Mbot2 Line Follower Code «UPDATED - 2027»

def search_for_line(self): """ When line is lost, search by rotating slowly Returns: True if line found, False if search timeout """ print("Line lost! Searching...") search_start = time.time() search_duration = 3 # Maximum search time (seconds) while time.time() - search_start < search_duration: sensors = self.read_line_sensors() position = self.calculate_line_position(sensors) if position is not None: print("Line found!") return True # Rotate slowly to search self.bot.set_left_motor_speed(self.MIN_SPEED) self.bot.set_right_motor_speed(-self.MIN_SPEED) time.sleep(0.05) print("Line search failed!") return False

def calibrate_sensors(self): """ Calibrate line sensors for current surface """ print("Calibrating line sensors...") print("Place robot on WHITE surface and press Enter") input() # Read white values white_values = [] for i in range(5): white_values.append(self.bot.get_line_sensor(i+1)) print(f"White readings: white_values") print("Place robot on BLACK line and press Enter") input() # Read black values black_values = [] for i in range(5): black_values.append(self.bot.get_line_sensor(i+1)) print(f"Black readings: black_values") print("Calibration complete!") return white_values, black_values

def follow_line(self, duration=None): """ Main line following loop Args: duration: Time to follow line in seconds (None = run until stopped) """ print("Starting line follower...") print("Press Ctrl+C to stop") try: running = True start_time = time.time() while running: # Check duration if duration and (time.time() - start_time) >= duration: print(f"Completed duration seconds of line following") break # Read sensors sensors = self.read_line_sensors() position = self.calculate_line_position(sensors) # Calculate time delta for PID current_time = time.time() dt = current_time - self.last_time self.last_time = current_time if position is not None: # Line detected - follow it self.line_lost_timer = 0 # Calculate error (0 = center) error = position # Get PID output turn_speed = self.pid_control(error, dt) # Dynamic speed adjustment based on how centered we are # Slower on turns, faster on straight lines speed_factor = 1.0 - (abs(error) * 0.2) current_base_speed = max(self.MIN_SPEED, self.BASE_SPEED * speed_factor) # Set motor speeds self.set_motor_speeds(current_base_speed, turn_speed) # Debug output print(f"Pos: position:+.2f | Turn: turn_speed:+5.1f | " f"Speed: current_base_speed:5.1f | Sensors: sensors") else: # No line detected - handle line loss self.line_lost_timer += dt if self.line_lost_timer > self.EMERGENCY_STOP_TIME: print("Line lost for too long!") self.stop() if self.search_for_line(): # Reset PID state after finding line self.reset_pid() continue else: print("Cannot find line. Stopping.") break else: # Short line loss - just stop and wait self.stop() print("Waiting for line...") # Small delay to prevent overwhelming the system time.sleep(0.02) except KeyboardInterrupt: print("\nStopped by user") finally: self.stop() mbot2 line follower code

def calculate_line_position(self, sensors): """ Calculate the line position as a weighted average Returns: position from -2.0 (far left) to +2.0 (far right), 0.0 = center, None if no line detected """ weighted_sum = 0 total_weight = 0 for i, reading in enumerate(sensors): if reading: # Line detected # Convert index to position: 0=-2, 1=-1, 2=0, 3=1, 4=2 position = i - 2 weighted_sum += position total_weight += 1 if total_weight > 0: return weighted_sum / total_weight else: return None # No line detected

class MBot2LineFollower: """Complete line follower implementation for MBot2 robot""" def search_for_line(self): """ When line is lost, search

def pid_control(self, error, dt): """ PID control algorithm Returns: turn speed (-MAX_TURN to +MAX_TURN) """ # Proportional term p_term = self.KP * error # Integral term (with anti-windup) self.integral += error * dt # Limit integral to prevent excessive accumulation integral_limit = 100 self.integral = max(-integral_limit, min(integral_limit, self.integral)) i_term = self.KI * self.integral # Derivative term derivative = (error - self.previous_error) / dt if dt > 0 else 0 d_term = self.KD * derivative # Calculate total turn speed turn_speed = p_term + i_term + d_term # Limit turn speed turn_speed = max(-self.MAX_TURN, min(self.MAX_TURN, turn_speed)) # Store values for next iteration self.previous_error = error return turn_speed

choice = input("\nSelect option: ").strip() Supports PID control for smooth tracking, speed adjustment,

""" MBot2 Line Follower Feature =========================== Uses the 5-channel line follower sensor to follow a black line on a white surface. Supports PID control for smooth tracking, speed adjustment, and emergency stop. """ import mbot2 import time import sys