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Is your Mavic hovering in place perfectly at night?
5464 16 2017-7-24
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chalde
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Since I didn't get a chance to fly my Mavic for 2 weeks or so, thought I'll just turn it on outside real quick to make sure I didn't get any forced FW update or the likes pushed on the remote or Mavic itself by the DJI top notch software engineers.

It's pitch black, right in front of my house, with one single street light, pretty far. So just wanted a very simple take off and landing flight, 3 meters high at most.
While leaving the drone in the air to make sure all is good, I've noticed that it was drifting , all direction, quite a bit. Not huge drifting, but definitely something that forces me to adjust its position. Compared to normal behavior, definitely a different experience.

Now, I realize that the Front Sensor and Bottoms sensor will not work because of darkness, but I thought the drone will still hover in place based on GPS? Do we still need enough light for stable hovering? I suppose I could just wait until tomorrow morning and do another check, but I assume it's simply darkness that causes this behavior...

For the few pilots who did some video at night, did you experience a similar behavior?
2017-7-24
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Lucas775
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Mine hover the same at night as it does in the morning.
2017-7-24
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dronist
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Same here stiff as block. You might need a COLD IMU!
2017-7-24
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DJI Diana
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Calibrate the IMU,  then try fly it in an open area, make sure the GPS signal is strong enough to fly(More than 10 satellites can be detected).
2017-7-24
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DJI Susan
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Generally, Mavic will hover when the GPS signal is good enough. Please change to another place and make sure the GPS bar is full and there are more than 10 satellites. Alternatively, please calibrate IMU and verify the issue in the daylight as well.
2017-7-24
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AACY
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Exactly what the DJI moderators are explaining is what I had notice during low light condition (enough for the VPS not to work) with more than 10 Satellites is stable as a rock, when it goes bellow that in mid flight, due to some cloud or something, it gets a bit drifty but still easy to fly.
2017-7-25
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DroneFlying
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AACY Posted at 2017-7-25 00:05
Exactly what the DJI moderators are explaining is what I had notice during low light condition (enough for the VPS not to work) with more than 10 Satellites is stable as a rock, when it goes bellow that in mid flight, due to some cloud or something, it gets a bit drifty but still easy to fly.

Exactly what the DJI moderators are explaining is what I had notice during low light condition (enough for the VPS not to work)

That's the correct answer and I wouldn't recommend an IMU calibration if it flies fine during the day. When there isn't enough light for VPS to stabilize it the Mavic will drift around a bit, and you can recreate this behavior even in good light by turning off VPS.
2017-7-25
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hallmark007
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As droneflying said this is not an Imu issue it's is almost certainly VPS try flying above 60 feet and see how stable it is.
2017-7-25
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chalde
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Just did a daylight test. A little bit of rising for the few seconds after the initial takeoff and hovering at about 1.5 m high, but then took it up and back down to maybe 2 meters and it was hovering super smoothly.

Didn't re-calibrate IMU. About 12 GPS lock. Didn't check last night, but it's the same location, and I also waited to get the green "ready to fly" warning. As I said, it was very dark, with of course, the warning about VPS not working due to poor light conditions.

I might try again tonight, at sunset.

2017-7-25
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DroneFlying
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chalde Posted at 2017-7-25 04:02
Just did a daylight test. A little bit of rising for the few seconds after the initial takeoff and hovering at about 1.5 m high, but then took it up and back down to maybe 2 meters and it was hovering super smoothly.

Didn't re-calibrate IMU. About 12 GPS lock. Didn't check last night, but it's the same location, and I also waited to get the green "ready to fly" warning. As I said, it was very dark, with of course, the warning about VPS not working due to poor light conditions.

Didn't re-calibrate IMU.

Good. The IMU doesn't know or care whether it's daylight or nighttime, so calibrating it isn't likely to affect something that happens only at night.

P.S. Also, a "cold" IMU calibration isn't any more accurate than a "warm" one but will sometimes allow you take off slightly sooner than if you had calibrated when the Mavic hadn't been "chilled" beforehand.
2017-7-25
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chalde
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DroneFlying Posted at 2017-7-25 04:10
Didn't re-calibrate IMU.

Good. The IMU doesn't know or care whether it's daylight or nighttime, so calibrating it isn't likely to affect anything that happens only at night.

By "Cold" IMU calibration, do you mean when the drone is just freshly started - compared to doing a calibration after the unit had been running for a while?

Why will this matter?
2017-7-25
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DroneFlying
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chalde Posted at 2017-7-25 04:34
By "Cold" IMU calibration, do you mean when the drone is just freshly started - compared to doing a calibration after the unit had been running for a while?

Why will this matter?

By "Cold" IMU calibration, do you mean when the drone is just freshly started

No, I mean one performed after the Mavic's temperature has been deliberately lowered, such as by putting it in front of an air conditioner.

When the Mavic is powered on the IMU immediately starts (literally) warming up and it won't want you to take off until the IMU's temperature is at least as high as the temperature at which you calibrated. What that means in practice is that a "cold" calibration can allow you to take off sooner than if you calibrated with the IMU at room temperature or higher, but aside from that a "cold" calibration isn't inherently superior to one done when the Mavic is at room temperature.
2017-7-25
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chalde
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Thank you for the info - didn't know about this at all.
2017-7-25
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hallmark007
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chalde Posted at 2017-7-25 05:06
Thank you for the info - didn't know about this at all.

You may save 1/2 minutes on battery time, so cool room for 30 minutes minus the battery, or if you can just do the calibration outside at normal temp.
2017-7-25
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STRIDE8
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chalde Posted at 2017-7-25 04:02
Just did a daylight test. A little bit of rising for the few seconds after the initial takeoff and hovering at about 1.5 m high, but then took it up and back down to maybe 2 meters and it was hovering super smoothly.

Didn't re-calibrate IMU. About 12 GPS lock. Didn't check last night, but it's the same location, and I also waited to get the green "ready to fly" warning. As I said, it was very dark, with of course, the warning about VPS not working due to poor light conditions.


I noticed drifting the other night as well after the initial take off, but when I went up 100-200 feet.. stayed in the same spot.  I need to test in daylight
2017-7-25
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Tombolian
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DroneFlying Posted at 2017-7-25 04:48
By "Cold" IMU calibration, do you mean when the drone is just freshly started

No, I mean one performed after the Mavic's temperature has been deliberately lowered, such as by putting it in front of an air conditioner.

Oh yeah, I know what I'm doing when I get home today!!!  Thanks DroneFlying!
2017-7-25
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AACY
Second Officer
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chalde Posted at 2017-7-25 04:02
Just did a daylight test. A little bit of rising for the few seconds after the initial takeoff and hovering at about 1.5 m high, but then took it up and back down to maybe 2 meters and it was hovering super smoothly.

Didn't re-calibrate IMU. About 12 GPS lock. Didn't check last night, but it's the same location, and I also waited to get the green "ready to fly" warning. As I said, it was very dark, with of course, the warning about VPS not working due to poor light conditions.

Just go over your flight record from that night and you will be able to see how many GPS you were locked onto when the drift happened.

Cheers!
2017-7-26
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