Hi everyone, I’m using Arduplane for my custom VTOL airframe and it’s been working great for a few flights.
But now I have a problem with the motor. It jitters when the flight controller tries to correct it. I’m using a Tarot motor 3515 400 kv with a Ready to sky 60-amp ESC. I’ve also tried other ESCs like cyclone 45 amp and Ready to sky 40 amp, but nothing helped.
I don’t know what ESC to use with the Tarot motor, since the manufacturer doesn’t recommend any. Does anyone have any suggestions?
Also, I don’t understand why the motor is jittering. Can anyone please explain that to me?
What flight mode are you in when you are moving the flight controller?
As you are moving the flight controller, you are changing what rates the gyros are measuring so the flight controller is correspondingly changing the output throttle to the ESC (based on config, PID gains, etc).
Generally speaking, it is very hard to infer anything about what is going on with everything on the ground or moving by hand. This is because the flight controller measures you movement, but cannot do any thing to actually correct that movement. It is a very artificial scenario.
From the vid/pics it looks like this motor is a VTOL motor. If you want to get confidence that your motor is working correctly use the motor test function in mission planner (Setup → Optional Hardware → Motor Test). This sends a direct throttle signal straight from the flight controller output and removes the flight control loops as a variable. Gradually step in throttle percent 10, 20, 30, etc until you reach 100%. If your motor runs smoothly at each of those then there is unlikely to be an issue.
I am using Qstabilize mode while moving the flight controller.
When I tested the manual mode on the ground, the motor did not show any signs of jittering. However, when I switched to the VTOL modes, the motor started to make sudden and erratic movements. I also tested the VTOL mode in the field, but the model did not lift off. Instead, it moved unpredictably in all directions and the motors are snapping.
I am not sure if the problem is caused by the ESC or the motor. Could the ESC refresh rate make any shuttering effects?
I would appreciate it if you could refer any ESC models that are compatible with the motor that I am using.
OK, it is as I suspected. QStabilise is a VTOL rate controlled mode. So the ESCs and motors are just responding to the flight controllers throttle outputs as you move the flight controller.
There is nothing wrong with the Esc’s and motors. If they run smoothly in manual over the whole throttle range then they are fine.
You mentioned trying it outside. Did you have rotors on or was it without? As I mentioned before, you cannot infer much about the way the controller tuned from it’s behaviour without the rotors on because the aircraft cannot respond to minimise rate and attitude errors. To give an analogy, it is like trying to see how well your car corners and taking the wheels off for the test.
The main thing is to make sure
your flight controller board orientation is correct for the vehicle. (check the hud moves in the correct direction when you pitch and roll the aircraft by hand)
your frame class and type are set correctly for your motor layout
do all of your calibrations (RC, Accels, compass, etc)
do an in sequence motor test to check the motor motors a) all start turning at the same pwm b) rotate in the correct direction, and c) are in the correct order.
setup E-stop on an easy to get to transmitter switch. This way, when you try flying it, if anything is going funny you can do an emergency stop of all motors.
Then try a short hop in QStabilise (do not use any other flight modes). The aim is to only just get off the ground by 50 cm or so. This way if anything goes wrong you can E-stop it and walk away from a hard landing.
By actually flying the aircraft it will be easier to understand how the aircraft will perform. From there you can start diagnosing the next problems.
I have tested the model and tried different flight controller and ESC, but it didn’t help. The motors work fine on the ground without propellers, even at full throttle. But when I put the propellers on and try to fly, some motors jitter between 40% and 70% throttle.
Could it be something to do with the ESC and low Kv motors, like the PWM refresh rate?
No need for a different flight controller or a different ESC. Best to keep things consistent when debugging/learning. Be methodical.
I think it is likely to be just be controller gains are too high. If you send me log of the flight I can take a look and confirm if it is what I suspect.
To make sure the log has what I need in it, before you fly, please find the LOG_BITMASK parameter, ensure that fast attitude (bit 0) and PID (bit 12) are set. Once you have set those params, it is best to do a flight controller reboot (I do not recall if it requires a reboot off the top of my head).
Do a small hop flight and retrieve the log, then post it here please.
