Photohigher skyline rsgs

jes1111

Active Member
Like a few others I'm sure, I bought 4 Piclocs in the past and had no satisfaction from any of them despite some very good back up and personal help from GM. A nice guy but doesn't want to listen. Until the penny drops with regard to FSR it will be like all of the other crap out there. Maybe it now has, who knows when he doesn't answer emails.

I don't hear any offers of part exchange for something that may now work, or not, as the case may be.

When one considers that you can buy a APM-2 for 199 usd that is a very good FC board and it also has a good set of camera mount outputs. It puts this all into perspective. We are being ripped off.

I was also interested in the Hoverfly Board. Nice bunch of guys with the right qualifications - how could it not work? Just before I got the credit card out I saw this and everything then changed. Sam makes a nice presentation but how could you fail to notice the response lag.
I've now read through most of the Hoverfly Gimbal threads and have seen no particular mention of the lag. The board seems to be using a DSP, so lag ought to be better than most other boards. Indeed, Hoverfly themselves are pointing out that the limitation is the mechanical side of things. I believe the video is (somewhat naively) demonstrating very poor servo response.

It's a pity too that Hoverfly don't seem to understand what's needed in a "results" demo video - what they are showing so far does nothing to convince us of the board's performance

Compare it to this one. I guess you get what you pay for. But having said that I am really unsure about this company. It has grown too fast and does not fall over backwards with any form of after sales service like a lot of the Chinese companies. It is time for someone like Hoverfly to take a close look at this stuff and get on the right track. :tennis:
Do we know what sensors DJI using or have they erased/potted them so we can't see? Their use of direct drive is an obvious mechanical advantage, but what do we know about their sensing and processing?
My S/800 Zen that was returned to China has been given a deliberate run around for about a month now, so it is still waiting delivery to the factory.
I know exactly what they are up to.
I have made my own camera mounts for years now using components from mil. spec. obsoletes. Replication is impossible due to the costs involved but DJI took the same tried and tested theories and made it affordable. Is it not time to abandon the stone age following and throw out the servos and flimsy wobbly gimbals and start afresh.
Exactly what "tried and tested theories" are you referring to? Low FSR gyros, sure. But what else? I totally agree with you about the servos, of course, but the alternatives (for now) are either too heavy, too expensive or both. Let's not forget that the Zenmuse's drive won't scale up cheaply! What would you propose for this "low-end" market?
 

MultiHexa

Member
Hi,

here's a new test movie with the skyline:


When the last wobbles away from the skyline still are the skyline would be really OK.
1 week is around and we are waiting for the promised update of PhotoHigher.

Knock, knock is anybody home? PhotoHigher!!!
 
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DennyR

Active Member
Just to diverse for a moment, The more that I look at this thing the less I like it. What intelligent person would design a landing gear so that it focusses all of the landing loads at the weakest point and then drills a nice hole at that point. Oh I get it. It's supposed to break. Yeah that would be very good for those expensive replacement parts.
View attachment 5533

@ jess I don't have a proposal for the low end market. In an effort to create a cheap solution I played with servo drives a while back and decided that it was never going to work properly. The professional market should be just that. The hobby market is something else but it should at least be fit for purpose.
 

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DennyR

Active Member
Jess
You are quite right about the results demo video. I looked at it closely. The P in P shows what the camera is seeing which purports to be raw un edited footage. Any similarity between that and what the GoPro shows as the true camera angle is purely coincidental. I can say with total confidence that the footage shown is not raw.

Given that I demonstrated how a reasonably stable edit could be produced with NO camera movements at all, you can see that almost anything can be made to look stable at internet quality.

I have every confidence that these guys will eventually come good but I wish they would stop taking the piss.
 
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Just to diverse for a moment, The more that I look at this thing the less I like it. What intelligent person would design a landing gear so that it focusses all of the landing loads at the weakest point and then drills a nice hole at that point. Oh I get it. It's supposed to break. Yeah that would be very good for those expensive replacement parts.
View attachment 7369

Normaly the landing gear must be plugged deeper. the vertical part nearly touch the ground.
Anyway on the new landing gear there is no more the skids but rods.
 

jes1111

Active Member
Well, the best thing I read in the Hoverfly threads is that Blue Yonder is doing a whole-day visit to Hoverfly (or by now already has) to help them sort some unspecified "issues". Good news - everyone should benefit, including all the owners of PH gimbals (regardless of controller) since I believe one of the issues at PH is their understanding of gimbal mechanical setup.

Let me persist, though, on the Zenmuse - because understanding how/why it excels is good for everyone. Skip over what we do know - direct drive, rigid drive train, etc. What I haven't seen is any detail about is its sensing and processing. MPU-6000? Silicon Sensing? DSP? What exactly is this "mil-spec" stuff that DJI has found a way to make cheaper?
 

thijmen5

Member
Where can I find another tilt gear to increase speed on tilt, so the gain can be a bit lower to remove jitter from high gains?
 

DucktileMedia

Drone Enthusiast
I have to say that my new av200 is plenty fast even at the default 5.1v supplied by the bec. It's not the speed that is the issue it's just trying to over correct and jitter because of it. It's weird because my av130 under the wookong gimbal outputs is way too sluggish at 6.5v. I think it's all software and bit a servo speed issue. But I don't have the electrical engineering background so I certainly wouldn't argue if you said otherwise. I can say that a gimbal doesn't have to compensate the dramatic swings people do when holding it by hand. The Heli really doesn't make those kinds of extreme movements and if it did you should probably try and land quickly as it is a sign something isn't right. It's nice that the ZenmuseHey can compensate for vibrations as well as erratic movements but I think most of us would be happy if the gimbal just performed a basic stabilization function.
 

jes1111

Active Member
I have to say that my new av200 is plenty fast even at the default 5.1v supplied by the bec. It's not the speed that is the issue it's just trying to over correct and jitter because of it. It's weird because my av130 under the wookong gimbal outputs is way too sluggish at 6.5v. I think it's all software and bit a servo speed issue. But I don't have the electrical engineering background so I certainly wouldn't argue if you said otherwise. I can say that a gimbal doesn't have to compensate the dramatic swings people do when holding it by hand. The Heli really doesn't make those kinds of extreme movements and if it did you should probably try and land quickly as it is a sign something isn't right. It's nice that the ZenmuseHey can compensate for vibrations as well as erratic movements but I think most of us would be happy if the gimbal just performed a basic stabilization function.
Denny suggested that the Zenmuse may be measuring vibration but I don't see how it could be compensating for it. Vibration will, by definition, produce translational as well as rotational errors - the Zenmuse, clever as it is, can't do anything about the translation.

Agree with you about the violent swings being an unrealistic test - although Denny's "in the mirror" video does demonstrate that the Zenmuse is unphased even by such exaggerated movements. Nevertheless, speed is vitally important here. However fast the electronics are, there's a delay between sensing/calculating the angular error and the correction command arriving at the servo. So the servo is already "behind the game" and must "catch up" as quickly as possible.

Something curious about the Hoverfly - I can see no mention in the manual about servo command rate, i.e. at what frequency is it sending updates to the servo? 50Hz? I don't see any mention of requiring digital servos (which can handle up to 333Hz). Many analog servos will self-destruct above 50Hz. Did I miss something in the manual? Maybe the demonstrated lag is for real!

Come to think of it - what update rate is the RSGS running?
 

After trying it with both digital and analog servos (with some interesting results, i already wrote about it some 70 pages ago) i believe it is driving them around the 50 hz mark but hey! Who cares..it's just refreshing the very same fixed signal so it is not influent :)
 
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jes1111

Active Member
Ok - thanks - so now I understand better about how the RSGS is working. It's sending a constant neutral signal to the servo's PWM input then tricking the servo into believing that it has moved away from that position and needs to get back there. Ingenious. But I also noted an apparent problem with Hitec servos (and presumably others) over the voltage level - 3.3V versus 5V. Has this issue been resolved?
 

jes1111

Active Member
That last realisation has given me an idea. Somebody with an oscilloscope should be able to exam what's happening on the pot connection from the RSGS to the servo. Since the PWM input doesn't vary, the only possible source of the jitter is the voltage on the pot line. So what does this jittery voltage look like on a scope? Is it stepped (i.e. digital) or smooth (i.e. analog). Loosely, stepping would indicate a runaway algorithm problem, i.e. the voltage output section is just doing what it's told. Conversely, a smooth trace would suggest that the voltage section is out of whack.
 
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DennyR

Active Member
Denny suggested that the Zenmuse may be measuring vibration but I don't see how it could be compensating for it. Vibration will, by definition, produce translational as well as rotational errors - the Zenmuse, clever as it is, can't do anything about the translation.


Wrong assumption Jes....
During Initialization it samples it's own independently generated oscillations systematically in X W and Z and calibrates the frequency dampening, this is based on the mass of each sample. That dampening combination would also include a parallax movement. It is quite something to behold. Which is where DJI have been very clever. The only slight vibration that ever gets through is high velocity (100 mph) wind blasts directly on the camera.

Full size systems utilize a sealed inner axis to provide a more advanced final correction using voice coil actuators that float the camera on a magnetic field. The outer axis does not look all that special as seen from the outside even though the main axis run in air bearings.

With regard to your comment about Zen not being able to support larger cameras. The mass inertial of the Pan axis is significantly higher than the pitch for example. Yet that axis works perfectly, so long as it is balanced correctly. Therefore it will support higher camera weights as I proved by fitting a much larger lens. That lens was fitted during the mirror test and the UN flight. The limitation from DJI's point of view is that they don't yet have the mechanical parts to support other cameras. And they could not entrust the set-up to the average hobbyist.

I don't want to get into how the DJI system works as I only understand about 90% it and I don't have it here at the moment. However its drive train is similar to most other systems that I know work and I don't want to get into that one either. One important factor that I can say is that Zenmuse is powered by a 6s battery. All of my other pro gimbals are also nominal 24 volt. That should provide you with a vital clue.

I am not sure about the image quality of the CX730 when the camera pans some slow movements, but if it is good then it would be my next choice over the Nex-7. With a full zoom range it could take us into the next level.:tennis:

All this is somewhat far from this original post however it does provide an interlude while PH digest were they currently are in the market place, and do something about it.
 
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There's the trick right there. Sample the W axis oscillations.

I have not seen this "in the mirror" video. Is it a Z15? Where?
EDIT: Found it a few posts back. That is VERY COOL.




During Initialization it samples it's own independently generated oscillations systematically in X W and Z and calibrates the frequency dampening, this is based on the mass of each sample. It is quite something to behold. With regard to your comment about it not being able to support larger cameras. The mass inertial of the roll axis is significantly higher than the pitch for example. Yet that axis works perfectly, so long as it is balanced correctly. It will support higher camera weights as I proved by fitting a much larger lens. That lens was fitted during the mirror test and the UN flight. The limitation from DJI's point of view is that they don't yet have the mechanical parts to support other cameras. And they could not entrust the set-up to the average hobbyist.

I don't want to get into how the DJI system works as I only understand about 90% it and I don't have it here at the moment. It is however similar to most other systems that I know work and I don't want to get into that one either. One important factor that I can say is that DJI is powered by a 6s battery. All of my other pro gimbals are also nominal 24 volt.
 
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ChrisViperM

Active Member
After seeing this:






there is only one conclusion: Get some R&D facilities, supply sufficient funds and team up DennyR and jes1111, together with some other talented guys and let them work for some time....the result would put some of the so-called "big guys" in the industry to shame....and we will see a video like the above in the Gimbal game....

Chris
 
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gadget

Member
Hi!

I just recieved my Skyline and spent 3 hours trying to set it up yesterday but cannot get it to work properly!
This question/solution might be in this conversation before but the thread is now 80 pages so i just cannot search them all.
My problem is that the servos respond incredibly slow and takes about 2-3 seconds to turn if i manually affect the skyline.
I´m using modified MKS HV787 and they should have plenty of speed but it doesn´t matter how high the gain is, they´re still
ridiculously slow.
Anyone know about this problem or even better, have a solution?

Regards
 

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