Thoughts on my mission speed being very slow

[marklyn]

I set up two missions recently and both missions did something that has never happened to me before. Both missions only had my Mavic going around 5-6 mph when those waypoints were supposed to be cruising speed (21.5 mph is what my cruise speed is set for each mission). I checked and double checked the speed settings between each waypoint and they checked out exactly how I'd set it, none of the speeds were lower than 10 mph.
I've attached one of my litchi missions in case that helps (zipped format). WP6 should have been cruising speed (21.6 mph) but the drone never moved faster than 6 mph. I ended up stopping both missions and flying manually in sport mode and could get up to 32 mph there so I'm clueless as to what the problem might be.
I should have set up a quick mission in DJI GS Pro to see if it did it there but I didn't think about that at the time.
Wind was probably 5-10 mph, and my mission was in the middle no-where (no interference/very rural).
Any thoughts?

 

[lisadoc]

It looks fine on the mission itself. Did you lose your connection with the remote at any time during the mission? The mission speed setting is only in effect when the aircraft is in range of the remote controller. If signal is lost during the mission, the aircraft will continue the mission at the speed it was travelling at when it lost signal.

Did you double-check your cruising speed setting when the mission was loaded into your app, immediately before uploading it to the Mavic? To avoid any issue with the overall settings, set the speed to an actual speed (21.4 mph for example), to ensure that the general cruise settings aren't the source of the issue.

 

[marklyn]

Good thought but no, the drone was only about 300' away and I'm certain I never lost signal. Yes, cruising speed was checked prior to the mission takeoff. I have it set to 21.5 in the mission settings but I do remember checking it anyway because I check other parameters in the mission setting when I am about to start a mission.

Also, when I load a mission from Litchi and it uploads to the Mavic, I recall that at that point the Mavic is autonomous and, even losing signal, it will still fly the pre-programmed route.

 

[lisadoc]

To avoid any issue with the overall settings, set the speed to an actual speed (21.4 mph for example), to ensure that the general cruise settings aren't the source of the issue.

 

[marklyn]

That's interesting. WP's 1-5 were custom speeds. Starting at WP6 was set to cruising speed (21.5) which is when it started to only go 5-6 mph, but I'm sure I had checked the mission settings and verified cruising speed was 21.5 so it is coincidental that the Mavic "slowed down" when it hit the first waypoint with the cruising speed... hrm.

 

[marklyn]

However. I just checked my second mission (that did the same thing). The very first waypoint is set to a custom speed (33 mph) and when it started off at WP1 it was only going 5-6 mph on that. Plus I remember that I had 16 sats locked in both missions.

 

[lisadoc]

Did it ever go faster than 5-6 mph on either mission? (at any waypoint)

 

[marklyn]

Did it ever go faster than 5-6 mph on either mission? (at any waypoint)

Well, in both cases I aborted the Litchi mission and took over control and under full throttle it didn't go any faster. However, I switched to sport mode, and using the throttle manually, I could go up to about 33 or so mph.

 

[lisadoc]

Well, in both cases I aborted the Litchi mission and took over control and under full throttle it didn't go any faster.

How did you abort the mission?

Well, in both cases I aborted the Litchi mission and took over control and under full throttle it didn't go any faster. However, I switched to sport mode, and using the throttle manually, I could go up to about 33 or so mph.

Did you check for the mission setting of "Max flight speed"? It can be slower than your set cruising speed (it's just below that setting) and restrict how fast you can go during a Litchi mission. I can't check it because it's what you have it set for in your general settings, not mine. Your mission waypoints look fine but the general settings can/will override them.

Also, when you put it into Sport mode, you were aborting the Litchi mission. Any flying after that was simply manual flying and not automated by Litchi.

 

[marklyn]

How did you abort the mission?



Did you check for the mission setting of "Max flight speed"? It can be slower than your set cruising speed (it's just below that setting) and restrict how fast you can go during a Litchi mission. I can't check it because it's what you have it set for in your general settings, not mine. Your mission waypoints look fine but the general settings can/will override them.

Also, when you put it into Sport mode, you were aborting the Litchi mission. Any flying after that was simply manual flying and not automated by Litchi.

Yes, the max flight speed is always checked when I check mission settings and it was 33.6mph. I didn't put it into sport mode until I aborted both missions and tried using the throttle to move it faster, but it wouldn't go faster. Then I thought of sport mode, put it into sport mode, and I could at least free-fly for a bit before bringing it home, at any speed (up to about 32.5 mph, give or take).

 

[lisadoc]

Yes, the max flight speed is always checked when I check mission settings and it was 33.6mph. I didn't put it into sport mode until I aborted both missions and tried using the throttle to move it faster, but it wouldn't go faster.

How did you abort the missions? And are you saying that in FPV mode, (in non-sport mode or P mode), you couldn't fly the Mavic any faster than 5-6 mph? Is it the same in DJI Go?

 

[marklyn]

I was using Litchi at the time so I used the mission end button to stop/abort the mission. And, yes, I couldn't faster than 5-6 mph by manually using the throttle. I've aborted missions before and use the stick to fly the max speed back or wherever but this time I couldn't. I didn't try it in DJI Go and the two missions are flight paths about an hour north of where I live so I can't re-do them but what I will do tomorrow is set up a small mission from my house with Litchi and also with GS Pro. I'm not going to be surprised if the Litchi mission works though.
I will be going back to that same location in about a week so I plan on setting up another mission with Litchi and GS pro. My plan will be to try to run one of the two missions first, then run the new Litchi mission and a new GS Pro mission to see what happens. I'm not sure what else to try but if GS pro works as expected then I have to look toward Litchi and see if maybe a recent update is causing some issue, I guess.

 

[lisadoc]

Let us know what you come up with.

 

[marklyn]

Well, I updated the RC and Drone last night to the latest firmware (was only 1 fw behind), created a new mission this morning from my home and the Litchi mission worked as expected. I guess I'll chalk this up to a fluke but I will be at that same location using the same mission in a few days, so I'll try it then (again).

 

[marklyn]

Update; a couple of missions later, but different time of day, it slowed down to 4-6mph on part of it's flight path. After perusing the forums it appears that something related to obstacle avoidance may be causing this issue, so the next time it does it, I'm going to turn off OA. That would support why when I turned on sport mode it flew as fast as I wanted it to. Doesn't sport mode turn off OA?

 

[lisadoc]

Update; a couple of missions later, but different time of day, it slowed down to 4-6mph on part of it's flight path. After perusing the forums it appears that something related to obstacle avoidance may be causing this issue, so the next time it does it, I'm going to turn off OA. That would support why when I turned on sport mode it flew as fast as I wanted it to. Doesn't sport mode turn off OA?

Yes. It shouldn't slow down though, but stop. Are there obstacles in the way? Is the drone facing into the sun?

 

[marklyn]

There were no obstacles but I can't recall sun position, although I believe it was around 2pm and in my area the drone would have been flying toward the position of the sun, but still the sun would have been high in the sky at this time.

 

[lisadoc]

There were no obstacles but I can't recall sun position, although I believe it was around 2pm and in my area the drone would have been flying toward the position of the sun, but still the sun would have been high in the sky at this time.

You can try turning off OA but if there were no obstacles and the sun wasn't low in the sky, then there should have been nothing to trigger the sensor. Also, like I noted before, if it was the OA, it would cause the Mavic to stop suddenly (like "hitting the brakes") and the controller should have vibrated and the app noted an obstacle. It wouldn't "slow down" the Mavic but yet continue forward if it sensed an obstacle. Next time, try the Litchi mission with the OA turned off (in DJI Go). If that doesn't change things (which it likely won't), try flying the same route manually. If it flies fine manually but slow in the mission, then you know it must be a mission setting.

You can always try to view the CSV log from Litchi, to see if it gives you a hint as to what is causing the issue during the mission.

 

[marklyn]

You're right lisadoc, it would have stopped flat if OA was the issue.
After several tests today I've pretty much determined that the wind (at 150-200') may be the culprit in slowing the drone to 5-6 mph.
Several tests show that when the drone is flying against the wind and set to go 25mph, it may struggle around 7-10mph, but on the way "home" with the wind it goes the speed it's set for.
I guess after all these flights (100+) I just flat didn't notice that, probably in part because I wasn't using gauge overlays in my flight videos until recently and noticed it more. Not sure.
I go back out to 'ground zero' tomorrow to repeat that original two missions that started this thread. Hopefully, with wind conditions likely different, I expect different results than the first time.
Thanks lisadoc for your insight.

 

[lisadoc]

When you said that winds were only 5-10 mph in your original post, I thought you had ruled that out. But it’s a good lesson to understand that surface winds can often differ drastically from winds aloft. Sometimes the simplest answer is the correct one.