Height loss phantom 4

skippype · Oct 7, 2016

Is anyone having this problem? When I take off and fly up to about 8 meters all is OK. The PH 4 hovers well but when I start to fly forward I start losing height. After about 30 meters of forward flight I am almost at groun level. I have to continually keep adjusting the height upwards. The really strange thing is if I stop and hover just above the ground then fly backward I start to gain height at about the same rate. What is going on? After flying 30 or 40 meters the height loss problem seems to disappear. I only happens when I stop, hover then g forward again....
Any help would be greatly appreciated.
Skippy

Mark The Droner · Oct 7, 2016

You're sure it's not an optical illusion and the field your on is not slanted?

Could it be your AC is not warmed up yet?

Could it be you need to check your IMU?

skippype · Oct 7, 2016

Marknmd said:
You're sure it's not an optical illusion and the field your on is not slanted?

Could it be your AC is not warmed up yet?

Could it be you need to check your IMU?

Thanks for those tips. I will check those out. It is a dead flat field. It happens no matter where I am flying. Very annoying .

John Locke · Oct 7, 2016

The craft won't fly until the imu is warmed up, that's not The problem. The barometer controls elevation, but an imu calibration may help. The vps shouldn't let the craft get that close to ground unless you command it with the sticks. You may want to calibrate the sensors, using digital assistant. However the visual sensors you calibrate don't control elevation in vps, the sonar does, so that's unlikely the problem.

Have you recently added any accessories to the craft? Did this behavior start spontaneously, or has it been doing that from the beginning?

alokbhargava · Oct 7, 2016

If nothing else works, try to calibrate sticks. If biases get changed, you will get this behavior, calibrate sticks to get it right.

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Michael Judd · Oct 7, 2016

exactly alokbhargava, most people forget to calibrate the rc

skippype · Oct 7, 2016

John Locke said:
The craft won't fly until the imu is warmed up, that's not The problem. The barometer controls elevation, but an imu calibration may help. The vps shouldn't let the craft get that close to ground unless you command it with the sticks. You may want to calibrate the sensors, using digital assistant. However the visual sensors you calibrate don't control elevation in vps, the sonar does, so that's unlikely the problem.

Have you recently added any accessories to the craft? Did this behavior start spontaneously, or has it been doing that from the beginning?

Thanks

skippype · Oct 7, 2016

alokbhargava said:
If nothing else works, try to calibrate sticks. If biases get changed, you will get this behavior, calibrate sticks to get it right.

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Sounds like that is the problem. It has been happening since new. Only has about 4 hits on it. I will try to calibrate the sticks and see what happens.

skippype · Oct 7, 2016

skippype said:
Sounds like that is the problem. It has been happening since new. Only has about 4 hits on it. I will try to calibrate the sticks and see what happens.

That is meant to read 4 hours not hits........

alokbhargava · Oct 7, 2016

skippype said:
That is meant to read 4 hours not hits........

You can always edit your posts.

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Yooper · Oct 31, 2016

alokbhargava said:
You can always edit your posts.

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Mine is doing the same thing. Going lower as I go frontward and the recorded height is way off. I can be 15 ft high and it registers 70 or 80 feet. Any suggestions?

John Locke · Nov 1, 2016

Yooper said:
Mine is doing the same thing. Going lower as I go frontward and the recorded height is way off. I can be 15 ft high and it registers 70 or 80 feet. Any suggestions?

I've had this occur too. I'm puzzled why VPS doesn't correct that when it's under 25' AGL. What's important is watching for this anomaly when flying autonomous with Litchi. You can easily run into a cliff if you launch from a cliff. You should pad the elevation for these errors from the craft barometer.

chazzm · Nov 3, 2016

Calibrating the bps was a pain using the assistant app, seemed like 3-4 voices overlapping at once, but even then after several tries I got my AC VPS done lol, I haven't had to calibrate the sticks but it would be nice to know how!

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