4ws steering servo with inversely prop gain

/*  this shetch allow yo use a poor quality 2ch radio to control 4ws
 *  the inversely proportional steering percentage is related to the rear servo end point values.
 *  when the correction value increases, the end point decreases, zero correction enables 4 steering wheels at any speed
 *  before setting the steering inversely percentage it is better to have set the rear end point values first
 *  this because if you go over the top you turn the servo direction
 *  you will have to try to find the right compromise, in any case it is easy to understand
 *  values here in define list are only default, you will have to modify them according to your model
 *  the connections are: pin 7 throttle signal, pin 8 steering signal, pin 10 rear servo output
*/
#define antsx 1000 //-- in front servo endpoint sx
#define antdx 2000 //-- in front servo endpoint dx
#define postsx 50//-- out rear servo sx if inverted with postdx it reverse
#define postdx 130 //-- out rear servo dx if inverted with postsx it reverse
#define center 0 //-- add or subtract xx value to center steering
#define tolerance 5 //-- if your poor quality servo vibrates try 5
#define max_correction 50 //--amount steering by throttle

#include <Servo.h>
Servo myservo;
unsigned int rxpulse;
unsigned int gaspulse;
unsigned int correction;
unsigned int newPos, oldPos;
void setup() {
myservo.attach(10); //-- rear servo signal out pin
pinMode(8, INPUT); //-- front servo signal in pin
pinMode(7, INPUT); //-- throttle signal in pin
}
void loop() {
rxpulse = pulseIn(8, HIGH);
gaspulse = pulseIn(7, HIGH);
correction = map(gaspulse, antsx, antdx, 0, max_correction);
newPos = map(rxpulse, antsx, antdx, (postsx+correction), (postdx-correction));
if (abs(newPos - oldPos)> tolerance) {
oldPos = newPos;

myservo.write(newPos + center);
}
}