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RTH strikes again

Discussion in 'Inspire 1 Discussion' started by dcbrewer, Apr 1, 2015.

  1. dcbrewer

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    I was in the middle of landing, with the front landing gear already touching the ground, when RTH kicked in and thrusted the Inspire forward. The props caught the ground and flipped the entire unit over. The motors continued to stay on. Some were chopping the ground and others were attempting to spin but couldn't move while on the ground, potentially burning up over time. This continued happening while the unit was entirely on its back.

    Now shame on me for not canceling the RTH or landing sooner, but I was already partially on the ground. It seems like this could be improved in a number of ways. For starters, if the bottom sensor picks up that the unit is basically on the ground, RTH should probably cancel automatically. Additionally, if the unit is on its back, the motors shouldn't continue running while causing more damage.

    Thankfully my Inspire is fine this time, but I could see this leading to a bigger issue for me or someone else in the future. Anyone else have similar RTH issues or problems when the unit continues running after a crash?
     
  2. damoncooper

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    They REALLY have to fix this issue where if left stick input is received during RTH no altitude is gained and it just GOES.
     
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  3. The Editor

    The Editor Moderator
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    But WHY did RTH kick in?
    Was your battery level so low that you hit critical?
    What are your low and critical levels set at?
     
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  4. dcbrewer

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    It did hit critical right as I landed, as I mentioned shame on me for not bringing it down with more battery left. However, I was thinking that there might be room for improving RTH-- say if the craft is half landed or basically on the ground already-- perhaps the autopilot could automatically cancel. For example, auto cancel if the bottom sensor detects that's it's inches from the ground.

    I'll double check the levels next time I fly.
     
  5. Eduardo Bilbao

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    The same exact thing happened too me thank God I only had to replace props recalibrate and just fly. They need to fix this issue.
     
  6. dcbrewer

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    I thought I read somewhere that the motors would automatically turn off after a crash. Is that not true?
     
  7. CaptainBadge

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    Set limits for yourself with respect to battery levels. Do you coast into the gas station with your car? I think if more users treated UAS like aircraft, fewer issues like this would arise. Make a checklist, follow it. When your battery is low... land. Change it, keep flying.
     
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  8. mdomeny

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    when i crashed i turned off the motors imediatly... thats tha auto... you cant expect that the machine will do everything for you... next might be a request to make coffee and bring it in silently while one is watching the play off... learn to handle sizuations and break8ng things will stay at a minimum... i learned with the other system costum build hex and okto that i have to be the master of the machine and not the other way around.
    my opinion.
     
  9. dcbrewer

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    I was able to turn the motors off promptly and as soon as I realized that they were in fact still running. My first thought was that it would happen automatically though. Still thinking I read that somewhere. Perhaps the misinformation led that that thinking as well.

    By the way, my thoughts about the RTH feature is that it is an advancement above and beyond manual control. So if an auto feature is to enable itself, it should be intelligent to a degree. Pure manual control in this situation wouldn't have resulted in a crash here. Definitely understand your sentiment though, it can't do everything automagically.
     
    #9 dcbrewer, Apr 2, 2015
    Last edited: Apr 2, 2015
  10. dcbrewer

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    Absolutely agree with the advice here.

    I would note though that my car doesn't automatically pull itself over across several lanes of traffic when it's low on fuel. If that was a future advancement in cars, they would have at least some basic safety features and automation baked in for various use cases, e.g., checking the perimeter of the car for obstacles. Definitely beyond the state of the art for consumer drones like this today though.
     
    #10 dcbrewer, Apr 2, 2015
    Last edited: Apr 2, 2015
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  11. RicK

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    Well this weekend I had the misfortunate of falling to this exact same issue. I had actually landed and was on the ground for almost 2 seconds when the Return to Home kicked in and the Inspire took off again. The problem was that just before Return to Home kicked in I had pulled both sticks down and in to shut the motors off. Within about another 1 1/2 seconds it reached a altitude of 13ft and then all motors shutdown and it fell out of the sky. Broke one of the graphite rods on the landing gear and the camera assembly separated from the craft. Contacted DJI and will be sending it back to them.

    I am hoping this will be covered under warranty as the flight log clearly shows that the craft was landed and I was shutting down the motors as it kicked into RTH and took back off. I didn't not get a warning that return to home was going to activate or a option to deactivate. It literally displayed the Low Point Warning Return to Home as it switched to GoHome Mode.

    Yes, I know that I should have landed and switched out batteries sooner and I will learn from this. However, I can't see how it makes any since for a aircraft that has been landed to automatically activate and takeoff again. I guess now we will just have to wait and see.
     
  12. lake_flyer

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    I never use the CSC (both sticks centred down) to stop the motors.
    Only for starting. After landing it easy and logical to just keep the throttle stick down for a while. Why would you do a CSC after touchdown anyhow? I personally would only if I needed to shut down in an emergency.

    A CSC results in spinning up all motors in a short burst before they shut down. I would suggest never to do a CSC when you have to hand catch for some reason. Very dangerous. Just keep the throttle down until the motors stop, which is about 2 sec.

    Edit: CSC instead of CNC (it was early, stupid)
     
    #12 lake_flyer, May 19, 2015
    Last edited: May 19, 2015
  13. m00se

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    have you seen the flight log?
     
  14. RicK

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    I was actually referring to the flight record found in the User Center of the App not the actual flight log. I am assuming that the actual flight log will show the same information though. The drone in clearly on the ground and I initiate a CSC then it switches to RTH and takes off. This is followed by all motors shutting down as per my CSC command and the Inspire falling from about 13 ft.
     
  15. RicK

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    Here I would say experience is everything. I only have about 50 flights under my belt and have not had any experiences that had made me think I should do something different. To answer you question of "Why would you do a CSC after touchdown anyhow?" Because in both places in the manual (under stopping the motors & under flight test) it lists a CSC as the first method. To me that meant that this was the preferred way by DJI. So...... until given a reason not to I was just using the method that DJI listed first. Of course now I have a reason not to.
     
  16. lake_flyer

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    Rick, I didn't want to question you about it. It was meant as question in general.
    For CSC you always need both hands, unless you don't want to play it safe. Sometimes CSC doesn't work right away. Sometimes you release one of the sticks too soon and it doesn't shut off. Keeping the throttle in the down position after landing is not an extra procedure, it's just waiting 2 sec to shut down. I was just wondering why anyone should CSC if it takes 2 hands and you have the throttle down already in the first place.

    The manual should list Throttle down as the first option and CSC as the second and last resort, in my opinion.
    That's just my opinion after many hundreds of flights with different types of multi rotors. One time I had to land some distance away (Phantom2) and did the CSC in the full confidence that it would shut down. But when I came to the bird it was actually about to take off again, people were curious and coming way too close. I couldn't see it from where was standing that the rotors were spinning up again. Apparently the motors were shut down already because I had the throttle stick down for 2 secs. From then on I only use the Throttle down, unless I would have to kill the motors in flight.

    For the P2, the new controllers even have a throttle lock that locks the throttle stick in the shut down position after landing so people are not tempted to CSC in the first place..
     
  17. Ibflyen

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    I don't have my i1 (today) yet but we set up my son-in-laws i1 last week and it would not stop the motors by holding throttle down. Only way was csc.
    I thought it was odd as my Matrix with naza V2 stops with throttle held down for a couple of seconds.
     
  18. The Editor

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    Yes it will - but not from idle. You must make the craft 'think' it has taken off by increasing the motor speed first. then the flight controller will accept throttle down and zero barometric pressure change for 2 seconds as a stop motor command.