Hi Guys,
Today I decided I had a minute to test the parameters of my last tuning setup, not long into the flight, I had a real hard roll/pitch of forward and left, ironically, I switched the log to included motors just before the flight.
Attached is the file is anyone has a moment to check it out. I've had a similar issue months ago where it did sort of the same thing, the front right motor seemed to have stopped and caused this type of crash, I thought it was the spring clip on the bottom of the motor shaft that had slipped off or out of it's groove causing the motor to slide off the stator in which losing power of course. I looked at the clips and all are in place this time.
Hope someone can shed some light on this. Motors are too large and draw alot of power, and with this type of failure, it doesn't leave a whole lot of confidence in the hex to allow it to fly longer and higher.
F550 hex,
flying in x formation,
Motor's 1350kv
ESC's Birdie 30amp.
APM 2.5 3.0.1 firmware.
Today I decided I had a minute to test the parameters of my last tuning setup, not long into the flight, I had a real hard roll/pitch of forward and left, ironically, I switched the log to included motors just before the flight.
Attached is the file is anyone has a moment to check it out. I've had a similar issue months ago where it did sort of the same thing, the front right motor seemed to have stopped and caused this type of crash, I thought it was the spring clip on the bottom of the motor shaft that had slipped off or out of it's groove causing the motor to slide off the stator in which losing power of course. I looked at the clips and all are in place this time.
Hope someone can shed some light on this. Motors are too large and draw alot of power, and with this type of failure, it doesn't leave a whole lot of confidence in the hex to allow it to fly longer and higher.
F550 hex,
flying in x formation,
Motor's 1350kv
ESC's Birdie 30amp.
APM 2.5 3.0.1 firmware.
before this mornings flight, I also added to my midhover throttle, from 300 to 330. The last thing was when I came back to my desk, my mission planner showed "fence breached" on the hud. not sure why being ch7 isn't connected to the receiver. I did however have geofence enabled, just not active with the radio since there was no ch7 hooked up from the receiver to the apm.
Curious, is there anyway to write an algorithm for the apm to recognize a motor failing, sectionalize (doubt that's a word) the area of the surrounding two motors to stabilize the copter and allow for a safer landing? I've seen a micro quad do it recently.. food for thought.
Curious, is there anyway to write an algorithm for the apm to recognize a motor failing, sectionalize (doubt that's a word) the area of the surrounding two motors to stabilize the copter and allow for a safer landing? I've seen a micro quad do it recently.. food for thought.
This was also posted on Ardupilot forum hoping for some light on this issue.
Replies
Hi Chris...Clearly there is something going on with motor 3. At line 1096 the fun begins. The APM senses the start of the roll/pitch and commands motor 3 to increase speed. Concurrently with that the APM is requesting motor 4 to slow down, as it's the opposite motor. The problem is, motor 3 doesn't increase speed and the error just keeps increasing. So motor 3 isn't doing what the APM wants. The question is why?
The first place I'd look is the ESC for that motor. It could be a flaky ESC or something as simple as a poor connection. In your video, if I heard right, you said something about the ESCs being in "airplane mode". What did you mean by this?
In looking at those Birdie ESCs at Hobbyking I see a lot of problematic reviews. It could be that the ESCs timing are not well optimized for the type of motors you are running, hence the erratic operation shown in your video. And they don't use SimonK. The net result could be very inefficient operation which brings me to....
I see you are using crazy amounts of power even at hover. Are your motors hot after flying? If so it could be a case of exceeding the motor's power rating, heating it up and temporarily weakening the magnets. What model motors are you using and what is their power rating?
A couple of other observations.....At one point your voltage under load drops to 9.34 volts. That's very low and you risk having an ESC hit a low voltage cutoff, especially ones like the Birdies which may not be very programmable. Also for some reason your throttle out is consistently lower than your throttle in. I'm not sure why that is, assuming your radio is calibrated properly. Typically they are pretty close in level hover conditions.
Sorry I can't offer anything beyond this. My hunch is that you have poor ESC timing or programming causing the motor stutter and a questionable #3 ESC or a bad connection on that power feed.
This weekend I ran the motors while holding the copter down and couldn't get a failed motor. So what I did tonight was demonstrate just how two motors react to throttle up. Hope someone can shed some light on this nonsense. Also while reprogramming each ESC, I ran the motors individually and each throttled up smoothly. What could be causing this stutter? I tried disconnecting several ESC's to see if it was a lack power getting to those two problem ESC's, but the stutter didn't go away.
https://www.youtube.com/watch?v=Nc-adV4fvJ8&feature=youtu.be
Hi,
Well around 1110 there certainly is a sharp turn down and left, but only for very short time and only 0.93 meters high.
I don't know how the fence is supposed to behave (never used it) but I don't think you can assume that removing an RC connection will mean disabled by RC. It might as well mean enabled, or it might mean keep using the previous or default value of the RC channel. Only looking at the source will really tell.
If a motor fails, a well made hex controller should not need to detect anything specially. It will just see that the corner with the dead motor is dipping, and apply more throttle to the dead motor and also to a lesser extent to its 2 neighbors (indirectly, wia pitch and roll controls and output mixers). This should go on until the neighbor motors have enough thrust to level the copter again, all by the normal working of the controller (and the dead motor probably has enourmous amounts of throttle applied to it, all to no avail. ArduCopter did, the last time I looked, additionally compensate for a motor getting more than 100% throttle by subtracting the excess from that of the diagonally opposite motor).
A hex is controllable on 2 axes with a dead motor. This should of corse be prioritized as pitch and roll, given that you can emergency land well enough without yaw control.
Try tie a big brick to that copter and let it run one or two batteries down at lots of power. Do all motors run well?
Regards
Soren