Mehdinik

Dear members

I am working on a research project for a control lab at our university. I would like to control the motion of an RC electrical boat in order to move on certain trajectory. My problem is selection of the boat. I need a boat with two propellers (twin DC motors) that also contains motor speed control. The size of the boat is also important. We have a small tank here in our lab. I would like to choose a boat which is less that 20� in length. is there any product like that which already contains all the components?

I would like to appreciate if you could kindly give me some suggestion and recommendation regarding the selection of the boat.

bubby83

How about an ebay boat? Most of them run on dual motor and props. You may need to buy a cheap ESC to controll the two motor speed and maybe mount up a rudder. Of course, only go this route if you don't plan on using it much afterwards as they are more of toys than hobby boats.

Mehdinik

Thanks for your reply, I found some boats with the size of 20" on ebay but they do not have speed control so I think I have to buy ESC and add to the boat I also have to change the motos to be speed controllable

Thanks
Mehdi

bubby83

The motors will be controlable but if the boat you buy is set up with "thrust stearing"(one motor shuts down to turn) then you'll need a rudder. Try www.offshoerelectrics.com for a speed controller which will controll 2 motors.

Mehdinik

Hi , Thanks for your reply,
I am working on a research project and we only need two inputs (two motors), I think we can make turns with two inputs
so waht is the problem when one motor shuts down for steering? You mean we can not make turn with one motors? if we add rudder the problem would be different, we have to make the tursn with the difference in forces that propellers provide , I really appreciate your reply I am new in this area and I am still learning
Mehdi

green-boat

I think you are looking for a mixer ( throttle/steering). It is controlled by 2 channels, throttle and steering with 2 outputs, one for each motor. One end plugs into your reciever and the other into each ESC. This setup allows full control of throttle and steering without the use of any rudders thru 2 screws and 2 channels.

cyclops2

Mehdinik.

Do you want to completly control all speeds of foward and reverse, and
also do any turns with just the 2 motors ?

Done all the time in any twin engined real boat.

You would need 2 speed controls that have reverse also.

A 3 channel Radio Set would allow the right stick to do all the mixing by just turning the transmitter 45 degrees . Pushing the stick into a long diagonal corner gives full speed F or R.

Moving the stick out of the corner slows the engines equally to 0 at the center.

Moving the stick left of the 0 point causes the boat to have left engine in full foward and right engine in full reverse.
It will do tight circles left or right.

The normal "square" control is a completely vectored dual engine control.
Different transmitter position at 45 degrees, but definately full control.

I can scan a simple diagram to you if it would help.
Send me a PM if needed.

Mehdinik

Thanks for all your information
I am not trying to control the boat manually , I need two motors and speed control then I will setup a C++ program to control the boat motion, i.e. moving on a circular trajectory or a simple path, I have already written the programs and I will implement it on a real boat, so the control algorithm will be automatic


Thanks
Mehdi