Line Follower Robot with Obstacle Avoidance and Parking

A reactive programming implementation of an autonomous line-following robot with advanced features including obstacle detection, avoidance, and automated parking capabilities.

Overview

This project implements a sophisticated line-following robot using a state machine architecture. The robot can follow both white and black lines, navigate around obstacles, and perform autonomous parking maneuvers when reaching designated parking areas.

Team Member

• Kush Mangukiya (24M0769)
• Jasbir Singh Kalsi (24M0745)
• Ashutosh Birla (24M0752)

Youtube: https://youtu.be/zMgxWs5Z_Xk?si=6Dp6FS3DhlVpJRIx

Features

• Dual Line Following: Supports both white line and black line following
• Adaptive Calibration: Automatic sensor calibration during startup
• PID Control: Smooth line following with proportional-integral-derivative control
• Obstacle Detection: Three-sensor IR obstacle detection system
• Obstacle Avoidance: Right-hand wall following algorithm for obstacle navigation
• Autonomous Parking: Automatic parking detection and execution
• U-turn Recovery: Automatic recovery when line is lost
• State-based Architecture: Robust finite state machine implementation

Hardware Requirements

Sensors

• 5 Line Sensors: Array of IR sensors for line detection (sen[0] to sen[4])

  • sen[0]: Leftmost sensor
  • sen[1]: Left-center sensor
  • sen[2]: Center sensor
  • sen[3]: Right-center sensor
  • sen[4]: Rightmost sensor

• 3 Obstacle Sensors: IR proximity sensors for obstacle detection

  • irsenLeft: Left obstacle sensor
  • irsenFront: Front obstacle sensor
  • irsenRight: Right obstacle sensor

Actuators

• 2 Motors: Differential drive system
  • Left motor speed: v_l
  • Right motor speed: v_r
• Direction Control: Movement direction indicator

System States

1. WhitelineFollower

• Purpose: Initial calibration phase
• Duration: 3000 cycles for sensor averaging
• Function: Calculates baseline sensor values for white surface detection

2. Whiteline

• Purpose: White line following mode
• Features:
  • PID control with gains (Kp=3, Ki=0.001, Kd=1)
  • Speed adjustment based on error magnitude
  • Transition detection for line intersections

3. LineSwitch

• Purpose: Handles line color transitions (white to black)
• Features:
  • Modified PID gains (Kp=2, Ki=0.001, Kd=1)
  • Inverted sensor logic for black line detection
  • Right turn detection capability

4. Blackline

• Purpose: Black line following mode
• Features:
  • Enhanced PID control (Kp=3, Ki=0.001, Kd=1)
  • Intersection counting for parking detection
  • U-turn detection and recovery

5. Obstacle Avoidance States

ObstacleRight

• Turns right when obstacle detected
• Continues until left sensor clears

ObstacleForward

• Moves forward along obstacle edge
• Monitors for line reacquisition

ObstacleLeft

• Follows left wall of obstacle
• Handles complex obstacle shapes

ObstacleFinalRight

• Final turn to rejoin line after obstacle
• Ensures proper line reacquisition

6. Parking System

ParkingState

• Navigation Pattern: Follows predefined timing sequence
• Parking Detection: Uses IR sensors at specific intervals
• Decision Logic:
  • Both sensors clear → Go straight
  • Left clear, right blocked → Park right
  • Left blocked, right clear → Park left
  • Both blocked → Default left

Parkleft/Parkright

• Duration: 1800 cycles
• Phases:
  • Approach (500 cycles): Move forward
  • Turn (1200 cycles): Execute parking maneuver
  • Align (100 cycles): Final positioning

Stopstate

• Final state - robot stops permanently
• All outputs set to zero

Calibration Process

1. White Surface Calibration (3000 cycles):

   • Robot placed on white surface
   • Sensors accumulate baseline readings
   • Average values calculated automatically

2. Threshold Setting:

   • Black line threshold = white_average - 150
   • Binary conversion: sensor ≤ threshold → line detected