Controlling a low-cost robot with two potentiometers

This tutorial will present a simple way to control directions of robot with two potentiometers and several wires.

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Controlling a low-cost robot with two potentiometers

Things used in this project

Hardware components

Arduino UNO

Cytron 2A Motor Shield

Arexx ARX-CH09 Robot base

4xAA battery holder

Jumper wires (generic)

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

Soldering iron (generic)

Story

Introduction

Since we watched Star Wars and other sci-fi movies, we always see autonomous robots around us. The overall goal of our project was to make a simple line follower. As a preliminary step, this tutorial will present a simple way to control directions of robot with two potentiometers and several wires.

We are a group of 1st year students at CentraleSupélec Rennes. This work is part of a short-term project we must achieve using our knowledge in electronics, signal processing and so on.

The features

For this Hackster tutorial, we will make the robot move according to two potentiometers (one for each wheel):

Potentiometer value will “decide” of the wheel speed.

If both potentiometers have the same value, the robot will go straight forward.

If different values are observed, the robot will turn left/right.

One remark: we decided to use a motor shield as the basic Arduino Uno cannot deliver enough current to control motors. Without this shield, wheels didn’t behave correctly. For the following schematics, we will use the official Arduino motor shield.

Perspectives

For later applications, there are several perspectives:

Implementing a wireless connection between the potentiometers and the robot (using NRF24L01 chips).

For a line follower application, using a sensor such as https://www.pololu.com/product/961. Calibration is quite difficult to do.

Developing an Android app to communicate with our system (wheels parameters, battery level, etc).

Here is a video of the result:

Code

Two-potentiometer command

int roue_droite = 10;
int roue_gauche = 11;
int potentiometre_direction = 2;
int potentiometre_vitesse = 3;

void setup() {
  pinMode(roue_droite, OUTPUT);
  pinMode(roue_gauche, OUTPUT);
  pinMode(potentiometre_direction, INPUT);
  pinMode(potentiometre_vitesse, INPUT);
}

void loop() {
  if (analogRead(potentiometre_direction) <= 100)
    { analogWrite(roue_droite,255 );
    analogWrite(roue_gauche, 0);
    delay(10);
  }
  if (analogRead(potentiometre_direction) >100 && analogRead(potentiometre_direction) < 200)
    { analogWrite(roue_droite,230);
    analogWrite(roue_gauche,25 );
    delay(10);
    }
  if (analogRead(potentiometre_direction) >200 && analogRead(potentiometre_direction) < 300)
    { analogWrite(roue_droite,200 );
    analogWrite(roue_gauche,55 );
    delay(10);
    }
  if (analogRead(potentiometre_direction) >300 && analogRead(potentiometre_direction) < 400)
    { analogWrite(roue_droite,175 );
    analogWrite(roue_gauche,80 );
    delay(10);
    }
  if (analogRead(potentiometre_direction) >400 && analogRead(potentiometre_direction) < 500)
    { analogWrite(roue_droite,155 );
    analogWrite(roue_gauche, 100);
    delay(10);
    }
  if (analogRead(potentiometre_direction) >500 && analogRead(potentiometre_direction) < 600) 
    { analogWrite(roue_droite,0 );
    analogWrite(roue_gauche,0 );
    delay(10);
    }
    if (analogRead(potentiometre_direction) >600 && analogRead(potentiometre_direction) < 700) //aller  droite
    { analogWrite(roue_droite,100 );
    analogWrite(roue_gauche,155 );
    delay(10);
    }
    if (analogRead(potentiometre_direction) >700 && analogRead(potentiometre_direction) < 800)
    { analogWrite(roue_droite, 80);
    analogWrite(roue_gauche,175 );
    delay(10);
    }
  if (analogRead(potentiometre_direction) >800 && analogRead(potentiometre_direction) < 900)
    { analogWrite(roue_droite,55 );
    analogWrite(roue_gauche,200 );
    delay(10);
    }
  if (analogRead(potentiometre_direction) >900 && analogRead(potentiometre_direction) < 1000)
    { analogWrite(roue_droite,25);
    analogWrite(roue_gauche,230 );
    delay(10);
    }
  if (analogRead(potentiometre_direction) >1000 && analogRead(potentiometre_direction) < 1023)
    { analogWrite(roue_droite,0 );
    analogWrite(roue_gauche, 255);
    delay(10);
    }
}

Credits

Pierre Ruffy & Roxane Alexandre

Posted by

Pascal Cotret

Thanks to Pierre Ruffy and Roxane Alexandre.

Controlling a low-cost robot with two potentiometers