Arduino KY-0008 Laser joystick controling robot drone flap

@daviddbrown70

There are a number of problems and untidy parts in your sketch. I'll try to describe them so that you can fix them.

 I've marked problems with *** and a number and then *** again. The following line(s) try to explain the problem.

#include <Servo.h>
#define DETECT 2 //pin 2 input receiver
#define ACTION 8 //pin 8 action output
#define POTPIN 0 // analog pin used to connect the potentiometer *** 1 ***
*** use A0 instead of just 0 because tis is an Analogue pin

void setup()
{
  Serial.begin(9600);//Begin Serial communication at a baudrate of 9600:
  pinMode(DETECT, INPUT); //define detect input pin 2
  pinMode(ACTION, OUTPUT); //define action output pin 8
}

void loop() {
  int detected = digitalRead(DETECT);//read pin 2
  if (detected == HIGH) //when laser bean detected value is high
  {
    Servo myservo; // create servo object to control a servo

    int potpin = 0; // analog pin used to connect the potentiometer *** 2 ***
*** 2 *** you don't need this because you have alreadt #defined a value for the pot pin number above
    int val; // variable to read the value from the analog pin
    
  } *** 3 ***
*** 3 *** This } terminates the code group (called scope) in which the value
***         "val" was declared as an int. SO val is no longer defined
***       It also marks the end of the "if (detected == HIGH)" condition
***       So from now on detected may or may not be HIGH

  { *** 4 ***
*** This { starts a new scope in which the value val is not declared
    val = analogRead(potpin); // reads the value of the potentiometer (value between 0 and 1023)
    val = map(val, 0, 1023, 0, 180); // scale it to use it with the servo (value between 0 and 180)
    delay(15); // waits for the servo to get there
  }

  delay(200);

}

I'm thinking that this is what you need to start with ...

#include <Servo.h>

#define DETECT 2 //pin 2 input receiver
#define ACTION 8 //pin 8 action output
#define POTPIN A0 // analog pin used to connect the potentiometer

Servo myservo; // create servo object to control a servo


void setup()
{
  Serial.begin(9600);//Begin Serial communication at a baudrate of 9600:
  pinMode(DETECT, INPUT); //define detect input pin 2
  pinMode(ACTION, OUTPUT); //define action output pin 8
}

void loop() {
  int detected = digitalRead(DETECT);//read pin 2
  
  if (detected == HIGH) //when laser beam detected value is high
  {
    int val; // variable to read the value from the analog pin
    val = analogRead(POTPIN); // reads the value of the potentiometer (value between 0 and 1023)
    val = map(val, 0, 1023, 0, 180); // scale it to use it with the servo (value between 0 and 180)
    delay(15); // waits for the servo to get there
  }

  delay(200);

}

 Note that I've moved the Servo creation out of the setup and loop code. It should be declared here so as to be available everywhere.