VW T1 Arduino code

#include <Arduino.h>
#include <Servo.h>

double angle_rad = PI/180.0;
double angle_deg = 180.0/PI;
Servo servo_steer;
Servo servo_throt;
char inputchar = char();
String string1 = String();
String commandype = String();
String commandvalue = String();
double steering;
double throttle;
char lightstate = 'B';


void setup(){
    Serial.begin(115200);
    servo_steer.attach(9); // init pin
    servo_throt.attach(10); // init pin
// Horn
    pinMode(12,OUTPUT);
// Headlight pwm ports
    pinMode(6,OUTPUT);
    pinMode(5,OUTPUT);
// Taillight pwm ports
    pinMode(3,OUTPUT);
    pinMode(11,OUTPUT);

    servo_steer.write(90); // write to servo
    servo_throt.write(91); // write to servo
       analogWrite(3,50);
       analogWrite(5,50);
       analogWrite(6,255);
       analogWrite(11,255);

}

void receive_bt() {
    while(!((( inputchar==';'))))
    {
        _loop();
        while(!(Serial.available()))
        {
            _loop();
        }
         inputchar= char(Serial.read());
         string1 += inputchar;
    }
}

void loop(){



inputchar= "";
string1= "";
commandype= "";
commandvalue= "";

  receive_bt();

    commandype= string1.substring(0, 1);
    commandvalue= string1.substring(1, string1.indexOf(';'));



    Serial.print("New instructions recieved;");
    Serial.println(string1);
    Serial.println(commandype);
    Serial.println(commandvalue);
    Serial.println(steering);


   if((( commandype)==("X"))){
    steering = commandvalue.toDouble();
        servo_steer.write(steering); // write to servo
    }

   if((( commandype)==("Y"))){
    throttle = commandvalue.toDouble();
        servo_throt.write(throttle); // write to servo
   if((( string1)==("Y91;"))){

       analogWrite(3,255);
       analogWrite(11,255);
    }
   if((( string1)!=("Y91;"))){
    if ( lightstate != 'A'){
       analogWrite(3,50);
       analogWrite(11,50);}
    if ( lightstate == 'A'){
       analogWrite(3,0);
       analogWrite(11,0);}
    }
   }

   if((( commandype)==("A"))){

       analogWrite(3,0);
       analogWrite(5,0);
       analogWrite(6,0);
       analogWrite(11,0);
       lightstate = 'A';
   }

   if((( commandype)==("B"))){


       analogWrite(5,50);
       analogWrite(6,50);
       analogWrite(3,50);
       analogWrite(11,50);
       lightstate = 'B';
   }

   if((( commandype)==("C"))){

       analogWrite(5,255);
       analogWrite(6,255);
       analogWrite(3,30);
       analogWrite(11,30);
       lightstate = 'C';
   }

   if((( commandype)==("H"))){
    tone(12,262,100);
    delay(150);
    tone(12,262,100);
    delay(150);
    tone(12,262,350);
    delay(350);
// turn taillights nback on because pwm get switched of by the tone library
    if ( lightstate != 'A'){
       analogWrite(3,30);
       analogWrite(11,30);}

    }


    inputchar= "";
    string1= "";
}

void _delay(float seconds){
    long endTime = millis() + seconds * 1000;
    while(millis() < endTime)_loop();
}
void _loop() {}