FreeFly - Please admit there’s a problem with the M5?

Discussion in 'ALTA' started by Adam Etheridge, May 3, 2016.

  1. Adam Etheridge

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    I’ve tried discussing this with FreeFly directly, but unfortunately they are no longer responding and don’t seem to want to answer my question:

    Is it possible to achieve a rock solid airborne image (with an Alta) with lightweight cameras on the M5, without adding additional weight to the gimbal?

    We’ve spent about 5 months trying to get the Alta/M5 to work with an A7sII - we have finally managed it, but only by adding weights to camera cage. We’d love to be able to use even lighter cameras, like Blackmagic’s excellent micro HD…but if the only way to make this work on an M5 is to add weights, then this negates the advantage of using lighter cameras in the first place (longer flight time etc). I love all our FreeFly gear (we have 3 x M5s, M10, M15, Alta, Controller etc), but this issue is very frustrating and it seems like FF are trying to sweep it under the carpet.

    Has anyone tried flying anything this light with the Alta/M5?
     
  2. Steve Maller

    Steve Maller UAV Grief Counselor

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    Just FYI, adding 1/2 pound to my M5 doesn't seem to have impacted my flight times at all. Here's a photo of what my MōVI looks like with six M16 shaft collars on it. They only add about 1/2 pound, but it seems to make a difference for me. If only my local hardware store had stocked the same color...oh well. ;-)
    IMG_7838.jpg
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Adam:
    The short answer to your question is no -- there is both a lower and upper bound on the weight that the M5 can handle.

    The technical reason for their being a lower bound is that the way the gimbal works is that there needs to be a certain "mass in motion" to provide some physical resistance to the whole arrangement otherwise the PID controllers (Proportional Integration Derivative) that are doing the balancing of the gimbal, "freak out" (technical term) start to oscillate. So you will need to add some mass if the camera is too light.

    The problem is further complicated by the mass in motion of the gimbal itself.

    It's frustrating to have to add "dead" weight as you say, but I believe what most folks do is use a larger battery for the M5 to give it more run time.

    I think the only reason that the likes of DJI can use much lighter cameras is that they can predict with some degree of accuracy what the camera weighs (they provide the camera, of course) and can mechanically and electronically tune the whole assembly to work with a lighter "mass in motion." (More on "mass in motion" in the world of physics here if you're interested: http://www.physicsclassroom.com/Class/momentum/u4l1a.cfm )

    I've used the iPhone adapter kit with an M5 (I'm not sure it's still available), but it comes with a couple of ballast weights that you have to use -- so I've experienced the problem you're describing first hand.

    Andy
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
    Chris Harrison likes this.
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Steve, I think these might fit and would be far less tacky than the shiny silver.... :rolleyes:
    http://www.amazon.com/Ruland-MSP-16...315429&sr=1-5&keywords=shaft+collar+16mm+bore

    Andy
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  5. Guillaume MARION

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    Probably this problem due to the motors are the same on M5 and M15, then maybe to big for just GH4...!

    On the other side there is few user who use the M5 with Mini and performing well... They just save about 7000$!!
     
  6. Dylan Glockler

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    I've been flying the MOVI M5 with the Alta and the Sony a7sii and it's totally stable, no added weight. I do have a MetaBones adapter and a Canon 24-105 L lens, so maybe that additional weight makes the difference.


     
  7. Walter Brokx

    Walter Brokx New Member

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    This makes me want to know the lower bound :)
     
  8. Adam Etheridge

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    I really want to fly a Blackmagic Micro HD, but I just think it's too light for the M5 airborn (although the M5 is advertised as compatible with the Micro...). Very frustrating.
     
  9. Christopher Morrison

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    Can you share your settings/tuning that's worked for you in getting such smooth video with your current payload?
     
  10. Dylan Glockler

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    I've been traveling but just got back and read this. I can pull my settings for you but they are all at defaults as I've never had any issues right out of the box. I haven't even changed the dampeners from the originally installed black.
     
  11. Fabien Deregel

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    Hi,

    you need to reduce the PAN stiffness and Hold a tthe maximum until the gimbal oscillates slow, then rise a bitthe value. If the pan motor has just a bit too much power, it will wobble slightly and make the entire system freak out. I could get the Panasolic GH4 perfectly stbale on a M10 gimbal with ALta 8 on a customer setup, mounted under or over, no matter :)
    BEst reagrds,
    Fabien
     
  12. Martin Osborne

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    Hi Fabien,
    Could you explain your method again? It seems like you have a method that works for you, but I couldn't quite understand your explanation.
    Thanks,
     
  13. Fabien Deregel

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    Hi Martin,

    First of all, always take into consideration that the IMU is leocated on the "last"' driven axis, aka pitch on the MOVI and many other gimbals: each axis wrongly tuned will bring consequences on the others.
    Second, people forget that balance is not only about static but also about dynamic. Sometimes, having a slight static voluntary misblanace can help solve dynamic balance problems, especialy when you fly at high speed.
    Third, having a high stiffness is not necessary always and leads to more problems than benefits....

    Now about the tuning itself :

    For mechanical tuning, with lightweight cameras / lenses, try to put the camera away as much as possible from the pitch motor and perform a simple balancing fpr the roll, do not hesitate to slide the roll to achieve a decent balance with thte camera as far as possible from pitch motor.

    Once done, time comes for the pan balance. This is here that everything will be allright, or not for the parameters tuning later.

    Make a static balance, and once done, put the gimbal on it's suport stand, if it is installed on a multi rotor, put the multirotor arms on 3 or 4 supports or between 2 tables with some very soft foam between motor mounts and the supports , so you can rotate the pan as you want but also will see the arms moving up / down a little when spinning the pan.

    Do not power the gimbal yet, just make it spin with a little manual pulse so it makes 2 or 3 revolutions freely. You should notice that dspite a good static balance, the handheld on it's support or the multirotor on foam supports will move forward / backward during the free revolutions. Adjust the pan tube slightly forward or backward until this dynamic unbalance phenomena is the smallest / lightest as possible.

    You might notice also the Pitch or the roll acting unbalanced during the revolutions, tune first the position of the roll arm then camera position from left to right to reduce the phenomena on roll, then proceed pitch forward /backward adjustment.

    Once there is as few "drifting" as possible, you can start with parameters tuning.

    Put all stifnesses as low as possible, and rise the pitch stiffness step by step according to manual, until you feel oscillations / vibrations, and go a few units back to stop the vibrations / oscillations ( you can touch the pitch motor and you will feel the smallest vibrations). You can also use temporary gum fix ( we call it patafix in france, it's a yellow paste to stick paper on the walls that you can remove) on the camera with a very thin metal wire + a small gum ball on top end, it will show you all vibrations.

    Then, process roll stiffness. Once done, go to the live datas and check accelerometers, and reduce a little the pitch so small peaks go away. Then reduce again roll very slightly to have as flat curves as possible. Small peaks are vibrations.

    Once done, you can tune the pan finaly. Process the same, and if there is too much power in any motors, you will either feel vibrations in the motors or see the small weighted " antenna" you made on the camera with the paste and wire vibrate. Reduce the values until it remains as quiet as possible.

    Next step is to go fly to finalize tuning on the Alta or any other multirotor flight controller.

    Hover in a safe area and make sure the multirotor is at a safe distance from you. Keep a seady hovering and then give very small but crisp aileron input on any direction and bring back aileron to neutral. If you notice a bounce on the gimbal, then you need to reduce a bit the gains on aileron on FC. Same on Pitch, same on Yaw. You will feel the multirotor maybe slightly " slow" when it stops or gets back to auto levelling, as long as it does not " bounce" back due to the giumbal wieght and dampening, everything is allright. This is the key to have a multirotor that does not send "bumps" to the gimbal because of too high FC gains, which will be translated in hiccups from the gimbal or vibrations.

    On heavy setups, sometimes getting rid of the dampening is better on some frames ( like the Gryphon frames) or have solid metal wires dampening. Problem with rubber dampers is that with aheavy load + the lever effect of the payload concentrated on a small area under the frame is that it will bring the damping plates to limits and hit the damper supports, these create the hard hiccups when flying fast forward and stopping for example.

    Multirotors are just a big and fair amount of comprimise : if you want to fly fast but are not used to anticipate side reactions to fast stops / inputs, you will naturaly rise the gains to feel the machine more " locked".But doing so will bring lot of bad things in the machine : heavy motors accelerations /decelerations, folding blades maybe hitting forth and back their supports on the roots by folding an instant to mechanical limits, stressing the arms supports and finally generate bumps and oscillations between the payload and the multirotor.

    Add to this fact that a gimbal reacts faster than a multirotor for mechanical and electronics reasons, and you will understand that tuning a gimbal is half on the bench, and half in the air + tuning the multi rotor also, especially for lightweight payloads on the gimbal..

    And this works the other way also; too high gains on the gimbals will lead to instant " shocks" for correction, half of it being absorbed by the dampeners between the gimbal and the multirotor, but at a cost : dampers are like spring, they would like to get back to their original shapes. So they will bounce back. Gumbal will react by bouncing back also.. And this is how you end up with a crazy gimbal :)

    It's not that easy to explain things with words, but i will try to make a small video to explain all this during the summer if i have time .

    Here is what can be done with a correctly tuned gimbal in 40 km/h wind over the sea ( 22 knots), this is a machine i built for a customer, a small Y6, 4KG, with 3 axis gimbal and phobotics board. Gains are reduced at the maximum and motor power just at the limit before the gimbal -" stalls" with the wind. You can see a few vibrations on the horizon due to the wind clapping on the GH4.



    I will see some friends for who i did setup the Movi + GH4 on an Alta 8 next week and will make a screenshot of the settings i did tune on the Movi (for the Alta 8 i can't as it has to go back to FreeFly) , we made the flight tests with top mounted gimbal and it worked flawlessly.

    BEst regards,

    Fabien
     
  14. Dave King

    Dave King Well-Known Member

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    I am using the Alta with a M5 and a GH4/12-35mm lens. I have the upgraded firmware and have a rock solid picture. In fact it doesn't even budge in 25 mph wind gusts. I use zero counter weights.

    I made this video for the purposes of tuning the alta in the wind. You can see how steady the footage is with no post stabilization.

     
  15. Adam Etheridge

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    Hi Dave

    Would you be happy to share your settings? Stiffness, hold strength, gyro/output filters especially...

    Best
    Adam
     
  16. Martin Osborne

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    Thanks Fabien. I'm going to try your balancing technique today.
     
  17. Martin Osborne

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    Hi Dave,

    Do you enable the lens stabilisation on the 12-35?

    Your footage looks quite stable, but is still showing some of the twitches that I am seeing with my own footage when using longer lenses and lenses without stabilisation. 12mm is quite wide and forgiving, and the stabilisation is quite good on these panasonic lenses. I am trying to stabilise my Voigtlander primes (10.5mm 17.5mm 25mm and 42.5mm) and the micro movements that you can just about pick up on in your footage become very exaggerated with these lenses.
    I get great results when using my Tokina 11-16mm with Speedbooster (very wide).
    I also get quite good results with the Panasonic 35-100 at 100mm when the stabilisation is turned on.
    But hard to get a good result with the Voigtlander primes (no lens stabilisation) from 17.5mm and longer.
     
  18. Dave King

    Dave King Well-Known Member

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    Yes I am using the stabilization feature on the lens. It also looks very good at 50mm.
     
  19. Adam Etheridge

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    I contacted FreeFly Support over a month ago to try ascertain if they believe it's possible to use even lighter cameras like the Blackmagic Micro HD without adding additional weight, but they will not answer. I've tried chasing with several follow up emails but each one is ignored.

    I must say I find this disappointing. Especially since cameras are only getter lighter as well as better (not to mention that the M5 is advertised to work with the BM Micro!). One of the reasons we choose FF is their commitment to professional support.
     

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