active aero project (Page 1 of 3)

Consider integrating an accelerometer chip.  That gives you some good additional information.  I have been playing with one I found for cheap on ebay.

Personally, I rather enjoyed the bowling ball pendulum/garage door springs solution.

Yeah definitely! Also might consider using Race Capture Pro. Price will be a bit steeper than Arduino + eBay components, but you get tons of other stuff for free (telemetry).

I have noticed the one on the 300zx, just never got around to asking you guys how it was setup.

I'm not expecting this to really add anything performance wise to the car. But the warning is a good one none the less.

I'd do a brake switch and a WOT switch. Full up when brakes are on, full flat when WOT (use a stiff button out of a Mercedes or something for it, one you have to overpower, so you can go almost wot in a turn and still have the wing up), and max downforce position when in a turn.

There is some merit to the split wing. See the new pagani huayra that does something similar. The outside half of the wing doesn't go into low drag mode in corners, it stays at it's normal setting, providing downforce. Raising the inside half serves to provide some counter to body roll by increasing downforce on that side of the car.

But again, I expect literally zero performance benefit from this. It's just a science project to get me to learn new things.

So it's kind of working. Something is screwy though, because it seems to disconnect and reconnect to the computer about every time it goes through the main loop. I'm sure i'm just being stupid. But it's actually working. I have a basic servo motor hooked up and it's responding as I request when I meet the conditions.

I'm using a real throttle body, a push button to simulate brake pressure switch, and a potentiometer to simulate steering. I have a half second delay built into the end of the loop to try and keep the serial readout on the computer screen readable.

The below is written in whatever language arduino uses in their standard program. And for anyone that actually does coding, I apologize now for what i'm sure are some serious flaws in structure and approach. I'm sure there is a much better way to do this than a bunch of if loops, but it's just how I started. Wing angles are arbitrary.

*
  Active_Aero 
*/
#include <Servo.h>

// create servo object to control a servo
Servo wing1;   
//variable declaration
int led = 13;
int wing;
int throttle;
int brake;
int steer;
int thottleThresh = 90;

// the setup routine runs once when you press reset:
void setup() {
  //LED setup and on, because I can
  pinMode(led, OUTPUT);
  digitalWrite(led, HIGH);
  // attaches the servo on pin 9 to the servo object
  wing1.attach(9); 
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);

}

// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 0 (Throttle Position):
  throttle = analogRead(A0);
  // read the input on analog pin 1 (Brake pressure);
  brake = analogRead(A1);
  // read the input on analog pin 2 (Steering Possition);
  steer = analogRead(A2);
 
  // Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):
  // Throttle
  float throttlePos = ((4.4 - (throttle * (5.0 / 1023.0))) / (4.4 - 1.3))*100;
  // Brake
  float brakePres = (brake * (5.0 / 1023.0));
  // Steering
  float SteeringPos = (steer * (5.0 / 1023.0));

 
 
  // controling rear wing
  // change wing if throttle goes high and steering straight
  if ((throttlePos > thottleThresh) && (2 < SteeringPos < 3)) {
    wing1.write(0);
  }
  //air brake if steering straight and brakes go high
  else if ((2 < SteeringPos < 3) && (brakePres > 4.9)) {
    wing1.write(180);
  }
  //lift wing if turning
  else if ((brakePres < 4.9) && (SteeringPos > 3)) {
    wing1.write(80);
  }
  else {
    wing1.write(40);
  }
 
  // print out the value you read:
  Serial.println("Brake");
  Serial.println(brakePres);
  Serial.println("Wing");
  Serial.println(wing);
  Serial.println("throttle");
  Serial.println(throttlePos);
  Serial.println("steer");
  Serial.println(SteeringPos);
  delay(500);
}

some homework reveals that my disconnect/reconnect issues might be the servo sucking too much power and resetting the board. I either need to throw a capacitor between the 5V rail and the servo, or power the servo via an external power supply. Will investigate.

Ah, so you're one of THOSE engineers. 

If you're sending any signals directly into your microprocessor, or sourcing any outputs directly, you're doing it wrong.  Your servos should be running from their own power supply, separated from the processor's supply by at least some sort of regulator if not a switching circuit.

If you need some tips send me an email.  I've done a bit of analog work in college, including a couple robotics projects.

I'm a mechanical engineer who has limited electrical experience, and zero programming experience.

I'm entirely new to the arduino, and since the servo motor was advertised as for an arduino I just assumed that it would be ok to run on the provided 5V line. I especially thought it was ok after one of the servo examples I found had you plugging it in just as I had. But I realized that the example asking for the servo to slowly move in a couple degree increments was far different than me asking it to rapidly move from one position to another. But lesson learned. I'll be changing the setup tonight.

I also need to figure out exactly what kind of motor the headlight motors are, and how to control them.

You could always do it like the original masters did with a clutch pedal controlling the wing with a auto Trans  in the car. Someone so needs to make a sucker car