Pixwhawk -> ESC -> Motors Don't spin enough for Takeoff

PX4 Autopilot
1

Hello,

I am using a Pixhawk 6X Pro running PX4 with a Standard VTOL configuration.

In the Actuators tab, the motors do spin, but not fast enough to achieve a real takeoff. During manual flight, the thrust produced by the motors is insufficient, and the aircraft is unable to take off.

In the log files I see that the signal of “1999” is sent from the pixhawk to the ESC, but it never really transfers into high RPM. I tried DSHOT 150, 300 and 600, no difference. Here my actuator outputs logs:

NuttShell (NSH) NuttX-11.0.0

nsh> listener actuator_outputs

TOPIC: actuator_outputs 5 instances

Instance 0:

actuator_outputs

timestamp: 10492336431 (0.001871 seconds ago)

noutputs: 8

output: \[0.00000, 0.00000, 1290.00000, 1690.00000, 1500.00000, 1500.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 1:

actuator_outputs

timestamp: 10492361459 (0.001511 seconds ago)

noutputs: 9

output: \[0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 2:

actuator_outputs

timestamp: 1165385 (10491.221680 seconds ago)

noutputs: 9

output: \[1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 3:

actuator_outputs

timestamp: 1308445 (10491.101563 seconds ago)

noutputs: 8

output: \[0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 4:

actuator_outputs

timestamp: 1308506 (10491.124023 seconds ago)

noutputs: 8

output: \[500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

nsh> listener actuator_outputs

TOPIC: actuator_outputs 5 instances

Instance 0:

actuator_outputs

timestamp: 10562657095 (0.002648 seconds ago)

noutputs: 8

output: \[0.00000, 0.00000, 1300.00000, 1700.00000, 1500.00000, 1500.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 1:

actuator_outputs

timestamp: 10562679580 (0.002069 seconds ago)

noutputs: 9

output: \[109.00000, 109.00000, 109.00000, 109.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 2:

actuator_outputs

timestamp: 1165385 (10561.535156 seconds ago)

noutputs: 9

output: \[1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 3:

actuator_outputs

timestamp: 1308445 (10561.415039 seconds ago)

noutputs: 8

output: \[0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 4:

actuator_outputs

timestamp: 1308506 (10561.441406 seconds ago)

noutputs: 8

output: \[500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

nsh> listener actuator_outputs

TOPIC: actuator_outputs 5 instances

Instance 0:

actuator_outputs

timestamp: 10566021136 (0.001716 seconds ago)

noutputs: 8

output: \[0.00000, 0.00000, 1300.00000, 1700.00000, 1500.00000, 1500.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 1:

actuator_outputs

timestamp: 10566041089 (0.005449 seconds ago)

noutputs: 9

output: \[1999.00000, 109.00000, 1758.00000, 350.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 2:

actuator_outputs

timestamp: 1165385 (10564.900391 seconds ago)

noutputs: 9

output: \[1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 1000.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 3:

actuator_outputs

timestamp: 1308445 (10564.779297 seconds ago)

noutputs: 8

output: \[0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

Instance 4:

actuator_outputs

timestamp: 1308506 (10564.802734 seconds ago)

noutputs: 8

output: \[500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 500.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000, 0.00000\]

nsh>

I have searched extensively—using ChatGPT, reading forum discussions, and reviewing the official documentation—but I have not been able to find a solution to this issue. Is there anyone knowledgeable who could help me troubleshoot this problem? I have been trying to resolve it for five days without success, and any assistance would be greatly appreciated.

Best regards,

2

Which ESCs are you using? Did you configure the KV and Poles? Hook up the TELEM signal from ESC to free UART RX on the FC (DSHOT_TEL_CFG) and check the reported RPM.

3

Dear Dakejahl,

first of all, thank you for replying.

I have 4x HAKRC BLHeli-32 35A ESC (https://www.getfpv.com/hakrc-blheli-32-bit-35a-2-5s-esc.html?srsltid=AfmBOorpVnVpFW0M-viu_AnDO9Vci0hmK2kacCDfpcEX9F4-dab5AxRZ) for the VTOL part.

The motor is T-Motor MN3510-13 Multirotor Fixed Wing UAV Motor KV700

The Mot_poles value is correct, the mot_kv value does not exist. When I try via mavlink console to set it to 700, it does also not work.

nsh> param set MOT_KV 700
ERROR [param] Parameter MOT_KV not found.
nsh>

param show MOT_KV
Symbols: x = used, + = saved, * = unsaved

1430/1913 parameters used.
nsh> #

It is a bit hard to “Hook up the TELEM signal from ESC to free UART RX on the FC (DSHOT_TEL_CFG) and check the reported RPM.” Because I have 4 separate ESCs.

However, when I start to fly, this is my ESC listener output which has RPM when I put full throttle up to launch (right joystick to the top):

nsh> listener esc_status

TOPIC: esc_status
esc_status
timestamp: 1127742867 (0.003749 seconds ago)
counter: 51490
esc_count: 4
esc_connectiontype: 5
esc_online_flags: 15 (0b1111)
esc_armed_flags: 15 (0b1111)

esc[0] (esc_report):
timestamp: 1127742868 (0.020886 seconds ago)
esc_errorcount: 0
esc_rpm: 1128
esc_voltage: 0.00000
esc_current: 0.00000
esc_temperature: 0.00000
failures: 0
esc_address: 0
esc_cmdcount: 0
esc_state: 0
actuator_function: 101
esc_power: 0

esc[1] (esc_report):
timestamp: 1127742868 (0.044765 seconds ago)
esc_errorcount: 0
esc_rpm: 1128
esc_voltage: 0.00000
esc_current: 0.00000
esc_temperature: 0.00000
failures: 0
esc_address: 0
esc_cmdcount: 0
esc_state: 0
actuator_function: 102
esc_power: 0

esc[2] (esc_report):
timestamp: 1127742868 (0.066681 seconds ago)
esc_errorcount: 0
esc_rpm: 1042
esc_voltage: 0.00000
esc_current: 0.00000
esc_temperature: 0.00000
failures: 0
esc_address: 0
esc_cmdcount: 0
esc_state: 0
actuator_function: 103
esc_power: 0

esc[3] (esc_report):
timestamp: 1127742868 (0.087625 seconds ago)
esc_errorcount: 0
esc_rpm: 1128
esc_voltage: 0.00000
esc_current: 0.00000
esc_temperature: 0.00000
failures: 0
esc_address: 0
esc_cmdcount: 0
esc_state: 0
actuator_function: 104
esc_power: 0

esc[4] (esc_report):
timestamp: 0
esc_errorcount: 0
esc_rpm: 0
esc_voltage: 0.00000
esc_current: 0.00000
esc_temperature: 0.00000
failures: 0
esc_address: 0
esc_cmdcount: 0
esc_state: 0
actuator_function: 0
esc_power: 0

esc[5] (esc_report):
timestamp: 0
esc_errorcount: 0
esc_rpm: 0
esc_voltage: 0.00000
esc_current: 0.00000
esc_temperature: 0.00000
failures: 0
esc_address: 0
esc_cmdcount: 0
esc_state: 0
actuator_function: 0
esc_power: 0

esc[6] (esc_report):
timestamp: 0
esc_errorcount: 0
esc_rpm: 0
esc_voltage: 0.00000
esc_current: 0.00000
esc_temperature: 0.00000
failures: 0
esc_address: 0
esc_cmdcount: 0
esc_state: 0
actuator_function: 0
esc_power: 0

esc[7] (esc_report):
timestamp: 0
esc_errorcount: 0
esc_rpm: 0
esc_voltage: 0.00000
esc_current: 0.00000
esc_temperature: 0.00000
failures: 0
esc_address: 0
esc_cmdcount: 0
esc_state: 0
actuator_function: 0
esc_power: 0

nsh>

Can you please help me with troubleshooting? Thank you in advance!

4

To follow up:

I have purchased a “LINKER” device, and could not connect to the ESC at all. I have now purchased differend ESCs, and now it works for manual flights and power. Skystars Jupiter 35A 3-6S AM32 | Rotorama

The problem was def. the firmware of the ESCs.

Nevertheless, if someone ever has successfully flashed the firmware of the HAKRC BLHeli-32 35A ESC (https://www.getfpv.com/hakrc-blheli-32-bit-35a-2-5s-esc.html?srsltid=AfmBOorpVnVpFW0M-viu_AnDO9Vci0hmK2kacCDfpcEX9F4-dab5AxRZ), please let me know! It would be a pity to throw them away or not use them for another project…

Best