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"boolean goesForward" ... Still Necessary?
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"boolean goesForward" ... Still Necessary?

by tpryan on Mon May 03, 2021 11:41 pm

We've all seen it 100 times. But is it still necessary? It doesn't show up in the latest Adafruit motor shield library. Can someone please fill me in as to ....
1 - Is it necessary?
2 - If not, where'd it come from.
3 - If so, what's it for?
4 - Is there a document somewhere that explains it and can you please give me the link.

Thanks folks,
TR

tpryan
 
Posts: 3
Joined: Mon May 03, 2021 5:26 pm

Re: "boolean goesForward" ... Still Necessary?

by adafruit_support_bill on Tue May 04, 2021 6:02 am

We've all seen it 100 times.

Guess I'm not one of you all. I have not seen it and it has never ben part of the Adafruit Motor Shield Library.
But is it still necessary?

If you can provide an example of it in some code, we might be able to answer that and the rest of your questions.

adafruit_support_bill
 
Posts: 81290
Joined: Sat Feb 07, 2009 10:11 am

Re: "boolean goesForward" ... Still Necessary?

by tpryan on Wed May 05, 2021 10:52 pm

I've been working on an obstacle avoiding robot for some time now. So I've looked up many different projects on line. The first one I ran across was this one by educ8s.tv via YouTube. See code below. (That term appears a few times in each sketch.) Below that, there's a second example with it's source link from a hackster project. Believe me, there are many examples out there. It's probably a case of copies of copies of the same thing. But I don't want to copy what I don't understand.
Thanks for your reply because it forced me to look. I would have bet my weeks pay that it existed in "DC Motor Test" example under the Adafruit_Motorshield. But no.
Any thoughts on why it was included in those other sketches to begin with?

Code: Select all | TOGGLE FULL SIZE
   //////////////////////////////////////////////
  //          Arduino ROBOT v0.1              //
 //                                          //
//           http://www.educ8s.tv           //
/////////////////////////////////////////////

#include <AFMotor.h>
#include <NewPing.h>
#include <Servo.h>

#define TRIG_PIN A4
#define ECHO_PIN A5
#define MAX_DISTANCE 200
#define MAX_SPEED 190 // sets speed of DC  motors
#define MAX_SPEED_OFFSET 20

NewPing sonar(TRIG_PIN, ECHO_PIN, MAX_DISTANCE);

AF_DCMotor motor1(1, MOTOR12_1KHZ);
AF_DCMotor motor2(3, MOTOR12_1KHZ);

Servo myservo;   

boolean goesForward=false;
int distance = 100;
int speedSet = 0;

void setup() {

  myservo.attach(9); 
  myservo.write(115);
  delay(2000);
  distance = readPing();
  delay(100);
  distance = readPing();
  delay(100);
  distance = readPing();
  delay(100);
  distance = readPing();
  delay(100);
}

void loop() {
 int distanceR = 0;
 int distanceL =  0;
 delay(40);
 
 if(distance<=15)
 {
  moveStop();
  delay(100);
  moveBackward();
  delay(300);
  moveStop();
  delay(200);
  distanceR = lookRight();
  delay(200);
  distanceL = lookLeft();
  delay(200);

  if(distanceR>=distanceL)
  {
    turnRight();
    moveStop();
  }else
  {
    turnLeft();
    moveStop();
  }
 }else
 {
  moveForward();
 }
 distance = readPing();
}

int lookRight()
{
    myservo.write(50);
    delay(500);
    int distance = readPing();
    delay(100);
    myservo.write(115);
    return distance;
}

int lookLeft()
{
    myservo.write(170);
    delay(500);
    int distance = readPing();
    delay(100);
    myservo.write(115);
    return distance;
    delay(100);
}

int readPing() {
  delay(70);
  int cm = sonar.ping_cm();
  if(cm==0)
  {
    cm = 250;
  }
  return cm;
}

void moveStop() {
  motor1.run(RELEASE);
  motor2.run(RELEASE);
  }
 
void moveForward() {

 if(!goesForward)
  {
    goesForward=true;
    motor1.run(FORWARD);     
    motor2.run(FORWARD);     
   for (speedSet = 0; speedSet < MAX_SPEED; speedSet +=2) // slowly bring the speed up to avoid loading down the batteries too quickly
   {
    motor1.setSpeed(speedSet);
    motor2.setSpeed(speedSet+MAX_SPEED_OFFSET);
    delay(5);
   }
  }
}

void moveBackward() {
    goesForward=false;
    motor1.run(BACKWARD);     
    motor2.run(BACKWARD); 
  for (speedSet = 0; speedSet < MAX_SPEED; speedSet +=2) // slowly bring the speed up to avoid loading down the batteries too quickly
  {
    motor1.setSpeed(speedSet);
    motor2.setSpeed(speedSet+MAX_SPEED_OFFSET);
    delay(5);
  }


void turnRight() {
  motor1.run(FORWARD);
  motor2.run(BACKWARD);     
  delay(300);
  motor1.run(FORWARD);     
  motor2.run(FORWARD);     
}
 
void turnLeft() {
  motor1.run(BACKWARD);     
  motor2.run(FORWARD);     
  delay(300);
  motor1.run(FORWARD);     
  motor2.run(FORWARD);





And then, just now, a quick search yielded this from ...
https://www.hackster.io/mvirus784/obsta ... tep%20back.

Code: Select all | TOGGLE FULL SIZE
#include <Servo.h>          //standard library for the servo
#include <NewPing.h>        //for the Ultrasonic sensor function library.

//L298N motor control pins
const int LeftMotorForward = 6;
const int LeftMotorBackward = 7;
const int RightMotorForward = 5;
const int RightMotorBackward = 4;

//sensor pins
#define trig_pin A1 //analog input 1
#define echo_pin A2 //analog input 2

#define maximum_distance 200
boolean goesForward = false;
int distance = 100;

NewPing sonar(trig_pin, echo_pin, maximum_distance); //sensor function
Servo servo_motor;

void setup(){

  pinMode(RightMotorForward, OUTPUT);
  pinMode(LeftMotorForward, OUTPUT);
  pinMode(LeftMotorBackward, OUTPUT);
  pinMode(RightMotorBackward, OUTPUT);
 
  servo_motor.attach(9); //our servo pin

  servo_motor.write(115);
  delay(2000);
  distance = readPing();
  delay(100);
  distance = readPing();
  delay(100);
  distance = readPing();
  delay(100);
  distance = readPing();
  delay(100);
}

void loop(){

  int distanceRight = 0;
  int distanceLeft = 0;
  delay(50);

  if (distance <= 20){
    moveStop();
    delay(300);
    moveBackward();
    delay(400);
    moveStop();
    delay(300);
    distanceRight = lookRight();
    delay(300);
    distanceLeft = lookLeft();
    delay(300);

    if (distance >= distanceLeft){
      turnRight();
      moveStop();
    }
    else{
      turnLeft();
      moveStop();
    }
  }
  else{
    moveForward();
  }
    distance = readPing();
}

int lookRight(){ 
  servo_motor.write(50);
  delay(500);
  int distance = readPing();
  delay(100);
  servo_motor.write(115);
  return distance;
}

int lookLeft(){
  servo_motor.write(170);
  delay(500);
  int distance = readPing();
  delay(100);
  servo_motor.write(115);
  return distance;
  delay(100);
}

int readPing(){
  delay(70);
  int cm = sonar.ping_cm();
  if (cm==0){
    cm=250;
  }
  return cm;
}

void moveStop(){
 
  digitalWrite(RightMotorForward, LOW);
  digitalWrite(LeftMotorForward, LOW);
  digitalWrite(RightMotorBackward, LOW);
  digitalWrite(LeftMotorBackward, LOW);
}

void moveForward(){

  if(!goesForward){

    goesForward=true;
   
    digitalWrite(LeftMotorForward, HIGH);
    digitalWrite(RightMotorForward, HIGH);
 
    digitalWrite(LeftMotorBackward, LOW);
    digitalWrite(RightMotorBackward, LOW);
  }
}

void moveBackward(){

  goesForward=false;

  digitalWrite(LeftMotorBackward, HIGH);
  digitalWrite(RightMotorBackward, HIGH);
 
  digitalWrite(LeftMotorForward, LOW);
  digitalWrite(RightMotorForward, LOW);
 
}

void turnRight(){

  digitalWrite(LeftMotorForward, HIGH);
  digitalWrite(RightMotorBackward, HIGH);
 
  digitalWrite(LeftMotorBackward, LOW);
  digitalWrite(RightMotorForward, LOW);
 
  delay(500);
 
  digitalWrite(LeftMotorForward, HIGH);
  digitalWrite(RightMotorForward, HIGH);
 
  digitalWrite(LeftMotorBackward, LOW);
  digitalWrite(RightMotorBackward, LOW);
 
 
 
}

void turnLeft(){

  digitalWrite(LeftMotorBackward, HIGH);
  digitalWrite(RightMotorForward, HIGH);
 
  digitalWrite(LeftMotorForward, LOW);
  digitalWrite(RightMotorBackward, LOW);

  delay(500);
 
  digitalWrite(LeftMotorForward, HIGH);
  digitalWrite(RightMotorForward, HIGH);
 
  digitalWrite(LeftMotorBackward, LOW);
  digitalWrite(RightMotorBackward, LOW);
}


Sure hope this "code" thing works. First time using it.

tpryan
 
Posts: 3
Joined: Mon May 03, 2021 5:26 pm

Re: "boolean goesForward" ... Still Necessary?

by adafruit_support_bill on Thu May 06, 2021 5:42 am

Looks like a case of a poorly named variable used for a misguided attempt at optimization. "IsGoingForward" would be more descriptive of its intended function. It is used to track the current direction of travel - sort of.

If you look at the functions moveForward() and moveBackward(), they check the direction of travel and only perform the digitalWrite commands if it thinks the direction has changed.

Unfortunately, they do not do the same for right and left turns which also change the direction of the motors, so I would expect that it does not work consistently. And there is no real downside to having redundant digitalWrites, so I would say that this 'optimization' is unnecessary. the code would be simpler - as well as more correct - if it were removed.

adafruit_support_bill
 
Posts: 81290
Joined: Sat Feb 07, 2009 10:11 am

Re: "boolean goesForward" ... Still Necessary?

by tpryan on Thu May 06, 2021 11:26 am

Hey, thanks Bill,
It's amazing how crappy software (and ideas in general) get perpetuated just because people don't (want to) really understand.
Well, this idea does not goesForward any more.
The buck stops here.
: - )
Thanks again.
Have fun,
TR

tpryan
 
Posts: 3
Joined: Mon May 03, 2021 5:26 pm

Please be positive and constructive with your questions and comments.