DJI Naza-H GPS

[R_Lefebvre]

The next step is to remove the system bring it to my software engineers and have them incorporate the RTH function.

I'm extremely curious on how you go about doing that? How would you ever get the source code? I'm pretty sure DJI has this stuff locked down tight?

[R_Lefebvre]

Originally Posted by NexxuSix

Upon further analysis, I believe what happened was, that I spooled up in manual mode on the pavement. I then got into a low hover, and then switched over to GPS mode. I ascended, then took my arial photography, then started to descend. When I got down to the low hover, I then attempted to land on the grass. I landed, full Headspeed in GPS mode, the attempted to switch over to manual. After all, I had done this several times today. I think I got into trouble by not landing back on the pavement.

Damages: Torque Tube tail boom strike, rear stabilizer mount broken, one stripped servo, main gear stripped, one broken blade, the other delaminated. Oh, and a GPS puck that got the wires cut right off at the shell. The shell is damaged, but the circuit board still looks in tact. I have contacted DJI to see if the offer a repair service... Basically, I would need a new cable and shell replaced. I can only hope their customer service is reasonable...



I'll keep you guys up to date with how things go. This will be a real test of DJI's customer service...

Sorry to hear this. But what exactly happened? Not so much the modes or whatever but... what actually caused the boom strike? Did you hit the ground too hard? Did it tilt the swashplate back when you were on the ground and that caused the blades to hit?

[flim63]

Originally Posted by NexxuSix

Basically, I would need a new cable and shell replaced. I can only hope their customer service is reasonable...

I'll keep you guys up to date with how things go. This will be a real test of DJI's customer service...

I have to say that since their system was not at fault, 'contact a dealer to buy a new GPS' might be the response.

I, too, have landed in gps mode but will discontinue that practice until new firmware adds semi-auto T/O and landing. On touchdown, if the heli leans due to uneven ground, the swash will move to correct and when the heli does not respond, will add more correction until...

On the compass aligning issue, I would not bother rotating the puck. They make a point to tell you to face it toward the front and believe the software uses relative heading info rather than absolute but that would depend on the correction algorithm they implement. I am at 14 degrees East variation and with the puck aligned to the front, GPS mode works quite well. How does Arducopter use magnetic information in loiter mode?

This stuff fascinates me.

[nightflyr]

Originally Posted by R_Lefebvre

I'm extremely curious on how you go about doing that? How would you ever get the source code? I'm pretty sure DJI has this stuff locked down tight?

Hmmmm..Futaba had expressed the same thoughts at the time....that does not stop those who do it for a living and have access to equipment I don't even try to pretend I understand.

[Altix]

Originally Posted by flim63

I... How does Arducopter use magnetic information in loiter mode? ...

In that case, there is a chapter in the Mission Planner software, where you have to enter a value for your local magnetic declination.




Gesendet von meinem iPad mit Tapatalk HD

[R_Lefebvre]

Originally Posted by flim63

How does Arducopter use magnetic information in loiter mode? .

It's really easy. Simply subtract (or add, can't remember, now you guys got me all confused too!) the declination from the compass heading to find the direction of true north.

The other thing to keep in mind is that magnetic fields can cause a big problem here as well. If you have the compass on the tail boom of a heli, you should be fine unless you make a REALLY ugly wiring setup on your motor power! (ie: don't wind your power wires up into a coil and aim it at the mag ) But you should also be aware that even using steel screws to mount the mag can cause problems. I try to use plastic screws to clamp a plastic plate to a common aluminum boom clamp. Then put the mag on top. No steel nearby.

We've also gone through a number of different magnetometer calibration techniques. You can do the common "do a little dance with your heli" as a start. Then we have this other one where after flying, you come down and have a PC run an analysis on the datalog, and come up with a best-fit in-flight calibration. This usually works the best, but not always. I have this problem right now on my 450. I think it's because it's so small, I can't put the mag far enough from the steel screws.

Hmmmm..Futaba had expressed the same thoughts at the time....that does not stop those who do it for a living and have access to equipment I don't even try to pretend I understand.

You hacked a receiver or what?

I have no idea how you could get anything usable back out of the DJI, but I'll be happy to follow along if you do.

As a non-professional-programmer, I am actually constantly amazed that I can change a few lines of code, upload, and have my heli fly completely differently. The whole thing just seems like such a miracle to me. Crazy I know but... It's not like cutting metal and turning screws. It's just magic.

[NexxuSix]

Originally Posted by R_Lefebvre

Sorry to hear this. But what exactly happened? Not so much the modes or whatever but... what actually caused the boom strike? Did you hit the ground too hard? Did it tilt the swashplate back when you were on the ground and that caused the blades to hit?

I started out on pavement, but landed on grass. I landed in GPS mode, with full Headspeed. But as I switched modes, suddenly the heli leaned to the left. I panicked, and went to correct the heli, but then I could not seem to correct the lean to the right. By then the blades dug into the ground, a servo gave out, which inevitably caused the boom strike, cutting my GPS cable in the process, and flinging the GPS module over my head and behind me. The GPS case is cracked, but the circuit board looks good.

I did contact Cliff at Atlanta Hobby, who says that DJI will be happy to sell me a whole new GPS unit rather than offer a repair. Basically, I would need a new cable soldered on, and a new case for the GPS unit. If DJI sent the parts to me, I could even repair the unit myself.

I have since returned another letter to Cliff at Atlanta Hobby, asking him to try to talk to someone about getting replacement parts. I have also sent and email to DJI as well. But have not received a response.

Needless to say, I'm not to thrilled about buying a whole new GPS module, when all I need is just the cable and the shell.

If anything, let me serve as the Guinea Pig here... And offer advice...

If and when I get my GPS module back into operational status, I have considered mounting it on top of the tail fin, clearly out of the "boom strike" area... Also, I will be routing my wire on the "non boom strike side" of the tail boom to prevent it from getting cut, if this should ever happen again.

DJI: It is in your best interest to respond to your customers needs regarding safety, and repairs. You will quickly lose customers by remaining silent.

[Tahoe Ed]

NessusSix,


Can I restate something? ""I landed in GPS mode, with full Headspeed. But as I switched modes, suddenly the heli leaned to the left. I panicked." Yet you want DJI to replace your GPS??? Why? If I mess up, I do not expect the MFG to cover my mistake.

Man up and take responsibility. DJI says land in manual, not GPS. Did you read the manual?? Probably not or you chose to disregard the instructions. If I were Atlanta Hobby I would tell you to pound sand. But I am not them and they may be more understanding than I am as a user not a distributor.

[flim63]

Originally Posted by Altix

In that case, there is a chapter in the Mission Planner software, where you have to enter a value for your local magnetic declination.

Mission Planner, yes it would need it for navigation, but Naza-H does not have any point-to-point navigation, just correction back to a single lat/long. You could say thats navigation, but in the Naza case the accelerometers know which way the heli drifted. Nothing the Naza does requires it to know true north. And unlike the Arducopter, you don't enter magnetic variation info anywhere. I still don't think rotating the puck is going to reduce errors. Aligns' APS system does do point to point and I don't think they do a mag-variation correction either. Just the same compass swing the DJI has you do. Now after a flight the system could build a variation correction by comparing the mag compass, GPS track AND accelerometer data, but they don't tell you to make such a flight. The self-aligning flight that is optional is to be made in as motionless a hover as possible and would not provide data to tell it true north.

While I know the sickening feeling of watching your heli tear itself apart, calling out DJI to address 'safety issues' is an over-reaction I think. The helicopter was operated outside the envelope they designed. They have said semi-auto land is NOT in this firmware. I'm all for pushing the envelope but you have to assume all responsibility at that point… your a test pilot for your own invention if trying to create your own auto-land. If you have an idea to create a new type of circuit breaker by sticking a screwdriver into a power panel, you can't yell at Craftsman for making the screwdriver that burned down the house. Did the rotor totally destroy the cable or could you use the remaining part to repair?

Has anyone heard of a crash with the Naza-H that was installed and operated per the manual? This would be insightful as to the companies response attitude.

[Tahoe Ed]

flim63 well stated. It has been stated before. If your Naza flies strait and has not have Toilet Bowl Effect, i.e., rotating around a point 2+ meters in diameter keep the GPS puck aligned to the boom. If not, try to rotate it to see if it helps. It is your choice.

[NexxuSix]

Originally Posted by Tahoe Ed

NessusSix,


Can I restate something? ""I landed in GPS mode, with full Headspeed. But as I switched modes, suddenly the heli leaned to the left. I panicked." Yet you want DJI to replace your GPS??? Why? If I mess up, I do not expect the MFG to cover my mistake.

Man up and take responsibility. DJI says land in manual, not GPS. Did you read the manual?? Probably not or you chose to disregard the instructions. If I were Atlanta Hobby I would tell you to pound sand. But I am not them and they may be more understanding than I am as a user not a distributor.

I understand where you are coming at... and I'm not blaming anyone. I'm just asking for a simple repair, or at least the means to have the unit repaired. Thats all I'm asking.

As for reading the manual, yes, I did read the manual. Thank you. There are others on this forum that have landed in GPS mode with no problem. My mistake is that I chose to land on an unstable surface, and paid the price.

By owning up to and posting my mistake, I have pointed at a potential problem area by crashing and posting my damage report. I have also suggested a better mounting method as well.

When it comes to helis, almost everyone on this forum has crashed at least once, and has suffered a boom strike as well. I can live with that... its a fact of flying an RC heli, and rightly comes with the territory.

I posted what I did to make others aware that there is a possibility to have exactly the same scenario unfold. I wouldn't want anyone else in this forum to experience what I have so far, by having their GPS module cut off and damaged. As I stated earlier, let me serve as the Guinea Pig.

I am awaiting DJI's response, and also to see what or if there are repair options, up to and including a DYI on my part.

Until then, I will keep you all posted out here on this thread. Perhaps there are a few things to learn here, and passing on the knowledge is what we do in these threads. Knowledge is power. And with my installation suggestions, I will inevitably save a few more heli pilots from a little grief and heartburn.

I will get off my soapbox now...

[Tahoe Ed]

I know several Naza M owners that have shortened their GPS leads. You should be able to reattach the wires to make it work. The question is whether you damaged the compass inside the puck. I am sorry if I misunderstood your original post.

[NexxuSix]

Originally Posted by Tahoe Ed

I know several Naza M owners that have shortened their GPS leads. You should be able to reattach the wires to make it work. The question is whether you damaged the compass inside the puck. I am sorry if I misunderstood your original post.

Apology accepted

Thank you for the information. I don't know how hardy the electronics are, but hopefully the unit will power up and calibrate. If it doesn't, then I will most likely buy another GPS unit.

Just a little update folks...

Please be careful with your GPS units. So far every dealer I have worked with seems to confirm the there is no repair service available... If you suffer a boom strike, most likely you will take out your GPS as well.

As for DJI, they still have not answered my request for repair...

[zeeflyboy]

DJI are possibly the worst company I have ever had the displeasure to deal with regarding emails. Well, I say deal with but in reality I mean ignored by.

I know my experience is far from unique in that regard.

They may as well not bother publishing an email address, I'm not sure why they do in all honesty.

[Tahoe Ed]

My experience has been just the opposite. I send an email and I usually get a response in 24-48 hours. I think it would be nice if they had a 24/7 skype customer service but I am just dreaming now. When you want to talk about non-existant customer support try Align. I have never gotten a response from them, along with most of the other flight controller manufactures that I have dealt with. Skookum was reasonable, about on par with DJI in my experience. The Germans are the worst. No offense to our German users just the manufacturers.

[R_Lefebvre]

How much is the GPS puck to buy as a replacement? Unfortunately, I think this will be a very common, and recurring thing for heli pilots.

The only solution is to put the GPS unit well inside blade tip radius. Just a few inches back from the boom holder.

On my 450, I have my GPS/Mag right on top of the boom holder actually, where the gyro would normally sit. This seems to be fine for the GPS, but not the mag as it's still a bit too close to all the magnetic noise. It works but it's not ideal.

If DJI were at all concerned with their customers, they should make the GPS cable detachable at the puck. You could put the puck inside or outside the blade radius, and worst case, just have to buy new cables. As long as the GPS puck doesn't take a direct hit from the blades, it should survive. But it's almost impossible to prevent the cable being cut.

The only time I've ever broken a GPS unit is because it got smashed when my quad flipped and hit hard, upsidedown on pavement. The units have survived countless helicopter crashes, and even an upsidedown Octo crash onto grass. I just need to replace the cable every once in a while.

[NexxuSix]

Originally Posted by R_Lefebvre

How much is the GPS puck to buy as a replacement? Unfortunately, I think this will be a very common, and recurring thing for heli pilots.

The only solution is to put the GPS unit well inside blade tip radius. Just a few inches back from the boom holder.

On my 450, I have my GPS/Mag right on top of the boom holder actually, where the gyro would normally sit. This seems to be fine for the GPS, but not the mag as it's still a bit too close to all the magnetic noise. It works but it's not ideal.

If DJI were at all concerned with their customers, they should make the GPS cable detachable at the puck. You could put the puck inside or outside the blade radius, and worst case, just have to buy new cables. As long as the GPS puck doesn't take a direct hit from the blades, it should survive. But it's almost impossible to prevent the cable being cut.

The only time I've ever broken a GPS unit is because it got smashed when my quad flipped and hit hard, upsidedown on pavement. The units have survived countless helicopter crashes, and even an upsidedown Octo crash onto grass. I just need to replace the cable every once in a while.

The GPS is about $180 right now... And rightfully so, I should buy one as a replacement. An even bigger problem has now emerged in all of this:

Last night I powered up the IMU for the first time since the crash. The IMU will not fully initialize now, telling me that the IMU is "abnormal, contact DJI or other agency". I have tried reloading the firmware, and even reloading the factory defaults, but I still get the red-green-yellow LED sequence over and over and over.

This is terrible... I know these IMU systems (especially at this price) aren't exactly bullet proof, and are intended for the hobbyist. But how about a little durability?

So now it seems, I am left to purchase a new GPS (a given fact in my case) and hopefully contact DJI to get my IMU back to operational status. As it stands, I essentially have a very expensive paperweight with no support, or repair options.

At this point, its safe to say I'm out of the Naza-H race early on... Go figure.

If I make any more progress, good or bad, I will post my latest to the group. If I somehow do get a new Naza-H system, I will consider mounting the IMU to Zeal Tape, and putting the GPS puck on the tail fin.... route the wires on the "non boom strike" side of the tail boom, and avoid any more crashes

[nightflyr]

It is possible your IMU ( which I assume was setup with the GPS) may be giving you trouble due to the fact your GPS is now not present.

[R_Lefebvre]

The GPS is about $180 right now... And rightfully so, I should buy one as a replacement. An even bigger problem has now emerged in all of this:

That's crazy. All this from a boom strike? You wouldn't believe the crashes I've had.

Check this one out:

[ame]http://youtu.be/fnC0YIENfYg[/ame]

Just skip to the half-way point if you want. Basically, this is an Octocopter, and the canopy wasn't secured well enough. The canopy popped off in flight, and damaged 5 propellers, and I think one propeller rotated on the boom making the terrible yaw, otherwise I think it would have survived.

It fell from that height, and smashed upside-down, then bounced. The avionics stack was squished flat. It's all fine. Just had to replace a few wires that got yanked.

Here's another, this one landed upside down on pavement. The GPS was shashed to oblivion, but the IMU is fine.

[IMG]http://api.ning.com/files/XmwcPoxLHk9eR5gKdVbfyfr7gCs5ozxbRFyj0vEMNL9pWtTpy5 pg2ZMivrnenocIS1S-UX-kIRVENI*btMInoQ__/DSC00765.JPG[/IMG]

[zeeflyboy]

Just a thought, you think it's possible you shorted something out when the wire got cut? Could easily have had a momentary short circuit that could have caused some damage to the Naza I guess?