Platinum Props on a Pro (standard) queries

[Davros007]

Hi All,

Been using Platinum props on my Pro. Few queries:

How many of you have adjusted the gain? And did you do it because you saw camera wobble at hover or because you got jello when moving? Did it solve it?

Also, would adjusting the gain have any impact on high wind velocity warning? Because, does the Pro calculate wind velocity by “speed over ground” vs current draw by motors? Or is it RPM vs speed over ground? Or something else?
If you have the Platinum props, they are effectively like putting your bike in a higher gear I guess... So if wind velocity is like ‘strain on rider’, then a higher gear would cause more strain (current draw). And would the PP props also get more ‘over current’ warnings?
Cheers, and Happy New Year!

 

[lannes]

is that a photo of little beach in Albany

 

[Davros007]

Nah mate, bit West of Denmark - Boat Harbour it’s called. Nice beach, 4x4 access only, but not hard-core. Be nice to do a vid by standing on the eastern point and flying from the west, over your head, and along the eastern surf beach (or the other way towards a sunset! Nice beach for swimming but a guy drowned off the western point when he was saving someone who fell in (where all that foam is). Also someone parked a new utility (‘truck’) on the rocks on the western (left) point and forgot the handbrake! Off topic but still interesting...

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[Davros007]

is that a photo of little beach in Albany

Sorry! Didn’t hit reply! As above

 

[FoxhallGH]

Hi All,

Been using Platinum props on my Pro. Few queries:

How many of you have adjusted the gain? And did you do it because you saw camera wobble at hover or because you got jello when moving? Did it solve it?

Also, would adjusting the gain have any impact on high wind velocity warning? Because does the Pro calculate wind velocity by “speed over ground” vs current draw by motors? Or is it RPM vs speed over ground? Or something else?
If you have the Platinum props, they are effectively like putting your bike in a higher gear I guess... So if wind velocity is like ‘strain on rider’, then a higher gear would cause more strain (current draw). And would the PP props also get more ‘over current’ warnings?
Cheers, and Happy New Year!

The reason for the gain change is to do with the motor control circuits that are responsible for keeping the Mavic stable in the hover. There is a very fine balance that relies on feedback to keep the drone stable. When the drone 'senses' that it is e.g. tipping left without any control input as such, it will tip right - to the same degree - to compensate for that. When you put the [more efficient] 8331 'quiet' prop's on the Mavic Pro, these can have the effect of over-compensating - so that when the drone tips left, the motor controls compensate with a tip right - but that goes just a tiny bit too far, which generates a tiny tip left - that goes a bit too far, that generates a tip right - etc. etc. So in essence, the drone ends up 'oscillating' - but at a frequency and degree of movement that is almost impossible to see. What does happen, however, is that the gimbal sets up a sympathetic oscillation at a lower [harmonic] frequency and that can be seen quite clearly if you hover the Mavic at head height. Changing the GAIN settings will compensate and tune the Mavic to use the 8331 prop's correctly and remove the oscillation/vibration.
You can also get the same effect when the Mavic is moving out of the hover and transitioning to some other 3D direction ...
This video is a bit long-winded - but well worth taking the time to look at all the way through, as it fully explains the nature of the problem and the 'cautious' approach to fine-tuning the GAIN settings ...

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[Davros007]

The reason for the gain change is to do with the motor control circuits that are responsible for keeping the Mavic stable in the hover. There is a very fine balance that relies on feedback to keep the drone stable. When the drone 'senses' that it is e.g. tipping left without any control input as such, it will tip right - to the same degree - to compensate for that. When you put the [more efficient] 8331 'quiet' prop's on the Mavic Pro, these can have the effect of over-compensating - so that when the drone tips left, the motor controls compensate with a tip right - but that goes just a tiny bit too far, which generates a tiny tip left - that goes a bit too far, that generates a tip right - etc. etc. So in essence, the drone ends up 'oscillating' - but at a frequency and degree of movement that is almost impossible to see. What does happen, however, is that the gimbal sets up a sympathetic oscillation at a lower [harmonic] frequency and that can be seen quite clearly if you hover the Mavic at head height. Changing the GAIN settings will compensate and tune the Mavic to use the 8331 prop's correctly and remove the oscillation/vibration.
You can also get the same effect when the Mavic is moving out of the hover and transitioning to some other 3D direction ...
This video is a bit long-winded - but well worth taking the time to look at all the way through, as it fully explains the nature of the problem and the 'cautious' approach to fine-tuning the GAIN settings ...

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Understood - and I’ve seen the video, it’s interesting. But without changing the gain, are there other implications as I queried? And will changing the gain also affect the amps the motors will draw (max current); or conversely, will NOT changing the gain cause more over - current warnings and even ‘high wind’ warnings than with standard props (how is wind strength measured? Speed vs current draw or revs?). Cheers Dave

 

[FoxhallGH]

Understood - and I’ve seen the video, it’s interesting. But without changing the gain, are there other implications as I queried? And will changing the gain also affect the amps the motors will draw (max current); or conversely, will NOT changing the gain cause more over - current warnings and even ‘high wind’ warnings than with standard props (how is wind strength measured? Speed vs current draw or revs?). Cheers Dave

If the Mavic is constantly over-compensating to maintain stability, then it stands to reason that the motor activity (rpm) will cover a greater range, and the power drawn from the batteries will increase - leading to decreased flight durations.
My understanding is that the GAIN settings are all about setting the stability of the Mavic in a hands-off hover. High-wind warnings come about due to the Mavic 'knowing' how much pitch and/or roll movement it needs to put on, to maintain a ground-speed (i.e. its change in GPS co-ordinates/time). The stronger the wind, the more the Mavic needs to pitch its 'into-wind' side down to maintain course or position. If the Mavic thinks that it's getting close to not being able to progress due to the wind speed, it will pop the warning. That is not going to be affected by the GAIN settings ... However, it is logical to believe that a Mavic with optimum GAIN tuning will hold its position in windy conditions better than one that is not correctly configured.

 

[Davros007]

If the Mavic is constantly over-compensating to maintain stability, then it stands to reason that the motor activity (rpm) will cover a greater range, and the power drawn from the batteries will increase - leading to decreased flight durations.
My understanding is that the GAIN settings are all about setting the stability of the Mavic in a hands-off hover. High-wind warnings come about due to the Mavic 'knowing' how much pitch and/or roll movement it needs to put on, to maintain a ground-speed (i.e. its change in GPS co-ordinates/time). The stronger the wind, the more the Mavic needs to pitch its 'into-wind' side down to maintain course or position. If the Mavic thinks that it's getting close to not being able to progress due to the wind speed, it will pop the warning. That is not going to be affected by the GAIN settings ... However, it is logical to believe that a Mavic with optimum GAIN tuning will hold its position in windy conditions better than one that is not correctly configured.

Ah! So wind speed calculation is likely related to tilt angle too?
But I still get a wind speed warning when flying around at speed into the wind? Just the safety margin I guess? “I’m not making the progress I think I should be at this angle, send wind warning”.
Gain is still utilised to maintain stability in flight though, yes? So ‘jello’ that you don’t get hovering but do get in flight could still be gain? Or more likely wind/worn gimbal rubber? (By that I mean less frequent jello, not in sport mode and not some constant wavering - but I did have wind warning).

 

[FoxhallGH]

Ah! So wind speed calculation is likely related to tilt angle too?
But I still get a wind speed warning when flying around at speed into the wind? Just the safety margin I guess? “I’m not making the progress I think I should be at this angle, send wind warning”.
Gain is still utilised to maintain stability in flight though, yes? So ‘jello’ that you don’t get hovering but do get in flight could still be gain? Or more likely wind/worn gimbal rubber? (By that I mean less frequent jello, not in sport mode and not some constant wavering - but I did have wind warning).

If you are 'flying at speed into the wind' then you will be very nose-down with a 'lower-than-expected' ground-speed ... Which again meets the criteria for the wind-speed warning.
You'll find that the GAIN adjustment is going to affect the drone when it's hovering and when it's transitioning from hover to flight in any axis. The reason for this, is that when the drone is in motion, the feedback circuits that are necessary to keep it steady, aren't needed. So the two signs that you have GAIN problems are; gimbal shudder in the hover, and/or gimbal shudder when transitioning from hover to e.g. forward flight.
There is a small 'tab' at the back of the gimbal mount, that should have a corresponding tab on the gimbal assembly slotted under it. If that comes out from under, then you can get a lot of gimbal wobble too. It's worth checking that is all OK.

 

[Davros007]

If you are 'flying at speed into the wind' then you will be very nose-down with a 'lower-than-expected' ground-speed ... Which again meets the criteria for the wind-speed warning.
You'll find that the GAIN adjustment is going to affect the drone when it's hovering and when it's transitioning from hover to flight in any axis. The reason for this, is that when the drone is in motion, the feedback circuits that are necessary to keep it steady, aren't needed. So the two signs that you have GAIN problems are; gimbal shudder in the hover, and/or gimbal shudder when transitioning from hover to e.g. forward flight.
There is a small 'tab' at the back of the gimbal mount, that should have a corresponding tab on the gimbal assembly slotted under it. If that comes out from under, then you can get a lot of gimbal wobble too. It's worth checking that is all OK.

Thanks! So, does the same gain setting used at hover to prevent left/right tilt come into play when flying straight forwards? To stop the drones body being tilted if hit by wind from the side?

 

[FoxhallGH]

Absolutely correct - There is a feedback control that keeps the attitude of the drone correct in the 3D directions other than that which the drone is flying in. Those feedback settings are the same for all conditions i.e. if the GAIN settings are correct for stable hover, then they will be correct for everything else.
Just think of it this way ... The GAIN setting is there & tuned to ensure that if the drone makes an uncommanded e.g. roll 1mm to the right, then the motor controls will input the exact reverse to roll the drone 1mm to the left. If the GAIN setting is incorrect and compensates by 1.1mm, then you'll get the vibration as the 'roll' compensation is not dampening the action immediately. The very fine nature of the setting is why the video I posted (#5 above) stresses the need to do any changes in small steps, and I'd also advise that you record all your GAIN settings before you make changes (so they can be restored to pre-fiddle settings ? ).

 

[Davros007]

Absolutely correct - There is a feedback control that keeps the attitude of the drone correct in the 3D directions other than that which the drone is flying in. Those feedback settings are the same for all conditions i.e. if the GAIN settings are correct for stable hover, then they will be correct for everything else.
Just think of it this way ... The GAIN setting is there & tuned to ensure that if the drone makes an uncommanded e.g. roll 1mm to the right, then the motor controls will input the exact reverse to roll the drone 1mm to the left. If the GAIN setting is incorrect and compensates by 1.1mm, then you'll get the vibration as the 'roll' compensation is not dampening the action immediately. The very fine nature of the setting is why the video I posted (#5 above) stresses the need to do any changes in small steps, and I'd also advise that you record all your GAIN settings before you make changes (so they can be restored to pre-fiddle settings ? ).

Thanks for the information!
I’ll have a ‘play’ - possibility try heading for the 89% he talks of. But I don’t tend to get any jello at hover. Mostly a blip at medium to full throttle in wind. So unsure if it’s gain or worn dampening rubbers (gimbal is all set properly, free to move, calibration ok). Or me just pushing it too much... But I might also calibrate the IMU again too before I get carried away. Also getting a faster SD card as the guy I bought mine off was just doing stills and supplied a U1 card. You can see the ‘jumps’ when watching video. The ‘jello’ though seems perhaps different. All good fun resolving! First I’ve gotta do some crazy flying with the original props again, to see if any issues persist with them reinstalled and gain set to 100.
I’ve also been into Land Rovers, so I’m into investigating and fixing stuff! At least I don’t need the M1P to get me home! ?
Been good getting your advice thanks. Too many sites and sources of information these days where emperor’s new clothes become reality with no one actually questioning the facts behind the information!

 

[FoxhallGH]

You are welcome - and fly safe & have fun ...
By the way - junk the U1 card, as that will introduce frame rate errors in HD video recording. It's recommended and best to use U3 (UHS speed bus 3) spec' cards, as they can maintain the write rate that's needed to store streamed HD video.

 

[Lapcat]

Oh, great, I just ordered a set of the 8331 props for my Mavic Pro! I’m not a drone geek but, from what I read, I may have problems using them. Should I cancel the order or send them back and stick with the OEM props? Does DJI not alert users when “upgrading” to the platinum low noise? Will I even notice an issue? What should I most be concerned with, other than destroying or losing my MP? Thanks.

 

[MAvic_South_Oz]

Get them, they are great.
Use them on my M1P without issues or gain adjustments like a very small % of users say they need to.
It’s an easy adjustment plenty of YouTube vids on it.

 

[Davros007]

Get them! The lower noise is noticeable, especially at height and full throttle. But the older type do seem a bit more stable.
I just damaged my new ones and put the older ones back on: I must say I seem to get less high wind warnings so far? But could be just in my head...
Think of the older ones like a ‘lower gear’ in your car. They spun faster and chew a little more juice whilst making loud revving noises, but to me seem a bit more stable. The new ones spin less, chew a little less juice and make less noise. The noise is probably the factor I note the most about them. Haven’t compared speed but the new ones may be faster!

 

[dronepilotbob]

Get them! The lower noise is noticeable, especially at height and full throttle. But the older type do seem a bit more stable.
I just damaged my new ones and put the older ones back on: I must say I seem to get less high wind warnings so far? But could be just in my head...
Think of the older ones like a ‘lower gear’ in your car. They spun faster and chew a little more juice whilst making loud revving noises, but to me seem a bit more stable. The new ones spin less, chew a little less juice and make less noise. The noise is probably the factor I note the most about them. Haven’t compared speed but the new ones may be faster!

Nope not in your head. Platinum props are great if there is no wind. As soon as there is wind, the drone does drift a lot (lots of wind warning on the app). Original OEM Pro props there are 0 issues when there is wind (no wind warnings). I actually prefer original Pro props just because of the wind part, and they seem like they won't brake off, whereas Platinum ones appear fragile. Would I buy Platinum props again for my Pro, probably not. I wouldn't recommend them personally, especially if you live in an area where wind is common. Also I don't feel comfortable changing GAIN, etc.

I'm curious if Platinum reacts the same way in the wind? I know that Platinum does have different motors, and probably fine tuned GAIN for the props.

 

[FoxhallGH]

Oh, great, I just ordered a set of the 8331 props for my Mavic Pro! I’m not a drone geek but, from what I read, I may have problems using them. Should I cancel the order or send them back and stick with the OEM props? Does DJI not alert users when “upgrading” to the platinum low noise? Will I even notice an issue? What should I most be concerned with, other than destroying or losing my MP? Thanks.

You MAY have to make some GAIN adjustments but most have reported that it's a direct swap and fly exercise. You can tell if the GAIN adjust is needed, by hovering the Mavic just above head-height, and looking closely at the gimbal. If you have feedback problems causing a 'tremble' then you'll be able to see the gimbal shaking. If it's steady, then all is OK. If you need to do adjustments, they are straight forward but see the video in my post #5 earlier in this thread to get the why's and how's ...

 

[FoxhallGH]

I'm curious if Platinum reacts the same way in the wind? I know that Platinum does have different motors, and probably fine tuned GAIN for the props.

The Platinum doesn't have different motors, it has different ESC controller electronics driving the motors. Instead of feeding a variable frequency 'square' wave into the motors, the MPP uses a variable frequency 'sinusoidal' wave to control them, which is a lot smoother and a bit more responsive. My Platinum is steady in the wind, but I do now use only Master Airscrew Stealth prop's on mine ...

 

[dronepilotbob]

The Platinum doesn't have different motors, it has different ESC controller electronics driving the motors. Instead of feeding a variable frequency 'square' wave into the motors, the MPP uses a variable frequency 'sinusoidal' wave to control them, which is a lot smoother and a bit more responsive. My Platinum is steady in the wind, but I do now use only Master Airscrew Stealth prop's on mine ...

View attachment 90114

Thanks for the above information. Very informative.

Side Q: With Airscrew props did you need to fiddle with any additional settings? Or were they good to go right out of the box?