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Toilet bowl effect-- big time

Discussion in 'General Discussion' started by obiwan_pierogi, Apr 12, 2014.

  1. obiwan_pierogi

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    Still having the toilet bowl effect with my copter.. It starts right after I rotate the copter.. Notice the circles get wider, and the copter moves faster.. " I am not touching any controls during this process.." I pulled out at the last minute, before hitting the trees.. But a slight fluster caused me to press the toggle the wrong way, which almost spelt disaster.. Thankfully, I averted the tree at the last moment.. Note than when I gained altitude for safety.. As soon as I input some rotation, the toilet bowl effect immediately stopped.. Incidentally, I was locked on to 10 satellites at the moment, and the dealer had just returned the copter, having replaced the gps unit.. The compass was recently calibrated, and in the normal range.. So what is causing this? Incidentally, the copter still has the major left turning tendency.. Even if I only travel about 15 feet in a straight line.. https://www.youtube.com/watch?v=VJBcAhd ... e=youtu.be
     
  2. kydan

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    In your youtube comment you mentioned you are using potentially bad props. I'd replace those to see if it helps to start with.

    Also, are you waiting before taking off to ensure you get the optimal satellites in GPS mode?
     
  3. obiwan_pierogi

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    When I got the copter back from the dealer, I recalibrated the compass.. Had access to 10 satellites.. Unit immediately went into toilet bowl effect when I rotated, as demonstrated on the video.. Unfortunately, I ended up bringing it down in some branches as a result of the close quarters, which took the ends off a couple of props... These props I put on to re-test have a warp or something, which causes a slight vibration, but the TBE effect is still the same, as it was with the new ones.. The dealer replaced the gps unit.. The copter still has a strong left turning tendency, even with a short straight run of 15 feet..
     
  4. ElGuano

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    Nice saves (including keeping it away from your face)!

    Intermittent TBE is a new one. It suggests that you're running into some kind of compass interference near the ground (maybe you should pick up a shovel and start digging for gold?), but from your video, when it is happening it is classic TBE. When you plug the Phantom into Assistant, what do the values show on the IMU calibration screen? Post a picture if you can.

    It is 100% not the GPS causing it, though having an absolute positional reference via GPS is what is conflicting with whatever sensor is getting confused. I think your problem can probably be solved by a compass and IMU calibration, or at worst a degauss. If you live in extreme northern latitudes it will be tougher to fix, and may involve removing and rotating your compass mount.
     
  5. obiwan_pierogi

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    All the readings are within the normal range.. I did the basic and advanced IMU calibrations tonight, and I'll give the unit a try again tomorrow.. I almost get the feeling there's either a bad solder, a broken wire, or a weak electronic part somewhere in the unit.. I have hovered, for a period of time, but even on this last flight.. I cut out the first part of the video, but I took off, and hovered at about 10 feet.. Then, just out of the blue, it started moving away from me, and went about 15 feet before stopping.. And yes, I am getting green flashing before I take off, and the I-phone says I have 10 satellites locked on.. And yes, I am in full view of the sky.. And yes, when I calibrate, I not only move my controller about 10 feet from the copter, but I even remove my ring-- just in case.. And I'm well away from anything metallic.. As I mentioned, the left turning tendency has been really bad.. Even, as I say, with distances of 15 feet, and moving at slow speed, it'll still deviate 6 feet to the left, when I release the controls.. I tell you, I'd really like the vision +, but until I get this corrected, I won't even think of buying another one.. I've only had this guy since Jan., and have flown it only about 1/2 dz. times.. Frustrating.. I tell you, if everyone got a copter like mine, DJI would go belly up, as everyone would've shipped their copters back.. Is it too much to expect to get a unit that works as least as good as the ones they advertise on all their sites? Geez...
     
  6. ianwood

    ianwood Taco Wrangler
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    It has nothing to do with the quality of the GPS fix or the props. It's your compass. You're in BC, right? That's 15 degrees declination which is enough to cause TBE from a hover due to the declination defect. There could also be other compass related issues like magnetization. What is the mod value for the compass?
     
  7. Jebus

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    Wouldn't be a Tx calibration issue - would it?
     
  8. ericdes

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    The going bowl effect that be easily solved by rotating your compass as I explained in another thread.

    You go tohttp://magnetic-declination.com

    Find your value, and rotate your compass to that value. If you get 15 degrees positive,you rotate 15 degrees clockwise, etc....

    After do another compass calibration and enjoy.

    Oh, and yes the compass will be tight and stay put on the leg.
     
  9. obiwan_pierogi

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    Yes, I recall reading your post about rotating the compasss.. Right now my mod values are in range, around 1600, and this is a 2nd compass, in an attempt to rule a faulty one out.. My declination is about 17 10 East.. positive.. I'm curious though.. If this is a sure-fire fix, how come dji aren't pushing the method, or coming up with a firmware upgrade to correct it?
     
  10. obiwan_pierogi

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    Incidentally, my copter will skew to its left, if I'm attempting to fly it directly towards me, from a distance.. And it would be approx. 17 degrees off..
     
  11. Marc70

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    I just got my Phantom 1.1.1 back from the dealer.
    Had a true flyaway. Flown 75+ times since Xmas, know all the procedures. Found it 3 days later, nothing but yellow flashing lights.
    Sent to dealer (http://multirotorheli.ca/), he replaced the receiver free of charge.
    Now I get the toilet bowl, real bad. Had it on a string (don't trust it yet, probably never will).
    After playing with it some, it stopped, but it was wild at the time.
    Finally hovered like it should.
    I agree with you obi wan, DJI would not make another cent if I had some input.
    Product worked great before, but suddenly a flyaway, now this TBE, what's next?
    P.s. I live in northern ontario, flew this copter at this same park quite a few times. Did proper calibration several times after getting it back, till the values were in the acceptable range.
     
  12. ianwood

    ianwood Taco Wrangler
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    Rotating the compass on the P2x does not fix the problem and it is a bad idea for multiple reasons. It may work on other platforms but not the P2x. DJI has acknowledged there is a problem with declination on the P2x and they are looking into it. In fact, they just sent me and a couple others with the same issue a Mark II OSD to do data logging so they can analyze it and figure out what is happening.

    As your declination is quite high, I would guess that to be the cause of your TBE. Your mod value is fine. Swapping out the compass is not a bad idea. It's pretty cheap. Just be sure to use a non-magnetized screwdriver!
     
  13. ericdes

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    Ian,

    It looks to me that my Fc40 (1.1.1) and your P2X have the same compass, on the same leg, at the same height.

    Page 28 of the NAZA manual SPECIFICALLY states to rotate the GPS puck the number of degrees that the magnetic declination you register at your location to FIX the toilet bowl effect.

    Now we all know that the GPS puck they are talking about has both GPS and compass inside it, so for us we don't rotate the GPS inside the Phantom, but we can rotate the compass on the leg WHICH WORKS.

    Ian, have you actually tried it??? Take a small 5 minutes of your time and yeah, try it. My Phantom has never flown so rock solid, it just behaves like it should. I would get the toilet bowl effect growing larger and larger until I corrected it several times. With gimbal and Gopro 3+ black attached, by the time it was steady, my flight time was over. Now I start when it lifts off.

    Let us know how that goes once you try it, unless you have a scientific explanation why we should avoid this proven fix.
     
  14. ElGuano

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    Ian's tried it. He's assiduously documented a very specific behavior with the P2. I haven't seen it on my P1, but I don't doubt his findings. However, I have my compass mounted on a rotating CF rod and can make changes to it in flight, which I've done countless times. It's currently exactly centered, but on my P1 you can absolutely correct for any kind of declination drift by rotating the compass module. I've tested this over several hundred meter runs and noted the drift corresponding to the turn of the compass.

    For MOST people who notice an issue, this solves the problem. For those who are especially persnickety about precise direction in forward flight with the P2, or course lock behavior, it may take something from the manufacturer, which may or may not be coming.
     
  15. ericdes

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    Right.

    The left or right hook isn't correct with the rotation, but the toilet bowl effect is.

    I wonder what makes the P2 act different than the 1.1.1 in terms of this fix. The left or right hook corrects itself during flight but once you unplug the battery it starts all over again.

    For me the toilet bowl effect was extremely annoying, but I can compensate during flight for the hook effect.

    I went to a local flying field and was approached by various phantom flyers once they saw my phantom lift off and hover on a dime. The all wanted to know how it did that.
     
  16. obiwan_pierogi

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    I tried rotating the compass a few degrees clockwise.. As viewed looking down on the copter, with the camera facing to the front-- away from me.. It worked.. I think... Now the copter either stops in a straight line, or veers just slightly to the right.. It is hard to tell whether this will correct the problem, as with the couple of warped blades I am currently using, the copter has a bad vibration.. I've ordered a few sets of props today.. We'll see how it flies with them attached.. It is also quite windy today..
     
  17. ianwood

    ianwood Taco Wrangler
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    Different branches of code would be my guess. Somewhere in the P2x branch there is likely a signing error (just a guess) that results in the symptoms people are reporting. Pronounced TBE from hover is only seen in high-declination areas (>= +/-18). For the rest of us, it is a pronounced hook with subsequent TBE that cleans up slowly with flight and is mostly gone after 5-8 minutes. Unlike the Naza on other platforms, the P2x is supposed to auto-declinate (i.e. adjust for declination automatically) as the compass isn't designed to rotate.

    The way to see if your props are a factor is the fly in ATTI. If you can go straight in ATTI, then your props aren't an issue. Rotating the compass will change the results for sure. The closer you rotate it to your actual declination, the faster it will straighten out. BUT, it will then over correct and go in the other direction as I think you have already described. To get it to fly straight from take off, you have to apply double your declination and after a few minutes it will then hook in the other direction.

    I've tried them all as have others. That said, I ordered a new compass last week and will retest with it to continue to rule out other potential factors. I am also looking for a way to hard reset (factory reset) the Naza to see if there are any persistent adaptions on top of the per flight adaptions that I don't know about.

    I will know more once I download the logs from the Mark II OSD. They're apparently raw CAN messages but I've got a bunch of meta information (thanks pawelsky on rcgroups.com) to decode them.
     
  18. obiwan_pierogi

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    LOL... This is my the latest response I got from DJI, when I requested to send my unit back for repair.. Are these guys on drugs or what? I just fired off a new e-mail, and included the video..


    ##- Please type your reply above this line -##

    Your request (10761) has been solved. Please submit a new request if you have any further questions.




    Jorge G.
    Jorge G. (DJI Technology)

    Apr 15 18:20

    Dear Jon

    Thank you for your email.

    We feel that we can better assist you through our live support team.

    You can reach our phone support by calling 818-235-0789. Our hours of operation are Monday through Friday 9:00 AM to 5:00 PM (PST).
    We will do our best to help you resolve this issue.

    Thank you.

    Customer Service Representative
     
  19. rustysd

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    Isn't the other fix to take a magnet and spin it in circles around the leg of the Phantom?

    And isn't the relevant question what the compass settings are in the NAZA and how close they are to the recommended settings of -300 to +300 and 1400-1800?

    I feel like if those steps arent attempted then other adjustments would be premature.
     
  20. obiwan_pierogi

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    I have to admit that rotating my compass 20 degrees on the leg has helped tremendously towards eliminating the toilet bowl effect.. I don't think my copter is 100%, but it's definitely 90% better, and I'm still currently operating with the wrong blades (I mis-ordered, and ended up with the smaller ones for the V1)