Aggressive takeoff with throttle stick at center non-zero

We aim to fly M1000 quad by T-motor with 24" propeller, however, for now we are checking the Herelink with a cheaper and smaller scale quad with orange Pixhawk. Please note the following issues have arisen upon flight tests:

  1. Q Ground Control app crashes if put in background while parallelly accessing the Here Link app and also if the drone is disconnected in between while the app is open.
  2. Battery voltage is not showing despite enabling the HV module in the app.
  3. With the throttle stick not centered (non-zero) by default (like DJI), the drone climbs very steeply soon after arming. With the throttle stick centered at zero, it climbs well, however, with fingers always pressed on the throttle stick (since it is spring mounted).

Please find the attached video links for reference:
Throttle stick non-zero: Redirecting

Throttle stick zero: https://drive.google.com/file/d/1XerGwd0-XxXHtiVkhJ3OvBAhVGZk95ZT/view?usp=drivesdk

Regards,
Abhilekh

  1. Q Ground Control app crashes if put in background while parallelly accessing the Here Link app and also if the drone is disconnected in between while the app is open.

This doesn’t sound right. Did you have Solex running in the background?
Try to reflash the firmware on Herelink to get QGC re-installed
https://docs.cubepilot.org/user-guides/herelink/herelink-user-guides/upgrading-firmware

  1. Battery voltage is not showing despite enabling the HV module in the app.

Have you set up the parameters in Mission Planner? Or at least is voltage monitor available in your Mission Planner HUD?

  1. With the throttle stick not centered (non-zero) by default (like DJI), the drone climbs very steeply soon after arming. With the throttle stick centered at zero, it climbs well, however, with fingers always pressed on the throttle stick (since it is spring mounted).

Under throttle stick non-zero, it could be the stick range being too small because you’re using half of it.
Try to modify throttle control variables like:
https://ardupilot.org/rover/docs/rover-tuning-throttle-and-speed.html#throttle-slew

or modify the hardware, if you don’t care possibility on voiding the warranty:
https://ardupilot.org/rover/docs/rover-tuning-throttle-and-speed.html#throttle-slew

Have you got this set for throttle from center position: PILOT_THR_BHV,7

Hi, I have tried this option. No change! What is the purpose of this function in Mission Planner?

OK, looking at the first video that was definitely an aggressive takeoff, the second one looked relatively normal. It looked like all Stabilise mode from the video.
If that was Stabilise mode the behaviour was probably expected. Stabilise can be hard to hold at a steady altitude, and is the best mode for making that moon shot :slight_smile:
Can you test AltHold mode?

PILOT_THR_BHV,7 suits a RC control with spring-centred throttle.

It would be good to have a flight log, so that we could compare the RC input and PWM output for throttle.

Hi Alvin,

Hope you’re doing fine. Please find the attached link below about undoing the stick centering in Herelink. Do you recommend it?

Link: Self Centring Throttle Mod
Let me know your suggestion.

Regards,
Abhilekh

It is doable as a customization if you need to remove the self-centering. However, you will void the warranty so think twice before actually doing it.