Emergency RTH Cancel request

kbirand

Well-Known Member
Hi Everyone,
Hi Alex,

I had few crucial situations where I had to disable RTH for emergency landing when the craft is far away.

For example, my craft is 17km far away and my battery is depleted, I spot a nice landing area. I start gliding, looks like a nice landing, start loosing video , baaaaaaammmm
RTH kicks in tries to return home, since there is no battery left actually thats not possible. Because my plane is far and when I decent ofcourse I loose radio signal and the flight
controller behaves as it is designed.

But as I explained there are few scenarios that you do not want RTH to kick in. So i was wondering in future releases there could be an option where you can assign this cancellation to a switch.

Best
Koray Birand
 

dayanki

Well-Known Member
Hi kbirand,
before losing video and RC signals, you can reduce to minimum the values of Set Cruise Throttle and Set Glide Throttle.
:)
 

kbirand

Well-Known Member
In my case I do not need that since the battery is depleted the craft is already gliding. The main problem are the servos...
 

kbirand

Well-Known Member
Thats not a realistic solution unfortunately :), you wont have enough time to reduce those values.. But a kill switch is more reliable.
And also when your battery is depleted 17 km away you want to land.. So you are already gliding and even the RTH kicks in there is no power.
But you still have enough power to steer and RTH tries to steer your aircraft towards home when you are trying to land straight.

Hi kbirand,
before losing video and RC signals, you can reduce to minimum the values of Set Cruise Throttle and Set Glide Throttle.
:)
 

bovick

Well-Known Member
Thats not a realistic solution unfortunately :), you wont have enough time to reduce those values.. But a kill switch is more reliable.
And also when your battery is depleted 17 km away you want to land.. So you are already gliding and even the RTH kicks in there is no power.
But you still have enough power to steer and RTH tries to steer your aircraft towards home when you are trying to land straight.
Maybe a setting to fly level for x seconds before RTH kicks in when there is signal loss?
I had the same exact situation (on the way back from an endurance flight, wind kicked up and battery ran out while still 1km out). I glided and looked for a safe place (video would cut if throttle was up since voltage would sag). There was a large empty field so I went for it and tried to ditch the plane there. Unfortunately, at about 15 feet off the ground, I lost video because the RTH kicked in from signal loss (trees and houses in the way) and there was just enough batteries to get the stupid thing up in the air again.. barely cleared the trees at the end of the field I imagine.. and ended up 1/2 km ahead in a neighborhood in a driveway between two houses! Got lucky that time, but I started looking for a solution to this...

The only thing I can think of with the APM/pixhawk is to set a larger wait time before RTH kicks in and set it to 'FBWA' (stabilize) mode while it doesn't have signal but is waiting for the needed 10 seconds of waiting before doing RTH.

An autopilot disengage switch would be nice to have better control over ditching the plane in a safe spot when needed.
 

evox

Member
17km is a loooong way from home to be running out of battery! i don't think its a good idea to disable the RTH better to have a loiter "lock" and and jump in the car and drive there
 

kbirand

Well-Known Member
Ofcourse I am going to drive there, but to be able to drive there and to be able to find IT there you need a good landing. Before you loose video and rc signal you adjust your course to a specific landing area and you start gliding towards there but when rth kicks in it takes you out of your course, and since there is no battery left, it is just the aileron servos, which does not make sense...

I think you should watch the following video to understand the experience, and why I am asking for it.

[video=youtube;kCrE36NqfZg]http://www.youtube.com/watch?v=kCrE36NqfZg[/video]

start watching from 01:17:18 .. my intention is to fly straight and land to the dirt road ahead of me and then RTH kicks in ... Every time RTH kicks in the plane flies towards the lake.. This plane was found exactly after 4 months after the crash by a person who does fishing around that area just near by the waterline.


17km is a loooong way from home to be running out of battery! i don't think its a good idea to disable the RTH better to have a loiter "lock" and and jump in the car and drive there
 

evox

Member
i see what your saying, if you have ezuhf for example you can hit the failsafe set button on the back and that would disable RTH failsafe ( as you will no longer have the throttle over failsafe point set ) and you can set your controls in what ever position you want
 

kbirand

Well-Known Member
Evox, what you say makes sense, very clever...
But still a kill switch for RTH would be a clean solution..
 

evox

Member
agreed, I just watched some your videos very nice!
how do you find the 1.5w 1.3 transmitter, do you run it outside of the case? I've been thing about upgrading to one.
 

kbirand

Well-Known Member

kbirand

Well-Known Member
Evox, I am already on that list with my 56km flight.. I will fly more then 70km and then post it to the list.. Yes I did recover my plane without a scratch. I do actually have a quite good recovery system installed on the plane GPS tracker, two buzzers, with backup power, dragonlink as a beacon after 5 minutes of inactivity.
 

Alex Villa

Super Moderator
Adding an RTH cancel switch is doable. However I think there is very limited use for it. If you are far away is very unlikely to have RC link bellow certain altitude. Maybe the switch could force controlled descending while keeping the actual heading(upon signal lost). This will let you set the emergency landing path at least.

And hopefully not cause people to set this by accident. Maybe a menu item you can access after realizing there is no battery left to go back home.
 

kbirand

Well-Known Member
To avoid accidents as you said it could be accessed via a menu option.


Adding an RTH cancel switch is doable. However I think there is very limited use for it. If you are far away is very unlikely to have RC link bellow certain altitude. Maybe the switch could force controlled descending while keeping the actual heading(upon signal lost). This will let you set the emergency landing path at least.

And hopefully not cause people to set this by accident. Maybe a menu item you can access after realizing there is no battery left to go back home.
 
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