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2 loss of control crashes within 5 minutes on dji fpv racer

1hander

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hello guys, im new here but ive been on the mavic forum for a while. ,,,i want to see if anyone else has had something like this happened..soo i was outside a while ago, it was about 1130 pm.. so dark and cool.. i fly around the back yard around the trees and in the alley, i have been using the Motion controller because i have use of only my right arm. i had the goggles on and connected but was flying LOS...i have had the horizontal yaw control enabled in the MC controller menu...where when you twist the MC the fpv yaws left and right but returns to center when you return the MC to center.. i use to make quicker turns in small places to assist the coordinated left and right turning. battery was at 58 percent.

i was doing figure 8s about 20 feet up and in the figure 8 i was descending and ascending i was not over the pool but it decided to start pirouetting left and flying forward and descending toward the pool.kinda like a nose in hover left tornado type thing... i had the MC pointing straight up and full right at about 30 percent throttle then 100 and everything in between.. but it finally stopped pirouetting over the yard and began a slow forward flight over the pool... it skimmed the water then at the last second it rose up just enough to clear the edge of the pool and crashed into the picnic table leg under the back porch about 1 foot from where i was sitting at about 5 mph///i was fighting it the entire time but it was not responding much at all. to the MC ...after it hit the table i checked and luckily no damage both the imu and compass show normal.. first thing i did was hit the emergency stop button but it did not stop

the second time i was also descending an making left and right inputs like in the figure 8s....this time it kind of jerked and bucked nose up, i heard the motors changing rpm, so it was doing something i was not commanding ..it started started to fly backwards and pirouette at the same time. i was inputting forward throttle and leaning the MC in the opposite direction of the pirouette.i didnt want it to go into the neighbors yard or into the pool, i seemed to have a little control in both situations but at the very limit of the MCs control so i put into a big tree.. again no damage but a bent prop.. compass and imu show normal. this time i hit the E stop button first again and it also failed to stop it

i checked the goggles both times and had a message ... it was something like Maximum control or input angle exceeded
i went in and disabled the horizontal yaw control..and it seems like it doesnt make jerky movements anymore when descending figure 8s..just as i was beginning to trust it.

my flying of RC helicopters i think saved my twice..so im not pushing my luck anymore tonight.. have any of you ever had an experience like this with either controller i dont know how to or if there us a flight log that might explain further. ive got 68 flights on it in normal and sport mode never crashed or bumped..

could it have had something to do with the dark..
or maybe the imu got confused or overloaded.when getting inputs from the left and right inputs plus the input from the horizontal yaw control causing it to get a maximum control angle exceeded type of thing. i just know its gonna be a while before i trust it again.. i have power lines like 75 yards from my yard..but i figure it cannot be that because i fly the P4Pv2,mavic platinum and inspire 2 back here to stay in practice and cycle the batteries regularly. but i guess anything is possible

i will converting the stick controller at some point to fly with my mouth and rydder knob the same way i fly my helis. i just couldnt wait and wanted to fly it so i got the MC. you know how that is
Rick
 
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1hander

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hery guys... after doing a nit more digging i discovered that the drone compass was calibrated correctly but after looking into the controller menu for the MC...i saw that the compass was not calibrated properly when it was before the flights because i check the compass calibration before every flight...its very sensitive to electronic and metal objects..so i thought..oh man the MC was sitting directly on top of the picnic table which my dad made out of steel...when looked in the goggles i noticed that there was a calibrate compass message but i thought it was for the drone which flies no problem when that comes up then goes away...but the message was actually for the MC compass..which had gotten screwed up while it was sitting on the table, ive not had problems with other drones sitting on the table..

so the only thing i can think of is that the controller compass being outta whack is what was causing the wonky controls..but still seemed to be giving me just enough control..to save it ..

opinions or theorys welcome
rick
 

1hander

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i was watching videos on youtube and i think i found the problem..even though i was not sustained flying over the water , on both occasions i passed over the pool for just a second slowly , i saw a video on youtube where a guy had the same problem and it went crazy as it got close to the smooth surface of the water. has to be the water thing causing a problem
 

Kilrah

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Water shouldn't matter but MC next to steel definitely can. Seems you did not make use of the Pause button, that would be the first thing to do if controls become whacky...
 

1hander

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I misspoke and called it the e stop button instead if the pause button but both times I tried the pause button
 

BudWalker

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hello guys, im new here but ive been on the mavic forum for a while. ,,,i want to see if anyone else has had something like this happened..soo i was outside a while ago, it was about 1130 pm.. so dark and cool.. i fly around the back yard around the trees and in the alley, i have been using the Motion controller because i have use of only my right arm. i had the goggles on and connected but was flying LOS...i have had the horizontal yaw control enabled in the MC controller menu...where when you twist the MC the fpv yaws left and right but returns to center when you return the MC to center.. i use to make quicker turns in small places to assist the coordinated left and right turning. battery was at 58 percent.

i was doing figure 8s about 20 feet up and in the figure 8 i was descending and ascending i was not over the pool but it decided to start pirouetting left and flying forward and descending toward the pool.kinda like a nose in hover left tornado type thing... i had the MC pointing straight up and full right at about 30 percent throttle then 100 and everything in between.. but it finally stopped pirouetting over the yard and began a slow forward flight over the pool... it skimmed the water then at the last second it rose up just enough to clear the edge of the pool and crashed into the picnic table leg under the back porch about 1 foot from where i was sitting at about 5 mph///i was fighting it the entire time but it was not responding much at all. to the MC ...after it hit the table i checked and luckily no damage both the imu and compass show normal.. first thing i did was hit the emergency stop button but it did not stop

the second time i was also descending an making left and right inputs like in the figure 8s....this time it kind of jerked and bucked nose up, i heard the motors changing rpm, so it was doing something i was not commanding ..it started started to fly backwards and pirouette at the same time. i was inputting forward throttle and leaning the MC in the opposite direction of the pirouette.i didnt want it to go into the neighbors yard or into the pool, i seemed to have a little control in both situations but at the very limit of the MCs control so i put into a big tree.. again no damage but a bent prop.. compass and imu show normal. this time i hit the E stop button first again and it also failed to stop it

i checked the goggles both times and had a message ... it was something like Maximum control or input angle exceeded
i went in and disabled the horizontal yaw control..and it seems like it doesnt make jerky movements anymore when descending figure 8s..just as i was beginning to trust it.

my flying of RC helicopters i think saved my twice..so im not pushing my luck anymore tonight.. have any of you ever had an experience like this with either controller i dont know how to or if there us a flight log that might explain further. ive got 68 flights on it in normal and sport mode never crashed or bumped..

could it have had something to do with the dark..
or maybe the imu got confused or overloaded.when getting inputs from the left and right inputs plus the input from the horizontal yaw control causing it to get a maximum control angle exceeded type of thing. i just know its gonna be a while before i trust it again.. i have power lines like 75 yards from my yard..but i figure it cannot be that because i fly the P4Pv2,mavic platinum and inspire 2 back here to stay in practice and cycle the batteries regularly. but i guess anything is possible

i will converting the stick controller at some point to fly with my mouth and rydder knob the same way i fly my helis. i just couldnt wait and wanted to fly it so i got the MC. you know how that is
Rick
There are two log files that might provide some insight. TBH, I'm not sure if a cause can be determined. There is a lot of experience analyzing log files from previous DJI platforms but almost none looking at the FPV log files. Also, I didn't quite follow your description - but that can be fixed.

If you want to have a look at the log data let's start with the .txt log file. It resides on the Goggles and can be retrieved by first transferring it to the Fly App and then transferring it to you PC or Mac.

1. Connect the goggles to a mobile device running the Fly App. Then power up the FPV drone. Make sure the goggles and drone are connected. Wait 10 minutes for all the log files to be transferred to the Fly App. You can actually see when the log files get transferred but describing how is complicated.

2. Next use iTunes to transfer the FlightRecords directory from the mobile device to a PC (or, I suppose, a Mac or Linux) machine. The .txt log files appear in the FlightRecords directory. Here is a really good description how to do this
HOW TO: Retrieve DJI Phantom Flight Logs from an Apple Device | Phantom Help

If you manage to do all this attach the .txt to a post here.
 

BudWalker

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Does the MC have a compass? The MC can accomplish it's functions with just gyros and accelerometers. It doesn't need to know actual heading, only a change in heading. I thought the "MC interference at location" message occurs when there is interference with the MC/drone link.

Edit: Just looked in the manual and there is a compass on the MC
 
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Kilrah

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It doesn't need to know actual heading, only a change in heading.
Theoretically only the gyro is needed but in practice it would just drift too much. Dealing with that = expensive and/or not user-friendly, adding a compass = cheap and easy.
 

BudWalker

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Theoretically only the gyro is needed but in practice it would just drift too much. Dealing with that = expensive and/or not user-friendly, adding a compass = cheap and easy.
Yeah, it may drift but not that much. And, the pilot would be compensating without knowing it. But, I can't imagine why else there would be a compass.

On a drone the attitude data has to be used to mathematically rotate the magnetometer data to obtain a correct compass heading. Same has to be true for the MC. Otherwise a pitch angle equal to the geomagnetic inclination and in the direction of magnetic north would yield an invalid or unstable heading. Maybe the MC isn't as robust as the drone FC in this regard. @1hander had the MC pointed up and was rotating the MC when the problems occurred.
 

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