Throttle scaling/limit

erskyTx runs on many radios and upgrade boards
ersky9x was a port of er9x for use on the sky9x board.
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voland
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Throttle scaling/limit

Post by voland » Thu Mar 14, 2019 1:59 am

Hi there, could not find anywhere in ersky9x where I can scale throttle. Can anyone guide me where/how it can be done (if it is possible at all).

I'm trying to scale down throttle input for a whoop drone, e.g. for 3s battery I'd like to scale it down so that the radio sends (let's say) 80% of throttle when the stick is fully moved up.

Ideally I'd like to set up a pot (or a switch) to scale throttle, could anyone help me with this?

Cheers


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jhsa
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Re: Throttle scaling/limit

Post by jhsa » Thu Mar 14, 2019 2:25 am

Try "Model setup / Limits". Set the upper limit to 80%

João
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voland
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Re: Throttle scaling/limit

Post by voland » Thu Mar 14, 2019 2:37 am

Thanks, is there anyway to do this on a switch/pot?

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mentero
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Re: Throttle scaling/limit

Post by mentero » Thu Mar 14, 2019 9:00 am

If you use a switch, Dual rates is all you need.

Configure one side of the chosen switch from -100 to +100 and the other from -100 to +80. Done.

Miguel
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ReSt
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Re: Throttle scaling/limit

Post by ReSt » Thu Mar 14, 2019 9:48 am

Add the MULTIPY mix to the e.g. throttle channel = channel 3
CH3 100% Thr
* 50% P1 Fix Offset 50 NoTrim !! Multiply

According to the position of P1 your CH3 output will be limited between 0 an 100%

Reinhard


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mentero
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Re: Throttle scaling/limit

Post by mentero » Thu Mar 14, 2019 11:36 am

ReSt wrote:
Thu Mar 14, 2019 9:48 am
Add the MULTIPY mix to the e.g. throttle channel = channel 3
CH3 100% Thr
* 50% P1 Fix Offset 50 NoTrim !! Multiply

According to the position of P1 your CH3 output will be limited between 0 an 100%

Reinhard
I'm afraid this will not allow to get to -100 to cut throttle.

Miguel
We demand rigidly defined areas of doubt and uncertainty. Douglas Adams.

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MikeB
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Re: Throttle scaling/limit

Post by MikeB » Thu Mar 14, 2019 12:40 pm

You may do this in 3 mixer lines:
CH3: +100% Thr (Offset 100%)
* 50% P1 (Offset 50%) Multiply
+ -100% HALF

The first mix moves the throttle to be 0 to 200% (from -100% to +100%)
The second scales this using pot P1.
The third moves the position back down so it always starts from -100%.

You could change the upper, dual-rate setting (even using a global variable to allow it to be adjusted using a pot), but that results in a non-linear throttle response, as does changing just the upper limit in "Limits".

The second mix allows the upper limit to be adjusted all the way from +100% down to -100%, this last resulting in NO throttle response.
Using something like:
* 20% P1 (Offset 80%) Multiply
would limit how far the upper limit is reduced. For this, have the weight and offset always add up yo 100%. THe amount of throttle reduction available is TWICE the weight percentage, so 40% in this case.

Mike
erskyTx/er9x developer
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The impossible takes a little longer!

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mentero
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Re: Throttle scaling/limit

Post by mentero » Thu Mar 14, 2019 2:37 pm

Food for thought in every mixer line. Thanks for the class.

I also never thought about the non linearity of asymmetric dual rates and limits. Anyway, maybe not that noticeable for a throttle channel.(?).

Miguel
We demand rigidly defined areas of doubt and uncertainty. Douglas Adams.

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jhsa
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Re: Throttle scaling/limit

Post by jhsa » Thu Mar 14, 2019 4:39 pm

Depends, if it is a multirotor linearity might be desirable.. :)

João

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voland
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Re: Throttle scaling/limit

Post by voland » Wed May 01, 2019 4:17 am

Thank you all for your help. I can confirm that this perfectly works to limit/scale throttle via pot (S1):

```
CH3: 100% Thr (Offset 100%)
* 50% S1 (Offset 50%) Multiply
+ -100% HALF
```

Also if anyone wants to use a three position switch instead of a pot, e.g. to limit/scale throttle for your tiny whoop when different batteries are used (2s and 3s and possible 1s):

```
CH3: 100% Thr (Offset 100%)
* -33% SB (Offset 67%) Multiply
+ -100% HALF
```

I use this for my mobula7 HD whoop to scale down / equalise throttle for 2s and 3s batteries, e.g.:
* switch off - 1s battery (or no limit/scale)
* switch half - 2s battery
* switch on - 3s battery


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