Inputting PWM servo signal into arduino

Hi, I would like to input a PWM servo signal from one output channel of my rc reciever and be able to alter the sinal with a potentiometer to reduce or increase the movement of a servo connected to the arduino output.

This will eventually be put into a remote controlled winch I am building that will tow paragliders into the air. A load cell will replace the potentiometer via a calibrated amplifier to get the 0 - 5 v input and measure the towing line tension and if the line tension is too high the output servo will back the winch throttle off to reduce the load.

I hope this makes sense.

Has anybody got any pointers for me please

Gaz

Reading RC Receivers and using the servo object to output the same or altered signal, its all here on my blog, start with the how to section -

rcarduino.blogspot.com

Duane B

Why not just use a servo connected to your rc receiver to turn a pot connected to the arduino for the desired tension reference value. This pot value could be compared to the load cell input value.

Thanks guys I'll do some reading up.

Gaz

It seems I need to gain more experience as I am a newbie.

I have thought of another approach that will work thou.
I can use an existing 2ch rc elevon mixer with one servo connected to the out put and the two inputs will be connected to rx direct and the other to the arduino running a basic servo potentiometer sketch.

My question is on the basic sketch shown below can the mapping be changed so the servo will only operate once the input pot reaches half way 2.5v, so the potentiometer can be turned half way before the servo moves.

val = analogRead(potpin); // reads the value of the potentiometer (value between 0 and 1023)
val = map(val, 0, 1023, 0, 179); // scale it to use it with the servo (value between 0 and 180)

Could I change the mapping values to (val, 512, 1023, 0, 179); to achieve this?

Regards
Gareth