Here comes the spider

/* Sweep
 by BARRAGAN <http://barraganstudio.com> 
 This example code is in the public domain.

 modified 8 Nov 2013
 by Scott Fitzgerald
 http://arduino.cc/en/Tutorial/Sweep*
 
 /*Calibration
 //created 29 Oct 2008
 //By David A Mellis
 //modified 30 Aug 2011//
// By Tom Igoe//
  //http://arduino.cc/en/Tutorial/Calibration*/
  //This example code is in the public domain. */
 
 // sensor reading code + values are from luckylarry.co.uk

#include <Servo.h> 
 
Servo myservo;  // create servo object to control a servo 
                // twelve servo objects can be created on most boards

const int ledPin = 9;        // pin that the LED is attached to
const int servoPin = 10;        // pin that the LED is attached to
const int actionzone = 100; // we start moving the spider when closer than this
const int closest = 24; // this is the minimum distance the prox. sensor can report
const float volts = 3.3;   // voltage we are powering prox. sensor with - if running 3.3.volts then change 5 to 3.3
 
int pos = 0;           // variable to store the servo position 
float distance = 0;   // worked out from graph 65 = theretical distance / (1/Volts)S - luckylarry.co.uk
int action = 0;   // this variable controls the servo swing, based on proximity
int ledintensity = 255; // initiql LED brightness

 
void setup() 
{ 
  myservo.attach(servoPin);  // attaches the servo on pin X to the servo object 
  Serial.begin(9600); 
} 

 
void loop() {
  // sensor reading code + values are from luckylarry.co.uk
  volts = analogRead(A0)*0.0048828125;   // value from sensor * (5/1024) - if running 3.3.volts then change 5 to 3.3
  distance = 65*pow(volts, -1.10);          // worked out from graph 65 = theretical distance / (1/Volts)S - luckylarry.co.uk
  
  Serial.println(distance); // this is just to find out min/max proximity values

  if (distance < actionzone) {
      ledintensity = 255; // lets keep full brightness on the led
      analogWrite(ledPin, ledintensity); // turn LED on!

     myservo.write(0);  // tell servo to go to a starting position 
     delay(map(distance, closest, actionzone, 200, 20)); // wait a little, depending on proximity
     action = map(distance, closest, actionzone, 180, 0); // calculate how much to move the servo
     for(pos = 0; pos <= action; pos += 1)  {   //  loop to move the servo, in steps of 1 degree 
          myservo.write(pos);     // tell servo to go to position in variable 'pos' 
          delay(1);
        }
}          else analogWrite(ledPin, 0); // if we are too far, turn LED off
}