active aerodynamics using arduino uno

Dear all,
When the speed of car goes beyond 70 kmph, my aerofoil spoilers should actuate to in increasing downforce on vehicle. I want to automate this procedure using arduino. How this can be done, please guide.
Thank you

Is this for a real car used on public roads?

If so, get a written statement of approval from your vehicle insurer before you embark on this project.

Also note the fine print in the Atmel datasheet

Atmel products are not suitable for, and shall not be used in, automotive applications.


Is this a road going car ?

If so are your insurance company charging you much to cover the custom mod ?

From your comment it sounds like you may not have a lot of experience with Arduino or coding, iif so it would be better to start the learning experience with some much simpler projects.

DON'T CROSS POST!!!!!!!!!!!!!!!!!!!!

Do you know how you intend to get the speed of the vehicle?

If you drive close to 70kph then the spoiler will be trying to go up and down a lot. You should add some hysteresis so that it doesn't move too much.

I remember the first Porsches to do this (in the late 90s) would raise the spoiler at 80kph and then lower it when the speed dropped below 30kph.

Software side is dead easy.

void loop() {
  if (speed > 70 && !spoilerUp) {
    digitalWrite(spoilerPin, HIGH); // Activate the spoiler.
    spoilerUp = true;
  else if (speed < 50 && spoilerUp) {
    digitalWrite(spoilerPin, LOW); // Lower the spoiler.
    spoilerUp = false;

There you go. It's so easy I'm not even going to bother to ask you what you have on that part already.

Now for the hard part.
The speed sensor.
How are you going to do this? Any direct source for the speed from your car? If not, what's your speed input going to look like?

Now for the really hard part.
The spoiler.
Strong - able to withstand the enormous forces of the wind and vibrations of your car, yet able to move up and down. That's some seriously strong actuators as the whole downforce (and all other stresses) from the spoiler has to be handled by these actuators, without being pushed back down, without shaking, etc.