Object Following Robot

const int in1 = 2;
const int in2 = 3;
const int in3 = 4;
const int in4 = 5;
const int L = 6;
const int U = 7;
const int R = 8;
const int D = 9;

int di;

int posY = 90;
#include <Servo.h>
#include <NewPing.h>

#define T 13
#define E 12
#define MD 50

NewPing sonar(T, E, MD);
Servo Y;

void setup()
{
  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);
  pinMode(in3, OUTPUT);
  pinMode(in4, OUTPUT);
  pinMode(L, INPUT);
  pinMode(U, INPUT);
  pinMode(R, INPUT);
  pinMode(D, INPUT);
  Y.attach(10);
}

void left() {
  digitalWrite(in1, LOW);
  digitalWrite(in2, HIGH);
  digitalWrite(in3, LOW);
  digitalWrite(in4, HIGH);
}
void right() {
  digitalWrite(in1, HIGH);
  digitalWrite(in2, LOW);
  digitalWrite(in3, HIGH);
  digitalWrite(in4, LOW);
}
void forwards() {
  digitalWrite(in1, LOW);
  digitalWrite(in2, HIGH);
  digitalWrite(in3, HIGH);
  digitalWrite(in4, LOW);
}
void OFF() {
  digitalWrite(in1, LOW);
  digitalWrite(in2, LOW);
  digitalWrite(in3, LOW);
  digitalWrite(in4, LOW);
}
void Distance() {
  di = sonar.ping_cm();

  if(di >= 10 && di <= 50) {
    forwards();
  }
  else {
    OFF();
  }
}

void loop()
{ 
  if(digitalRead(U) == 1 && digitalRead(D) == 0)
  {
    while(digitalRead(U) != 0 && digitalRead(D) != 1)
    {
      if(posY == 50)
      {break;}
      posY--;
      Y.write(posY);
      delay(3);
    }
  }
  else if(digitalRead(U) == 0 && digitalRead(D) == 1)
  {
    while(digitalRead(U) != 1 && digitalRead(D) != 0)
    {
      if(posY == 160)
      {break;}
      posY++;
      Y.write(posY);
      delay(3);
    }
  }

  if(digitalRead(L) == 0 && digitalRead(R) == 1) {
    left();
  }
  else if(digitalRead(L) == 1 && digitalRead(R) == 0) {
    right();
  }
  else {
    Distance();  
  }
}