Hello,
I noticed that I have different variation of RPM measurements when my motors at minimum rpm (on ground) (check image below). If I check the RCOU logs, which my understanding is what the controller is commanding to the motors, they show the same variation. Any ideas what could be wrong? I am asking because i dont think that this is normal
Thank you for your help
Sounds normal to me. What does Motor test in Mission Planner show?
Is the copter level when you tried this?
Even if it was level there would be no expectation of the motor command outputs being equal running in the control loop. That’s why Motor Test is used as it is not.
Thank you for your comment.
From my understanding the motor test in Mission planner is intended to be used when i need to set spin min and spin arm. The values i achieved are Q_M_SPIN_MIN = 0.2 and Q_M_SPIN_ARM = 0.08.
Is their anything else i shall interpret from motor test in open loop?
My concern of having different variation of RPM measurements is stability. I am not sure if the drone have properly balanced weight. But i wanted to check if there are other concerns i can should check?
Its a VTOL drone with an H-frame config.
If the goal is to determine what the post title says then you would use Motor Test for that.
okay, so do you mean when i command certain amount of thrust, i should see the same rpm measurements, if there are no issues?
With Motor Test it’s a throttle percent only. That’s why it’s a valid test for its intended purposes. Essentially passthru.
“Thrust” depends on several factors.
You’re chasing ghosts. Testing open loop control on the ground does virtually nothing other than confirm that commands are sent and received. Per motor RPM should be similar during motor test of same throttle %, but depending on a ton of factors, may not be identical. ArduPilot’s attitude controller takes care of all of that during flight, so your concern is almost certainly a non-issue.
Okay, thank you guys for explaining it
