Losing MMs and RTH Question...

[Terry851]

In a MM video I watched yesterday, the person suggested that if you're in RTH mode and it's too windy at your RTH height, you could use your sticks to drop your height and increase your forward speed to help your MM return to you. I believe you can not change the direction in RTH, but you can change height and speed. Keep in mind if you increase your forward speed, you will use more battery.

 

[mullern88]

I wonder about the reference value for RTH setting. If I set it to e.g. 50 metres, is that 50m above take-off altitude? That would mean that if I fly uphill a rising terrain, RTH value could not be enough to avoid a 30m high tree that is standing on the elevated terrain. Or is the RTH setting referenced to the GPS altitide of the current drone position? This would mean that the drone clims to 50m above CURRENT GROUND LEVEL, so would avoid the 30m high tree.

 

[new2mavic]

I wonder about the reference value for RTH setting. If I set it to e.g. 50 metres, is that 50m above take-off altitude? That would mean that if I fly uphill a rising terrain, RTH value could not be enough to avoid a 30m high tree that is standing on the elevated terrain. Or is the RTH setting referenced to the GPS altitide of the current drone position? This would mean that the drone clims to 50m above CURRENT GROUND LEVEL, so would avoid the 30m high tree.

50m above take-off altitude

 

[mullern88]

Thanks for the fast reply, New2Mavic (you don't seem to be that new though ). Straight, clear answer.

So the eye level of my position (assuming standing at HP) is the zero line and reference for everything around me, regardless of terrain. If the terrain in the flight path climbs 50m, there is a tree of 30, and I want a safety margin of 20m, RTH needs to be 100m. Good to know before I start to explore beyond just short training flights over flat ground (I'm living in the mountains.........)

 

[Meta4]

I wonder about the reference value for RTH setting.

All heights are relative to your starting point.
As your drone has no sensors that could measure height above the ground or above sea level, it's the only height that makes any sense.

 

[mullern88]

All heights are relative to your starting point.
As your drone has no sensors that could measure height above the ground or above sea level, it's the only height that makes any sense.

Well........ it has a GPS, and my phone's GPS for example gives me pretty accurate altitude ASL information, I was thinking that the MM systems could possibley do that as well....... apparently not, but that was the base for my initial question. Good enough for me as long as I know that.

BTW, can I assume that "starting point" in the contributions here means the HomePoint? Correct? That would mean that it (and with it the reference "zero" altitude) can be changed in DJIFly App during flight?

 

[Meta4]

Well........ it has a GPS, and my phone's GPS for example gives me pretty accurate altitude ASL information, I was thinking that the MM systems could possibley do that as well.

Your drone uses a barometric sensor for height data.

BTW, can I assume that "starting point" in the contributions here means the HomePoint? Correct? That would mean that it (and with it the reference "zero" altitude) can be changed in DJIFly App during flight?

No .. the drone sets its height to zero when it is powered on.
If you reset the home point during a flight, that home point is only Lat & Long data without any data for height.
You would have to power off and on again to reset the height reference.

 

[mullern88]

Thank you Meta4, "loud and clear"!!

 

[netsonic]

I thought it would be cool to put a remote payload dropper with a small foam airplane attached to the bottom of my mini.
I went outside to test it out, did a hand launch and all of the sudden the drone went into a steady constant climb. I pulled all the way down on the stick and it just kept climbing! finally i somehow got it into land mode and it came back down. WHOLY CRAP. so the deployment servo and plane were blocking the ground sensor and making it go into climb mode!

It would have worked if you cover the VPS with duct tape. The key is to block them in such a way that no IR light is reflected, otherwise what happened to you is expected.

So the eye level of my position (assuming standing at HP) is the zero line and reference for everything around me, regardless of terrain. If the terrain in the flight path climbs 50m, there is a tree of 30, and I want a safety margin of 20m, RTH needs to be 100m.

As you have a mini, if your RTH is set to 100m and you face a stronger wind, your drone is gone! Be sure that at 100m it will be significant more than the wind measured/felt on the ground.
This is good to know before you start to explore further. Do not rely on RTH alone and do not assume that it will do come back without manual actions from your side. These actions would be to cancel RTH, put it in Sports mode, descend and fly it manually back to safety.

Acquaint yourself with the mini and it's capabilities. When you learn or practice, fly low and slow.

 

[douglas_in_philly]

That means the drone will react to stick inputs during RTH ? This is new to me.

It definitely responds to yaw movements, and you can control the gimbal still. ****Just second guessing myself.....*does* it respond to yaw when in RTH? I thought it did from personal experience, but maybe I'm misremembering. It would seem like it shouldn't, since that changes heading/direction.

 

[douglas_in_philly]

Here's a video I posted a couple weeks ago. It's a situation similar to what the OP was asking about:

 

[TDZHDTV]

It definitely responds to yaw movements, and you can control the gimbal still. ****Just second guessing myself.....*does* it respond to yaw when in RTH? I thought it did from personal experience, but maybe I'm misremembering. It would seem like it shouldn't, since that changes heading/direction.

Yes it does, also you can hit top speed in RTH is you full stick forward, you can also get creative with RTH and use it like course lock

 

[TDZHDTV]

So I was looking forward to taking my Mini to the mountains in the Lake District, this weekend...... do you think it’s safe to use RTH? ?

 

[DanMan32]

Well........ it has a GPS, and my phone's GPS for example gives me pretty accurate altitude ASL information, I was thinking that the MM systems could possibley do that as well....... apparently not, but that was the base for my initial question. Good enough for me as long as I know that.

BTW, can I assume that "starting point" in the contributions here means the HomePoint? Correct? That would mean that it (and with it the reference "zero" altitude) can be changed in DJIFly App during flight?

Yes, it has GPS, but use of GPS for what you're asking for has two issues:
Altitude based on GPS is subject to error, often considerable error.
Sure your phone can tell your altitude, you're standing on the ground. It can't tell you though how tall you are, which would be the difference between determined GPS altitude and how high the phone is from the ground you're standing on. If you walk uphill, your phone is increasing GPS altitude even though distance to ground isn't changing. The AC has no means of seeing the ground. If you fly level, the GPS and barometric altitude isn't going to change no matter what the ground directly underneath is doing.