Line Follower Robot (LFR) is a simple robot concept that is autonomously guided to follow a line, that is drawn over white surface as dark lines or over a considerably dark surface as white lines. These lines are detected via the on the robot. The code uses a PID algorithm in order to actuate motors, deciding whether turn left or right. The robot smoothly follows the line with these decisions of slight turns.
About Tools and Materials:
2x ()
()
()
2x ()
()
Step 1: Hardware & Software Overview
Project Key Components
The SMD acts as a bridge between the script and the modules. It is responsible for interpreting the commands sent by the script and translating them into actions that read input from the and meanwhile, actuate the motor for the continuous reading of the script.
The 100 RPM BDC Motor with Encoder is used to rotate the radar mechanism in a full circle. The user can precisely control the motor and get the position through the built-in encoder.
The Reflectance Sensor Module is a tool that used to detect contrast on a surface. It works by detecting the reflectance of a surface using infrared light and differentiating the contrast by measuring the amount of reflected light to the ratio of emitted light.
Key Features
• PID-Controlled Line Following
Uses QTR sensors and a PID algorithm for precise tracking.
• Dynamic Speed Adjustment
Adjusts motor speed based on deviation from the line.
• Real-Time Visualization
Graphical representation of robot movement using Tkinter Canvas.
• Smooth Path Tracking
Implements differential drive control for accurate turns.
• Modular & Expandable
Supports easy modifications for different sensor setups.
Step 2: Assemble
Ensure the SMD is powered and all connections are properly secured.
Project Wiring Diagram
Step 3: Run & Test
1. Connect the Line Follower Robot to your PC using the appropriate USB port. Ensure all connections are secure.
2. Run the Python script to initialize the SMD and set up the motor control.
3. Press the “Start” button in the GUI to begin the line-following operation.
4. The robot will use QTR sensors to detect the line and adjust its movement using a PID algorithm.
5. If needed, adjust the PID parameters (kp, ki, kd) to optimize the tracking accuracy.
6. Press “Stop” to halt the robot, or “Clear” to reset the path tracking.
7. Verify that the motors respond correctly to sensor input and that the robot follows the line smoothly.
Codes
from smd.red import *
import time
import tkinter as tk
import math
from serial.tools.list_ports import comports
from platform import system
class LineFollower:
def __init__(self, port):
# Initialize master and motors
self.m = Master(port)
self.redLeft = self.m.attach(Red(1))
self.redRight = self.m.attach(Red(0))
# PID parameters
self.kp = 0.13
self.kd = 0.38
self.ki = 0.0
# Control variables
self.error = 0
self.prev_error = 0
self.integral = 0
self.main_speed = 50
# Create GUI
self.root = tk.Tk()
self.root.title("Robot Movement")
# Create canvas
self.canvas = tk.Canvas(self.root, width=1200, height=800, bg='white')
self.canvas.pack(pady=20)
# Robot position
self.robot_x = 600
self.robot_y = 400
self.robot_angle = 0
self.path_points = []
# Robot size
self.robot_size = 15
# Robot shape
self.robot = self.canvas.create_rectangle(
self.robot_x - self.robot_size,
self.robot_y - self.robot_size,
self.robot_x + self.robot_size,
self.robot_y + self.robot_size,
fill='red'
)
# Direction indicator
self.direction = self.canvas.create_line(
self.robot_x,
self.robot_y,
self.robot_x + self.robot_size * math.cos(self.robot_angle),
self.robot_y - self.robot_size * math.sin(self.robot_angle),
fill='black',
width=2
)
# Control buttons
self.button_frame = tk.Frame(self.root)
self.button_frame.pack(pady=10)
self.start_button = tk.Button(self.button_frame, text="Start", command=self.start)
self.start_button.pack(side=tk.LEFT, padx=5)
self.stop_button = tk.Button(self.button_frame, text="Stop", command=self.stop)
self.stop_button.pack(side=tk.LEFT, padx=5)
self.clear_button = tk.Button(self.button_frame, text="Clear", command=self.clear_path)
self.clear_button.pack(side=tk.LEFT, padx=5)
self.running = False
def setup(self):
"""Initial robot setup"""
try:
# Set to PWM mode
self.m.set_operation_mode(1, OperationMode.PWM)
self.m.set_operation_mode(0, OperationMode.PWM)
# Enable motors
self.m.enable_torque(1, True)
self.m.enable_torque(0, True)
return True
except Exception as e:
print(f"Error: {e}")
return False
def read_line(self):
"""Read line position from QTR sensors"""
try:
qtr_values = self.m.get_qtr(0, 1) # Get QTR values
if qtr_values is not None:
left = qtr_values[0]
middle = qtr_values[1]
right = qtr_values[2]
# Calculate weighted sum
weighted_sum = (left * 0) + (middle * 1000) + (right * 2000)
sensor_sum = left + middle + right
if sensor_sum > 0:
return weighted_sum / sensor_sum
return None
except Exception as e:
print(f"Sensor read error: {e}")
return None
def calculate_pid(self, position):
"""PID calculation"""
self.error = position - 1000 # Middle point is 1000
self.integral += self.error
derivative = self.error - self.prev_error
# Limit integral
self.integral = max(min(self.integral, 500), -500)
# Calculate PID output
output = (self.kp * self.error) + \
(self.ki * self.integral) + \
(self.kd * derivative)
self.prev_error = self.error
return output
def update_robot_position(self, left_speed, right_speed):
"""Update robot position"""
# Normalize speeds (-100 to 100 -> -1 to 1)
left_speed = left_speed / 100.0
right_speed = right_speed / 100.0
# Calculate angular velocity
angular_velocity = (right_speed - left_speed) * 0.1
self.robot_angle += angular_velocity
# Calculate forward speed
forward_speed = (right_speed + left_speed) * 0.5
# Calculate new position
self.robot_x += forward_speed * math.cos(self.robot_angle) * 5
self.robot_y -= forward_speed * math.sin(self.robot_angle) * 5
# Update robot shape
self.canvas.coords(
self.robot,
self.robot_x - self.robot_size,
self.robot_y - self.robot_size,
self.robot_x + self.robot_size,
self.robot_y + self.robot_size
)
# Update direction line
self.canvas.coords(
self.direction,
self.robot_x,
self.robot_y,
self.robot_x + self.robot_size * math.cos(self.robot_angle),
self.robot_y - self.robot_size * math.sin(self.robot_angle)
)
# Draw path
self.path_points.append((self.robot_x, self.robot_y))
if len(self.path_points) > 1:
self.canvas.create_line(
self.path_points[-2][0],
self.path_points[-2][1],
self.path_points[-1][0],
self.path_points[-1][1],
fill='blue',
width=2
)
# Update canvas
self.root.update()
def set_motors(self, pid):
"""Set motor speeds"""
base_speed = self.main_speed
error_abs = abs(self.error)
if error_abs > 400:
base_speed = self.main_speed * 0.3
elif error_abs > 200:
base_speed = self.main_speed * 0.5
elif error_abs > 100:
base_speed = self.main_speed * 0.7
if pid < 0:
right_speed = base_speed + abs(pid)
left_speed = base_speed * (1 - abs(pid)/100)
else:
right_speed = base_speed * (1 - abs(pid)/100)
left_speed = base_speed + abs(pid)
right_speed = min(100, max(-100, right_speed))
left_speed = min(100, max(-100, left_speed))
self.m.set_duty_cycle(0, -left_speed)
self.m.set_duty_cycle(1, right_speed)
# Update GUI
self.update_robot_position(left_speed, right_speed)
def clear_path(self):
"""Clear path"""
self.canvas.delete("all")
self.path_points = []
self.robot_x = 600
self.robot_y = 400
self.robot_angle = 0
# Redraw robot and direction line
self.robot = self.canvas.create_rectangle(
self.robot_x - self.robot_size,
self.robot_y - self.robot_size,
self.robot_x + self.robot_size,
self.robot_y + self.robot_size,
fill='red'
)
self.direction = self.canvas.create_line(
self.robot_x,
self.robot_y,
self.robot_x + self.robot_size * math.cos(self.robot_angle),
self.robot_y - self.robot_size * math.sin(self.robot_angle),
fill='black',
width=2
)
def start(self):
"""Start the robot"""
self.running = True
self.run()
def stop(self):
"""Stop the robot"""
self.running = False
self.m.set_duty_cycle(0, 0)
self.m.set_duty_cycle(1, 0)
def run(self):
"""Main operation loop"""
if not self.setup():
print("Setup failed!")
return
print("Starting robot...")
try:
while self.running:
position = self.read_line()
if position is not None:
pid = self.calculate_pid(position)
self.set_motors(pid)
self.root.update()
time.sleep(0.001)
except KeyboardInterrupt:
print("\nStopping program...")
finally:
self.m.set_duty_cycle(0, 0)
self.m.set_duty_cycle(1, 0)
def USB_Port():
ports = list(comports())
usb_names = {
"Windows": ["USB Serial Port"],
"Linux": ["/dev/ttyUSB"],
"Darwin": [
"/dev/tty.usbserial",
"/dev/tty.usbmodem",
"/dev/tty.SLAB_USBtoUART",
"/dev/tty.wchusbserial",
"/dev/cu.usbserial",
"/dev/cu.usbmodem",
"/dev/cu.SLAB_USBtoUART",
"/dev/cu.wchusbserial",
]
}
os_name = system()
if ports:
for port, desc, hwid in sorted(ports):
if any(name in port or name in desc for name in usb_names.get(os_name, [])):
print("Connect")
return port
# Eğer uygun port bulunmazsa mevcut portları yazdır
print("Mevcut portlar:")
for port, desc, hwid in ports:
print(f"Port: {port}, Açıklama: {desc}, HWID: {hwid}")
else:
print("Port not found!")
return None
def main():
port = USB_Port()
if port:
print(f"Port found: {port}")
robot = LineFollower(port)
robot.root.mainloop()
else:
print("Port not found!")
if __name__ == "__main__":
main()
