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IMU CALIBRATION AND WARMING UP

Discussion in 'Pro/Adv Discussion' started by Jbundy63, Jun 13, 2015.

  1. Jbundy63

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    I have flowed my P3P numerous times without any issues and I know that I read the manual over and over, watched tutorials and tried to get as much information as I could before I received it. After numerous flights I had got a IMU error, the first time I just recycled everything off and back on and flew it around easily because it hadn't done that before, so,after a few more flight it popped up again and decide I needed to do the IMU calibration, I did go into the status for IMU check and it did fail. Completed the IMU calibration and all of sudden I realized that the next time I flew and since then that it goes into the warm up stage for about a minute or so ( yellow led flashing) like it should. I thought before this it did it's warm up and was just quick. So I guess for FYI it may be a good idea to do a IMU calibration right out of the box which kind of makes sense to me.

    Has anyone ever noticed this?
     
  2. DrChris

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    I think you may have answered your own question, but to clarify:

    The IMU calibration should be done with the P3 cool (some people cool it in the refrigerator a bit first). Place the P3 on a perfectly level surface (but metal doesn't matter for this one like it does with the compass calibration). After starting the P3, move as quickly as possible to the calibration setting in the app and start the calibration. Walk away (without causing any vibration) and wait.

    During the IMU calibration, the P3 is collecting data at various temperatures about it's IMU sensors. If it has data from a relatively cool point, in the future it will be able to "warm up" faster. If you calibrate it while the P3 is warm (just after a flight), it will have to return to that temperature during the "warm up" and will therefore take a much longer warm up time.

    Good flights!
    Chris
     
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  3. bobmyers

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    Yes, apparently most of the IMU are disturbed during initial shipping. It should be a part of the official quick start procedures when the copter is unboxed and set up the first time. At the first sign of camera, gimbal or operational issues, this is the first remedy that should be performed.
     
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  4. Jbundy63

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    Thanks @DrChris that's some good info and Yes @bobmyers that's exactly one of the things I noticed was the gimbal operation.
     
  5. AmosMoses

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  6. Jbundy63

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    That's more good information from Mad RC

    Thanks for posting @AmosMoses
     
  7. danjordrone

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    After IMU calibration is it good to do stick calibration also
     
  8. Jbundy63

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    Good question, You know I don't know, haven't had any issue but in a way it's probably good to go through all the calibration procedures, just to be safe. Especially being right out of the box and also it will get you use to how and the method of doing it.
     
  9. danjordrone

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    Not heard a lot as regards stick calibration i do it as i think its kind of VERY important if you think of it and having sticks not calibrated right i hate to imagine the outcome
     
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  10. mtnmaddman

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    I just noticed the warm up time also after an imu calibration I was having no problem and I was not getting the imu error message I decided to calibrate and check my imu status anyway after about 20 flights I checked to see if it needed calibrated it did not I calibrated it anyway I then started receiving the warm up period I would guess it was provably because of the calibration after the latest firmware update was applied, had you loaded the upgrade before calibrating? there are tons of software pilot app problems I don't think this is a problem it probably is a good idea to calibrate imu anyway
     
  11. mtnmaddman

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    Why not ? good idea calibrate sticks also
     
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  12. Jbundy63

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    No I was already up to date on software, I was just starting to get an IMU ERROR message. Mine has been fine since. That is interesting.
     
  13. Jbundy63

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    @mtnmaddan check out the #2 post on this thread from DrChris, I thought that was interesting as well.
     
  14. TonG

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    Thanks! Now I know why it did such a long time to 'warm up'. Almost a minute.
    I did the IMU-calibration uncooled in my living room while flying outside.

    I wil do the IMU-calibrating outside in the morning. Curious about the time differences when 'warming up'.

    My next question was: why does it 'collecting data at various temperatures'.
    After a quick search I found the answer. "https://www.mdpi.com/1424-8220/13/9/12192/pdf

    Abstract: The errors of low-cost inertial sensors, especially Micro-Electro Mechanical Systems (MEMS) ones, are highly dependent on environmental conditions such as the temperature. Thus, there is a need for the development of accurate and reliable thermal compensation models to reduce the impact of such thermal drift of the sensors. Since the conventional thermal calibration methods are typically time-consuming and costly, an efficient thermal calibration method to investigate the thermal drift of a full set of gyroscope and accelerometer errors (i.e., biases, scale factor errors and non-orthogonalities) over the entire temperature range in a few hours is proposed. The proposed method uses the idea of the Ramp method, which removes the time-consuming process of stabilizing the sensor temperature, and addresses its inherent problems with several improvements. We change the temperature linearly for a complete cycle and take a balanced strategy by making comprehensive use of the sensor measurements during both heating and cooling processes. Besides, an efficient 8-step rotate-and-static scheme is designed to further improve the calibration accuracy and efficiency. Real calibration tests showed that the proposed method is suitable for low-grade IMUs and for both lab and factory calibration due to its efficiency and sufficient accuracy."
     
    #14 TonG, Jun 13, 2015
    Last edited: Jun 13, 2015
  15. ianwood

    ianwood Taco Wrangler
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    I would not put it in the refrigerator unless you plan on flying in temperatures close to freezing. Ideally the IMU should be a few degrees cooler than the temperature you intend to fly at when you start the calibration.
     
  16. tyrell

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    I had a similar problem and i am not sure why, I have had no problem with warm up issues but, I got my P2 last fall and never once had a flyaway or any issue with M.C. and controller untill 3 flights ago, I had flown it all winter in the cold in and it is now summer so im wondering if maybe its not used to the heat. After the 2nd time the controller failed I decided to recalibrate. I then got the message the M.C. is to hot to calibrate error and to let cool down and try again in 5min. I did so and got the message again but calibrate it anyway, then again just like before I again lost communication with the R.C. and the unit about 5 minutes or so into the flight and Ive been flying it everywhere from near my home to the middle of the mountains in up state NY and everytime about 5min into the flight it starts flashing yellow, I lose control and it goes into failsafe and auto lands? any idea what it can be? its very annoying and caused the gimbal to break which has been at dji for almost a month now but even after recalibrating over and over and flight with no gimbal just to see if the error is fixed, it still is not?
     
  17. denodan

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    My imu was fine out of the box. All figures where fine so no need to calibrate it. It will tell you if you need to and can check it.
     
  18. 30secs

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    I still don't mind the fact that in Android there is no way to see the sticks in the Dji app. It obviously knows what the controller is doing... Why not have a section to view and dare i say calibrate. If it's so smart why not?? Just kill the quad connection and do calibration.. Ughhh
     
  19. Mako79

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    Don't power up the P2 for an hour. Charge the battery and during this time, find your self a spirit bubble level to find a perfectly levelled surface - more levelled, better the yaw.

    have the phantom app on the adv calibrate screen. Plug phantom in and power up. The moment its powered up, calibrate IMMEDIATELY. If done quickly, the MC temp warning will not appear. If it does, just process. The cooler your phantom is, the faster the IMU is done. It should get 2 greens in less than 2 minutes. Any longer, just let the bird cool and restart.
     
  20. Okie72

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    Is it okay to do the IMU Calibration inside the house?