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Tuning Reality Check
#1
I'm just starting to tune my first quad but I'm not sure if my instincts are correct. If someone with more experience could weigh in, I'd appreciate it.

By looking at the BB, I'm getting oscillations in pitch and roll which tells me that I need to bring the P-term on each of those down.
Looking at the pitch and roll D-terms however looks like very little, if any, bounce back in extreme maneuvers, but lots in gentle flying, so I'm not sure what's going on there. (TPA maybe? I just realized it's set super low (1250) from trying to diagnose vibration issues with different motors.) I'm thinking I should reduce the D-term and see if that oscillation goes away.

BB screenshot of a flip:
   
BB screenshot of a roll:
   

Overall, in my opinion the BB is telling me that the P and D terms are too aggressive and that TPA is set too low. Does this seem correct?
Right now I'm just concerned with the P and D-terms on pitch and roll because they seem the worst. I'm planning on getting to the yaw tuning and I-terms later.

Setup:
FC: Holybro Kakute F4 AIO
ESCs: DYS XSD 30A (DShot600, BLHeli 16.67_dshotcmd firmware)
Motors: Emax RS2205s 2300kV
Props: DAL 5045x3
For reference, I'm flying BF3.2 with the dynamic filter and anti-gravity mode enabled with the D-term low-pass filter set on PT1 and TPA set to 1250. The PIDs are stock.

Thanks for helping out a newbie,
Joe

Blackbox Link (Google Drive)
CLI:
Code:
# version
# Betaflight / KAKUTEF4 (KTV1) 3.2.0 Sep 28 2017 / 16:29:56 (ceb6f70) MSP API: 1.36

# name
name BangBang

# resources
resource BEEPER 1 C09
resource MOTOR 1 B00
resource MOTOR 2 B01
resource MOTOR 3 A03
resource MOTOR 4 A02
resource MOTOR 5 A00
resource MOTOR 6 C08
resource MOTOR 7 NONE
resource MOTOR 8 NONE
resource SERVO 1 NONE
resource SERVO 2 NONE
resource SERVO 3 NONE
resource SERVO 4 NONE
resource SERVO 5 NONE
resource SERVO 6 NONE
resource SERVO 7 NONE
resource SERVO 8 NONE
resource PPM 1 C07
resource PWM 1 NONE
resource PWM 2 NONE
resource PWM 3 NONE
resource PWM 4 NONE
resource PWM 5 NONE
resource PWM 6 NONE
resource PWM 7 NONE
resource PWM 8 NONE
resource LED_STRIP 1 A01
resource SERIAL_TX 1 A09
resource SERIAL_TX 2 NONE
resource SERIAL_TX 3 B10
resource SERIAL_TX 4 NONE
resource SERIAL_TX 5 NONE
resource SERIAL_TX 6 C06
resource SERIAL_TX 7 NONE
resource SERIAL_TX 8 NONE
resource SERIAL_TX 9 NONE
resource SERIAL_TX 10 NONE
resource SERIAL_TX 11 NONE
resource SERIAL_TX 12 NONE
resource SERIAL_RX 1 A10
resource SERIAL_RX 2 NONE
resource SERIAL_RX 3 B11
resource SERIAL_RX 4 NONE
resource SERIAL_RX 5 NONE
resource SERIAL_RX 6 C07
resource SERIAL_RX 7 NONE
resource SERIAL_RX 8 NONE
resource SERIAL_RX 9 NONE
resource SERIAL_RX 10 NONE
resource SERIAL_RX 11 NONE
resource SERIAL_RX 12 NONE
resource INVERTER 1 NONE
resource INVERTER 2 NONE
resource INVERTER 3 B15
resource INVERTER 4 NONE
resource INVERTER 5 NONE
resource INVERTER 6 NONE
resource INVERTER 7 NONE
resource INVERTER 8 NONE
resource INVERTER 9 NONE
resource INVERTER 10 NONE
resource INVERTER 11 NONE
resource INVERTER 12 NONE
resource I2C_SCL 1 B06
resource I2C_SCL 2 NONE
resource I2C_SCL 3 NONE
resource I2C_SDA 1 B07
resource I2C_SDA 2 NONE
resource I2C_SDA 3 NONE
resource LED 1 B05
resource LED 2 B04
resource LED 3 B06
resource RX_BIND 1 NONE
resource RX_BIND_PLUG 1 NONE
resource SPI_SCK 1 A05
resource SPI_SCK 2 NONE
resource SPI_SCK 3 C10
resource SPI_MISO 1 A06
resource SPI_MISO 2 NONE
resource SPI_MISO 3 C11
resource SPI_MOSI 1 A07
resource SPI_MOSI 2 NONE
resource SPI_MOSI 3 C12
resource ESCSERIAL 1 C07
resource CAMERA_CONTROL 1 NONE
resource ADC_BATT 1 C03
resource ADC_RSSI 1 C01
resource ADC_CURR 1 C02
resource ADC_EXT 1 NONE
resource BARO_CS 1 NONE

# mixer
mixer QUADX

mmix reset


# servo
servo 0 1000 2000 1500 100 -1
servo 1 1000 2000 1500 100 -1
servo 2 1000 2000 1500 100 -1
servo 3 1000 2000 1500 100 -1
servo 4 1000 2000 1500 100 -1
servo 5 1000 2000 1500 100 -1
servo 6 1000 2000 1500 100 -1
servo 7 1000 2000 1500 100 -1

# servo mix
smix reset



# feature
feature -RX_PPM
feature -INFLIGHT_ACC_CAL
feature -RX_SERIAL
feature -MOTOR_STOP
feature -SERVO_TILT
feature -SOFTSERIAL
feature -GPS
feature -SONAR
feature -TELEMETRY
feature -3D
feature -RX_PARALLEL_PWM
feature -RX_MSP
feature -RSSI_ADC
feature -LED_STRIP
feature -DISPLAY
feature -OSD
feature -CHANNEL_FORWARDING
feature -TRANSPONDER
feature -AIRMODE
feature -RX_SPI
feature -SOFTSPI
feature -ESC_SENSOR
feature -ANTI_GRAVITY
feature -DYNAMIC_FILTER
feature RX_SERIAL
feature TELEMETRY
feature OSD
feature AIRMODE
feature ANTI_GRAVITY
feature DYNAMIC_FILTER

# beeper
beeper GYRO_CALIBRATED
beeper RX_LOST
beeper RX_LOST_LANDING
beeper DISARMING
beeper ARMING
beeper ARMING_GPS_FIX
beeper BAT_CRIT_LOW
beeper BAT_LOW
beeper GPS_STATUS
beeper RX_SET
beeper ACC_CALIBRATION
beeper ACC_CALIBRATION_FAIL
beeper READY_BEEP
beeper MULTI_BEEPS
beeper DISARM_REPEAT
beeper ARMED
beeper SYSTEM_INIT
beeper ON_USB
beeper BLACKBOX_ERASE

# map
map TAER1234

# serial
serial 20 1 115200 57600 0 115200
serial 0 32 115200 57600 0 115200
serial 2 64 115200 57600 0 115200
serial 5 8192 115200 57600 0 115200

# led
led 0 0,0::C:0
led 1 0,0::C:0
led 2 0,0::C:0
led 3 0,0::C:0
led 4 0,0::C:0
led 5 0,0::C:0
led 6 0,0::C:0
led 7 0,0::C:0
led 8 0,0::C:0
led 9 0,0::C:0
led 10 0,0::C:0
led 11 0,0::C:0
led 12 0,0::C:0
led 13 0,0::C:0
led 14 0,0::C:0
led 15 0,0::C:0
led 16 0,0::C:0
led 17 0,0::C:0
led 18 0,0::C:0
led 19 0,0::C:0
led 20 0,0::C:0
led 21 0,0::C:0
led 22 0,0::C:0
led 23 0,0::C:0
led 24 0,0::C:0
led 25 0,0::C:0
led 26 0,0::C:0
led 27 0,0::C:0
led 28 0,0::C:0
led 29 0,0::C:0
led 30 0,0::C:0
led 31 0,0::C:0

# color
color 0 0,0,0
color 1 0,255,255
color 2 0,0,255
color 3 30,0,255
color 4 60,0,255
color 5 90,0,255
color 6 120,0,255
color 7 150,0,255
color 8 180,0,255
color 9 210,0,255
color 10 240,0,255
color 11 270,0,255
color 12 300,0,255
color 13 330,0,255
color 14 0,0,0
color 15 0,0,0

# mode_color
mode_color 0 0 1
mode_color 0 1 11
mode_color 0 2 2
mode_color 0 3 13
mode_color 0 4 10
mode_color 0 5 3
mode_color 1 0 5
mode_color 1 1 11
mode_color 1 2 3
mode_color 1 3 13
mode_color 1 4 10
mode_color 1 5 3
mode_color 2 0 10
mode_color 2 1 11
mode_color 2 2 4
mode_color 2 3 13
mode_color 2 4 10
mode_color 2 5 3
mode_color 3 0 8
mode_color 3 1 11
mode_color 3 2 4
mode_color 3 3 13
mode_color 3 4 10
mode_color 3 5 3
mode_color 4 0 7
mode_color 4 1 11
mode_color 4 2 3
mode_color 4 3 13
mode_color 4 4 10
mode_color 4 5 3
mode_color 5 0 9
mode_color 5 1 11
mode_color 5 2 2
mode_color 5 3 13
mode_color 5 4 10
mode_color 5 5 3
mode_color 6 0 6
mode_color 6 1 10
mode_color 6 2 1
mode_color 6 3 0
mode_color 6 4 0
mode_color 6 5 2
mode_color 6 6 3
mode_color 6 7 6
mode_color 6 8 0
mode_color 6 9 0
mode_color 6 10 0
mode_color 7 0 3

# aux
aux 0 0 0 1300 2100
aux 1 13 2 1700 2100
aux 2 35 1 1700 2100
aux 3 0 0 900 900
aux 4 0 0 900 900
aux 5 0 0 900 900
aux 6 0 0 900 900
aux 7 0 0 900 900
aux 8 0 0 900 900
aux 9 0 0 900 900
aux 10 0 0 900 900
aux 11 0 0 900 900
aux 12 0 0 900 900
aux 13 0 0 900 900
aux 14 0 0 900 900
aux 15 0 0 900 900
aux 16 0 0 900 900
aux 17 0 0 900 900
aux 18 0 0 900 900
aux 19 0 0 900 900

# adjrange
adjrange 0 0 0 900 900 0 0
adjrange 1 0 0 900 900 0 0
adjrange 2 0 0 900 900 0 0
adjrange 3 0 0 900 900 0 0
adjrange 4 0 0 900 900 0 0
adjrange 5 0 0 900 900 0 0
adjrange 6 0 0 900 900 0 0
adjrange 7 0 0 900 900 0 0
adjrange 8 0 0 900 900 0 0
adjrange 9 0 0 900 900 0 0
adjrange 10 0 0 900 900 0 0
adjrange 11 0 0 900 900 0 0
adjrange 12 0 0 900 900 0 0
adjrange 13 0 0 900 900 0 0
adjrange 14 0 0 900 900 0 0

# rxrange
rxrange 0 1000 2000
rxrange 1 1000 2000
rxrange 2 1000 2000
rxrange 3 1000 2000

# vtx
vtx 0 0 0 0 900 900
vtx 1 0 0 0 900 900
vtx 2 0 0 0 900 900
vtx 3 0 0 0 900 900
vtx 4 0 0 0 900 900
vtx 5 0 0 0 900 900
vtx 6 0 0 0 900 900
vtx 7 0 0 0 900 900
vtx 8 0 0 0 900 900
vtx 9 0 0 0 900 900

# rxfail
rxfail 0 a
rxfail 1 a
rxfail 2 a
rxfail 3 h
rxfail 4 h
rxfail 5 h
rxfail 6 h
rxfail 7 h
rxfail 8 h
rxfail 9 h
rxfail 10 h
rxfail 11 h
rxfail 12 h
rxfail 13 h
rxfail 14 h
rxfail 15 h
rxfail 16 h
rxfail 17 h

# master
set align_gyro = DEFAULT
set gyro_lpf = OFF
set gyro_sync_denom = 1
set gyro_lowpass_type = PT1
set gyro_lowpass_hz = 90
set gyro_notch1_hz = 0
set gyro_notch1_cutoff = 0
set gyro_notch2_hz = 0
set gyro_notch2_cutoff = 0
set moron_threshold = 48
set gyro_use_32khz = OFF
set align_acc = DEFAULT
set acc_hardware = AUTO
set acc_lpf_hz = 10
set acc_trim_pitch = 0
set acc_trim_roll = 0
set align_mag = DEFAULT
set mag_hardware = NONE
set mag_declination = 0
set magzero_x = 0
set magzero_y = 0
set magzero_z = 0
set baro_bustype = I2C
set baro_spi_device = 0
set baro_i2c_device = 1
set baro_i2c_address = 0
set baro_hardware = NONE
set baro_tab_size = 21
set baro_noise_lpf = 0
set baro_cf_vel = 0
set baro_cf_alt = 0
set mid_rc = 1500
set min_check = 1000
set max_check = 1900
set rssi_channel = 0
set rssi_scale = 30
set rssi_invert = OFF
set rc_interp = AUTO
set rc_interp_ch = RP
set rc_interp_int = 19
set fpv_mix_degrees = 0
set max_aux_channels = 14
set serialrx_provider = SBUS
set sbus_inversion = ON
set spektrum_sat_bind = 0
set spektrum_sat_bind_autoreset = ON
set airmode_start_throttle = 1350
set rx_min_usec = 885
set rx_max_usec = 2115
set serialrx_halfduplex = OFF
set input_filtering_mode = OFF
set blackbox_p_ratio = 32
set blackbox_device = SPIFLASH
set blackbox_on_motor_test = OFF
set blackbox_record_acc = ON
set min_throttle = 1000
set max_throttle = 2000
set min_command = 1000
set dshot_idle_value = 450
set use_unsynced_pwm = OFF
set motor_pwm_protocol = DSHOT600
set motor_pwm_rate = 480
set motor_pwm_inversion = OFF
set thr_corr_value = 0
set thr_corr_angle = 800
set failsafe_delay = 5
set failsafe_off_delay = 10
set failsafe_throttle = 1000
set failsafe_kill_switch = OFF
set failsafe_throttle_low_delay = 100
set failsafe_procedure = DROP
set align_board_roll = 0
set align_board_pitch = 0
set align_board_yaw = 0
set gimbal_mode = NORMAL
set bat_capacity = 1300
set vbat_max_cell_voltage = 43
set vbat_full_cell_voltage = 41
set vbat_min_cell_voltage = 33
set vbat_warning_cell_voltage = 35
set vbat_hysteresis = 1
set current_meter = ADC
set battery_meter = ADC
set vbat_detect_cell_voltage = 30
set use_vbat_alerts = ON
set use_cbat_alerts = OFF
set cbat_alert_percent = 10
set vbat_cutoff_percent = 100
set vbat_scale = 110
set ibata_scale = 224
set ibata_offset = 0
set ibatv_scale = 0
set ibatv_offset = 0
set beeper_inversion = ON
set beeper_od = OFF
set beeper_frequency = 0
set beeper_dshot_beacon_tone = 0
set yaw_motors_reversed = OFF
set 3d_deadband_low = 1406
set 3d_deadband_high = 1514
set 3d_neutral = 1460
set 3d_deadband_throttle = 50
set servo_center_pulse = 1500
set servo_pwm_rate = 50
set servo_lowpass_hz = 400
set tri_unarmed_servo = ON
set channel_forwarding_start = 4
set reboot_character = 82
set serial_update_rate_hz = 100
set accxy_deadband = 40
set accz_deadband = 40
set acc_unarmedcal = ON
set imu_dcm_kp = 2500
set imu_dcm_ki = 0
set small_angle = 180
set auto_disarm_delay = 5
set disarm_kill_switch = ON
set gyro_cal_on_first_arm = OFF
set gps_provider = NMEA
set gps_sbas_mode = AUTO
set gps_auto_config = ON
set gps_auto_baud = OFF
set gps_wp_radius = 200
set nav_controls_heading = ON
set nav_speed_min = 100
set nav_speed_max = 300
set nav_slew_rate = 30
set fixedwing_althold_reversed = OFF
set alt_hold_deadband = 40
set alt_hold_fast_change = ON
set deadband = 0
set yaw_deadband = 0
set yaw_control_reversed = OFF
set pid_process_denom = 1
set tlm_switch = OFF
set tlm_inverted = ON
set tlm_halfduplex = OFF
set frsky_default_lat = 0
set frsky_default_long = 0
set frsky_gps_format = 0
set frsky_unit = IMPERIAL
set frsky_vfas_precision = 0
set hott_alarm_int = 5
set pid_in_tlm = OFF
set report_cell_voltage = OFF
set ledstrip_visual_beeper = OFF
set osd_units = METRIC
set osd_rssi_alarm = 20
set osd_cap_alarm = 1300
set osd_alt_alarm = 150
set osd_ah_max_pit = 20
set osd_ah_max_rol = 40
set osd_tim1 = 2560
set osd_tim2 = 2561
set osd_vbat_pos = 2445
set osd_rssi_pos = 91
set osd_tim_1_pos = 54
set osd_tim_2_pos = 2340
set osd_flymode_pos = 364
set osd_throttle_pos = 129
set osd_vtx_channel_pos = 359
set osd_crosshairs = 0
set osd_ah_sbar = 200
set osd_ah_pos = 200
set osd_current_pos = 2355
set osd_mah_drawn_pos = 2371
set osd_craft_name_pos = 2059
set osd_gps_speed_pos = 66
set osd_gps_lon_pos = 82
set osd_gps_lat_pos = 65
set osd_gps_sats_pos = 386
set osd_home_dir_pos = 302
set osd_home_dist_pos = 303
set osd_compass_bar_pos = 266
set osd_altitude_pos = 161
set osd_pid_roll_pos = 322
set osd_pid_pitch_pos = 354
set osd_pid_yaw_pos = 386
set osd_debug_pos = 1
set osd_power_pos = 2388
set osd_pidrate_profile_pos = 418
set osd_warnings_pos = 329
set osd_avg_cell_voltage_pos = 76
set osd_pit_ang_pos = 257
set osd_rol_ang_pos = 289
set osd_battery_usage_pos = 392
set osd_disarmed_pos = 2186
set osd_nheading_pos = 311
set osd_nvario_pos = 279
set osd_esc_tmp_pos = 82
set osd_esc_rpm_pos = 2048
set osd_stat_max_spd = OFF
set osd_stat_max_dist = OFF
set osd_stat_min_batt = ON
set osd_stat_min_rssi = OFF
set osd_stat_max_curr = ON
set osd_stat_used_mah = ON
set osd_stat_max_alt = OFF
set osd_stat_bbox = ON
set osd_stat_endbatt = OFF
set osd_stat_bb_no = OFF
set osd_stat_tim_1 = OFF
set osd_stat_tim_2 = ON
set task_statistics = ON
set debug_mode = NONE
set cpu_overclock = OFF
set pwr_on_arm_grace = 5
set vtx_halfduplex = ON
set vcd_video_system = 2
set vcd_h_offset = 0
set vcd_v_offset = 0
set max7456_clock = DEFAULT
set displayport_msp_col_adjust = 0
set displayport_msp_row_adjust = 0
set displayport_max7456_col_adjust = 0
set displayport_max7456_row_adjust = 0
set displayport_max7456_inv = OFF
set displayport_max7456_blk = 0
set displayport_max7456_wht = 2
set esc_sensor_halfduplex = OFF
set led_inversion = 0
set dashboard_i2c_bus = 1
set dashboard_i2c_addr = 60
set camera_control_mode = HARDWARE_PWM
set camera_control_ref_voltage = 330
set camera_control_key_delay = 180
set camera_control_internal_resistance = 470

# profile
profile 0

set dterm_lowpass_type = BIQUAD
set dterm_lowpass = 100
set dterm_notch_hz = 260
set dterm_notch_cutoff = 160
set vbat_pid_gain = OFF
set pid_at_min_throttle = ON
set anti_gravity_threshold = 350
set anti_gravity_gain = 1000
set setpoint_relax_ratio = 100
set dterm_setpoint_weight = 0
set acc_limit_yaw = 100
set acc_limit = 0
set crash_dthreshold = 50
set crash_gthreshold = 400
set crash_setpoint_threshold = 350
set crash_time = 500
set crash_delay = 0
set crash_recovery_angle = 10
set crash_recovery_rate = 100
set crash_limit_yaw = 200
set crash_recovery = OFF
set iterm_windup = 50
set iterm_limit = 150
set pidsum_limit = 500
set pidsum_limit_yaw = 400
set yaw_lowpass = 0
set p_pitch = 58
set i_pitch = 50
set d_pitch = 35
set p_roll = 40
set i_roll = 40
set d_roll = 30
set p_yaw = 70
set i_yaw = 45
set d_yaw = 20
set p_alt = 50
set i_alt = 0
set d_alt = 0
set p_level = 50
set i_level = 50
set d_level = 75
set p_vel = 55
set i_vel = 55
set d_vel = 75
set level_limit = 55
set horizon_tilt_effect = 75
set horizon_tilt_expert_mode = OFF
set gps_pos_p = 15
set gps_pos_i = 0
set gps_pos_d = 0
set gps_posr_p = 34
set gps_posr_i = 14
set gps_posr_d = 53
set gps_nav_p = 25
set gps_nav_i = 33
set gps_nav_d = 83

# rateprofile
rateprofile 0

set rc_rate = 100
set rc_rate_yaw = 100
set rc_expo = 0
set rc_expo_yaw = 0
set thr_mid = 50
set thr_expo = 0
set roll_srate = 70
set pitch_srate = 70
set yaw_srate = 70
set tpa_rate = 12
set tpa_breakpoint = 1250

#


Attached Files
.txt   dump.txt (Size: 14.42 KB / Downloads: 292)
Reply
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#2
I don't see any oscillation on the roll axis at all in your log. In fact, it looks very clean. There is some noise on the P and D-terms for pitch, but the PID settings on that axis are much stronger than they are on roll. You might like to reduce the pitch axis PIDs to match. If this cleans up pitch as well then you should start to increase the TPA breakpoint back to the defaults and see how it goes. Your quad looks quite powerful and seems to hover at around 25% throttle.

You don't say which frame you are using.

Here's the most important question though: How does the quad fly?
[-] The following 1 user Likes unseen's post:
  • RedCatJoe
Reply
#3
I just noticed your throttle command is not smoothed... If you left smoothing at defaults, then yaw isn't either. Not saying it is a problem here, but sometimes the hard steps in command can cause some "irritation" to other axis as well.
[-] The following 2 users Like fftunes's post:
  • RedCatJoe, unseen
Reply
#4
(30-Dec-2017, 12:35 PM)unseen Wrote: I don't see any oscillation on the roll axis at all in your log. In fact, it looks very clean. There is some noise on the P and D-terms for pitch, but the PID settings on that axis are much stronger than they are on roll. You might like to reduce the pitch axis PIDs to match. If this cleans up pitch as well then you should start to increase the TPA breakpoint back to the defaults and see how it goes. Your quad looks quite powerful and seems to hover at around 25% throttle.

You don't say which frame you are using.

Here's the most important question though: How does the quad fly?

Aha! Yes, I see that now. I was seeing the noise in the PID loop and assuming that was oscillation in the quad. I will bring the pitch PIDs down to match the roll PIDs and see how it flies then. 

The frame is a 5in (220mm) Crazepony Martian. (I know, I know, clones are bad, but I didn't understand how much difference a good frame makes when I bought it and how important it is to support original designers. I quickly learned just trying to put this one together.)

AUW is 536g with a 45-90C 4s Nano-Tech or 564g with a 65C 4s Graphene.

Overall, I think it flies pretty nicely. My point of comparison is the same quad with Emax RS2205s 2600kV motors that had a horrible vibration problem, so pretty much anything is better. I changed to the 2300kV motors trying to get rid of the vibration and because I realized I was never using more than 1/2 throttle.

One other thing I've noticed going through the logs is that on full throttle punches, the back left motor maxes out before the other three. It looks to me like an ESC calibration issue, but I thought that DShot eliminates the need to calibrate. Am I missing something?

Thanks for the help,
Joe
[-] The following 1 user Likes RedCatJoe's post:
  • unseen
Reply
#5
(30-Dec-2017, 01:56 PM)fftunes Wrote: I just noticed your throttle command is not smoothed... If you left smoothing at defaults, then yaw isn't either. Not saying it is a problem here, but sometimes the hard steps in command can cause some "irritation" to other axis as well.

I didn't even know that RC smoothing was possible. I found Joshua Bardwell's video on RC interpretation and followed that. (use only CH1-8 on the Taranis, tune the rc_interp parameter, and set the rc_interp on all four channels)

Is there more to RC smoothing? I found a few references to a parameter called rc_smooth_interval, but it doesn't seem to exist in BF3.2.

Thank you,
Joe
Reply
#6
(30-Dec-2017, 09:19 PM)RedCatJoe Wrote: Aha! Yes, I see that now. I was seeing the noise in the PID loop and assuming that was oscillation in the quad. I will bring the pitch PIDs down to match the roll PIDs and see how it flies then. 

The frame is a 5in (220mm) Crazepony Martian. (I know, I know, clones are bad, but I didn't understand how much difference a good frame makes when I bought it and how important it is to support original designers. I quickly learned just trying to put this one together.)

AUW is 536g with a 45-90C 4s Nano-Tech or 564g with a 65C 4s Graphene.

Overall, I think it flies pretty nicely. My point of comparison is the same quad with Emax RS2205s 2600kV motors that had a horrible vibration problem, so pretty much anything is better. I changed to the 2300kV motors trying to get rid of the vibration and because I realized I was never using more than 1/2 throttle.

One other thing I've noticed going through the logs is that on full throttle punches, the back left motor maxes out before the other three. It looks to me like an ESC calibration issue, but I thought that DShot eliminates the need to calibrate. Am I missing something?

Thanks for the help,
Joe

DShot does indeed free you from any need to calibrate the ESCs.

If one motor maxes out before others, it is most likely a matter of balance. I looked at the punch out in your log and the rear motors are working a little harder than the front motors (which is normal on most quads). The fact that motor 3 maxes out just slightly before motor 1 is nothing to worry about. Maybe the quad is slightly heavier to the aft, port side, maybe the wind was blowing from the starboard side. Whatever the reason, the inbalance is minimal and not worth investigating.

I always leave smoothing and other parameters at default. I'm not a good enough pilot to notice the very minor and subtle differences that tuning these parameters might bring.

The first rule of tuning is that you shouldn't change stuff unless you have a genuine need to. If you have handling problems, then you should be able to define what the problem is and only change what is needed to address the specific and identified problem.
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#7
(30-Dec-2017, 09:55 PM)RedCatJoe Wrote: Is there more to RC smoothing? I found a few references to a parameter called rc_smooth_interval, but it doesn't seem to exist in BF3.2.

It's rc_interp_ch, if set to RP it's roll/pitch only, then there's RPY (roll/pitch/yaw) and RPYT (all four).
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#8
(31-Dec-2017, 01:00 PM)unseen Wrote: DShot does indeed free you from any need to calibrate the ESCs.

If one motor maxes out before others, it is most likely a matter of balance. I looked at the punch out in your log and the rear motors are working a little harder than the front motors (which is normal on most quads). The fact that motor 3 maxes out just slightly before motor 1 is nothing to worry about. Maybe the quad is slightly heavier to the aft, port side, maybe the wind was blowing from the starboard side. Whatever the reason, the inbalance is minimal and not worth investigating.

I always leave smoothing and other parameters at default. I'm not a good enough pilot to notice the very minor and subtle differences that tuning these parameters might bring.

The first rule of tuning is that you shouldn't change stuff unless you have a genuine need to. If you have handling problems, then you should be able to define what the problem is and only change what is needed to address the specific and identified problem.

I have been doing a rough balance when I put the battery on, but I'll try shifting it forward a bit and see if that helps even things out.

Maybe I approached the tuning wrong in the first place. I was trying to get a great tune for the sake of a great tune, but if it already flies fine, then what's the point.

We've been in the deep freeze here the last few days, but I should be able to get some flights in tomorrow.

(31-Dec-2017, 05:22 PM)fftunes Wrote: It's rc_interp_ch, if set to RP it's roll/pitch only, then there's RPY (roll/pitch/yaw) and RPYT (all four).

That's the one I adjusted. I set it to RPYT.

Thanks!
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#9
I went out flying today and got some more log data. 
The big changes:
TPA setpoint changed from 1250 to 1750
Pitch PIDs reduced to match roll pids
RC smoothing enabled on all channels and set to 12ms

The results:
Overall, the traces are much smoother. I bumped the pitch and roll Ps up 3 points and I started to get some oscillations in roll so that will come down a point or so, but I think that the pitch P can still go a few spots higher. I don't have any hunting in yaw, so the I-term there feels good. I think I'll start increasing the yaw P-term to make it snappier. I feels kinda loose.

A roll:
   

A flip:
   

I tried moving the battery forward an eighth of an inch to get the motors working the same but it didn't seem to matter. What I don't get is that I have to hold some back pitch (right stick toward me in mode two) during the punch to keep it level, even though the aft motors are working harder. Seems like if I have to do that, it should be the front motors that are running harder. Anyway, it doesn't really matter. I'll probably keep playing with it, but only because it bothers me.
Punch:
   

Blackbox Log


Thanks for the help!
Joe
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#10
Today, I learned a very important lesson: verify your build integrity before diving down any troubleshooting rabbit holes.

Back when I built my quad, the supplied camera mount didn't work with my Runcam Swift 2 (reason 9000 not to buy a cloned frame), so I used the supplied u-mount and attached it to the frame with a single M3 bolt. It seemed sturdy enough.
As I flew and tuned, I started to get some pretty bad mid-throttle vibrations. I attributed these to a natural frequency in the frame and tried to use filters to get rid of it, but was unsuccessful.

My next step was to try new motors and as part of the installation, I went through the quad and tightened up all of the hardware. The first flight with the new motors was magical! The vibration was almost totally gone! Naturally, I wanted the new motors to be the reason, so that's what I told myself.

Fast forward a few weeks. I'd been flying my quad a bunch and the vibration had been getting worse over time. I was scratching my head trying figure out what was going wrong. I tried to tune it out. I was running only brand new props. I was about to just give up and buy a new frame and hope to fix it that way.

Then, today I was looking over my quad and noticed that the camera had significant play in roll when I pushed it with my finger. The bolt was still tight, but use had slightly bent the u-mount and allowed it to rock back and forth. I used zipties to snug it down and went to fly.

Bingo! No more vibration in the video feed! With only the single bolt, there was a throttle setting that would drive the camera mount at its natural frequency cause vibrations in the video feed. By adding zipties, I was able to hold the mount still.

So, if I have one take away from this experience, it would be to make sure that your quad is structurally sound before you take drastic action to chase down a problem. I ended up spending $80 on new motors when $0.03 of zipties would have solved the problem.

Obviously, zipties are not a permanent solution to this problem, so my plan is to fly this frame as hard as I can until it breaks, then upgrade to better, not cloned, frame.
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#11
Its just a part of the human condition - always expecting the worst! Glad it's sorted anyway. I hope you get that killer tune set up soon...
Windless fields and smokeless builds
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#12
My dad worked long and hard to get me to catch on to two of engineering's simple lessons...look at the easy things first and resist jumping to the most complicated possibilities first. He is a retired aerospace engineer and those two lessons have served well throughout my years of breaking things... Smile

Glad you found the issue...the silver lining, you have an extra set of motors!
SoCal Kaity :D
OMG, no one told me it would be this much fun!  Addicted :)
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