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[davem99]

I agree this may work in some situations but requires a y-lead for the ESCs which means you lose the ability to reverse individual motor direction. I well remember using such a set up in my flying days with two servos for which this mix is designed. Using Elevon results in Ch1<=Ch2+Ch1 and Ch2<=Ch2-Ch1 so the rudder will also be affected by the other channel.


Using the mix function, one stick and channel control the rudder, whilst another stick controls the ESCs by two channels. The rudder also mixes its output with each ESC channel to increase or decrease the speed.


FlySky have developed their Tx to cover all forms of modelling and the Mix function certainly makes the Tx more model boat friendly. For simple setups it is comparable with some of the functions found on my Taranis but at a fraction of the cost.


Hopefully more people will develop their skillsets to take advantage of the new equipment and functions and share their experiences for all our benefit.

[npomeroy]

Despite the warning this is an old topic, I think I'd be better to abandon this thread https://www.modelboatmayhem.co.uk/forum/index.php?topic=66150.new#new and resume here.


I will digest the previous posts w.r.t. my intention to run two motors on a tug with something like "tank" steering.  I note that the "mixers" use two channels to integrate rudder with differential motor speed and direction.  I'm thinking of keeping rudder separate on the RH Tx stick (I have a 9-channel plane/helicopter Tx) and using the left stick as up/down for motor power and left/right for left/right motor mix.  But perhaps the mixers like these https://www.componentshop.co.uk/action-electronics/mixers-multifunction.html give a more practical result, and presumably the 2 channels could both be off the left stick.  I'm thinking of a bow thruster as well and that could be on the right stick.


I admit this is my first boat project although I've good experience with RC electronics in aircraft and have programmed microprocessors (I had thought of doing my own mixer with Arduino but it seems unnecessary).  I'd appreciate any feedback on the likely manouverability with these systems and in particular the merits of having separate vs integrated rudder channel.


Cheers
Nelson

[npomeroy]

Looking further, My transmitter, JR DSX9, has mixing functions and also you can control ailerons with one stick throw using two channels and two servos, so that should be able to be hacked to produce differential throttle on 2 motors.

[npomeroy]

Looking further, My transmitter, JR DSX9, has mixing functions and also you can control ailerons with one stick throw using two channels and two servos, so that should be able to be hacked to produce differential throttle on 2 motors.

And pricewise, there's not much difference between a P94 mixer with built in ESC's, and just 2 ESC's like this https://www.rchobbies.co.nz/dynamite-dyns2210-wp-60a-fwd-rev-brushed-esc/ with the mixing done in the TX.

[npomeroy]

Looking further, My transmitter, JR DSX9, has mixing functions and also you can control ailerons with one stick throw using two channels and two servos, so that should be able to be hacked to produce differential throttle on 2 motors.

I think the answer is to change the "model" to Mode 1 (the Tx is assembled as Mode 2 with left stick for throttle un-sprung) then use V-tail mixing which would for aircraft put rudder and (two-channel) elevator on left stick, and wire the 2 motor ESC's to the 2 elevator channels on the Rx.  Hopefully the various "elevator" and rudder parameters can be tweaked to get the steering required.

[DJW]

Morning All


My input on this, I have a twin motor Aquarama in build. And started out with a Futaba 6EX.  I wanted independent ESC control but also some mixing with the rudder.  I achieved it by enabling V-Tail mixing on the TX, and switching my TX to Mode 1 got the sticks into the 'right' place.  I created a test rig to figure it out and test, results are here:


https://youtu.be/wmmUGpZXJyA


Since that I've run out of channels on the Futaba, so have taken the plunge with an FrSky QX7S TX and R8 Pro RX, as others have said, bit of a learning curve but once learnt the possibilities are many...


My current programming here:


https://youtu.be/MLLzn5WOcZI


Similar basic control as the Futaba, but tweaks aimed at improving control.


So my aim is not exactly two motors from two sticks, but an approach where the TX takes the mixing strain and I use the TX in a more conventional way.


Best regards
David.

[GG]

Glad to hear that the TOM (Together Or Mixed) method of twin motor control works for others, previously published in the Feb 2018 issue of Model Boats. 
As many might not have access to this issue, I could (time readily available courtesy of the latest "lock-down") write out a brief description of this method?
Glynn Guest 

[hama]

Please do, always interesting!
I managed to program my radio so that I by flicking a switch can choose between no mix, combined motors, mixed motors, mixed motors and thruster and mix to have all things combined to crab/go sideways on one stick.
Don't ask how I did it  I did try to explain it in a thread here but don't think I succeeded.
Hama

[hama]

Please do, always interesting!
I managed to program my radio so that I by flicking a switch can choose between no mix, combined motors, mixed motors, mixed motors and thruster and mix to have all things combined to crab/go sideways on one stick.
Don't ask how I did it  I did try to explain it in a thread here but don't think I succeeded.
Hama
Edit: found the thread
https://www.modelboatmayhem.co.uk/forum/index.php/topic,49976.msg509345.html#msg509345

[GG]

OK here goes, the TOM (Together Or Mixed) electric motor control method sailing using a transmitters internal mixing circuits.


Firstly, you need a transmitter with two dual axis stick units and the option to have "V-tail" mixing.  This means that the functions of Rudder and Elevator are combined into to control the two separate surfaces on the "V-tail" of a model aircraft with two servos.


It also makes life a lot easier if the transmitter is in "Mode 1".  This refers to the way our aeromodelling cousins fly their models, see attached figure.


With the transmitter in Mode 1, the rudder servo is plugged into what the flyboys would call the Aileron socket of the receiver and the ESC's are plugged into the Elevator and Rudder sockets, see figure.


Now the horizontal moment of the Right-Hand transmitter stick should operate the models rudder as normal.  Also normal will the motors response to the vertical movement of the Left-Hand stick i,e. push the stick up and the model moves ahead, pull it down and the model goes astern.


But, the clever bit is that if the Left-Hand stick is moved horizontally then the motors will rotate in the opposite directions.  Combinations of the vertical and horizontal movements of this stick can either tighten a models turn or allow it to rotate "on the spot" and anything inbetween.


It might not work exactly right at first but adjustments are easily made (usually swapping the motor wires or the receiver sockets the esc's are plugged into and maybe the servo reversing switches).  I've often set the controls up out of the model using servos (easier to see when they move in the same or opposite directions).


I find this method of sailing such an equipped model is more natural and in emergencies my instinctive "rudder-throttle" control is safely reverted to.  Plus, it's nice to use something I've already paid for in the transmitter....
Glynn Guest




 

[npomeroy]

My JR DSX9 Tx allows twin motors with separate throttle curves (for twin-engined aircraft). I can add in mixing from the rudder that has it's own response curve.  And with a switch the mixing can be turned off for synchronous motors plus rudder for normal cruise.  All on the conventional (for here and the US) mode 2 with throttle and rudder on the left stick.   Sorry - just saw the recent posts - I don't seem to be getting notifications.
Cheers
Nelson