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Jeti DS-12

Old 08-17-2020, 09:26 AM
  #251  
wfield0455
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Originally Posted by JSF-TC
I'm just starting to play with an Assist prior to installing in my next project and looking for some clarification on the Damping Only (allows trims and butterfly) menu item.

Coming from Cortex/ Cortex Pro, I understand the Normal (Damping) Flight Mode and the effect trim has on Stick Priority and gain fade out.

I interpret the Damping Only option to not include Stick Priority gain fade when you have to trim away from the learned neutral point, however, assuming that trim and stick position are treated the same by the gyro (it can't tell one from the other), I could not detect any difference in apparent servo response to moving the Assist between having the Damping Only box checked or not and with a trim offset selected. It would still fade out the gain as the stick/ trim was moved

Can someone provide an explanation of what the Damping Only option is actually doing in Normal (Damping) Flight Mode?

Thanks

Paul
Normal damping has not only a damping component but a small hold component as well. Because of that you really can't use trim as the Assist always sees this as you holding stick input and it constantly makes corrections to move the aircraft in the trimmed direction. If you select hold mode and apply trim this is very easily observed on the bench as the control surface will creep in the trimmed direction. Normal damping, without damping only set has this behavior to a small extent but it's not nearly as noticeable.

Damping only completely disables that hold component in normal damping mode and allows trims to be used with out a negative effect on the aircraft in flight. Trim inputs DO have an affect on stick priorities but it's generally small, assuming you leave the stick priorities at the default 100%. If you increase them to 125%, this disables the Assist with very small stick inputs (15%????) and by adding trim you can completely disable the Assist with such large stick priority settings IF you don't repeat the stick calibration procedure. With the stick priorities set to the 100% default the effect it small but the Assist is never using the full, programmed gain on any axis that has trim. So even though the is not a big problem, it's so easy to repeat the stick calibration following trimming that there is no reason not to..








Old 08-17-2020, 11:23 AM
  #252  
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Wayne,

Thanks for the information. Again, not described in any official documentation.

With that new info, I did some more investigations on the bench.

At no time in Normal (Damping) Flight Mode could I induce any servo response related to any underlying Heading Hold function, either with Damping Only on or off.

What I found was that with Damping Only turned on, the trim works as expected, but, with Damping Only turned off, whilst the trim again seems to work as normal, the amount of servo deflection was different compared to Damping Only turned on. In fact, the amount of servo deflection was a factor of both trim steps and gyro gain. Higher gain = larger servo movement for a given trim offset. Servo travel with the stick/ trim at zero and at full stick deflection were identical both Damping Only on or off; it was just at partial travel that you could see a difference.

I have no idea why you would want your trim to be variable with the gain setting - it would seem that you would always be having to re-trim if you changed gain setting.

I'm happy to now leave Damping Only always turned on.


Paul
Old 08-17-2020, 11:31 AM
  #253  
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So for example if one has down trim with full flaps for landing, it would be best to calibrate in that configuration? Therefor the gain would be a little higher in landing mode than cruise mode since the assist would consider landing mode as the calibrated non trimmed condition.
Old 08-17-2020, 11:40 AM
  #254  
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Mark,

On my current Cortex/ Cortex Pro models, I calibrate with flaps up and have the gain on my Flight Mode switch. While I may have 20-30% gain with flaps up, I have around 70% with take off flap and 100% gain with full flap.

During initial flights, I had the gain on a rotary knob, but once I had found a suitable value for each flight mode, I transferred that to the Gyro page as a hard-coded setting.

On my Ultra Flash which has a significant trim change with flaps, some of that 100% gain is washed out due to stick priority gain fade-out. At the end of the day, I achieved a set of gain settings that gave the model a locked in feeling in all flight modes.

I'll try the same approach with the Assist.


Paul
Old 08-17-2020, 12:32 PM
  #255  
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Originally Posted by causeitflies
So for example if one has down trim with full flaps for landing, it would be best to calibrate in that configuration? Therefor the gain would be a little higher in landing mode than cruise mode since the assist would consider landing mode as the calibrated non trimmed condition.
No, it's best to calibrate with the trims set for the way the plane normally flies. Just trim, re-calibrate and adjust the gain as high as you can for the speed you expect to fly at in the Assist flight mode used in "cruise mode".

While the trim associated with flaps down will decrease the gain slightly, it's a very small amount and you probably won't even notice it. If you really want to maximize gain for landing have your "flaps down" position select a different Assist flight mode configured for a higher gain since the plane will be flying slower with flaps deployed. This will allow you to maximize gain for landing, even though stick priority may be reducing it slight due to the minor trim change involved.

Last edited by wfield0455; 08-17-2020 at 12:42 PM.
Old 08-17-2020, 12:36 PM
  #256  
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Originally Posted by JSF-TC
Mark,

On my current Cortex/ Cortex Pro models, I calibrate with flaps up and have the gain on my Flight Mode switch. While I may have 20-30% gain with flaps up, I have around 70% with take off flap and 100% gain with full flap.

During initial flights, I had the gain on a rotary knob, but once I had found a suitable value for each flight mode, I transferred that to the Gyro page as a hard-coded setting.

On my Ultra Flash which has a significant trim change with flaps, some of that 100% gain is washed out due to stick priority gain fade-out. At the end of the day, I achieved a set of gain settings that gave the model a locked in feeling in all flight modes.

I'll try the same approach with the Assist.


Paul
Paul,
I have a cortex set up like this also. I just recently updated my assist that I have been flying Since it first came out and canít see where I can do the same with flight mode other than Harryís method of using a digital trim in each flight mode. I only have three flights on the updated version and Iím trying to tweak it.
Old 08-17-2020, 12:45 PM
  #257  
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Originally Posted by wfield0455
No, it's best to calibrate with the trims set for the way the plane normally flies. Just trim, re-calibrate and adjust the gain as high as you can for the speed you expect to fly at in that Assist flight mode.

While the trim associated with flaps down will decrease the gain slightly, it's a very small amount and you probably won't even notice it. If you really want to maximize gain for landing have your "flaps down" position select a different Assist flight mode configured for a higher gain since the plane will be flying slower with flaps deployed. This will allow you to maximize gain for landing, even though stick priority may be reducing it slight due to the minor trim change involved.
I know the difference in gain should be very small. I want to make the gains flight mode dependent but havenít been able to see where to do it in the flight modes. For instance I could turn the nose gear steering off in one flight mode but couldnít see where to adjust gains. I was in kind of a rush so I may be able to look at it closer this evening.
Old 08-17-2020, 12:49 PM
  #258  
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Mark,

I have not installed the Assist yet and I'm still playing with it to get familiar, but I don't see why the same approach as used on the Cortex wouldn't work with the Assist, using the built-in Gyro page on the transmitter.

While the max gain for the Assist can only be set to 2x the initial gain via a knob or switch, if you can get to more than 2x the nominal gain you could use one of the other Gyro Flight Modes to have a different gain value set, and use the flight mode switch to select the different gyro settings.

I'm happy with the Cortex approach, just getting comfortable with Assist seems a challenge at the moment. I'm sure it is just a familiarity thing.


Paul
Old 08-17-2020, 01:45 PM
  #259  
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Originally Posted by causeitflies
I know the difference in gain should be very small. I want to make the gains flight mode dependent but haven’t been able to see where to do it in the flight modes. For instance I could turn the nose gear steering off in one flight mode but couldn’t see where to adjust gains. I was in kind of a rush so I may be able to look at it closer this evening.
There are several ways to do this. If you're using the Jeti Gyro function, selected with a 3 position switch, to control your gain tuning channel you should be able to get 3 different gains for each Assist flight mode.IT should be basically just like the Cortex, except the center position doesn't need to be gyro disabled. I haven't tried this but I think it should work fine. If someone know swhy it won't please explain.

If you don't want to use the gyro function for gain tuning then each assist flight mode has a "default" value which is set to 50%. by default. Increasing the default value for that flight mode will increase the effective gain for that flight mode.Decreasing the default value decreases the effective gain for that flight mode.

Lets assume you selected Normal Damping / Damping Only for all 3 flight modes and configured an Assist Off control. Lets also assume you are using Assist FM1 for high speed flight or cruise mode. Assist FM2 to disable nose wheel steering and Assist FM3 for your Landing flight mode. With those things in mind, leave the "default" value for FM1 and FM2 at 50%. This will have FM1 and FM2 use the "programmed" gain values. You can then simply increase the "default" value for FM3 slightly to increase the effective gain for FM3 and test fly the plane. While landing, if the plane isn't as locked in as you want, increase your gain tuning knob until it is. When you land take a look at your gain tuning value and if it reads something like 30%, then increase FM3's default value by approximately 30%. For example, if you left the default value for FM3 at 50% increasing the by 30% give you a value of 65 so try increasing the default value to 60% or 65% and try it again.

I posted spread sheets to accurately calculate all this stuff but so many people complained how complicated the Assist is so I figured I'd use the same basic method that the beloved Cortex uses to determine gain, which is pick a value, test fly and adjust accordingly.

Last edited by wfield0455; 08-17-2020 at 02:00 PM.
Old 08-17-2020, 01:49 PM
  #260  
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duplicate post.

Last edited by wfield0455; 08-17-2020 at 01:57 PM.
Old 08-17-2020, 01:56 PM
  #261  
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Originally Posted by wfield0455
So if you use 100% rate (you really should) to calibrate the sticks and also use lower rates, then the Assist will never fully be disabled at full stick deflection for the lower rates and you WILL need to increase the rate to maintain a similar roll rate at full stick, etc.
That makes sense Wayne, I had thought you meant that you were increasing the normal (or full rate) travel.
Old 08-17-2020, 02:05 PM
  #262  
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Originally Posted by HarryC
That makes sense Wayne, I had thought you meant that you were increasing the normal (or full rate) travel.
No I only increase the rates and decrease the expo for Assist modes that use rates of less than 100%. For full rates I only decrease the expo. I guess i never actually said that last bit though so it's no surpirse that it was missed.
Old 08-18-2020, 02:15 PM
  #263  
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Originally Posted by causeitflies
I know the difference in gain should be very small. I want to make the gains flight mode dependent but haven’t been able to see where to do it in the flight modes. For instance I could turn the nose gear steering off in one flight mode but couldn’t see where to adjust gains. I was in kind of a rush so I may be able to look at it closer this evening.
Mark asked this question, I don't think it was answered, I also have the same question, I think this is the last piece of the puzzle on assist for me.

Is this the menu where I can make the gyro gains flight mode dependant when using a knob for all 3 flight modes?

Tks.



Last edited by CARS II; 08-18-2020 at 02:23 PM.
Old 08-18-2020, 03:07 PM
  #264  
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Carlos,
I did figure it out. To make the gains flight mode dependent in the Assist you have to go to the gain tuning knob and change that percentage Per flight mode.
This can also be done with the Gain curve using S instead of G for the different flight modes as you are thinking.
What I have decided to do is turn my P8 knob into a digital trim and use it as a function control for the gains. This is set to S and is flight mode dependent just like any other trim. The beauty of this is you do not have to land and make adjustments for each mode and you don’t have to worry about where the knob is.
Old 08-18-2020, 03:26 PM
  #265  
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I see, the default gain is 50% for each FL mode, what percentage are you planing to use for each FL mode to start with? ( CRUISE/TO/LAND )

Last edited by CARS II; 08-18-2020 at 03:32 PM.
Old 08-18-2020, 03:30 PM
  #266  
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Old 08-18-2020, 03:36 PM
  #267  
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No radio with me at the moment, using the manual.
Old 08-18-2020, 04:02 PM
  #268  
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Originally Posted by CARS II
I see, the default gain is 50% for each FL mode, what percentage are you planing to use for each FL mode to start with? ( CRUISE/TO/LAND )
As I said in an earlier post the default value allows you to increase or decrease the effective gain used by that Assist flight mode and 50% is equivalent to setting your gain tuning channel to centered or 0%. Increase the default value (or gain tuning or both) and you increase the effective gain that is used for that Assist flight mode, decrease them and you decrease the effective gain for that Assist Flight mode..

Until you get this all sorted out and decide exactly what you need to configure it's best to leave the default value in each flight mode alone and set to 50%.
There are lots of ways to do things and mixing and matching them without fully understanding how they interact can be a recipe for disaster. There are ways to have multiple gains for a single Assist Flight mode(transmitter flight modes specific) and there are ways to have a unique gain for each Assist flight mode.
You need to decide which way you want to go and configure things in a way that is consistent with that goal. Don't try to mix and match methods unless you COMPLETELY understand how each control affects all the others.

Old 08-18-2020, 04:54 PM
  #269  
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I understand Wayne.

For my first flight I will be using the knob for all 3 gains, I will be disabling the gain a chl at the time as it gets to the appropriate setting till all 3 gains are set to the appropriate percentage.

Will keep to simple.

Tks.
Old 08-18-2020, 05:21 PM
  #270  
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As Wayne suggests I will leave the default gain at 50% and the main gains at 22 for now. Only do one step at a time to begin. Since I updated this Rx I'm treating it as a brand new gyro even after flying the previous version for several years. I'm thinking somewhere between 0% and 100% on the knob will give me enough gain in each mode to get close and if not I can increase the default. Then I may go to each axis and tweak further but usually I don't get that ambitious My Tx flight modes and Assist flight modes are on the same switch and all three axis are on the same knob, makes it simple. Ideally I can adjust the P8 gain knob in each flight mode during one flight and be done.
Old 08-18-2020, 05:42 PM
  #271  
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Since I use the same knob for gain on all of my planes that have gyros, I'm thinking of changing it on all of them to digital trim so I never have to worry about the knob position.
I always thought about doing this and Harry's videos gave me the push to try it. I think it will work out great even with my Cortex, I-gyro, and Aura.
Old 08-18-2020, 07:19 PM
  #272  
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I'm going to set it up the same way as you, my friend Nick is going to help with the gyro portion and first flight adjustments as he has been flying a mini T1 with a Jeti assist.

He is planing to disabled the knob for each control as soon as we get it adjusted, this way we will be able to tune all 3 axis in one afternoon, I like how Harry used a funtion curve ( think ) to store the gain percentage so he doesn't have to worry about the knob moving also, here are the steps to make the radio give you the gain in percentage, I tried it and it works just fine.


Old 08-18-2020, 08:01 PM
  #273  
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OK, still struggling a bit with the Assist with assignment of gain control using the transmitter Gyro Settings page, but I think I found a way to do it.

I have assigned 3 flight modes (Flaps Up, Take Off and Landing) and want to use the same switch to set 3 different Gyro Gain settings, with gain values manually selected from the TX Gyro Settings page.

In setting up the Assist, it appears that you can't assign the transmitter auto-created Gyro Sens. function directly to the Assist as it looking for a physical switch/ knob as an input for gain control (under Additional Channels).

What ended up working is not intuitive at all (to me).

Step 1 - Assign the TX auto-generated Gyro Sens. function to a rotary knob (I use P8) under the TX Function Assignment page
Step 2 - Set the Gyro Gain Tuning Channel on the Assist (Assign Additional Channels page) to the Step 1 assigned knob (I use P8)
Step 3 - Re-assign the Gyro Sens. function to the Flight Mode 3 position switch under the TX Function Assignment page
Step 4 - Set the required Gyro Gain levels for each TX Flight Mode on the TX Gyro Settings page
Step 5 - Assign the Gyro Settings tuning control and amount to enable fine tuning of each flight modes gain if required. (Disable this once the gain for each Flight Mode are established)


Hope that helps.

If there is a simpler and more obvious way, I'd love to hear about it.


Paul
Old 08-18-2020, 10:41 PM
  #274  
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I recommend that you do not use the Tx Gyro function with Assist. The gyro functions were not designed for Assist and need to be re-written by Jeti to work properly with Assist. The gyro function is based on the behaviour that 0% is no gain, +% is heading hold mode (or bank 1) and -% is rate mode (or bank 2). The gyro function only allows travel in one of those directions. That is not how Assist works. Assist at 0% gives default gain and turning the gain + or - increases or reduces from the default gain. If the default gain is too high you want to turn it down which needs a -% but if you have set the gyro function to a +% you cannot do it.
Old 08-18-2020, 10:49 PM
  #275  
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Please be careful with the use of the phrase "flight modes". In several of the posts above people are confusing Tx flight modes and Assist gyro modes because the one phrase "flight mode" is being used for both. Sometimes a question and an answer are talking about different things! If you stick to "flight mode" for the Tx and "gyro mode" for the Assist's 3 modes it would help to avoid confusion.

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