p3s - rth vs smart rth

[JohnnyB]

Thinking of different scenarios, if having the smart RTH turned off and knowing its tied in with the toggle, would this also disengage the toggle RTH on the P3S, or the RTH button on the P4? If so, a person could quickly turn it back on if they were to get disoriented during flight. I need to test my P4 on this so I'll know myself.

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[MacPhantom]

It was good to go on with it. RodPad has interest in how this ties in with Litchi. These settings are not accessible in Litchi, (smart RTH on/off) therefore DJI Go is needed to go along with Litchi.

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Good point, I have not delved into Litchi yet so mistakenly I don't consider the implications outside of the DJi app.

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[jwmcgrath]

Seems to me, 5 pages of posts could have been resolved had they simply named the modes:

Low battery RTH
Loss of Signal RTH
User Initiated RTH

The part about being able to turn it off... somewhat disturbing. Mostly because if you do need to turn it on in a low battery emergency, you may only have seconds to remember where to find it...


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[JohnnyB]

Seems to me, 5 pages of posts could have been resolved had they simply named the modes:

Low battery RTH
Loss of Signal RTH
User Initiated RTH

The part about being able to turn it off... somewhat disturbing. Mostly because if you do need to turn it on in a low battery emergency, you may only have seconds to remember where to find it...


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Agreed. One subject I can think of, as I've read in post early on, is "knowing your batteries". One way to test their limits to find out how much time each of your batteries have is to turn off the smart RTH and fly close by and in the last 3 or 4 minutes be hovering just a few feet in front of you. It was suggested to write down the time of each of your batteries which I think is a smart thing to do. I do have one battery that don't seem to produce the same results as the rest but I haven't tested them like this. So, testing batteries could be one reason to use this feature.

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[SkyHog]

It was good to go on with it. RodPad has interest in how this ties in with Litchi. These settings are not accessible in Litchi, (smart RTH on/off) therefore DJI Go is needed to go along with Litchi.
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I happened to be running a Litchi mission two days ago where Smart RTH kicked in, and I was very grateful to have it enabled. It was a long mission, and I knew I would need about 70% of battery to make it. But the winds outbound were slightly worse than forecast. So just before the bird reached to furthest waypoint, I got the Smart RTH message which asked me if I wanted to return to home. I had never seen that message in any flight before. But even before I could answer the message, I got a Signal Lost message. So now I'm in the dark as to what is happening, no video, no control link, and no way to even initiate an RTH manually. Just a few minutes later, the link re-established and I could see that the bird was already making a beeline for home.

As it turned out, it arrived home with 35% battery remaining. If it had run the rest of the waypoints instead, it probably still could have made it back with at least 30% battery remaining, just as I had estimated, because those last waypoints were pretty well aligned with the path home anyway. But the lesson learned for me is that Smart RTH is a very good feature that will help keep us out of trouble. I have a lot more confidence flying with Litchi, knowing that this Smart RTH feature actually works as advertised. However, it seems to be set a little too conservative, returning with 35% unused battery, maybe because of the tailwind on the inbound path in this case. Maybe the next iteration of Smart RTH will get even a little smarter yet, and measure windspeed, using ground track-made-good (GPS), vs power, and heading.

 

[JohnnyB]

In a couple of hours, I will test the RTH button on my P4 with smart RTH turned off just to know that I know that I know... And will post results.

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[JohnnyB]

@SkyHog
Good post and info. A suggestion for that mission, you can adjust at what % low battery kicks in. I would back it off a bit and run the mission again to complete it.

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[solentlife]

Agreed. One subject I can think of, as I've read in post early on, is "knowing your batteries". One way to test their limits to find out how much time each of your batteries have is to turn off the smart RTH and fly close by and in the last 3 or 4 minutes be hovering just a few feet in front of you. It was suggested to write down the time of each of your batteries which I think is a smart thing to do. I do have one battery that don't seem to produce the same results as the rest but I haven't tested them like this. So, testing batteries could be one reason to use this feature.

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Forgive me for saying that this is a recipe for crash. Why ?

Flying entails different loads on the battery and can have a dramatic effect on battery run time. Ask any regular RC flyer. With respect to a Drone or Helicopter - you can actually use more power to hover than to move horizontally depending on weather / wind etc.

What you can do is log times and % battery left after flights with conditions at time .. wind direction and strength. After a few flights you will build up a good idea of what you can safely fly.

Unfortunately DJI have chosen to not let us check power levels when connected up ... normal RC models, we can connect a Wattmeter and test max amps draw - then calculate shortest flight time. This gives us a safe flight time based on max power drain. Flight tests after allow us to adjust the timer accordingly.

DJI claim 25mins on the P3 ... yeh well don't expect to get your AC back if you insist on trying that !! At best I have had 21mins and landed out at what I consider lowest battery level. The App was already screaming at me ... about the battery level. I was on flight home - so it did not need to RTH.

I do suggest caution on this ... I now restrict flights to under 20 mins with 18 mins as my usual target.

Nigel

 

[solentlife]

"Skyhog" .....

"I got a Signal Lost message. So now I'm in the dark as to what is happening, no video, no control link, and no way to even initiate an RTH manually. Just a few minutes later, the link re-established and I could see that the bird was already making a beeline for home. "

Because the AC itself is designed to go home if no control signal is detected. You may not have control or video - but AC knows its home point. It does not need you to tell it ...

Nigel

 

[JohnnyB]

@solentlife
Good point. Like I said, I hadn't done this, but was trying to simply think of a reason to use the option of turning off smart RTH. They have the option, but not certain why we would use it besides wanting to have control over when you want to come home without RTH kicking in.

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[SkyHog]

"Skyhog" .....

"I got a Signal Lost message. So now I'm in the dark as to what is happening, no video, no control link, and no way to even initiate an RTH manually. Just a few minutes later, the link re-established and I could see that the bird was already making a beeline for home. "

Because the AC itself is designed to go home if no control signal is detected. You may not have control or video - but AC knows its home point. It does not need you to tell it ...

Nigel

No, not on a Litchi waypoint mission. It doesn't return home with signal loss, by design. I routinely run out of signal range on Litchi missions and it keeps running along merrily through the waypoints and eventually returns home and recaptures the link as it approaches home. That alone doesn't bother me. This particular mission was more worrisome because of longer total flight distance, signal lost, while the battery was low, and far from home. But it still worked out well because of the Smart RTH.

EDIT: One additional note. In my post flight log analysis, I noticed that Smart RTH kicked in while I was 10,989 ft from home, with 64% battery remaining!! When you are that far from home, even 64% battery was considered "battery low", and kicked in the Smart RTH. It's good to have the system watching out for you.

 

[jwmcgrath]

Agreed. One subject I can think of, as I've read in post early on, is "knowing your batteries". One way to test their limits to find out how much time each of your batteries have is to turn off the smart RTH and fly close by and in the last 3 or 4 minutes be hovering just a few feet in front of you. It was suggested to write down the time of each of your batteries which I think is a smart thing to do. I do have one battery that don't seem to produce the same results as the rest but I haven't tested them like this. So, testing batteries could be one reason to use this feature.

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I did something like this a couple of weeks ago... I wanted to force the low battery RTH to activate.

I was in a wide open field and intentionally kept the bird about 50 yards away and 50' off the ground. I wanted to give myself enough altitude to deal with whatever happened.

To be honest, I'd initially forgotten that at "critical" battery it would start to auto land (which was why I was testing things to start with!) knowing that a 50 yard walk was worst case scenario.

Shortly after realizing it was auto landing, I remembered that I could still control direction, and still had enough altitude to bring it home.

It was a fun, informative exercise. Taught me that you have to keep thinking while things are happening!


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[JohnnyB]

So, failsafe RTH is disengaged on a litchi mission, but smart RTH, if enabled in Go, still works. Not trying to turn this in to a Litchi thread, but these questions have been discussed without definite answers and this sheds good light on the subject.

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[SkyHog]

Yes, DJI Go is still necessary for firmware updates. But I usually fly with Litchi even when I am not doing a waypoint mission. All DJI Go settings persist in the bird, even after you uninstall DJI Go, e.g. RTH altitude. But you can change most of those settings with Litchi if you want to.

 

[JohnnyB]

I did something like this a couple of weeks ago... I wanted to force the low battery RTH to activate.

I was in a wide open field and intentionally kept the bird about 50 yards away and 50' off the ground. I wanted to give myself enough altitude to deal with whatever happened.

To be honest, I'd initially forgotten that at "critical" battery it would start to auto land (which was why I was testing things to start with!) knowing that a 50 yard walk was worst case scenario.

Shortly after realizing it was auto landing, I remembered that I could still control direction, and still had enough altitude to bring it home.

It was a fun, informative exercise. Taught me that you have to keep thinking while things are happening!


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Good to get to know your bird and what it does. I had done the same thing once and it landed at the first low battery warning, which I cancelled, but then remembered I was within the 30M radius of home point so it lands where it's at. Glad I could cancel at the time.

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[JohnnyB]

Yes, DJI Go is still necessary for firmware updates. But I usually fly with Litchi even when I am not doing a waypoint mission. All DJI Go settings persist in the bird, even after you uninstall DJI Go, e.g. RTH altitude. But you can change most of those settings with Litchi if you want to.

I've only updated once since I bought the P4 in sep, '16, and she has been flying flawlessly so I'm scared to touch anything firmware wise so I'll not be uninstalling anything for now..lol I didn't know all this was stored in the bird and remained the same if go was uninstalled. Interesting.
Edit.. just hit me.. that's how it knows what to do on a fail-safe RTH.. i guess I did know.

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[SkyHog]

I've only updated once since I bought the P4 in sep, '16, and she has been flying flawlessly so I'm scared to touch anything firmware wise so I'll not be uninstalling anything for now..lol I didn't know all this was stored in the bird and remained the same if go was uninstalled. Interesting.
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Yes, I understand that concern. To be clear though, running Litchi doesn't require uninstalling anything at all. I've never uninstalled DJI Go, and I usually just keep it closed when using Litchi. I was just making the point that you could uninstall DJI Go from your tablet/phone, and your bird still retains its settings, and you can see those settings when your fire up the Litchi app. So I switch between apps, depending on what flights I want to make, and no installation or uninstallation is required (though you do want to be sure that only one app is running on your phone/tablet on any given flight; force close the other one).

 

[higgipops]

I thought smart return home is to do with the battery level going down ,


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[SkyHog]

I thought smart return home is to do with the battery level going down ,
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Yes, it is. As mentioned earlier in this thread, it would have been better to have named it Low Battery RTH. It essentially calculates how much battery is needed to return home safely, and when battery level reaches that point a message is sent to the pilot to ask if he wants to allow RTH, and if there is no answer, RTH is activated by default.

 

[higgipops]

Ok I got lost in the thread [emoji30][emoji30][emoji30]


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