4 on the Taranis Outputs screen.
Taxi the aircraft along the ground and adjust the mechanical alignment of the nose wheel so that the aircraft goes in a straight line when the rudder stick is centred. Adjust the rudder trim in the transmitter to perform fine adjustment.
Tune the ground steering in FBWA mode before trying an auto take off. Follow the tuning procedure described here.
The throttle parameters are set as follows.
The throttle setting for normal flight TRIM_THROTTLE is set to 55%. This throttle setting is used when there is no airspeed sensor.
‘Stabilise’ mode or ‘Auto’ mode keep the wings level after the aircraft is released making launching less demanding on the pilot.
If ‘Auto’ mode with a takeoff command in the command list is used, the aircraft can be launched by hand even without holding the transmitter. The aircraft will stabilise and climb automatically after leaving your hand.
The parameter TKOFF_ROTATE_SPD should be 0 for all hand launches.
No Auto Throttle Control
If the parameter TKOFF_THR_MINACC is zero, then the throttle starts immediately after ‘Auto’ mode is selected.
When no auto throttle control is used, these are the parameter values used.
Auto Throttle Control
If the parameter TKOFF_THR_MINACC is not zero, then the throttle is armed only after the time in TKOFF_THR_DELAY has passed and the GPS ground speed is above TKOFF_THR_SPD.
This feature is used when launching by hand
When auto throttle control is used, these are the parameter values used.
The maximum throttle value during takeoff is set to the same as THR_MAX. See here for THR_MAX setting.
The maximum throttle slew rate during takeoff is set to the same as THR_SLEWRATE. See here for THR_SLEWRATE setting.
The TKOFF_ROTATE_SPD parameter is set to 0 m/s so it will rotate as soon as the air speed allows it.
The parameters TKOFF_TDRAG_ELEV and TKOFF_TDRAG_SPD1 are left at the default value 0 because they only apply to tail dragging configuration aircraft.
The Fly By Wire altitude change rate FBWB_CLIMB_RATE default value is used. It is 2.0 m/S.
(Refer here for Arduplane documentation on automatic landing.)
These are the landing parameters.
The LAND_PITCH_CD angle is set to zero so flaring is disabled because altitude measurement is not accurate enough without sonar or lidar rangefinder.
These are the key TECS landing parameters.
The TECS_LAND_SPDWGT parameter sets the priority between airspeed control versus height control.
The Landing Air Speed is set by the parameter TECS_LAND_ARSPD.
The glide slope is set by the ratio of the distance from the last waypoint to the landing point and the height difference between the last waypoint and the landing point. A recommended glide slope is a maximum of 10%.
(Refer here for Arduplane documentation on ESC Calibration)
The ESC is a 30A.