I also have the slow spin up problem on the rear left motor, the chance is about 2 out of 10.
Sometimes it even triggers emergency cut off(one orange before 4 reds).
This problem only occurs with 1.10.10 and 1.10.12, not 1.7.11 nor the pervious version.
This may be related to different motor software.
Variance of motor may also be the reason, you can rotate the propeller to feel the resistance of the un-powered motor .
But your crash started from right banking, not left one, so the slow-spin-up motor may not be related.
The reasons of the crash may include
Too much payload
System is able to lift off and hover does not mean it have enough reserved power to yaw and bank.
The upthrust needed for a 45 degree tilted vehicle is twice of it is leveled. (extra 15% for 30 degree)
CG may not be centered
Your Gopro seemed to be right shifted, doesn't it ?(or only right turned ?)
Too fast yawing
For such payload, system does not have enough reserved power to do that.
The flow before the crash could be like these,
Left yawing command received
System started the yawing by reducing 2 motors' speed. In order to maintain height and leveling, system will try to increase the other 2 motors' speed
The targeted speed of the latter exceeded the limit of the power system( speed controller and motor)
The targeted speed(hence the upthrust) was not attained, right side start to lose height earlier than left(may be because of the CG positioning or an right banking command), resulting a right banking.
System tried to increase all motors' speed to maintain height,but the targeted speed exceeded the limit of the power system, vehicle started to lose height.
You should test the payload limit by using dummy weight with banking and yawing.
Also, I suggest you should disassemble the ARdrone to visual check whether everything is dried before further powered test.
Thanks for responding ccme...
I am running 1.10.10, mirumod v17
Your reasoning sounds right on the mark. Drained battery might have been the crux of the issue as I was at the end of about 12 minutes of flight and had both a GoPro and 2250 mAH battery which is considerably heavier than the stock battery. The drone flew fine most of the time but a few times just previous to the crash the drone slowly descended and bounced off the ground before taking off again with the trottle pinned at the top. And right at the time of the crash I had the throttle pinned up but the drone kept descending...
The GoPro was pretty much centered but was angled diagonally which is why the video is taken a little off to the starboard side. As mentioned, during the flight the drone bounced a few times so that could have pushed the camera off center position a little I guess.
Regarding the flow you described it sounds dead on. I was starting to bank to get closer to the tree line (and away from the lake) and the drone seemed to initially yaw right and then spin left towards the lake.
So, that probably explains why the crash occurred. I tried the drone this morning and the first couple of attempts (with iPhone) caused a flip. However on the third attempt the drone flew fine again! I might have a failing motor(s) issue. I'll hook up the mirumod again and test with that later this afternoon when I have more time. Is there some way I can telnet in and view the motor logs to see if there are any issues reported. I seem to recall something about telnetting in and restarting the program.elf process or something like that.
Yesterday I ordered a 1.3 GHz 800 mW FPV Video TX/RX but based on these findings I'm not sure the AR.Drone can carry all this weight. Might have to ditch the GoPro for a smaller camera.
[Edit: The drone flys fine with the mirumod again after drying out. Must have been some moisture or debris somewhere or I have a bad motor. Very happy to have a working Drone after crashing in the lake.]
Last edited by kgeange; May 08, 2012 at 12:43 PM.
1. 4 pods LED turns red, Arduino LED blinks slowly in 1 flash.
2. Arduino LED and the 4 pods LED keep solid green .
I also tried to delay the downloading manually by wrong gear position(take off), wait for a period of time and switch back to landing. Tried 10, 20, 30......60 and 70 sec after the 4 green lights, sometimes 30 sec and 60 sec work, but the results seem to be random.
I tried change the NS_boot value to 34. It had worked for about 8 flights before in 100% success.
After I updated it to 1.10.12 and downgraded it to 1.7.11 again, 34 did not work anymore.
I use Drone Control and I have to do it twice every time for a successfully downgrading.
At every 1 st time I will get a log file with the following content
Usage /bin/checkplf <plf_filename>
At the 2nd time the content of the log file will change to
Something wrong with the downgrade process ?
You changed one or two motors ?
With 2250mAh & a Gopro ? That surprised me.
What are the weights ?
12 mins + of flight time is also impressive.
Did you compare 1.7.11 with 1.10.10 ?
The throttle of 1.7.11 seems to be more powerful than 1.10.10. They are of different motor software.
Feel like the difference between 1st gear & 3rd gear.
For heavy loaded AR.Drone, may be 1.7.11 serve the purpose better than 1.10.10.
I am interested in FPV, I have not ordered the equipment yet, since my AR.Drone have midair motor cut off issue.
Before your equipment arrives, you may test more with different loads.
Keep updating your status.
Last edited by ccme; May 10, 2012 at 04:36 AM.
Didn't need to change either motor. Yesterday morning, the first two attempts to takeoff resulted in pretty aggressive flips and on the third attempt the drone hovered fine when I pressed the take off button!!! Not sure if I dislodged some debris in one of flips, if I cleared some moisture or if a component was seated better. However I'm relieved.
Was out flying yesterday afternoon for 15-20 minutes and during one flight I did notice that near the end of the flight the drone flipped (clockwise roll) 360 degrees and luckily since I was only .5 meters off the ground it landed in the grass right side up. Not sure if this was caused by a motor cutoff.
Naked GoPro is 96g
2250mAh battery (got it on eBay) is substantially heavier than stock battery (can't find exact specs but similar batteries are 140g)
My plan is to not use the GoPro for FPV but a small CCD Sony camera. The drone was really struggling to get off the ground with the GoPro and larger battery.
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