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Project Documentation

Semi-Autonomous GPS-Navigated Wheelchair with Obstacle Avoidance and Joystick Control

Image of Semi-Autonomous GPS-Navigated Wheelchair with Obstacle Avoidance and Joystick Control

Circuit Documentation

Summary

The circuit in question appears to be designed for a semi-autonomous wheelchair addon. It includes a GPS module for navigation, ultrasonic sensors for obstacle detection, a joystick for manual control, a motor driver for controlling the wheelchair's motors, and an Arduino Mega 2560 microcontroller as the central processing unit. The circuit also includes a step-down module to regulate voltage, an emergency stop mechanism, batteries for power supply, a buzzer for alerts, a push button board for additional controls, and an LCD display for user interface.

Component List

GPS NEO 6M

A GPS module used for obtaining geographical location data.

HC-SR04 Ultrasonic Sensor (x3)

Ultrasonic sensors used for measuring distances and detecting obstacles.

24v e-bike DC Motor (x2)

Motors used for driving the wheelchair.

MDDS30 A Cytron Motor Driver

A motor driver used to control the speed and direction of the motors.

Step Down Module

A voltage regulator that steps down the voltage to a lower level.

Adafruit Mini Analog Thumbstick

A joystick used for manual control of the wheelchair.

Arduino Mega 2560

The microcontroller that serves as the brain of the circuit, processing inputs and controlling outputs.

12V 200Ah Battery (x4)

Batteries that provide power to the circuit.

Emergency STOP

A safety feature that allows immediate stopping of the wheelchair.

Buzzer

An audible alert device.

8 Push Button Board PCB

A board with push buttons for additional input controls.

LCD Display 16x4 I2C

A display used for showing information to the user.

30A Motor Controller

A controller used for managing the power to the motors.

DC Motor (x2)

Additional motors that may be used for other functions in the wheelchair.

Wiring Details

GPS NEO 6M

VCC: Connected to 5V power supply.
RX: Connected to TX1 (D18) on Arduino Mega 2560.
TX: Connected to RX1 (D19) on Arduino Mega 2560.
GND: Connected to the common ground.

HC-SR04 Ultrasonic Sensor (Front)

VCC: Connected to 5V power supply.
TRIG: Connected to D26 on Arduino Mega 2560.
ECHO: Connected to D27 on Arduino Mega 2560.
GND: Connected to the common ground.

HC-SR04 Ultrasonic Sensor (Left)

VCC: Connected to 5V power supply.
TRIG: Connected to D22 on Arduino Mega 2560.
ECHO: Connected to D23 on Arduino Mega 2560.
GND: Connected to the common ground.

HC-SR04 Ultrasonic Sensor (Right)

VCC: Connected to 5V power supply.
TRIG: Connected to D24 on Arduino Mega 2560.
ECHO: Connected to D25 on Arduino Mega 2560.
GND: Connected to the common ground.

24v e-bike DC Motor (Left)

VCC: Connected to MLA on Cytron Motor Driver.
GND: Connected to MLB on Cytron Motor Driver.

24v e-bike DC Motor (Right)

VCC: Connected to MRB on Cytron Motor Driver.
GND: Connected to MRA on Cytron Motor Driver.

MDDS30 A Cytron Motor Driver

SIG1: Connected to D2 PWM on Arduino Mega 2560.
SIG2: Connected to D3 PWM on Arduino Mega 2560.
GND: Connected to the common ground.
5V: Connected to 5V power supply.
VB+: Connected to 12V power supply through Emergency STOP.
VB-: Connected to the common ground.

Step Down Module

24v IN+: Connected to Emergency STOP.
GND: Connected to the common ground.
5v OUT+: Connected to VIN on Arduino Mega 2560.
5v OUT-: Connected to the common ground.

Adafruit Mini Analog Thumbstick

VCC: Connected to 5V power supply.
YOUT: Connected to A2 on Arduino Mega 2560.
XOUT: Connected to A0 on Arduino Mega 2560.
GND: Connected to the common ground.

Arduino Mega 2560

GND: Connected to the common ground.
5V: Connected to 5V power supply.
VIN: Connected to 5v OUT+ from Step Down Module.
Various digital and analog pins: Connected to sensors, motor driver, and other peripherals as detailed above.

12V 200Ah Battery

GND: Connected to the common ground.
12V: Connected to the 12V power supply rail.

Emergency STOP

NC: Connected between the 12V power supply and the motor driver/motor controller.

Buzzer

PIN: Connected to D53 on Arduino Mega 2560.
GND: Connected to the common ground.

8 Push Button Board PCB

K1-K8: Connected to various digital pins (D31, D33, D35, D37, D30, D32, D34, D36) on Arduino Mega 2560.
GROUND: Connected to the common ground.

LCD Display 16x4 I2C

SCL: Connected to SCL on Arduino Mega 2560.
SDA: Connected to SDA on Arduino Mega 2560.
VCC: Connected to 5V power supply.
GND: Connected to the common ground.

30A Motor Controller

M1: Connected to pin 1 on both DC Motors.
M2: Connected to pin 2 on both DC Motors.
12V +: Connected to 12V power supply through Emergency STOP.
12V -: Connected to the common ground.
SW2: Connected to D52 on Arduino Mega 2560.
SW1: Connected to D51 on Arduino Mega 2560.

DC Motor (x2)

Pin 1: Connected to M1 on 30A Motor Controller.
Pin 2: Connected to M2 on 30A Motor Controller.

Documented Code

Arduino Mega 2560 Code

/*
 * Semi-Autonomous Wheelchair Addon
 * This code controls a wheelchair using 2 motors, 3 ultrasonic sensors, a GPS
 * module, and a joystick. The wheelchair avoids obstacles and navigates to a
 * set location using GPS. The joystick allows manual control. Safety features
 * include sensor checks before operation and interrupt-based emergency stop.
 */

#include <SoftwareSerial.h>
#include <TinyGPS++.h>

#define TRIG_LEFT 22
#define ECHO_LEFT 23
#define TRIG_RIGHT 24
#define ECHO_RIGHT 25
#define TRIG_FRONT 26
#define ECHO_FRONT 27
#define MOTOR_LEFT_SIG1 2
#define MOTOR_LEFT_SIG2 3
#define MOTOR_RIGHT_SIG1 4
#define MOTOR_RIGHT_SIG2 5
#define JOYSTICK_X A0
#define JOYSTICK_Y A2
#define GPS_RX 19
#define GPS_TX 18

TinyGPSPlus gps;
SoftwareSerial gpsSerial(GPS_RX, GPS_TX);

const double targetLat = 0.0; // Set target latitude
const double targetLon = 0.0; // Set target longitude

volatile bool obstacleDetected = false;

void setup() {
  pinMode(TRIG_LEFT, OUTPUT);
  pinMode(ECHO_LEFT, INPUT);
  pinMode(TRIG_RIGHT, OUTPUT);
  pinMode(ECHO_RIGHT, INPUT);
  pinMode(TRIG_FRONT, OUTPUT);
  pinMode(ECHO_FRONT, INPUT);
  pinMode(MOTOR_LEFT_SIG1, OUTPUT);
  pinMode(MOTOR_LEFT_SIG2, OUTPUT);
  pinMode(MOTOR_RIGHT_SIG1, OUTPUT);
  pinMode(MOTOR_RIGHT_SIG2, OUTPUT);
  pinMode(JOYSTICK_X, INPUT);
  pinMode(JOYSTICK_Y, INPUT);
  gpsSerial.begin(9600);
  Serial.begin(9600);
  attachInterrupt(digitalPinToInterrupt(ECHO_FRONT), emergencyStop, CHANGE);
  attachInterrupt(digitalPinToInterrupt(ECHO_LEFT), obstacleInterrupt, CHANGE);
  attachInterrupt(digitalPinToInterrupt(ECHO_RIGHT), obstacleInterrupt, CHANGE);
}

void emergencyStop() {
  stopMoving();
  while (true) {
    if (digitalRead(ECHO_FRONT) == LOW) break;
  }
}

void obstacleInterrupt() {
  obstacleDetected = true;
}

long readUltrasonicDistance(int trigPin, int echoPin) {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  return pulseIn(echoPin, HIGH) / 58.2;
}

void moveForward(int speed) {
  analogWrite(MOTOR_LEFT_SIG1, speed);
  analogWrite(MOTOR_LEFT_SIG2, 0);
  analogWrite(MOTOR_RIGHT_SIG1, speed);
  analogWrite(MOTOR_RIGHT_SIG2, 0);
}

void moveBackward(int speed) {
  analogWrite(MOTOR_LEFT_SIG1, 0);
  analogWrite(MOTOR_LEFT_SIG2, speed);
  analogWrite(MOTOR_RIGHT_SIG1, 0);
  analogWrite(MOTOR_RIGHT_SIG