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Jan 13, 2015, 03:28 PM
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Mini-HowTo

Deviation: getting rid of a deadzone


The new HiSKY HCP100S has a deadzone around center for the rudder channel. I find this annoying and could get rid of it thanks to a Deviation "Complex Mixer".
Here's the output we want:


As soon as the rudder stick is moved to the left or to the right we want the Tx to transmit a value to "jump" over the deadband.
The following shows a way to achieve this using a complex mixer defined in 3 pages. Note I use a Devo 8S but a similar result can be accomplished with any Walkera Tx that supports the Deviation firmware.
You can get more information about the steps involved in this mini-howto by reading the well written Deviation Documentation.

1) Setup a complex mixer with 3 pages to the RUD channel.
The first page is an EXPO mixer defining a straight curve from -100% to 100%.


2) On page 2 we define a Min/Max mixer that will add its value on positive rudder and subtract the value on negative rudder. The Scale value is the value you want to go directly as soon as you move your stick.
For the HCP100S a value of 8 is good but you may adjust it to your liking.


3) The third page is probably optional. I added it so the RUD output sent to the Tx is 0% at middle stick. It is a Deadband mixer set to a value of 0.5 [actually 0.1 is even better] multiplied with the previous page output. Like the step above you can change this value to your liking.


4) Once we got rid of the deadband by adjusting the Min/Max mixer value we may want to adjust the page 1 curve so we don't overshoot the rudder. Since in this example we added (or substracted) a value of 8 we have to reduce end points of this curve to -92 and +92.


5) We now go back to the Main Screen. Before binding our brand new HCP100S we are going to visually check the Rudder output.


6) We go to the GUI editing page


7) And select to display the value of Channel 4 which is the rudder channel in this example.


8) Back to the main screen we can visually check that the rudder values now directly jump from -8 to 8 around the center.


9) You can now enjoy your HCP100S

I added my .ini file and the image to this post in a zipped file.

*** Update 7/30/2015 ***
I added a DSMX ini file (I use a Lemon Rx sat on my HCP100S) and added 10 points of Expo on the rudder. Expo on rudder really helps in tail-in banked turns.
Last edited by sdelaroq; Jul 30, 2015 at 11:22 AM.
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Jan 19, 2015, 01:39 AM
Vids: YouTube.com/FyreSG
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Does this apply to Deviation only? What if I'm using another TX but with HT-8? Would there be rudder deadzone?
Jan 19, 2015, 05:21 AM
MightyG
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This is great! I was trying to do the same with -ve expo, but this is produces a MUCH better result! Thx!

MG
Jan 19, 2015, 02:14 PM
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Works great thankyou.
Jan 21, 2015, 04:30 PM
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Thanks guys! I did not see your messages!

@Fyre: I don't know. If your Tx supports mixers you may be able to duplicate the behavior.
I experience the deadzone with Devo 7 + HT-8, Deviation + HT-8 and Deviation + DSMX sat. And dadio experiences it with X-6S.

Note I set the deadband value to 0.1 instead of 0.5 and get finer rudder control. I now can piro very slowly
Last edited by sdelaroq; Jan 21, 2015 at 04:35 PM.
Feb 02, 2015, 11:02 AM
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I just try'd this on my 7e ,must have gone wrong somewhere as the rudder swapped to the right stick and I lost aile altogether ? I re set it to normal and I'll have another go tomorrow .I try'd the expo bodge on the x6s but its not really right either ,not sure if it's better or not .
Apr 09, 2015, 04:21 AM
What goes up...............
Flyingboats's Avatar
Thanks sdelaroq Hadn't been flying the 100S much following a crash. Fixed it at the weekend and have been getting annoyed with the rudder deadband. Took me a while to get this sorted as I haven't played with Complex setups on Deviation previously, but great solution!

I'm a sport flier, so small amounts of rudder are critical to get smooth high speed turns. Just completed a successful indoor flight with a rather whopping amount of expo (50%) on the rudder and it feels nice. Looking forward to a good thrash outside and getting it finetuned.

Cheers.
Apr 09, 2015, 03:40 PM
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Thanks for letting me know this works for you!
Jul 04, 2015, 10:53 AM
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microrcfiend's Avatar
Thanks for posting the deviation fix and the model.ini too.
Jul 30, 2015, 11:20 AM
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You're welcome

I now use a lemon sat with my deviated Devo and it is far more comfortable not to have to plug HT-8 module to the Tx.
And I also added a bit of expo on the rudder (first mixer): this allows getting more control of the rudder and I can now do nice tail first banked turns.
Sep 07, 2015, 08:37 AM
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Excellent guide, thanks alot sdelaroq!
Nov 25, 2015, 10:33 AM
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Quote:
Originally Posted by FyreSG
Does this apply to Deviation only? What if I'm using another TX but with HT-8? Would there be rudder deadzone?
Deviation allows us to use curves on the rudder channel (actually on any channel). We use the curves to generating something with a step at the centre to counter the tail dead zone in HCP100S RX.

Instead of using a combination of curves, we may use a single curve say with 13 points instead to generate that effect.

If you can do that on your TX, it would work too.
Nov 25, 2015, 11:45 AM
Vids: YouTube.com/FyreSG
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Quote:
Originally Posted by Wasp09
Deviation allows us to use curves on the rudder channel (actually on any channel). We use the curves to generating something with a step at the centre to counter the tail dead zone in HCP100S RX.

Instead of using a combination of curves, we may use a single curve say with 13 points instead to generate that effect.

If you can do that on your TX, it would work too.
I wasn't actually asking why this trick work, or how to do in on another TX. It is pretty clear from his post.

When I asked "does "this" apply to Deviation only" I meant does the rudder deadzone problem only affects DeviationTX. Or was it affecting every TX, such that even using HT-8 on a non-DeviationTX will also experience it. "This" does not refer to the fix.

Thanks for your explanation nevertheless.

FYI, the way to do this on ER9X or OpenTX is not using a curve. It won't work because you can't define the X-axis of the curve.
Last edited by FyreSG; Nov 25, 2015 at 11:51 AM.
Nov 25, 2015, 02:17 PM
Registered User
To my understanding the tail dead zone issue is inside the RX. No matter what TX you use, you have to address it.

Most TX/FW would have fully programmable curves/points for throttle and pitch channels only. That is why we need deviation.

Even if we cannot define the X-axis, but when we have enough points, i.e. short distance between 2 points, practically we can jump the dead zone without using the dead band curve.
Last edited by Wasp09; Nov 25, 2015 at 02:24 PM.
Nov 26, 2015, 04:59 AM
Vids: YouTube.com/FyreSG
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In theory, yes, if we have enough points on the X-axis, we can achieve that. Let's say the dead zone starts at +5% and -5%. How many "enough points" do we need to define a dead zone between +5 and -5?

5-point curve: 0, 25, 50, 75, 100. Not enough.
7-point curve: 0, 16.67, .... Still not enough.
13-point curve: 0, 8.33, .... Still not enough!

For ER9X and OpenTX, I don't think it supports more than 7 points. In any case, the solution is simply mixing and using virtual switches:
Code:
CH1: +100% AIL Offset 5%
CH1: R 100% AIL Switch(SW1) Offset -5%
CH1: R 0% AIL Switch(SW2)

CS1: v>ofs AIL 0
CS2: |V|<ofs AIL 5
Source: http://openrcforums.com/forum/viewtopic.php?t=1372

This is a very elegant solution that does not involve curves.


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