Don't crash your Mavic 3 with Waypoints missions

[Jake Fortune]

Does obstacle avoidance even work during waypoints? Almost took out a streetlight yesterday flying one, and it didn't even flinch.

I tried to fly a waypoint mission between rows of grape vines. The plan was to shoot several weeks apart to get a Timelapse. I couldn't set it up in normal, because the sensors kept telling me there were obstacles in the way, so I created the waypoints in Sport mode (sensors off). When I went to fly the mission, the drone refused, even though I was still in Sport Mode and verified the sensors were turned off. The drone recognized there were obstacles (which I would not hit if the waypoints stayed accurate) and would not fly the mission.

 

[Meta4]

I tried to fly a waypoint mission between rows of grape vines. .. The drone recognized there were obstacles (which I would not hit if the waypoints stayed accurate) and would not fly the mission.

Consumer GPS does not have the precision to fly close to obstacles.
It is not pinpoint accurate and you need a safety margin of several metres when placing waypoints near obstacles.

 

[shb]

I tried to fly a waypoint mission between rows of grape vines. The plan was to shoot several weeks apart to get a Timelapse. I couldn't set it up in normal, because the sensors kept telling me there were obstacles in the way, so I created the waypoints in Sport mode (sensors off). When I went to fly the mission, the drone refused, even though I was still in Sport Mode and verified the sensors were turned off. The drone recognized there were obstacles (which I would not hit if the waypoints stayed accurate) and would not fly the mission.

I always keep obstacle avoidance on during waypoint missions. Ive had maybe 6 missions abort and return to home because it got within a few feet of an obstacle even though it wouldn't of hit it. Better safe than sorry i guess. I'm wondering how accurate the missions are when you repeat them.

 

[Meta4]

I'm wondering how accurate the missions are when you repeat them.

They are as (in)accurate as consumer GPS.
That's +/- a few of metres.
Don't even think of using waypoints close to obstacles.

 

[shb]

I always keep obstacle avoidance on during waypoint missions. Ive had maybe 6 missions abort and return to home because it got within a few feet of an obstacle even though it wouldn't of hit it. Better safe than sorry i guess. I'm wondering how accurate the missions are when you repeat them.

They are as (in)accurate as consumer GPS.
That's +/- a few of metres.
Don't even think of using waypoints close to obstacles.

I don't know. I think that is a conservative specification. I take off from this little mark on my driveway. The other day, after flying a long way, it landed exactly on the mark with no pilot intervention. I know this is unusual. But if you watch captain drones videos, tyey usually land withing a few feet of his landing pad

 

[Meta4]

I don't know.

You're correct ... you don't know.

I think that is a conservative specification. I take off from this little mark on my driveway. The other day, after flying a long way, it landed exactly on the mark with no pilot intervention. I know this is unusual. But if you watch captain drones videos, tyey usually land withing a few feet of his landing pad

GPS accuracy is variable.
Sometimes the error will be small, most of the time it will be within +/-2 metres and sometimes it will be more than that.
You cannot rely on GPS to be pinpoint accurate, particularly when you need it to be.

 

[shb]

You're correct ... you don't know.

GPS accuracy is variable.
Sometimes the error will be small, most of the time it will be within +/-2 metres and sometimes it will be more than that.
You cannot rely on GPS to be pinpoint accurate, particularly when you need it to be.

I agree that my experience is, that waypoint missions that require pinpoint accuracy don't work. That's why i gave up on them.

 

[Meta4]

I don't know. I think that is a conservative specification.

There's a great deal of misunderstanding about GPS accuracy.
It's a little complicated so I've found an article which explains it well:

 

[GadgetGuy]

I don't know. I think that is a conservative specification. I take off from this little mark on my driveway. The other day, after flying a long way, it landed exactly on the mark with no pilot intervention. I know this is unusual. But if you watch captain drones videos, tyey usually land withing a few feet of his landing pad

You are confusing Precision Home Point with GPS accuracy. Precision Home Point uses photos upon launching to add precision to the RTH landing point, beyond what GPS alone is capable of.

 

[Jake Fortune]

I always keep obstacle avoidance on during waypoint missions. Ive had maybe 6 missions abort and return to home because it got within a few feet of an obstacle even though it wouldn't of hit it. Better safe than sorry i guess. I'm wondering how accurate the missions are when you repeat them.

I won't be able to repeat the mission, because it never flew the mission. The flight was programmed to be slow and VLOS. It doesn't appear to matter if you "keep the sensors on" or not, because in waypoints they are on, as evidenced by my attempt to fly the vineyard in Sport mode and verifying that they were off in the menu. As soon as the mission begins, the sensors appear to be turned back on.

 

[Gary Moyer]

I don’t recall this being an issue with Litchi likely because Litchi missions were entirely based upon GPS altitude and position. That said, I nearly crashed with a Litchi mission when flying a mission created a couple of years before. A tree had added enough height to clip my drone where it had cleared it before.

I have created and flown several missions in Litchi with my air s2. I live in a mountainous area and very remote. Rarely takeoff from anywhere with internet available. Therefore when preplanning a mission elevation changes of where your flying must always be factored into the mission planning. Mavic 3 does not work with Litchi is my understanding. If that's not correct I hope someone will let me know.

 

[zAvi]

I have created and flown several missions in Litchi with my air s2. I live in a mountainous area and very remote. Rarely takeoff from anywhere with internet available. Therefore when preplanning a mission elevation changes of where your flying must always be factored into the mission planning. Mavic 3 does not work with Litchi is my understanding. If that's not correct I hope someone will let me know.

Litchi does not work directly with Mavic3 because it has no SDK [ probally never will ]

This may be of interest:

Litchi Waypoint Mission to Mavic 3 Waypoint Mission converter

I have completed my “Litchi Waypoint Mission to Mavic 3 Waypoint Mission converter. With this web application, one can design a waypoint mission from the comfort of your office on a large monitor using Litchi’s Mission Hub then convert that mission to one that can be flown with a Mavic 3...

mavicpilots.com

 

[cinclodes]

Your drone uses the barometric sensor for altitude, whether you are flying with Litchi or a DJI app.

I never knew this, and I don't understand how it can work. How does it account for variations in pressure due to weather events (high vs low pressure systems)? How can it reliably get the correct altitude within a tolerance that means the difference between passing over an obstacle (such as a tree) or hitting it?

 

[Meta4]

I never knew this, and I don't understand how it can work. How does it account for variations in pressure due to weather events (high vs low pressure systems)?

Drone flights are usually quite short and air pressure variation over 20 minutes or so aren't enough to cause a significant issue.
You might see a difference between starting height and landing height of 10 feet or so.
Real planes use barometric sensors for altitude measurement too.
Because they fly for longer and they could land hundreds of miles away, they call the airport to confirm the local air pressure to adjust their altimeter so they can have an accurate height above sea level.
Flying drones, we're not concerned about height above sea level and only concerned with height relative to the launch point.

How can it reliably get the correct altitude within a tolerance that means the difference between passing over an obstacle (such as a tree) or hitting it?

Next time you launch, watch the indicated height as you slowly take the drone up just a foot at a time to get an idea how accurately the barometric sensor can detect small increases in height.

But whether you pit a tree or clear it, should be up to your piloting rather than relying on your indicated height.

 

[cinclodes]

But whether you pit a tree or clear it, should be up to your piloting rather than relying on your indicated height.

I had Litchi missions in mind when asking that question. If the altitude isn't consistent (within a reasonable tolerance), a mission that is designed to fly a little above the forest canopy might go fine on one occasion but hit a tree if there is a bias of, say five meters, during a repeat of the same mission. I have done many such missions without ever hitting a tree. So the altitude estimate must be very reliable.

 

[Meta4]

I had Litchi missions in mind when asking that question. If the altitude isn't consistent (within a reasonable tolerance), a mission that is designed to fly a little above the forest canopy might go fine on one occasion but hit a tree if there is a bias of, say five meters, during a repeat of the same mission. I have done many such missions without ever hitting a tree. So the altitude estimate must be very reliable.

I'd always want a safety margin of >5 metres if flying close to treetops or other obstacles.

 

[Gary Moyer]

Litchi does not work directly with Mavic3 because it has no SDK [ probally never will ]

This may be of interest:

Litchi Waypoint Mission to Mavic 3 Waypoint Mission converter

I have completed my “Litchi Waypoint Mission to Mavic 3 Waypoint Mission converter. With this web application, one can design a waypoint mission from the comfort of your office on a large monitor using Litchi’s Mission Hub then convert that mission to one that can be flown with a Mavic 3...

mavicpilots.com

Thank you

 

[Alex Baxter]

My history page is blank. I set a couple of waypoints, fly the mission, then try to save it with no luck. I tap the white icon that brings up the history page and it is blank and with no option to save. I also try tapping the waypoint icon on the left of the screen. I tap save and close and nothing happens. I can only close without saving or cancel. I'm using a RC Pro with a newly formatted sd card in it. I've also tried with no sd card in it..

Edit: it finally started working. I updated to Fly app 1.9.1 and it still didn't work. While the bird was still in the air, I just clicked through every setting including the camera controls on the bottom right of the screen (didn't change anything). Then, all of a sudden it started working correctly.

I also found that if you take off, set a random waypoint, then land, you can then edit any mission with the M3 on the ground?!

 

[GadgetGuy]

I also found that if you take off, set a random waypoint, then land, you can then edit any mission with the M3 on the ground?!

Are you not able to edit existing missions from the RC Pro only, without first taking off and setting a random waypoint and landing? I know you can create them from the RC Pro only.

 

[Alex Baxter]

Are you not able to edit existing missions from the RC Pro only, without first taking off and setting a random waypoint and landing? I know you can create them from the RC Pro only.

Thanks for the clue. I've discovered I do not need the M3 airborne, or even switched on, just need to have the Wi-Fi on on the RC. That'll teach me patience whilst it gets it's bearings..