Well, it finally happened on flight #87

[Richard in ky]

While we are on the subject (not sure this is the right thread) I am a little confused on the GPS systems, there is a GPS of course in the inspire 1 and I am told there is a gps in the remote and also it uses the GPS from your smart phone. Does it just use the GPS in your smart phone to download satellite images are is it also used for navigation. Has anybody ever downloaded maps into their phone and then turned the phone gps off and see if it works, or just pre loaded the maps in case you are in a area that you can not receive a phone signal.

 

[Kilrah]

Would it make sense...in a situation like this...to flip the physical switch on the RC into Atti mode and try to control the craft?

YES that is absolutely what you should do. OP never mentions switchng to ATTI, had he done this he would likely have had no problem landing smoothly.

 

[skylabimaging]

YES that is absolutely what you should do. OP never mentions switchng to ATTI, had he done this he would likely have had no problem landing smoothly.

Well, the op also stated that he only had a bit of xp in atti...which landing in atti vs gps is much different, thing lands like rock in gps. In atti, while you or I may not have issues someone with less time in it could have slight issues getting a smooth landing. I do agree though, switch to atti physically helps.

 

[Highrpm955]

I'll switch to atti if this ever happens again... It just kinda caught me off guard.

 

[Eduardo]

Yes the Editor of this site seems very knowledgeable but I was flying about the same way you stated. if everything shows to be in the right spot on the map and pointing in the right direction that should do it as it is using the compass at the time to determine the direction it is pointed. I have a drawer full of gps devices and they all just use the compass while standing still. Once you move they quickly know you moved from point A to point B and a line between those points show the exact direction you are heading, to many things can affect the compass that it should only be needed while not moving I don't quite see how a compass would get the inspire lost in flight as long as gps is working.
I do a compass calibration before flight but not on each battery change, but I do look at its position, and direction it is pointing on the satellite map before taking off and I test the RTH also.

Agree, you should never lose an AC due to a compass problem (unless you are flying under instruments, not visual conditions, which should not be the case here).

The control sticks should override everything.

 

[The Editor]

Agree, you should never lose an AC due to a compass problem (unless you are flying under instruments, not visual conditions, which should not be the case here).

The control sticks should override everything.

Unfortunately, I wish this was the case, however, with GPS reliant flight controllers on multirotor aircraft this can happen.
If the compass error is large enough and the craft is in GPS mode the conflicting data of directional information from the GPS receiver and the erroneous data from the compass are at odds with each other. This can cause a major control problem as corrections try to be made in attitude and direction from the flight controller but the results from the feedback from the compass are not what the fc expects. It then tries to correct further resulting in some pretty scary flying with any stick input not always reacting as the pilot expects. Remember, we are NEVER flying these things, it is the flight controller doing the clever bit and interpreting our stick inputs. There is no direct output from the receiver to servos/control surfaces like conventional RC aircraft.
It is SO important to have a good compass calibration for the declination you are flying at and this is why IT IS NOT necessary to compass calibrate every time you cross the road! By doing excessive compass cals you run the risk of introducing an erroneous result. If you were standing in a car park and unknown to you there were a trillion tons of steel beneath your feet you may do a compass calibration in that parking lot and the mod values would adjust to bring the compass values in line. Then you take off and get a few feet in the air, the influence of that steel is then non existant and the magnetic flux acting on the compass is purely in respect of that geographical locations declination. However, the poor old compass is now out of whack because it took off from what it 'thought' was a good and true reading.
Result......disaster.
If at any time you are getting odd behaviour from your aircraft, switch immediately to Atti mode. Although this is not manual it's as close as we can get with the Inspire and it takes both GPS and compass out of the loop. The craft then only relies on barometer for altitude hold and accelerometers and gyroscope for attitude stability.

Hope that helps.

 

[Eduardo]

Unfortunately, I wish this was the case, however, with GPS reliant flight controllers on multirotor aircraft this can happen.
If the compass error is large enough and the craft is in GPS mode the conflicting data of directional information from the GPS receiver and the erroneous data from the compass are at odds with each other. This can cause a major control problem as corrections try to be made in attitude and direction from the flight controller but the results from the feedback from the compass are not what the fc expects. It then tries to correct further resulting in some pretty scary flying with any stick input not always reacting as the pilot expects. Remember, we are NEVER flying these things, it is the flight controller doing the clever bit and interpreting our stick inputs. There is no direct output from the receiver to servos/control surfaces like conventional RC aircraft.
It is SO important to have a good compass calibration for the declination you are flying at and this is why IT IS NOT necessary to compass calibrate every time you cross the road! By doing excessive compass cals you run the risk of introducing an erroneous result. If you were standing in a car park and unknown to you there were a trillion tons of steel beneath your feet you may do a compass calibration in that parking lot and the mod values would adjust to bring the compass values in line. Then you take off and get a few feet in the air, the influence of that steel is then non existant and the magnetic flux acting on the compass is purely in respect of that geographical locations declination. However, the poor old compass is now out of whack because it took off from what it 'thought' was a good and true reading.
Result......disaster.
If at any time you are getting odd behaviour from your aircraft, switch immediately to Atti mode. Although this is not manual it's as close as we can get with the Inspire and it takes both GPS and compass out of the loop. The craft then only relies on barometer for altitude hold and accelerometers and gyroscope for attitude stability.

Hope that helps.

In that case, couldn't the flight controller see the IMU is showing a different movement direction, compared to control stick position, for example?

And if so, give priority to the control sticks?

 

[The Editor]

In that case, couldn't the flight controller see the IMU is showing a different movement direction, compared to control stick position, for example?

And if so, give priority to the control sticks?

Don't shoot the messenger......take it up with DJI

 

[Eduardo]

Don't shoot the messenger......take it up with DJI

No worries, I'm in peace ;-) Probably would like to work with a manufacturer like DJI or 3DR on usability issues.

Will try my hand on the SDK, altough it seems scary to develop something over a buggy software.. could just make things worse..

 

[SRH]

Unfortunately, I wish this was the case, however, with GPS reliant flight controllers on multirotor aircraft this can happen.
If the compass error is large enough and the craft is in GPS mode the conflicting data of directional information from the GPS receiver and the erroneous data from the compass are at odds with each other. This can cause a major control problem as corrections try to be made in attitude and direction from the flight controller but the results from the feedback from the compass are not what the fc expects. It then tries to correct further resulting in some pretty scary flying with any stick input not always reacting as the pilot expects. Remember, we are NEVER flying these things, it is the flight controller doing the clever bit and interpreting our stick inputs. There is no direct output from the receiver to servos/control surfaces like conventional RC aircraft.
It is SO important to have a good compass calibration for the declination you are flying at and this is why IT IS NOT necessary to compass calibrate every time you cross the road! By doing excessive compass cals you run the risk of introducing an erroneous result. If you were standing in a car park and unknown to you there were a trillion tons of steel beneath your feet you may do a compass calibration in that parking lot and the mod values would adjust to bring the compass values in line. Then you take off and get a few feet in the air, the influence of that steel is then non existant and the magnetic flux acting on the compass is purely in respect of that geographical locations declination. However, the poor old compass is now out of whack because it took off from what it 'thought' was a good and true reading.
Result......disaster.
If at any time you are getting odd behaviour from your aircraft, switch immediately to Atti mode. Although this is not manual it's as close as we can get with the Inspire and it takes both GPS and compass out of the loop. The craft then only relies on barometer for altitude hold and accelerometers and gyroscope for attitude stability.

Hope that helps.

So how do you know the compass is out of whack? If the mod is with in the 1400-1600 range what are you really looking for?

 

[The Editor]

So how do you know the compass is out of whack? If the mod is with in the 1400-1600 range what are you really looking for?

I calibrate my compass in a known good area that I have used on all my multirotors for the last three years.
Personally I have never had a problem using this method but people need to make their own minds up and do what they feel comfortable with.
A tell take sign you have a bad compass cal is your craft just won't 'feel' right in the air. It will not be 'locked in' and will fly like it is drunk if that makes sense. There may also be TBE when you put it in one spot and hover.
My rule is if ANYTHING doesn't look or feel right, land asap and find out what the problem is. If it can't be sorted. ...don't fly.
Take offs are always optional, landings are obligatory.

 

[turbodronepilot]

So how do you know the compass is out of whack? If the mod is with in the 1400-1600 range what are you really looking for?

Your inspire one will not hover in place very well and if you hit the rth there's a good chance it will fly in the wrong direction!!
Have had this happen to me..
Make sure you're doing your compass calibration correctly..
I believe you rotate counter clockwise during both steps of the procedure ..meaning nose out ,then nose down..
I know I'm about to get edited again ..lol..
Turbo..

 

[The Editor]

Your inspire one will not hover in place very well and if you hit the rth there's a good chance it will fly in the wrong direction!!
Have had this happen to me..
Make sure you're doing your compass calibration correctly..
I believe you rotate counter clockwise during both steps of the procedure ..meaning nose out ,then nose down..
I know I'm about to get edited again ..lol..
Turbo..

Nope......... Not going to edit you

Other than....... It actually doesn't matter which way round you dance (cw or ccw),its the rotation that's important, nose out and nose down.

And you are absolutely right Turbo, it won't fly right on a bad compass cal.

 

[turbodronepilot]

Nope......... Not going to edit you

Other than....... It actually doesn't matter which way round you dance (cw or ccw),its the rotation that's important, nose out and nose down.

Thanks man..
I don't mind being edited..I usually learn something..
I agree compass calibrating isn't necessary every flight !!
Just when you move locations or you know your instuments aren't giving you the correct data..
Also if it rains that will effect your compass calibration..
If you flew the day before a rain in the same place I would recommend not calibrating it..
I did the other day and my instruments didn't line up..but rth worked so I still flew but only within los..
I cant give you a technical reason why this happens ..all I know is it does..
Turbo..

 

[SRH]

I calibrate my compass in a known good area that I have used on all my multirotors for the last three years.
Personally I have never had a problem using this method but people need to make their own minds up and do what they feel comfortable with.
A tell take sign you have a bad compass cal is your craft just won't 'feel' right in the air. It will not be 'locked in' and will fly like it is drunk if that makes sense. There may also be TBE when you put it in one spot and hover.
My rule is if ANYTHING doesn't look or feel right, land asap and find out what the problem is. If it can't be sorted. ...don't fly.
Take offs are always optional, landings are obligatory.

So if it flies 'Drunk' and you land to sort out the problem what is the next step? Re cal in a different location? Compass degassing? I had to send mine in because is would go crazy right after take off... I live in the middle of know where and went into a field with nothing around and did a compass cal thinking I had interference. Still crashes right after take off... Lucky no real damage and I sent it as a precaution. When I get it back and what to know how to anticipate before issues happen... It flew so good for 20 flights and then disaster...

 

[The Editor]

So if it flies 'Drunk' and you land to sort out the problem what is the next step? Re cal in a different location? Compass degassing? I had to send mine in because is would go crazy right after take off... I live in the middle of know where and went into a field with nothing around and did a compass cal thinking I had interference. Still crashes right after take off... Lucky no real damage and I sent it as a precaution. When I get it back and what to know how to anticipate before issues happen... It flew so good for 20 flights and then disaster...

Always, always, ALWAYS check your mod values right before take-off. If any do not look right do not fly.
If your compass mod value and IMU values all look fine and it still flies drunk, then land immediately and look for the problem. If you have inadvertently calibrated your compass in a bad area but the mod value is showing as 1400-1600, try picking up the Inspire and moving it a few feet somewhere else. Once you are clear of an influencing factor you will see a vastly different mod value.
Basically, if you have calibrated your compass correctly you will see very little difference from location to location (assuming not thousands of miles) between your compass mod values.
Remember though, if something isn't right.....do not fly.

 

[damoncooper]

^^^^^^ what he said

 

[rilot]

And what should the mod value be?

 

[turbodronepilot]

And what should the mod value be?

1400 to 1600 for compass..

 

[Gigs]

and what is a good range for IMU?