I have been struggling setting up Pixhawk for a small sized quadcopter with high kv/response motor/esc equipment as below and would like to share my experience with you guys.
Motor: FR1806-2300KV from RCTimer
ESC: K18A ESC(KISS ESC18A) 2-4S also from RCTimer
- Above ESC has jumper to switch between High speed and normal operation mode.
- I set the jumper to normal mode.
Pixhawk is updated with latest f/w and reported as below.
PX4: 34e1d543 NuttX: 7c5ef883
APM:Copter V3.3.3 (acf2e10c)
First try: Copter completely uncontrollable right after throttle up at Stabilized mode.
Full ESC calibration and Radio calibration again
Second try: Same. Motor speed diverge and uncontrollable.
Reducing PID : No effect. Copter jumps and uncontrollable.
Finally working setup:
I found high response esc has very steep response to its pwm input. So my guess is reducing the range and response might solve this issue.
Change I made.
On mission planner, go to CONFIG/TUNING tab and open Full Parameter Tree
Go to MOT section and change following items
MOT_THST_MAX to 0.4 (was 0.95) which means PX will use only 40% of the full range of throttle.
MOT_THST_EXPO to 0.5 (was around 0.65)
With above setup the copter finally get stabilized and fully controllable.
I know I may give up some additional power from the motor but I don't need that much of power for most of my project.
So now I am happy about it.
More detailed description is on my blog here http://kyubot.tistory.com/69
Hope this helps you to solve similar problem with setting up PX