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Helpful hints: Phantom Vision 2+: water crash, PC connection, IMU calibration

Discussion in 'General Discussion' started by ATDGUY, Jun 9, 2015.

  1. ATDGUY

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    Given the help that a couple forums have provided me I wanted to share my learnings from a recent event. I’m going to put this on two forums, so you might see this twice.


    I took my Phantom Vision 2+ out for a spin over a fresh water lake. Due to some heavy winds and pilot error, I managed to slam it into a flag flapping in the wind, whereupon it dropped straight down into five feet of water. It was on the bottom of the lake within 3 seconds. With a quick sprint and jump off the end of the dock I was able to haul it out of the water within about 30 seconds. I had the battery out of it within 40 seconds of it hitting the water.


    The good news is: I was able to fully recover from the crash – it is back to 100% working condition.


    Here is my saga to getting it back in the air. Hopefully this will help others:


    Water problem: The obvious issues was to quickly, but patiently, deal with the water issue. I immediately pulled the battery, and then gently shook all the water out, turning it every angle I could to be sure it was draining. I then put it in porch with lots of air flow and in front of a fan for about 6 hours, rotating it every now and then. It took every ounce of patience I had to not fire it up too early as I knew that would simply fry anything that was still wet. This approach seemed to do the trick, as I was rewarded with that beautiful startup music, a wifi connection, and a working gimbal/camera.

    Leaning: get it out of the water, the battery out, and drain the water as quickly as possible. Then be patience and get air moving inside to let it dry.


    On to the next issue.


    Red-Green-Yellow LED flashes combined with a “Sensor error – maintenance required”: It would clearly do a power up, but then would get stuck with the blinking lights and the Vision app on my phone would give me the “sensor error”. It would not allow me to get the motors spinning, so I knew I had to get connected to the PC and the desktop app to try to recalibrate.


    PC Connection/Windows Drivers problem: This should have been a simple task but it took me over two hours to get straightened out. I fired up the Phantom 2 Vision+ Assistant Software v3.8 on my Windows 7 PC, plugged in the phantom and turned it on. Nothing. I did this repeatedly, only getting a connection once for a few minutes. I switched USB cables, USB ports, rebooted, switched batteries, etc. After trying for an hour to connect to the drone via the PC Assistant Software, rebooting the PC, the phantom, etc., I finally started to think that maybe this wasn’t a waterlogged phantom issue, but a PC issue. While the drivers were indeed installed as I had used this PC before, I re-installed them and rebooted everything. I also realized I did not have my transmitter (remote control and wifi) turned on, so I turned both of them on. Problem solved – I could connect to the drone, update the firmware, etc. And indeed – it was calling for an IMU calibration…. Time to simply click that button and calibrate the IMU.


    Not so fast.


    The IMU calibration tool is one of the klunkiest pieces of software I have ever used. You click through several warnings about needing the Phantom to be completely flat (it was), don’t touch it (I didn’t) and it’s too hot. Now, if you’ve done any research on the IMU calibration you will know all about the “false” too-hot warning message In fact, every web site says to just skip over it. More on that later.


    The calibration process was taking forever to run. The green progress bar was bouncing around as if it was working, but it went on for an hour. I then realized the message above the bar said “ready” rather than “calibrating”. Something was wrong. More reboots, more battery resets. Same thing.


    Another hour later I stumbled upon an obscure post where it was pointed out that the reason the heat warning message was there in the first place had something to do with the fact you were calibrating the internal measuring unit (IMU) which is probably a pretty complex and sensitive piece of equipment! So, what it really was too hot after basically idling on my desktop for the past four hours?


    I pulled the battery, and put the phantom in front a cool breeze coming in through the window. Ten minutes later I plugged everything back in and the calibration worked the first time and was complete with in few minutes!


    Learnings: The heat warning is real. You can probably get away with clicking through it a few times, but if you have been sitting with the power on for a while, you should first cool the phantom before connecting it. Also, make sure the message says “calibrating” vs. “ready”, and look for the little green checkmark to the right of the green progress bar to know you really are complete.


    When I fired up the Phantom the next day (by this time it was midnight), no more sensor warning and it flew perfectly! Pretty amazing considering what it just went through.
     
  2. Mako79

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    WINNING!!! and congrats.
    The IMU has a barometric pressure sensor that is affected by heat. With a wifi module sitting next to the NAZA which has the IMU, its very easy for it to warm up. It only takes about 1 minute for the temp warning to appear. Its best that you have the IMU calibration screen ready and do it immediately the moment you turn it on. You will notice the temp warning no longer appears and that the calibration only takes a minute or so.

    And also, try doing the IMU on a surface levelled with the horizon in all axis. This will help the phantom yaw on a dime
     
  3. Mal_PV2_Ireland

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    Well done but you turned it back on after 6 hours, big mistake. I did the same but in salt water. You really need to have it turned off immediately, if salt water rinse out with fresh water and really douse it for 20 mins, shake it out, air compressor or hair dryer it out for as long as possible (hairdryer not on hot of course) and into a big plastic bag of rice for a few days at least. Turning on 6 hours after getting her wet is just asking for trouble you most likely had moisture still inside somewhere.
     
  4. ATDGUY

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    Like I said... it's 100% back to normal, so maybe I got lucky. I'm pretty sure it was dry based on the airflow/fan/etc, but would agree your approach would be better!.
     
    Mal_PV2_Ireland likes this.