6S Tri-Baby build (Matek F405-AIO)

[Kevin_Erik]

Started work on the Tri-Baby and already have the motors and servos attached to the FC. If all goes well I should be able to test fly Monday / Tuesday of next week.

Reference the following thread for F405 wiring info: https://rcexplorer.se/forums/topic/matek-f405-fcs/

Motors: Emax LS2207-2550kv, later build plans for F80-1900kv @ 6S or EMAX LS2207-1900kv
ESC: Tricopter standard 35A (45 burst)
FC: Matek F405-AIO
Propellers: HQ 5x4x3BN
VTX: Matek 5.8G VTX-HV W/ BFCMS CONTROL
Receiver: Frsky R-XSR with Telemetry
Camera: RunCam Micro
LiPo: 1800 mAh later builds plan for 6S 1300 or 1550.
Capacitors: 1000uf @ 25v (Battery) 470uf @ 35v (ESC’s)
Firmware: See Attached link at bottom of first thread.
Servo Feedback: Uses the RSSI pad and is set via Betaflight CLI.

Final resource mapping used:
# resource
resource BEEPER 1 C13
resource MOTOR 1 C06
resource MOTOR 2 C07
resource MOTOR 3 C08
resource MOTOR 4 C09
resource MOTOR 5 A15
resource SERVO 1 A08
resource PPM 1 A03
resource LED_STRIP 1 B06
resource SERIAL_TX 1 A09
resource SERIAL_TX 2 A02
resource SERIAL_TX 3 C10
resource SERIAL_TX 4 A00
resource SERIAL_TX 5 C12
resource SERIAL_RX 1 A10
resource SERIAL_RX 2 A03
resource SERIAL_RX 3 C11
resource SERIAL_RX 4 A01
resource SERIAL_RX 5 D02
resource I2C_SCL 1 B06
resource I2C_SDA 1 B07
resource LED 1 B09
resource LED 2 A14
resource SPI_SCK 1 A05
resource SPI_SCK 2 B13
resource SPI_SCK 3 B03
resource SPI_MISO 1 A06
resource SPI_MISO 2 B14
resource SPI_MISO 3 B04
resource SPI_MOSI 1 A07
resource SPI_MOSI 2 B15
resource SPI_MOSI 3 B05
resource ESCSERIAL 1 A03
resource ADC_BATT 1 C05
resource ADC_RSSI 1 B01
resource ADC_CURR 1 C04

PID Defaults for 3.2.2

P_Roll = 40
I_Roll = 40
D_Roll = 30

P_Pitch= 58
I_Pitch = 50
D_Pitch = 35

P_Yaw= 70
I_Yaw = 45
D_Yaw = 20

Attachments:

1. triflight_bf_3.2.2_v2_MATEKF405.hex_.zip

[Kevin_Erik]

Mediafire link to BLHeli-32, this one works with the “Aikon” AK32 35A 6S BLHeli_32 ESC’s: http://www.mediafire.com/file/3py2dgw629hy3x9/BLHeliSuite32_32302.zip

Here are my current settings for the ESC’s:

Here is a copy of the Diff or at least the important parts:

# Triflight on Betaflight 3.2.2 v2 / MATEKF405 (MKF4) 3.2.2 Dec 31 2017 / 15:24:22 (30f68c8) MSP API: 1.36

# resources
resource MOTOR 5 NONE
resource MOTOR 6 NONE
resource SERVO 1 A08
resource SERIAL_TX 11 A15

# mixer

# servo
servo 5 989 1883 1432 100 -1

# feature
feature MOTOR_STOP
feature DYNAMIC_FILTER

# map
map TAER1234

# serial
serial 30 32 115200 57600 0 115200

# master
set gyro_notch1_hz = 0
set gyro_notch2_hz = 0
set motor_pwm_protocol = DSHOT1200
set failsafe_kill_switch = ON
set servo_center_pulse = 1520
set servo_pwm_rate = 240
set tri_tail_servo_speed = 270
set tri_servo_feedback = RSSI
set pid_process_denom = 1
set dterm_lowpass_type = PT1
set dterm_notch_hz = 0
set p_pitch = 29
set p_roll = 20
set p_yaw = 35
set i_yaw = 20
set d_yaw = 40
set i_level = 25

[Kevin_Erik]

16-Jan-2018

Completed In-House tail-calibration and test hover today.
All went Great!

See attached blackbox log. Please note that this flight is with PID’s that are 1/2 the default and that only Dynamic filtering is active.

Kevin

Attachments:

1. LOG00015.zip

[Kevin_Erik]

Build and first test flight completed!

Next, will fine tune stuff and prep for the first flight outside.

[Kevin_Erik]

Here is some usefull information about Bluebird servos: https://www.blue-bird-model.com/news_detail/15.htm?cfrom=1

Looks like the BMS-210DMH Servo we are using has a max Frequency of 250hz. This maybe important for the correct CLI settings such as “servo_pwm_rate”. Should also note that the Servo center position isn’t 1500 but instead 1520us. (“servo_center_pulse”)

This video shows one possible solution (ferrite core) to servo-flutter or in our case Tail-Wag: https://www.youtube.com/watch?v=sEp4VT6NL6o

[Kevin_Erik]

A Gyro Soft Lowpass Frequency [HZ] setting of “20Hz” all but removes the Tail-Servo jitter when stationary. Will reset the PID’s back to defaults and contnue tuning the Tri-baby from there.

Note: I salvaged a simple ferrite-core from an old Microsoft mouse and now have it installed over the servo cable. With this I have elevated the flight controller board slightly higher to allow the ferrite-core to fit. There is also the advantage that the tail servo’s axis is now closer to the FC-Gyro ‘s “Center”. Hoping that this will make the yaw more responsive and less prone to oscillations.

Updated “Diff”

# version
Triflight on Betaflight 3.2.2 v2 / MATEKF405 (MKF4) 3.2.2 Dec 31 2017 / 15:24:22 (30f68c8) MSP API: 1.36

# resources
resource MOTOR 5 NONE
resource MOTOR 6 NONE
resource SERVO 1 A08
resource SERIAL_TX 11 A15

# servo
servo 5 1018 1886 1520 100 -1

# feature
feature MOTOR_STOP
feature DYNAMIC_FILTER

# map
map TAER1234

# serial
serial 30 32 115200 57600 0 115200

# aux
aux 0 0 0 1800 2100
aux 1 1 2 900 1200
aux 2 2 2 1300 1700
aux 3 37 1 1800 2100

# master
set gyro_lowpass_hz = 10
set gyro_notch1_hz = 0
set gyro_notch2_hz = 0
set motor_pwm_protocol = DSHOT1200
set failsafe_kill_switch = ON
set bat_capacity = 1800
set ibata_scale = 165
set servo_center_pulse = 1520
set servo_pwm_rate = 240
set tri_tail_servo_speed = 291
set tri_servo_feedback = RSSI
set pid_process_denom = 1
set dterm_lowpass_type = PT1
set dterm_notch_hz = 0
set i_level = 25

[Kevin_Erik]

Removed the ferrite-core and have noticed that the jitter has returned but not as strongly a it once was. I still have the gyro LPF set to 20Hz so it proves that in combination this works well. However, i beleive having more than one winding throught the core os required to make it worth the added weight and complexity.

Currently using Yaw PID’s of 35 / 15 / 40

[Kevin_Erik]

Did a flight today despite the resent bad weather and the Tri-Baby behaved really well.
I think I am making signifigant progress as the only issue seams to be the low frequency oscillation.
I may drop the Yaw-I down a wee bit to see if this helps.

Kevin

[Kevin_Erik]

Changed the Yaw-I to 10 from 15.
p_pitch = 58
i_pitch = 50
d_pitch = 35
p_roll = 40
i_roll = 40
d_roll = 30
p_yaw = 35
i_yaw = 10
d_yaw = 40

[Kevin_Erik]

Was able to do a full throttle punchout today! Baby-Tri drew over 100 Amps, while shooting 100 meters into the air. Still seeing a bit of I-term low freq Oscilation so I may drop the i_yaw down a bit more.

Note: I can record video on the Baby-Tri, only the mini can record video.

[Kevin_Erik]

Used the following settings today and saw a nice reduction in WAG and Oscillation. Will do a test flight outside shortly to confirm everything.

**PID Tab**
Roll: 40 / 40 / 30 (Stock Roll)
Pitch: 58 / 50 / 35 (Stock Pitch)
Yaw: 40 / 25 / 20
D-Term Lowpass Filter: PT1
Gyro Soft Lowpass Frequency [Hz]: 100hz
D Term Lowpass Frequency [Hz] = 110
Yaw Lowpass Frequency [Hz] = 10
Dynamic Filter is active

Note: All other filters disabled

**CLI Settings**
acc_lpf_hz = 10
tri_dynamic_yaw_boost = 300

[Kevin]

How much does this weigh?

[Kevin_Erik]

With 1800 mAh battery, it’s 500.5 grams. (flight ready) With the correct sized 4S battery it should be about 440-450 grams combined. This is without the landing gear, which by the way I’ve removed. (Those skids were an extra 10-15 grams)

For the record, this Tri is hella-fast!

Edit: With a new antenna I have coming, the Tri should weigh-in at 495g using the 1800 mAh LiPo.

[Kevin_Erik]

Note to self…

Too the following can cause severe yaw oscilations:
-low CLI “servo_pwm_rate” < 100-150
-low CLI “servo_lowpass_hz” < 10 hz
-Motor arming during first 2-5 seconds. (should stabilize)
-Ground effect
-Overly heigh P & I-Term

[Kevin_Erik]

Current “Diff” atached.

Note: Added Anti-Gravity (3) to fix yaw instability during punch-outs, Lowered Roll P and Yaw I by 5 each (from stock values), TPA set to .2 @ 1500. Hoping that the term changes and the TPA (Throttle PID Attenuation) help offset the oscillations encounted during sharp turns.

Attachments:

1. Diff-1-30-2018.txt

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