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Author Topic: Twin motor control with rudder off 2 sticks  (Read 6839 times)

johnf

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Twin motor control with rudder off 2 sticks
« on: August 31, 2018, 01:44:40 pm »

Hi everyone,

Could anyone tell me how to programme my 2.4Ghz TX to provide separate control of 2 shafts with rudder off the standard 2 sticks to enhance a model's turning circle in harbour.

I understand the old idea of using a separate "mixer" to speed up or slow each motor according to rudder settings.     However, with modern programmable TXs, surely it is possible to "mix" the rudder with the two ESCs to give such an important function.   Indeed, I am pretty sure I have read corresponding articles in model boat magazines.

I have tried everything pushing countless buttons and looking through old magazines but have failed to date.      I have an "all singing and dancing" HK Orange DRX Spectrum DSM2 compatible TX together with the popular FlySky FS i6 and the somewhat simpler Spectrum DX5i with aileron/elevator mix switch.

I am sure this will be of interest to numerous model tug skippers - so please help if you can.  <:(           
Dr John Fowler Leeds & Bradford MBC
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malcolmfrary

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Re: Twin motor control with rudder off 2 sticks
« Reply #1 on: September 01, 2018, 11:07:32 am »

The basic idea of using a mixer, whether software in the transmitter or hardware in the boat,  is that one stick (the throttle) provides speed information, the other (rudder) control provides distribution information to control the relative speeds and directions of the two motors.  the rudder stick (certainly in the hardware type) can also work the rudder.  A second throttle stick is not needed, unless a third motor is involved.
Going from automatic mixing to manual tank steering would probably involve a change of profile in mid sail.  This might or might not be possible.  I'm just guessing since I don't have that kind of transmitter, but two conflicting sets of logic in the same box rarely works.
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Colin Bishop

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Re: Twin motor control with rudder off 2 sticks
« Reply #2 on: September 01, 2018, 11:29:24 am »

I think that one of the problems in using the internal mixing facilities in the TX can be that they are set up for aircraft use (V Tail I believe) and do not act on the channels needed for controlling a model boat. These complications are why people tend to buy dedicated mixers.

There is a cheap and cheerful solution which I use on my fishery cruiser model. Each motor has its own ESC and is controlled separately by the two vertical TX sticks which gives tank steering. I have then used the undercarriage toggle switch on the TX to trip a switch on the RX which cuts out the signal from the right hand TX stick and transfers it to the left hand stick so that both motors are controlled from the Left hand stick together. This means that for general sailing around the pond I can run the two motors together and just rely on the rudder for steering but at the flick of the undercarriage switch revert back to independent tank steering for close quarters manouevering.
It works fine.
Colin
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Colin Bishop

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Re: Twin motor control with rudder off 2 sticks
« Reply #3 on: September 01, 2018, 12:37:31 pm »

Sorry for the typos - was in a bit of a rush earlier!Colin



Typos corrected.

Peter.
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john44

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Re: Twin motor control with rudder off 2 sticks
« Reply #4 on: September 01, 2018, 01:39:33 pm »

I think that one of the problems in using the internal mixing facilities in the TX can be that they are set up for aircraft use (V Tail I believe) and do not act on the channels needed for controlling a model boat. These complications are why people tend to buy dedicated mixers.

There is a cheap and cheerful solution which I use on my fishery cruiser model. Each motor has its own ESC and is controlled separately by the two vertical TX sticks which gives tank steering. I have then used the undercarriage toggle switch on the TX to trip a switch on the RX which cuts out the signal from the right hand TX stick and transfers it to the left habd stick so that both motors are controlled from the Left hand stick together. This means that for general sailing around the pond I can run the two motors together and just rely on the rudder for steering but at the flick of the undercarriage swaitc revert back to independent tanl steering for close quarters manouevering.
It works fine.
Colin


Hi Colin, have you got a wiring dia. For that tx mod please, I like the idea very much.


John
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Colin Bishop

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Re: Twin motor control with rudder off 2 sticks
« Reply #5 on: September 01, 2018, 02:02:37 pm »

John,
Not immediately available I'm afraid, I wired it some years ago, the baot had a long construction period!. I will try and sketch it out and put it up on here within a day or so.
Colin
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Colin Bishop

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Re: Twin motor control with rudder off 2 sticks
« Reply #6 on: September 01, 2018, 02:31:47 pm »

Bingo! I vaguely remembered that I might have done a rough diagram which I saved on my PC and here it is!
You just need a simple latching switch which mimics the action of the retract switch on the TX by switching the signal input wire to the right hand ESC from the RX right stick signal output to the left stick output. I think the diagram makes it clear.
There are lots of R/C switches available but you need one suitable for retract gear i.e. it stays where it is set until you change it back. Not all of them do that. I am not sure which would be the most suitable switch these days but no doubt someone on here can recommend one.
Colin
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steamboat66

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Re: Twin motor control with rudder off 2 sticks
« Reply #7 on: September 01, 2018, 03:36:50 pm »

you can do this with a servo and microswitch if you want, rough as, but it will work. an RC switch would be a tidier solution.
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john44

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Re: Twin motor control with rudder off 2 sticks
« Reply #8 on: September 01, 2018, 06:35:45 pm »

Thanks guys, I get it, switching the signal wire from one esc to the signal wire of the other
Esc through a rc / mechanical switch creates a Y lead to the left stick.
Is that correct.


John
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Colin Bishop

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Re: Twin motor control with rudder off 2 sticks
« Reply #9 on: September 01, 2018, 07:01:06 pm »

Yup, that's it.
Colin
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JimG

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Re: Twin motor control with rudder off 2 sticks
« Reply #10 on: September 01, 2018, 08:28:18 pm »

I think that one of the problems in using the internal mixing facilities in the TX can be that they are set up for aircraft use (V Tail I believe) and do not act on the channels needed for controlling a model boat. These complications are why people tend to buy dedicated mixers.

Colin
If you buy one of the more advanced transmitters you can program the channels to whichever stick you want. e.g. vtail mixing is normally on rudder and elevator on planes, this is left hand stick for rudder and right hand stick for elevator on a mode2 set. this could be reprogrammed to give elevator on the left handstick, forward and reverse used for speed control and motor steering on the left stick, left to right. The vtail mix will then mix both channels together. The right stick , left to right can be used for the rudder for normal steering. Most transmitters will have programmable free mixing for more advanced setups.Of course if you just buy the cheapest set such as a Planet you lose any such ability.
Jim
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Colin Bishop

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Re: Twin motor control with rudder off 2 sticks
« Reply #11 on: September 01, 2018, 09:26:27 pm »

Yes Jim, not everyone wants to buy the more expensive sets for a relatively simple model boat setup. Horses for courses really. The arrangement in my fishery cruiser does all I need really with its handling combination.
Colin
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GG

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Re: Twin motor control with rudder off 2 sticks
« Reply #12 on: September 02, 2018, 09:50:14 am »

The method of using "Vitail" mixing in Mode 1 to give twin screw model conventional rudder/motor control with the option of motor steering, was fully described in the Feb issue of Model Boats.
If the transmitter has the mixing functions you need, it does seem unnecessary to buy extra bits.  But there again you do have to read the instructions that ought to have come with the radio outfit.
Glynn Guest
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davem99

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Re: Twin motor control with rudder off 2 sticks
« Reply #13 on: September 08, 2018, 03:04:06 pm »

Apologies my previous post was missing the last paras, moderator please remove.
I have just purchased an FS-i6 for £34 post paid from a UK E-bay supplier. I already have the FS-i6s but wanted to have model names hence the new purchase. The radio has memory for 20 models and remembers all the settings for each model. First job is to name your model and save the setting. Press and hold the OK button select System Setup move to model name, choose a number then give it a name. You need to press and hold the cancel button until the screen changes or the settings will not be remembered!! Select the model you have named
I use Aero Mode2: channel 1 (right horiz stick, centre spring) for my rudder;
                 channel 3 (left vert stick, no spring) for the motors

I use receiver channel 1 for the rudder
Channel 3 for 1st ESC
                    Channel 6 for 2nd ESC
Mixing[]
Select Functions from the Menu then Mix
Select Mix1; Mix is On; Master Ch1; Slave Ch2; Pos-mix -20%; Neg-mix -20%; Offset 0%. Press and hold the cancel button until the screen changes
Select Mix2; Mix is On; Master Ch3; Slave Ch6; Pos-mix 100%; Neg-mix 100%; Offset 0%. Press and hold the cancel button until the screen changes
Select Mix3; Mix is On; Master Ch1; Slave Ch3; Pos-mix 20%; Neg-mix 20%; Offset 0%. Press and hold the cancel button until the screen changes.
Move back to Display and press OK.
The channel stick positions are displayed.
Moving Ch1 rudder shows full movement
Moving Ch3 ESCs shows Ch3 and Ch6 movement. Moving Ch1 at the same time shows Ch3 and Ch6 increasing or decreasing.
There is the adjustment movement on Ch3 and Ch6 when the ESC Ch3 is at neutral but this should not pose a problem as normal practice is to move ahead or astern before moving the rudder.
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John W E

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Re: Twin motor control with rudder off 2 sticks
« Reply #14 on: September 08, 2018, 05:06:52 pm »


hi there Colin
What speed controllers did you use when you were switching the signal on/off?  because using modern day speed controllers - when you switch the signal off, and then back on, they sometimes reset themselves at Zero - wherever the throttle stick is positioned on the handset.   


In other words, if you are running two speed controllers off one channel - and say you are running at half speed, you switch one of the speed controllers off (say, for arguments sake the portside speed controller) then switch it back on - where your transmitter throttle stick position is set - this will now become the midway position for the portside speed controller, if you follow what I mean :-)


so therefore when you bring your throttle stick back to neutral for the starboard speed controller, the port one will still be running at half speed - due to the fact that it has reset itself at a different position.


In 'olden days' when the very early ACTion speed controllers & Electronize you could switch on/off quite easily using the signal wire as they did not have the technology built into them for memorising the stick position.


John
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Colin Bishop

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Re: Twin motor control with rudder off 2 sticks
« Reply #15 on: September 08, 2018, 06:10:47 pm »

Hi John,


Yes, I do see what you mean. Not at home at the moment so can't check but they are quite old controllers and would be of the more simple type. Sometimes progress isn't progress I feel, having fitted a brushless/LiPo setup in latest model whch needs careful managing, cell balancing and the correct charging regime.


Just like computers really. Used to be just switch on and go!




These days I would use a mixer as they don't break the bank.

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roycv

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Re: Twin motor control with rudder off 2 sticks
« Reply #16 on: September 08, 2018, 09:56:19 pm »

Hi all, good point about switching signals and coming back to a new neutral. 
I remember an old mixer I had that shared the full signal across two servos and you only got half the movement on each servo being mixed.

 Have the new ones got a full movement of the mixed servos?

regards
 Roy
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gerritv

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Re: Twin motor control with rudder off 2 sticks
« Reply #17 on: September 08, 2018, 11:41:52 pm »


Thank you Dave for those settings.
I have the FS-10ch but hadn't reached your level of sophistication. Just using 2 mixes so far. Will try yours out before next launch.


Thanks
Gerrit
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davem99

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Re: Twin motor control with rudder off 2 sticks
« Reply #18 on: September 09, 2018, 09:52:19 am »

Hi Gerrit
Glad to have helped. I should have mentioned you need to set your chosen second channel to none so that no other stick or switch interferes with the mix. Haven't tried it but if your motors are not matched using say VRB on ch6 allows you to make slight adjustments. The adjustment need to be small and works from the centre position of VRB.
Enjoy and please post your experience as this is very much in the early stages of development
Dave
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gerritv

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Re: Twin motor control with rudder off 2 sticks
« Reply #19 on: September 10, 2018, 02:52:19 am »


Hi Dave
Got it set up, only testing using the display for now.
Ch 6 doesn't change with movement of Ch 1 (rudder), only Ch 3 ESC moves a bit.

Not sure what you meant by 'setting second channel to none'?


I do have VrB as Trim for Ch6
They only draw back I see so far is that I loose using Sport/Normal mode switch to tone down my throttle. That switch only works on Ch 1,2 and 4 :-(

Gerrit
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davem99

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Re: Twin motor control with rudder off 2 sticks
« Reply #20 on: September 10, 2018, 09:26:34 am »

Hi Gerrit
Sorry when I said second channel I was referring to the channel you had selected for the second ESC ie ch6. Any other control on Ch6 will overide the mix. As you have VrB also on Ch6 this needs to be in the central position or it will override the mixing. Slight movement of VrB either side of the central position will act as Trim, but it needs to be slight. I suggest you turn this off initially to see the mixing effect.
I agree you can't use Ch3 with the Sport/normal, but you can use Ch2 in place of Ch3 and that should work. All control is then on the right stick
OR Switch to MODE1 and Ch2 and Ch3 sticks reverse position(sides) and you just need to re program your settings, changing Ch3 to Ch2


Hope this helps
Dave
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johnf

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Re: Twin motor control with rudder off 2 sticks
« Reply #21 on: September 10, 2018, 12:55:21 pm »

Hi Everyone,

Many thanks for all the replies to my original post.

I have concluded that my 3 TXs do not have the "stick to channel" feature found on the best systems.    Thus I cannot have the Throttle/Rudder or Aileron/Throttle mix I need.

I really cannot do "tank steering" with a separate rudder.     However, I will try switching a TX from Mode 2 to Mode 1 and programming an existing V-Tail or Elevon mix to see if that does the job.

with best wishes      John %%
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gerritv

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Re: Twin motor control with rudder off 2 sticks
« Reply #22 on: September 10, 2018, 03:25:53 pm »


Hi Dave
Sorted:
I switched to Mode 1, Ch 4 RH side horizontal is now rudder. Ch 3 LH side vertical is throttle.


Mixes:
1- Master Ch4, Slave Ch6, -25%
2- Master Ch3, Slave Ch6, 100%
3- Master Ch4, Slave Ch 3, 25%
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davem99

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Re: Twin motor control with rudder off 2 sticks
« Reply #23 on: September 10, 2018, 05:02:04 pm »

Hi Gerrit
Glad to have helped. Please update on actual on water usage, thanks.


Hi John
In your original post you said "I have an 'all singing and dancing' HK Orange DRX Spectrum DSM2 compatible TX together with the popular FlySky i6 ..."
My solution was based on the FlySky i6 with firmware version 2.0 16-Aug-2017. If your FS-i6 has an earlier version it may need to be upgraded to at least this version.
I do not use the built in Elevon and V-Tail mixes as they restrict the channels you can use. I used the three Mix settings selected just above the Elevon and V-Tail on my Tx screen. This will allow you to choose which channels to mix unlike the Elevon and V-Tail settings.


Hope you can get your setup to work. As an ex flyer I can appreciate your problem with multiple controls but your i6 set is certainly capable of providing the solution and at fraction of the price of other named offerings.
 I am no expert on the Spectrums but suspect they could also be made to do similar mixes.


Dave

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Umi_Ryuzuki

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Re: Twin motor control with rudder off 2 sticks
« Reply #24 on: September 10, 2018, 09:17:26 pm »

Okay, I have been reading this thread on and off, and my itty bitty brain says,
Put your throttles on the Elevator channel and mix, for Vtail, on the rudder.
So the elevator would be up(fwd) and down(rev) and rudder would then
control the rudder, and slow one motor in a turn.
Isn't this what needs to be done, or is it just not that simple.  :((
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