Failsafe RTH issue?

rimb05 · Mar 9, 2015

I had an unusual thing happen the other day and I'm wondering if it's a bug or intended behavior. I took off from the top of a building which was 80 feet tall. I then flew to another location and decended to an altitude of -50 feet (50 feet lower than the takeoff altitude). I lost signal at this point, and the inspire went into failsafe RTH. However, instead of climbing up to the RTH altitude (I have this set to 60 meters), it flew straight home (and almost crashed into a tree

. Since I have my RTH set to 60 meters, I assume it should have ascended to 60 meters above my takeoff point first before coming home, but it didn't do that for some reason.

Could it be that the higher takeoff altitude confused it?

DaBone · Mar 9, 2015

No idea.

But I discovered in the flight simulator available in the app, that you apparently can rise manually during RTH. I was in the 120m that was my roof, rising to 160m during RTH, could surely rise higher. Just wondering why I could fly higher then my "flying roof".. or is it just a bug in the program?

Bought mine last Friday, but has not been able to fly yet. Have got the flu and fever, but are looking to defy it tomorrow. Want out and fly sometime!

The Editor · Mar 9, 2015

rimb05 said:
I had an usual thing happen the other day and I'm wondering if it's a bug or intended behavior. I took off from the top of a building which was 80 feet tall. I then flew to another location and decended to an altitude of -50 feet (50 feet lower than the takeoff altitude). I lost signal at this point, and the inspire went into failsafe RTH. However, instead of climbing up to the RTH altitude (I have this set to 60 meters), it flew straight home (and almost crashed into a tree . Since I have my RTH set to 60 meters, I assume it should have ascended to this altitude first before coming home, but it didn't do that for some reason.

Could it be that the higher takeoff altitude confused it?

Nope - Zero Take-off is relative to the start point not the ASL. So in other words, if you climb to the top of Mt Everest and take off from the summit THAT will be zero. If you had your RTH set at 100m in that example and then triggered it, the Inspire would climb to 100m above Mt Everest summit (your take off altitude) and then come home.
Flying below your take off point should not affect the RTH behaviour - It should always CLIMB to your RTH height setting above your start point (unless you are within 65 ft of home point)

rimb05 · Mar 9, 2015

The Editor said:
Nope - Zero Take-off is relative to the start point not the ASL. So in other words, if you climb to the top of Mt Everest and take off from the summit THAT will be zero. If you had your RTH set at 100m in that example and then triggered it, the Inspire would climb to 100m above Mt Everest summit (your take off altitude) and then come home.
Flying below your take off point should not affect the RTH behaviour - It should always CLIMB to your RTH height setting above your start point (unless you are within 65 ft of home point)

Right, that's what I would expect, but in my case, when failsafe RTH triggered, it did not climb to 60 meters above my takeoff point like I would expect.

Meta4 · Mar 9, 2015

How far away from launch point was the Inspire (horizontally)?

Richard-Inspire · Mar 9, 2015

I've read a few reports about RTH not resulting in an ascent to the correct height. Is this proven 'known behaviour' yet?

Mazz · Mar 9, 2015

This has been mentioned once or twice before. I am not sure if it is a bug but some people have said their inspire makes a straight line to the home position. In your case you used it for what it was made for and there was a loss of signal. It is unfortunate that it did not function correctly. This is also why I tell people never to lean on the RTH as your primary landing method. There are chances things can go wrong and there is no need to increase those chances. I know people like to test it but I have been sky diving several times and never tested my reserve. I just hope it works but know full well it may not.

Yt2 · Mar 9, 2015

I put this in the help section under (should return to home return to home). Maybe it is the same issue?

Went out again tonight and found the following.
Set flight height and advanced fail safe to 25 metres. Went to set home point to quads location and was confronted with the following. Blar blar, Whenrequired It will return to this point at a minimum altitude of 0.00m of as set according to your fail safe settings.
As I set this to 25m, is this a bug or am I missing something? I then set the home setting to the remote, it lifted and came home spot on.
Is it me or what?

damoncooper · Mar 9, 2015

Yt2 said:
I put this in the help section under (should return to home return to home). Maybe it is the same issue?

Went out again tonight and found the following.
Set flight height and advanced fail safe to 25 metres. Went to set home point to quads location and was confronted with the following. Blar blar, Whenrequired It will return to this point at a minimum altitude of 0.00m of as set according to your fail safe settings.
As I set this to 25m, is this a bug or am I missing something? I then set the home setting to the remote, it lifted and came home spot on.
Is it me or what?

Bug I believe

blade strike · Mar 9, 2015

If you were within 20m of homepoint it will not rise, it will just come home. Remember, You have full control when in rth, so you could have increased altitude.

rimb05 · Mar 9, 2015

The place where it lost signal and came home was about 2000 feet away horizontally from the takeoff point.

damoncooper · Mar 9, 2015

blade strike said:
If you were within 20m of homepoint it will not rise, it will just come home. Remember, You have full control when in rth, so you could have increased altitude.

I sincerely hope this becomes configurable. Several forum members here have been surprised at this behavior and either had crashes or near-misses as the mad beeline for home point at current altitude began. Children, pets, cars, trees, etc could all be in the path, and at low altitudes, an accident only takes seconds.

Better to make this configureable, in my opinion, perhaps defaulting to "raise to default altitude first" behavior.

This follows the "law of minimum astonishment" as we say in the software engineering world.

Kilrah · Mar 10, 2015

2 more reports of the machine not climbing before RTH - I really start to believe it is a bug and the minimum height is not being obeyed at all regardless of the distance at the moment.
I've again forgotten to test it myself.

Heiifyre · Mar 11, 2015

I have noticed that If I take off and fly below my start altitude, IE: down a hill, it messes with the inspire. When you climb back up to your start altitude the Inspire will think it is much higher than it is. It does not display a negative value for altitude when you fly below your starting point, so when you climb back up to your starting point it counts that as positive altitude. This could be why it does not climb to your preset altitude when in RTH. I am using a Invidia Shield with the latest version of the app.

rimb05 · Mar 11, 2015

Interesting... In my case, when I went below my takeoff altitude, it did display a negative altitude value. It got all the way down to -50 when it went into failsafe RTH, then made a bee-line back to home without climbing...

Heiifyre · Mar 11, 2015

when you would fly below yourself would the inspire drop along the hill by its self? Mine will follow the terrain as it goes down without my input. I think it only does that when it is using the vision cameras. I know for a fact that my app did not register the negative altitude though.

Richard-Inspire · Mar 11, 2015

"Remember, You have full control when in rth, so you could have increased altitude.

unless you don't have, of course! We are talking about a failsafe here, not a lazy "I can't be bothered to fly back and land" situation.

Surely the point about RTH is you pre-determine what you consider to be the safe criteria for its return, and it then does what you tell it to.

This 20m thing is frankly bizarre. It's just as likely that you'll hit something within that 20m as it is anywhere else, so I see no reason for this "behaviour".

Mazz · Mar 11, 2015

Richard-Inspire said:
unless you don't have, of course! We are talking about a failsafe here, not a lazy "I can't be bothered to fly back and land" situation.

haha I am with you. Funny thats what most people use it for though.

As for the issue I just don't like it. I don't care if it is 5 meters from me, I want it to go straight up and come back and land from 60ft every time like my phantom would. I can not see why relative distance would make a difference. Granted you are supposed to fly in open spaces but things move. Cars, kids, animals, etc. If something runs between the inspire and me, I would prefer not to have to worry about the machine just come straight back and clocking them in the face.

blade strike · Mar 11, 2015

Mazz said:
haha I am with you. Funny thats what most people use it for though.

As for the issue I just don't like it. I don't care if it is 5 meters from me, I want it to go straight up and come back and land from 60ft every time like my phantom would. I can not see why relative distance would make a difference. Granted you are supposed to fly in open spaces but things move. Cars, kids, animals, etc. If something runs between the inspire and me, I would prefer not to have to worry about the machine just come straight back and clocking them in the face.

This is why they have given full control when rth is activated, unlike your phantom.