3D Robotics

More gimbal news

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For this post, we want to let you inside 3DR by providing a look into the overall management process for a product like the gimbal. In the past we’ve focused mostly on technical matters, so we hope this is an interesting change of pace.

To cut to the chase: we were not happy with the performance of our gimbal over the past month while we’ve been tuning performance. So we decided to make it better, which means starting production this week (first week of August), not in late July as we last promised. This was a tough decision, to be sure - this post explains our logic.

So, first things first. The gimbal performance we were seeing wasn’t bad. In fact, we were right in that gray area where we could have reasonably decided to ship it right now.  Our user tests on “naive users” - people that haven’t seen much aerial video - were uniformly positive. But with a trained eye, you could see movement in yaw in windy conditions.

So, we had a decision to make. Ship the gimbal as-is, or make it better. We decided to make some changes to make our gimbal work great, even if it meant taking a little longer to do so.

Decisions like this are always challenging because they aren’t black and white. At 3DR, one of our guiding principles is to prioritize the user experience (UX) over schedule over cost. We write it this way, as system of inequalities:

UX > schedule > cost

If you ever come to 3DR, you’re likely to see this little equation on whiteboards, in notebooks, in our internal docs.

We know perfection is impossible. Nothing we will do is ever going to be perfect. It’s hard to even write that sentence, because at 3DR, we strive for absolute perfection. Sounds pretty hokey, right? But that’s really the way we work.

And while we know we may not achieve perfection, there is some difficult-to-define point where the team can say, “That looks good. I’d put my name on that. Let’s ship it.” Not all companies have enough synchrony across engineering, design, ops, marketing and every other team such that the whole group hits that point at about the same time. At 3DR, we do have that synchrony. And we just weren’t feeling like the system was ready to go.

So specifically, what weren’t we happy with in the gimbal performance?

Over the past month, we’ve been tuning the performance to get the gimbals to stabilize well across the unavoidable variance of the manufacturing process. In so doing, we pushed our software control system really hard.

At some point in that tuning process, we got together to try and understand how much more performance we could get purely out of software.

Taking a step back: in any hardware/software product, whether it’s a thermostat, fitness tracker or drone, there’s an interplay between hardware and software engineering. The hardware sets the bounds of what software can do. Software can move fast to improve things but cannot operate outside the basic design of the hardware. Hardware is slower to develop, but can open up new territory for software performance and features.

In our case, the weight (or lack thereof) of the top part of the gimbal compared to the bottom part taxed our yaw motor’s ability to correct for disturbances in yaw. Basically, when the copter and gimbal get hit by wind or other disturbances, your video might look like it is vibrating or drifting from left to right. There’s a lot of technical detail here that I will omit, but our decision boiled down to: leave performance as-is, or find a way - a way that would add time to the schedule, no doubt - to address the yaw wandering.

We did find a way. Adding mass to the ends of the spider bracket - the piece that holds the dampers on the gimbal at the very top of the assembly - increases the overall mass of the top part of the gimbal. This allows the yaw motor to react to and correct disturbances hitting the bottom part of the gimbal where the camera lives, resulting in more stable video.

This improvement is relatively straightforward to implement in mass production (as much as anything is straightforward to implement in mass production), so we decided to go for it (after, of course, designing and testing the improvement).

It wasn’t an easy call. We know we could work on the gimbal forever and it would get better each day. We set strict requirements and checklists during our product development process to make that process as efficient and objective as possible. But at the end of the day, it boils down to a subjective, qualitative, ineffable judgment call - “That looks good. I’d put my name on that. Let’s ship it.”

We are very eager to get this gimbal out to you! Solo’s not complete without it. And we know not to let perfect be the enemy of the good. Actually, that’s not quite right - good isn’t good enough. I’ll rephrase: we know not to let perfect be the enemy of the great.

So that’s where we stand. We made some changes and started production. We'll check our product thoroughly before we ship the units. Fixing yaw wandering is only part of the story - there is so much more work that has gone into the gimbal (and is going into the gimbal, and will continue to go into the gimbal via software updates) that I don’t have room to describe here.

But the decision to improve the product and take the schedule hit vs. shipping as-is seems to me to be the most interesting thing to share with you all.  We hope we’re painting a clear enough picture - perhaps with this information, you could even imagine yourself here at 3DR, doing this work, and making these decisions.

Thanks for your support and patience. We’re continuing to work hard on your behalf.

Finally, most important, here is some video that does not include any of the recent tuning, but has a version of the latest hardware. This was shot by one of the 3DR team, Jon.

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Comments

  • Developer

    Yes. Combining the battery and the gimbal, is the only realistic way to add mass to the camera without adding weight to the copter.

  • My 2 cents:

    I find that integrating gimbal mount and battery plate helps a lot.

  • DJI make great products and 3DR have their work cut out for them to compete in their market, given the headstart that DJI have.  I get the feeling the Solo was rushed out to try and take some of the thunder away from the p3 launch and to keep some of those people sitting on the fence around.  But it's backfired a bit, I think they would have been better off waiting until the entire package was really ready and tested.  Announcing shipping dates ahead of time for a product they've never made before (gimbal) and still clearly hadn't finished designing and testing was.. ambitious at best.

    I was really interested in the Solo when it was announced but I'll wait a bit while the early adopters beta test it for the rest of us (and I'm normally one of those early adopters).  I still have great faith that the Solo+Gimbal will eventually be a kick-ass product though and it's definitely on my christmas list!

    In the meantime I just got a Z1-Tiny2 gimbal for my tarot 650 to tide me over and oh my word is it good.  >P3 levels of good.  Really, really good.  Gimbal technology, or at least the packaging into useable good products, is really coming on leaps and bounds.  The 3DR gimbal potentially takes it to a next level with control and digital fpv straight from the gopro.  Here's hoping that it will work on diy copters, not just the Solo.

  • @John - sorry. Never meant to suggest the Phantom 3 was perfect. I just meant when doing AP and flying gently, the reports are it delivers very consistent footage and is generational improvement on the previous model. DJI have been working this platform for years with 100s of engineers. The footage 3DR posted was twilight and gentle flying -- and it was sub standard for the conditions. I am quite sure with spirited flying any of these machines would struggle. I am really hoping it all works out in Q4 for the Solo. I think they should stop posting these videos though.

  • Developer

    @Marc: "why were you not a consultant on this project!"
    The "Solo project" involved other team related to 3DR, not all the "APM:Copter" contributors, because it's a "commercial project" and they were made decisions related to investments, it's correct.

  • Developer

    I agree with John, in some situation also the PH3 fail, but with balanced propellers and different damper the jello is totally absent here.
    The problem of the propellers in the video there's only if you are flying in ATTI, where the quad takes the maximum angle, like in my example here.
    Normally this doesn't happen, there's some video on my Youtube channel.
    There's other know problem, like the "gimbal roll issue", the IMU calibration, etc. etc....
    Personally i prefer the quality of GoPro 4, but not the boring fisheye, and absolutely i'm "APM:Copter" fan... :)

    3702060241?profile=original

  • Developer

    P3 still has vibration induced rolling shutter jello in the video, during difficult conditions. I.e. bright sunlight and ascent/descent or fast forward flight maneuvers that cause strain on the propellers.

  • Marco - why were you not a consultant on this project! It seems like you would have a lot to contribute.

    @John. I do not own a P3 now but I may get one -- it will be my first ever DJI product. The trouble is I understand that you can get this level of performance from a Phantom 3. Nearly perfect video all the time. This is the world 3DR is in with the Solo. So it is not an unreasonable consumer desire. But you are right about how difficult it is. I could not home build a 450-sized quad that eliminated vibrations well. I use a heavier machines (600-700 size) with very carefully balanced props/motors, and significant dampening.

    Considering this is a 'system' I find it amazing that it was launched without a gimbal as though it was some after thought. I would have thought it was an integral part of the system and before this thing could be mass produced they may have wanted to get the gimbal working in case any changes needed to be made to the vehicle. Personally I would have coupled the battery mass to the dampened gimbal platform somehow. That is how I have achieved vibe-free platforms without going OTT with balancing. If the FC and battery were on an internally damped/floating platform the gimbal could have been attached by spacers through the shell to this platform. I am not an engineer, so this is layman's speak, but I have always followed that principal and it seems to have worked.

    I understand that DJI are field testing ROI and Waypoints for the Phantom 3.

    I would like 3DR to succeed.

  • Developer

    A part of the problem is that for some reason with the latest generation (P3 and Solo), suddenly people expect perfect results from a 450 class hobby grade copter. But, consistent perfect results might not even be physically possible because of the small size and weight of the gimbal and camera.

    The reason being that there will always be a certain level of vibration in a propeller driven copter. Especially during high speed maneuvers. And to isolate the camera from these vibrations, you put the gimbal on soft mounts to dampen it. But you also need a certain amount of weight (increase mass to lower natural frequency) in the gimbal to make the dampeners work. So a small lightweight gimbal is much harder to isolate then a bigger and heavier one.

    http://www.newport.com/Fundamentals-of-Vibration/140234/1033/conten...

  • Developer

    I agree Hugues, my Youtube channel is full of these comparative tests.
    For example also the propellers type can make a difference.
    And the motors, mine are balanced individually, one by one, with a special instrumentation.
    Everything makes a difference result, not only the gimbal hardware/software tuning and dampening.
    Indeed, the most important part is to remove as much as possible the vibrations from the quad.
    I'm not involved with the "Solo" project so i don't know this product, but if motors and propellers were not only perfectly and maniacally balanced is impossible to have acceptable results, the gimbal can not work miracles.
    I speak from lived experience.

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