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How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 11:14 am
by pstimpel
Hi,

I am sorry if I am using the wrong terms, but I am brand new to RC control hobby. Due this I do not even know what terms to search for.

I have two motors, two ESC, one FRSky x8r, and a turnigy 9x pro flashed with Er9x I got from a friend - using Mode 2. I am able to setup simple things like an RC car having one motor and one servo.

However, right I am doing a new project on my 3d printer, I want to build a bulldozer. The 3d modeling is going well, but I am struggling to setup the RC part. What I want:

left stick left/right: steering
right stick up down: throttle, forward/backwards

Each of the tracks of my bulldozer is run by its own motor, each motor has its own ESC.

Goal: if I push the right stick forward, both motors should turn "forward" the same speed. But if I use the left stick left/right, the motor of the inner side of the desired driving curve should go slower.

To make it more clear:
left stick / right stick / desired result

full left / up / drive forward, only the right motor, 100%
half left / up / drive forward, left motor 50%, right motor 100%
middle / up / drive forward, both motors 100%
half right / up / drive forward, left motor 100%, right motor 50%
full right / up / drive forward, only the left motor, 100%

Edit:this part is working adding the left stick in the mixer to both motor channels, and reverse the outcome on the second. However, it works forward this way, but not backwards.

I would need:
full left / down / drive backward, only the right motor, 100%
half left / down / drive backward, left motor 50%, right motor 100%
middle / down / drive backward, both motors 100%
half right / down / drive backward, left motor 100%, right motor 50%
full right / down / drive backward, only the left motor, 100%

The way using the added channel to the mixer of both motors is resulting in:
full left / down / drive backward, only the LEFT motor, 100%
...
full right / down / drive backward, only the RIGHT motor, 100%

Which is the wrong way. :(



I hope you get what I mean and can help me.

I appreciate any pointer to the right terms, or to manuals how to setup this using my hardware/software listed at the top of the posting.

Regards,
Peter

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 4:03 pm
by jhsa
Hi, welcome to the forum.
If you have the 9XR-PRO radio, then you have ErskyTX installed not Er9x.
ErskyTX is a more powerful version of Er9x. But there is only an Er9x manual at the moment.
The basic stuff, like the mixer is basically the same.

viewtopic.php?f=5&t=6473

João

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 5:30 pm
by pstimpel
Thanks a lot, Joao. This is the manual I was aware of. However, I cannot figure out how to fix my problem. I wastrying curves. I am a software developer, and in a programming language I would just invert the added value if the original input was negative. I have no idea how to make that in ErskyTX.

I would have thought anyone running a tank as example, should run into this problem. Is this the wrong subforum? The one you linked to seems to be firmware development specific.

Regards
Peter

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 6:10 pm
by ReSt
one first trial could be:load the V-tail template.

Reinhard

Reversing a direction is either done in the limits menu (NOR/INV) or in a mix by changing the sign of an amount e.g. +100% => -100%

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 7:40 pm
by pstimpel
Hi Reinhard,

That's not working as desired, unfortunately. It inverts the whole action. In pseudo code Im looking for something like this


if right stick > 0 then
outcome = rightstick + leftstick
else
outcome = rightstick - leftstick
endif

Regards
Peter

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 8:04 pm
by jhsa
That doesn't work that way :)

you could try only with one stick for now, and use the "Elevon" template. that will kinda work. but you are asking for some functionality that might require a little bit more effort :) Which is the positions you required, like full left/Up, right motor full and left stoped.. this together with the other requirements, and also backwards :)

João

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 8:19 pm
by pstimpel
OK, so this is simply not available (yet). I was under assumption people driving tanks and bulldozers could have use for that. The mix you are mentioning is basically what I was setting up in the first place. It works for driving forward, and does the steering. But as soon as you go backwards, the steering is the wrong way, aka wrong direction.

Maybe I will push the values through something like an arduino to make such more complicated calculations then.

Another would be to use 2 sticks, left for left motor, and right for right motor But this means I would have to change the hardware setup of my controller each time I switch vehicles :)

Thanks, Joao.

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 8:38 pm
by jhsa
The radio can do that and much more. You have to learn how to do it.. :)
I have been looking at it, but did't have much time yet.
I never said that the radio couldn't do it.. :)

João

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 8:45 pm
by pstimpel
I am glad I made it so far - by reading the manual and some try and error. But I cannot figure out what step is needed to complete the desired setup. Now, if someone has an idea and could share it with a poor soul, please.

Regards,
Peter

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 8:58 pm
by jhsa
Try this. I am a bit rusty as I have been busy with other stuff :)

left motor on Ch 2, and right motor on Ch 4

Ch2 +100% Ele
+100% Rud Offset (-50%)

Ch4 +100% Ele
-100% Rud Offset (50%).

Like this it will probably work the way you want, at least forward :)
And if you give full left and full right with the throttle at center, it will spin like a io-io. :mrgreen:

João

EDIT: I think backwards it is turning the wrong direction, right?
Let me see

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 9:24 pm
by pstimpel
Exactly, The forward part works fine, as expected. It is the backwards part that puzzles me, since it turns into the wrong direction.

Thanks for looking into it.

Regards
Peter

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 9:51 pm
by jhsa
Try some curves..

I will look into it again.. But am busy with other things as well :)

João

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 10:29 pm
by ReSt
Try the following:
CH01 -100% RUD
* +100% THR (This is a multiply mix!!)
+100% THR Curve(c9)

CH02 +100% RUD
* +100% THR (This is a multiply mix!!)
+100% THR Curve(c9)

Curve C9
100, 67, 33, 0,0,0,-33, -67, -100

The curve is not required, but gives you a wide dead zone around neutral, so that both motors can be stopped safely.

Reinhard

Re: How to mix the input from two sticks to control 2 motors

Posted: Sat Oct 26, 2019 11:08 pm
by jhsa
Reinhard, that works, but he will have to invert both channels in the "Limits menu" otherwise the motors will run the opposite way.

Channel 1 is left motor, and channel 2 connects to the right motor.

João

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 10:25 am
by pstimpel
Oh, that was GOLD!

Cheers, Reinhard and Joao for coming up with a solution.

My final setup

CH1 left motor, CH2 right motor, ELE is the throttle stick, and RUD the steering stick

CH1 100 RUD
* 100 ELE
+ 100 ELE
CH2 -100 RUD
* 100 ELE
+ 100 ELE

Curves can be applied if needed, no INVERT needed.

Cheers, guys.

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 12:27 pm
by jhsa
Great.. :)
Now try to understand why it ts working.
And don't you ever dare to say again that there is something your radio can't do :mrgreen:

João

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 12:28 pm
by jhsa
By the way, do you have "Eepskye" installed on your computer? If not, you should. You can program and simulate your models with it.

João

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 12:46 pm
by bob195558
If you do not, you can find it here: (http://www.er9x.com/).
You will have both eepe and eepSkye installed and just select eepSkye.
You will like it a lot. :)

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 1:20 pm
by pstimpel
OK, my radio can do it all :)

Giving the software a try, but have to finish the 3d model of my bulldozer first.

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 1:41 pm
by ReSt
@pstimpel:

The solution given above can slow the inner motor down to 0.

Here comes a more advanced setup that can drive the inner motor to full reverse speed.

This is what I have for a 2 motor ship, but in the endeffect does the same for a bagger or a tank. But in the moment this setup is for a mode 1 transmitter, that is throttlestick is on the right. But the left stick is used as throttle due to neutral in the middle and not at the end of the stickrange.

THR switch activates the motor,
RUD switch activates steering with left horizontal stick (inner motor slow down to 0),
AIL switch adds the right stick to enlarge the inner motor speed change down to full reverse speed. The effect of the right stick right/left depends on its up/down position. Fully down, the left/right effect is zero, fully up the left/right effect is 100%.


The effect of the two sticks is added,so both horizontal sticks fully in the same direction increase the effect of slowing down the inner motor so that the inner motor runs 100% backward, both sticks in opposite direction compensate the effect.

remove the curve and/or the slow/up/down from the mixes if you dont need them (slow and curve delay the reaction of the output channels. Was needed by my ESC's)

Code: Select all

Mixers
CH01 +100%CH15 Switch(THR) Curve(c9)
CH02 +100%CH16 Switch(THR) Curve(c9)
CH10 +50%Ail Switch(AIL) noTrim
* -100%Thr noTrim Offset(100%)
-100%Rud Switch(RUD) noTrim
* +100%Ele
CH12 -50%Ail Switch(AIL) noTrim
* -100%Thr noTrim Offset(100%)
+100%Rud Switch(RUD) noTrim
* +100%Ele
CH15 +100%Ele Slow(u2:d2)
+100%CH10 Slow(u2:d2)
CH16 +100%Ele Slow(u2:d2)
+100%CH12 Slow(u2:d2)
pt 1 pt 2 pt 3 pt 4 pt 5 pt 6 pt 7 pt 8 pt 9
Curve 9 100 67 33 0 0 0 -33 -67 -100
Reinhard

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 3:50 pm
by pstimpel
Hey Reinhard,

This looks...crazy :) Thanks a lot, I will give it a try once the bulldozers gearbox and basic tracks are ready for a first test. :)

I was under the assumption I would start understand mixers :D

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 3:58 pm
by jhsa
It is not that difficult if you understand the concept.. wait until you start using Logical switches :)

João

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 4:04 pm
by pstimpel
Yep, I guess it would just need some more time. A basic understanding is there, already. Amazing, what one can do with this software. Well done, guys

Re: How to mix the input from two sticks to control 2 motors

Posted: Sun Oct 27, 2019 5:21 pm
by jhsa
Blame Mike for that :) :mrgreen:

João