Thursday, October 5, 2017

Downward vision sensor error

I guess this post will make as much sense as those you will find on DJI related forums.

A couple of times I have seen this system error, the first I managed to clip a few branches in the back yard. So I learnt not to ignore the warning assuming it was the same as the lack of GPS signal and all I needed to do was to get a bit of altitude to get a better look at the satellites. Come to think of this it was not logical as if ground recognition was poor, due to mis-calibration, then it was not likely to improve with more height.

In the first instance, when I was at home, the error went away after re-booting the controller and the Mavic Pro. I got the same error yesterday when I was out on the meadows and decided that it was wise to come up with a better solution to the problem. On perseverance I found a menu setting that allowed me to recalibrate the down-sensors. This involved the movement of the MP in a square formation in front of me while I was holding it above the ground in my left hand. Strangely, this was not to be found anywhere on the forums???? I gave up as I was getting the message that a calibration could not be done on a terrain that was textured, this being the grass of the meadow. So I decided to go back into town and look up a solution in the library on their computers.

Here I found references to the DJI Assistant, which runs on the computer while you have the FP connected directly using a USB cable. This allows you to do the same calibration using the computer screen as a target for the sensors, both forward and downward. I did, however, manage to perform the calibration using just the drone and the "square movement" procedure that I tried in the field. I was hampered in this in finding an unobstructed and texture free area in the back yard and had to resort to the picnic table again. Still, I proved that the same calibration could be performed away from my computer. When enough data had been captured by the sensors the FP seemed to recalibrate in the same way  as it did with the computer. I will be interested to see if this technique appears on the forums, where videos of how to use the Assistant and more prevalent.

There also seemed to be a lack of understanding of the difference between the forward sensors and the downward sensors.

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