Problem with NAZA-H

[FPVflyer]

Oh yea! Next time I have to make some works in the lab and take out blades, I will try it!

[Tahoe Ed]

Ok, when in GPS or GPS/ATTI the Naza H hovers on loss of RC signal. When in Manual control with no attitude, altitude or position control the Naza cuts the throttle when the receiver looses signal. What would you like it to do? Switch to ATTI or GPS/ATTI then hover? What happens when you are flying with another FBL controller and you loose Tx signal? Flies away, drops like a rock, what? I have used many FBL controllers but I have never flown beyond their capability to maintain RC signal. I need more education since I seem to be naive. What are the other controllers doing in the way of failsafe when RC signal is lost?

[nightflyr]

I agree with Tahoe Ed,
The Naza - H fail safe works exactly as described in the instructions.
If you want the helicopter to do something different if it engages fail safe while in manual mode you'll need to set your Rx fail safe and rebind accordingly.

Though by from what I've read...
You will have a helicopter with absolutely no cyclic control but still have the motor spinning.
Not the best case situation being the helicopter will go where ever it wants ( most likely earth bound ) under power

[FPVflyer]

Mine is set now with RC FS, and if RC signal get lost it switch to GPS ATTI and maintain the position, and give me the time needed (very easy) to boost up the power of the transmitter, then gain more the RC controls and come back.
In some situations I got FS @ 3km with this helicopter, yesterday I've done 5km and NEVER go under 85% with QL, who know why? So, this is why is important that the FS is a predetermined setup and MUST be like you set it up. If DJI say that a FS in manual cut the throttle, mmmmh..... I prefer that my receiver switch to GPS ATTI and the NAZA feel like RC signal EVER present.

[nightflyr]

Setting up your Rx fail safe to engage the Naza - H in GPS/ATTI mode is a solution...

But a pilot will need to be fully aware that it is possible that the helicopter could switch between Rx fail safe mode ( GPS/ATTI ) and manual mode.

This may or may not be a good thing depending on if you have your sticks off center at that time.
Not sure how the Naza would interpret this or react to it.

[FPVflyer]

I tested it at the field, fly it in manual and turn off the tx, and it is gone in GPS ATTI and stayed in his position. The only thing I'm worried is if I lost the RC link when flying high speed in manual mode, the GPS will hold the copter violently, but it should work anyway.

[R_Lefebvre]

But a pilot will need to be fully aware that it is possible that the helicopter could switch between Rx fail safe mode ( GPS/ATTI ) and manual mode.

Yes, this is an issue. We have had situations where people have landed a copter, lets say 20 feet away from "home". Then the turn off the Tx because they are done flying. The copter goes into RTL, takes off, and flies back to "home".

The issue is not really a problem with the controller, so much as it is a problem with a lot of newbies buying advanced flight controllers, thinking it will make flying easy. And they have not learned some RC basics, such as not turning off your Tx until the model is powered down.

We've been going through a maddening array of checks and balances to try and prevent this. The decision tree is getting huge.

What does a FBL controller do? I would think a smart user would program the Rx to output mid-stick, throttled up, and self-leveling if they have it. If no self-leveling then... yeah, it's probably going to crater under power. So maybe it is best to shut off the motor?

DJI must have figured that if you are flying in manual, you are probably doing acrobatics, at close range. Doing an RTL under power might be dangerous, so we're just going to kill it with in the safest way, that being, motor off.

[zeeflyboy]

Not naive ed, but perhaps a bit narrow sighted.

Just because something is not an issue for you of course doesn't mean it isn't for others.

Granted during normal flying failsafe is so unlikely as to be a negligible risk. Radio failure, flat Tx battery, loose antenna... That's about it.

However a significant segment of the market will be approaching the Naza with a mind towards FPV/AP where failsafes are much more of a concern.

Failsafe auto hover should be EXACTLY that. When the radio failsafes, the heli should enter (preferably relatively smoothly) a GPS position and altitude locked hover.

It should make no difference what mode you were flying in, only that the unit sees failsafe, and failsafe = auto hover.

Does the fact you were flying in manual mean you want the heli to crash when it failsafes? Of course not... Just like in any other mode you would want it to enter the auto hover.

Sticks will automatically be centred when it switches as you will have had the sticks central when setting the failsafe.

I believe this is the behaviour of the Naza-M... No matter what mode you were in, it will auto hover/RTH when it hits failsafe.

[Tahoe Ed]

Nightlflyr's response:
Setting up your Rx fail safe to engage the Naza - H in GPS/ATTI mode is a solution...

But a pilot will need to be fully aware that it is possible that the helicopter could switch between Rx fail safe mode ( GPS/ATTI ) and manual mode.

This may or may not be a good thing depending on if you have your sticks off center at that time.
Not sure how the Naza would interpret this or react to it.

[zeeflyboy]

Yes, it's a work around. It would need careful consideration of where the collective stick is placed during setting failsafe however in order not to elicit a climb or descent.

The failsafe hover mode SHOULD in fact do exactly the same thing though. It should enter the GPS Atti mode, but with a locked altitude. Like I say, the fact you were flying in manual when you lost signal shouldn't mean your heli crashes. Failsafe mode should be failsafe mode, no matter what you were in previously.

[nightflyr]

Yes, it's a work around. It would need careful consideration of where the collective stick is placed during setting failsafe however in order not to elicit a climb or descent.

You would need to have your sticks centered as per the instructions and GPS/ATTI mode selected when rebinding your Rx.

The failsafe hover mode SHOULD in fact do exactly the same thing though. It should enter the GPS Atti mode, but with a locked altitude. Like I say, the fact you were flying in manual when you lost signal shouldn't mean your heli crashes. Failsafe mode should be failsafe mode, no matter what you were in previously.

The above Rx fail safe setup will do what you are asking, but is only going to work as long as your batteries last..
Sooner or later your helicopter will fall to the ground.

A serious consideration is ...where you fly.
Being at a totally isolated area, damage to people and property would be kept at a minimum.

But if you fly anywhere near the general public..
Just for sake of argument...
Take the fact that most folks who do not fly helicopters find them quite interesting especially younger people.
Now your out flying in the local park or field or even flying club..
Your machine gets too far out (over who knows where or what) and goes to fail safe...

Now it is just sitting say 25 meters up in a stationary hover, and starts catching the attention of some on lookers who happen to notice it sitting up there and a small crowd starts to gather. ( I have been witness to this many, many times over the years )
At this point, the batteries reach their drain limit and the machine descends down towards the group of on lookers...

Another possibility..
Take the same type of situation, but you happen to go into fail safe in an area where the GPS encounters interference.

Bottom line with any of these helicopters and platforms you plan for the worst and pray for the best.

JMHO I would not think twice before sending any of my helicopters into a tree or the ground before there would be any chance of it harming anyone.

But with most things in life and this hobby you are free to do as you see best.

Some possibilities are quite frightening.......
Granted it is not a helicopter but .....
Look at the last 10 seconds and impose the on the frames starting at :50 seconds

[ame]http://www.youtube.com/watch?v=QZ1MdK41UhQ[/ame]

[zeeflyboy]

But as you say it's up to the person flying to fly it responsibly... to be honest I'd never fly a helicopter this size where there was anythign but the remotest chance I might encounter anyone, especially kids.

RTH would in fact be safer here since it would start coming back to you and thus come back into range.

It's not an issue for me however as the EzUHF has a high power booster mode - all I need the thing to do is not crash for the time it takes me to hit the booster switch and regain control. The chances of not being able to regain control in this fashion are remote, which combined with the areas I fly in means that the possibilities you describe are highly unlikely.

[nightflyr]

As I stated...

It is all dependent on the pilot and conditions...
Not to forget the human factor.. people sometimes do foolish things.
Not with the intent to cause harm, but more in line with not thinking completely through what might occur..

As you say you fly in an isolated area with a signal booster, most do not.

Nothing is perfect in life..man or machine... you just hope.

[zeeflyboy]

Yup I was agreeing with you on that bit lol, hence the "but as you said".

I don't think it is or should be DJI's responsibility here. They provide the tools and the user has to be responsible for how they chose to use those tools... If you don't want failsafe hover, just don't enable it. If you do want it, it should be available whenever the rx failsafes.

[Titusx]

The problem with Naza failsafe is that it records Tx hover position when you switch from Manual to Atti/GPS Atti mode. If you are flyng in manual mode and lost signal, Naza will record 0 throttel position. I think the only way that it works fine is to set Rx throttel failsafe at hover throttel position.

[Tahoe Ed]

I think that is where having a preset failsafe come in. Set throttle, sticks etc when Tx signal is lost.

[nightflyr]

Well just for grins I decided to try to setup Rx fail safe so that the Naza-H would revert to GPS/ATTI mode during signal loss while flying in manual mode.

With a Futaba setup the basics are fairly easy..

1) Set your Rx to bind mode

2) Set your Tx switch to GPS/ATTI mode

3) Center your sticks

4) Now here is where I may differ from some..
I have SET RPM GOV mode set up on my Castle Creations ESC,and 3 flight modes set for different HS RPM settings.
So in order to get throttle to function correctly on Tx/Rx fail safe, I needed to set the fail safe value in the Tx in order to have it set the flat curve for the ESC in order to maintain the SET RPM GOV mode.

As best as I can see via the software and watching the mechanics of the helicopter...
While in Naza-H manual mode and powering down the Tx,the Naza does switch over to GPS/ATTI mode and maintains the SET RPM GOV mode on the ESC.

Now according to what I see the platform will react the same no matter what mode your flying and a fail safe condition occurs.

What I want to tinker with is.... if it is possible to to get the Naza to engage a controlled decent to the ground while in fail safe.

Considering on how it operates while in fail safe mode to maintain altitude.... It appears that lowering the HS while in fail safe may be the only way.
I am assuming that with a locked, set HS, that the Naza will not apply collective pitch.
If this is the case, lowering the HS while in SET RPM GOV mode of the ESC to the point of a slow decent should allow for a slow (semi) controlled decent.

Only issue that is left to over come..is that you should not land in GPS/ATTI mode.

Now it comes to the consideration of getting the helicopter down in a some what controlled slow decent, and hope that it will not topple over once it lands.
My thinking is if the decent is slow enough it may not tip over once on the ground.
May be a very expensive test to try to prove out if I'm wrong.

[R_Lefebvre]

I can tell you from much experience, that landing in Atti mode should be fine. Landing in GPS mode, is a disaster.

You also have to be careful about your gains, because it can cause a nasty jerk if your attitude gains are high and you touch down hard.

But the GPS thing is a big problem. The GPS signal drifts, and the heli will try to drift with it. If it tries to drift and is restrained, the I-terms will probably build up until it tips over.

So, landing in this mode is only feasible if you're there, and can take back control. However, if you have completely lost control well... the damage from a tip-over is still much less than the full-on crash you'd have had otherwise.

You guys are in a "lesser of evils" situation with this.

In GPS Atti mode, does the Naza-H actively manage collective to maintain altitude? Does it allow you to adjust altitude setpoint with the collective stick?

[Titusx]

Originally Posted by R_Lefebvre

...In GPS Atti mode, does the Naza-H actively manage collective to maintain altitude? Does it allow you to adjust altitude setpoint with the collective stick?

Yes, it manage collective to maintain altitude.
Collective stick works this way, as more you push it, the faster it climbs, like a car throttel. You cannot set max or min altitude, you could set speed.

[R_Lefebvre]

Yup, OK, thanks.

Why not just set the failsafe to have a touch of down-stick, instead of trying to do it with headspeed?

Maybe I misunderstood what you guys are talking about, but it sounds like instead of relying on the internal Naza failsafe (since it won't help you if you were in manual mode) you are using an external failsafe, having your Rx simply transmit a GPS-Atti signal, as well as center sticks. So if you lose the link in Manual, it will flip into position hold.

If you want it to descend, why not simply set the Rx failsafe with the collective just below the middle?