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Twin motor control

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Nick-R:
I have returned to the hobby after decades!  My last experience of r/c until recently was in the sixties with single channel sets sending a sort of morse code to (semi) control the boat.   I have now six channel unit using only two - steering and motor control.


I am looking at my next project being a twin motor set up and I would like full independent control of each motor - speed/forward/reverse.  I was into real boats for many years and had twin throttles and steering wheel.  I wonder if anyone does a tx that comes close to replicating this.  My current tx has the usual twin levers but what envisage would need the right stick to double as motor control in the vertical plane and steering horizontal.  Would be better to have steering separate from throttle control. 


Anyone know if any manufacturer does something like this!

Colin Bishop:
Nick,

Yes, you do have a bit of catching up to do. For some background have a read of this on the Model Boats Magazine website, it is a bit out of date now but lots of useful basic information.

https://www.modelboats.co.uk/1112/but-i-dont-understand-electronics/

There are two ways of getting what you want. The first is known as tank steering as each of the vertical sticks controls one motor and only two channels are needed. Each motor needs its own speed controller. You can also plug in a servo to the rudder channel to operate the rudder horizontally on the right hand stick. Tank steering can be a bit difficult to maintain a straight course but is very useful when turning a boat at slow speeds.

The other option is to use a mixer. This facility may be built into your 6 channel set but can be tricky to set up. A straightforward solution is to use an ACTion Electronics P94 twin controller/mixer. (but check that your Radio is compatible - see notes on the link below.)

https://www.componentshop.co.uk/p94l-dual-esc-and-mixer-2-x-10-amp.html.html

Data sheet:

https://www.componentshop.co.uk/media/sparsh/product_attachment/P94L%20Manual%20SMT.pdf

This unit offers the options of tank steering and two motor mixing modes plus a thruster mode which is probably not relevant to you. It is all explained in the data sheet.

There used to be a Radio called Robbe Navy which grouped the two motor controls in the same way as throttles on a full size motor boat but I don't think is is available these days except secondhand.

https://engel-modellbau.eu/shop/en/R-C/ROBBE-Futaba-40MHz/Robbe-Navy-Twin-Stick-for-F-14-and-FC-16-F1564.html

Hope this helps,

Colin

Nick-R:
Cheers for that Colin.  I will read the articles you suggest!

GG:
Nick-R,
         Came across this post whilst searching for something else and can offer a third option, if it's not too late, to the ones suggested by Colin Bishop. But this will only work with transmitters intended for use with model aircraft.


This is to use a transmitter in Mode 1 and use the "V-Tail mix option".
The ESC's are plugged into receivers rudder and elevator sockets and the rudder servo into the aileron socket.


This will allow the "usual" transmitter control of rudder on the side to side movement of the right-hand stick and both motors working in the same direction controlled by the vertical moment of the left-hand stick.
The clever bit is to leave the rudder stick alone and only move the left-hand stick horizontally then the motors run in the opposite directions.


It is possible to combine stick movements;
1) Just using the L-H stick for "tank steering" with up-down for ahead-astern and sideways for motor steering
2) If a rudder only turn isn't tight enough add to motor steering
3) just use L-H stick movement to rotate "on the spot"


It saves buying an extra piece of kit, which may or may not work exactly as you want.  It also avoids, assuming you can plug into the receiver sockets and battery connections correctly, any risk of damage.


You might have to alter transmitter trims and Normal/Reverse functions to get the right actions.  I do recall having to swap over a motor-ESC connection once.  For this reason I suggest setting up with two servos first rather than motor-ESC-batteries.
 This method, which I call "TOM" (Together Or Mixed), has been described before in this Forum and in the Model Boats magazine.
Glynn Guest

Colin Bishop:
Glynn is quite right, V-Tail can be an effective cheap solution but, as he says, getting the settings right can be quirky depending on what RC gear you have. My Radiolink TX has V-Tail functionality but the manual indicates that it is quite complex to set up, trim and save. You still need 2 ESCs of course. The cost of Mtroniks ones would be less that the P94 although you could save by getting cheapie Chinese ones which can introduce their own complications as recent posts have shown and anyway, I prefer to buy British if I can afford it rather than support President XI!

It does seem that some TXs are easier to set up than others though, so horses for courses really.

Colin

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