Fixing DJI's Compass Problem

[Dadcat]

A question to the beta testers..... Are you flying 100% ATTI in your tests? So far, that seems to be the only way to isolate the compass data from the GPS Data cable where it is presented to the NAZA. I don't see a NAZA input for compass only data.

Excuse me if I misunderstand your question. The problem only exists in GPS Mode, Course Lock and Home Lock where the bird is trying to fly a GPS course. It doesn't hook or anything in ATTI so no point to testing it. Wait a minute: Maybe somebody should actually try flying 3.05 beta in ATTI just to make sure nothing wacky has cropped up.

By the way, Dalite, the GPS BBRAM battery does charge up when the power is on. I posted about it over here:

viewtopic.php?f=27&t=17974&start=10#p166247

 

[Shartzilla]

The problem only exists in GPS Mode, Course Lock and Home Lock where the bird is trying to fly a GPS course. It doesn't hook or anything in ATTI so no point to testing it. 7

Course lock does not use GPS at all. It relies solely on the compass to determine orientation.

Page 20 of the Naza Manual. http://download.dji-innovations.com/dow ... .26_en.pdf

 

[d4ddyo]

The problem only exists in GPS Mode, Course Lock and Home Lock where the bird is trying to fly a GPS course. It doesn't hook or anything in ATTI so no point to testing it. 7

Course lock does not use GPS at all. It relies solely on the compass to determine orientation.

Page 20 of the Naza Manual. http://download.dji-innovations.com/dow ... .26_en.pdf

Hmm... Well whatever the manual says... IOC... CL or HL are functions of GPS mode. you have to be in GPS mode for it to work.

Even so... Both course lock and HL operate exactly like GPS mode. when you let go of sticks ... it will maintain its coordinate and altitude... doesn't it? if you pull it or a wind blows... it will stay there.. doesn't it? I don't remember i haven't flown in a while because of J-Hooking!

IOC means Intelligent Orientation Control. It has to do with orientation so when you film you can create an imaginary gimbal. but it still flies exactly like GPS mode. if it doesn't operate on GPS then we don't need a stinking GPS and save some money on production and retail cost.

 

[Dadcat]

Course lock does not use GPS at all. It relies solely on the compass to determine orientation.

Page 20 of the Naza Manual. http://download.dji-innovations.com/dow ... .26_en.pdf

I don't see where says that on page 20, but thanks for the newer version of the Naza manual. On page 18 it says that Course Lock will work in either ATTI or GPS-ATTI. Is that where you're getting this?

I've never tried CL in ATTI, but if it only uses compass without GPS, then how come it's able to follow the correct course in a crosswind?

 

[riblit]

The problem only exists in GPS Mode, Course Lock and Home Lock where the bird is trying to fly a GPS course. It doesn't hook or anything in ATTI so no point to testing it. 7

Course lock does not use GPS at all. It relies solely on the compass to determine orientation.

Page 20 of the Naza Manual. http://download.dji-innovations.com/dow ... .26_en.pdf

Agreed, however what we are seeing boils down to a difference in the location of North between the compass and the GPS.

If you have ever done a map reading course or bush walked before the days of the GPS system, think back to what you would do.

1 Obtain map of the area.
2 Find GR of your start location on map.
3 Find GR of your destination on map.
4 Calculate distance and bearing from start to destination.
5 Subtract ( in Australia ) magnetic declination using date of map and declination data on map to get magnetic ( compass ) bearing
6 Set prismatic compass to bearing.
7 Sight object in distance on bearing.
8 Walk to object, counting paces.
9 At destination?
10 No, goto 7
11 rest, have a cuppa.


The phantom firmware in course lock will be flying along the compass bearing ( angle between magnetic north and the direction the front is facing ) however as it's learning the local magnetic declination it's north position will be changing - it's comparing the compass bearing and the GPS bearing and adjusting the compass bearing so both agree, effectively making the compass point to true north.

Because it has locked in a bearing before it has calculated the local declination it will fly off course until course lock is reset after the local declination is learnt.

 

[N017RW]

Course lock does not use GPS at all. It relies solely on the compass to determine orientation.

Page 20 of the Naza Manual. http://download.dji-innovations.com/dow ... .26_en.pdf

I don't see where says that on page 20, but thanks for the newer version of the Naza manual. On page 18 it says that Course Lock will work in either ATTI or GPS-ATTI. Is that where you're getting this?

I've never tried CL in ATTI, but if it only uses compass without GPS, then how come it's able to follow the correct course in a crosswind?

I think it's being looked at backwards...
It does not state anywhere which sensors are used for the different IOC options.

The Phantom's DJI Wiki page does state that CL will work in GPS or Atti., whereas HL only works in GPS.
http://wiki.dji.com/en/index.php/Phanto ... lying_Test

To me it means you can use CL in either Atti. or GPS modes while HL will only work in GPS mode.

 

[Shartzilla]

CL is not dependent upon or related to the GPS. It works off the compass.

Horse. water. lead. Drink. Etc.

 

[wkf94025]

At the risk of going OT, you guys just switched on a light bulb for me regarding a possible life ring when GPS goes out far from home. My GPS has gone out a couple different times recently, and sometimes when I am waaay BVR. If FPV also went out at the same time, I am quite likely f*cked. I have not used Course Lock much at all, but assuming I confirm its orientation shortly after take-off, and I know the general vicinity of my quad relative to Course Lock when the lights would go out on GPS and FPV, switching to CL while in ATTI and pulling in the correct opposite direction on the right stick should help bring me back into FPV range. Sound right? Assuming my distance runs are in the Course Lock right-stick-forward direction, pulling straight back on right stick should be the right response if GPS goes out far from home and FPV is scratchy or lights out altogether.

Make sense?

Kelly

 

[Dadcat]

Assuming my distance runs are in the Course Lock right-stick-forward direction, pulling straight back on right stick should be the right response if GPS goes out far from home and FPV is scratchy or lights out altogether.

Make sense?

Kelly

Fascinating idea. I'll bet we know tomorrow. I would check it out tonight but this horse got lead to the Scotch bottle instead of the water so it's too late now.

 

[ianwood]

Course lock, as its name would imply, still uses GPS to maintain the course otherwise it would be like flying ATTI with a heading lock. But, the course flown by the GPS is set purely by the compass at the time it is recorded. This is why it is a perfect way to demonstrate the declination issue. This has all been covered.

 

[wkf94025]

Ian,

Not quite sure what you're saying. If GPS goes out, and youre dumped in ATTI, and you have (or put) IOC switch in CL position, and you pull back on right stick, what will happen? Will Phantom travel in direction opposite that which nose was facing when HL/CL set?

A bit hard to test GPS going out mid flight. I am not sure switching into ATTI while GPS still good is the same as GPS going out and Naza concluding ATTI is our only option. This matters so that pilots have one more trick up their sleeve if GPS goes out far from home, which I can attest is quite possible.

Kelly

 

[ianwood]

That's a good question. I am not sure CL would work as without GPS it could not hold a course. Wind would cause it to drift off course without GPS to correct for it. But you can hold a heading without GPS.

 

[wkf94025]

In the GPS-out situation I have found myself in several different times recently with two different P2's, precision isn't as important as getting generally back toward home, where FPV becomes useful again at some point. So if I have CL set to North (don't care which North for sake of this discussion), and I fly 2km North, and GPS suddenly bails just when FPV getting snowy, all I care about is that going ATTI+CL and pulling right stick back will *generally* get me closer to home. Even if strong easterly wind during all this, heading mainly toward home has big value.

I still suspect Garmin GTU-10 calling out may have something to do with GPS outage, but now I am waaay OT.

Kelly

 

[ElGuano]

In the GPS-out situation I have found myself in several different times recently with two different P2's, precision isn't as important as getting generally back toward home, where FPV becomes useful again at some point. So if I have CL set to North (don't care which North for sake of this discussion), and I fly 2km North, and GPS suddenly bails just when FPV getting snowy, all I care about is that going ATTI+CL and pulling right stick back will *generally* get me closer to home. Even if strong easterly wind during all this, heading mainly toward home has big value.

I still suspect Garmin GTU-10 calling out may have something to do with GPS outage, but now I am waaay OT.

Kelly

That is WAY out there indeed! You must have some gorgeous footage out there in wine country though.

 

[ianwood]

Definitely drifting OT but if your GPS goes out and CL still works, definitely correct for wind as it can get pretty far off course over 2km depending on the effective crosswind. As for the GPS being interrupted by the tracker, it's possible but I would be surprised. The GPS is already shielded from the electronics below and uses a saw filter to keep the noisy electronics from disrupting the GPS signal. But best way to find out is to remove the tracker and see if the GPS is more reliable.

EDIT: If your FPV is working and your GPS goes out far away, your best bet is dead reckoning. I wouldn't depend on CL alone in that case.

 

[Pazz]

In the GPS-out situation I have found myself in several different times recently with two different P2's, precision isn't as important as getting generally back toward home, where FPV becomes useful again at some point. So if I have CL set to North (don't care which North for sake of this discussion), and I fly 2km North, and GPS suddenly bails just when FPV getting snowy, all I care about is that going ATTI+CL and pulling right stick back will *generally* get me closer to home. Even if strong easterly wind during all this, heading mainly toward home has big value.

I still suspect Garmin GTU-10 calling out may have something to do with GPS outage, but now I am waaay OT.

 

[justin]

Hi,
i'm justin from south america.
and i have the same problem I thought i was calibrating the compass wrong.
but then i searched google and found this forum.
hope they fix soon.

 

[spunrdneck]

This why Drones will get banned, flying over these distances in unfavorable wind conditions with a known unreliable system which you are winging it to get it home. God knows what attitude you are flying at, but thats so irresponsible as you could end up meeting a plane, crash on a road & cause a car accident etc. You have no ability to know what is going on around you at that distance. All I can hope is you do crash/lose it soon to get one more maniac out of the air.

I assume with that level of disdain you know that where they are speaking of flying is in an area where planes are routed and there are roads and traffic? It seems kinda harsh to wish that somebody crashes or loses their hobby craft and label them a "maniac" based on a somewhat hypothetical statement... don't you, Pazz?

 

[Pazz]

xxx

 

[spunrdneck]

This why Drones will get banned, flying over these distances in unfavorable wind conditions with a known unreliable system which you are winging it to get it home. God knows what attitude you are flying at, but thats so irresponsible as you could end up meeting a plane, crash on a road & cause a car accident etc. You have no ability to know what is going on around you at that distance. All I can hope is you do crash/lose it soon to get one more maniac out of the air.

I assume with that level of disdain you know that where they are speaking of flying is in an area where planes are routed and there are roads and traffic? It seems kinda harsh to wish that somebody crashes or loses their hobby craft and label them a "maniac" based on a somewhat hypothetical statement... don't you, Pazz?

Do you know???

What I know is irrelevant. I have never wished ill will on anyone based on a statement taken out of context or without a complete understanding of that persons intentions, Nor will I ever.

Most folks here (including myself) are trying to get answers from others that may have experience in solving similar problems or just keep up on pertinent topics. Some (again including myself) offer clean, friendly, fact based assistance for the sake of perpetuating our hobby...

You sir have been seemingly argumentative and somewhat combative from the beginning of your posts... what is your goal here?