Hi,
I would like to know if anyone can help me with this problem I am having. My multiwii (no baro or mag) is installed on a 250 quad and it is working great. I really love the handling characteristics. There is one specific area I am having trouble with and that is getting the motors to spool up in flight after the throttle has been brought down to idle. Yes I am doing some extreme flying. The main scenario is this: In ANGLE mode, I put the throttle to max and the quad rockets up into the sky. Then I bring the throttle to idle, the motors are spinning very slowly (as they do at idle on the ground). The quad starts tumbling down towards the ground. I apply power to recover. Twice now the motors have not spooled back up and the quad has slammed into the ground. It seems if I am at idle for a very short period of time, the power comes back without issue. But if I am at idle for more than a few seconds, applying power will not have any effect! Is there a setting issue here or a logic issue that I am missing? From my understanding the power should come back no matter what unless I have disarmed the motors, which I have never done.
Thank you for any help with this!
Multiwii issue - Crashed twice now!
Re: Multiwii issue - Crashed twice now!
Does it do this if tied down or without props?
Does it do this if you do not go full throttle but say half throttle?
Maybe increase the motor speed at idle. I use 1150 as a minimum.
One thing to try is load and run the clear_EEPROM sketch. power off then back on and re-load the MW code.
If there was something corrupted in the EEPROM or code this will fix it.
Do you have the Fail Safe enabled in config.h?
If not then I suggest this be enabled and set the time delays and then the FS throttle in the MW SETTINGS tab of MW config.exe gui.
Does it do this if you do not go full throttle but say half throttle?
Maybe increase the motor speed at idle. I use 1150 as a minimum.
One thing to try is load and run the clear_EEPROM sketch. power off then back on and re-load the MW code.
If there was something corrupted in the EEPROM or code this will fix it.
Do you have the Fail Safe enabled in config.h?
If not then I suggest this be enabled and set the time delays and then the FS throttle in the MW SETTINGS tab of MW config.exe gui.
Re: Multiwii issue - Crashed twice now!
Waltr, thanks for your informative reply!
To answer you I have tried this with the quad held in my hand. I cut the power and simulate the gyro inputs by rocking the quad around as if it were tumbling down. Of course I cannot simulate the accelerometer inputs. In all cases the motors have responded immediately when I've applied power so I am unable to reproduce the in-air condition.
I have made the changes to the motor idle speed and enabled the fail safe as you recommended. I also found that MOTOR_STOP was uncommented in config.h. I'm not sure what this does but it didn't sound good, so I commented it out, which is the default setting. I will fly the quad in the coming days and let you know the outcome.
To answer you I have tried this with the quad held in my hand. I cut the power and simulate the gyro inputs by rocking the quad around as if it were tumbling down. Of course I cannot simulate the accelerometer inputs. In all cases the motors have responded immediately when I've applied power so I am unable to reproduce the in-air condition.
I have made the changes to the motor idle speed and enabled the fail safe as you recommended. I also found that MOTOR_STOP was uncommented in config.h. I'm not sure what this does but it didn't sound good, so I commented it out, which is the default setting. I will fly the quad in the coming days and let you know the outcome.
Re: Multiwii issue - Crashed twice now!
MOTOR_STOP will stop the motors when throttle stick is at minimum. Some people like this enabled but I do not. I prefer to have the motors run at idle with the throttle at minimum.
I've never flown with MOTOR_STOP enabled but think I remember reading that sometimes if the motors stop in flight they don't always start again. This might be what you are seeing.
With the motors running at idle (1150) there is almost no lift so the copter can still tumble (lots of fun doing the recovery) but the motors can quickly come back up to speed since they are still turning.
This is probably what the issue was so lets us know how it works now.
I've never flown with MOTOR_STOP enabled but think I remember reading that sometimes if the motors stop in flight they don't always start again. This might be what you are seeing.
With the motors running at idle (1150) there is almost no lift so the copter can still tumble (lots of fun doing the recovery) but the motors can quickly come back up to speed since they are still turning.
This is probably what the issue was so lets us know how it works now.
A few aerobatic pilots have told me never to take the throttle right down as inertia will often stop the props from getting back up to anything resembling a useful speed.
Some disable motor_stop but they still have a fairly high idle speed defined, when I say fairly high idle speed I mean high enough so the spin up has negligible inertia to combat
Some disable motor_stop but they still have a fairly high idle speed defined, when I say fairly high idle speed I mean high enough so the spin up has negligible inertia to combat
Re: Multiwii issue - Crashed twice now!
Kilby, that's an interesting point but can you explain why the inertia of the propellers would be any different in the air versus on the ground? As far as I can tell, from the perspective of the motors, it should be the same spinning up the props on the ground versus in the air.
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BirdShredder
- Posts: 31
- Joined: Mon Jun 16, 2014 10:50 pm
Re: Multiwii issue - Crashed twice now!
I could imagine your ESCs are bailing out? It requires so much current to spin up your engines the ESC will conclude the motor is stuck and fail saves are kicking in. To prevent melting your motors. If you can't disable that feature on your ESCs, maybe you could try smaller props. (just pulling a suggestion out of thin air.)