Lesson 26 - Autonomous Frontier Exploration
Learning Objective
- Configure autonomous exploration profiles using
bot.setup_for_exploration(). - Launch and halt autonomous frontier mapping using
bot.start_explore()andbot.stop_explore(). - Monitor exploration state (
is_exploring()) and block for map completion usingbot.wait_for_map_complete().
Introduction
In unknown environments, manual driving or pre-planned waypoints are impossible. Autonomous frontier exploration algorithms analyze the boundaries (frontiers) between mapped free space and unmapped unknown space, directing the robot to drive to new frontiers until the entire room is mapped.
The bonicbot_bridge SDK provides automated exploration control managed by ExploreController.
Code
import time
from bonicbot_bridge import BonicBot
with BonicBot(host="192.168.0.188") as bot:
print("1. Configuring system for autonomous exploration mode...")
bot.setup_for_exploration()
print("2. Launching autonomous frontier exploration...")
bot.start_explore()
print("Is autonomous exploration active?", bot.is_exploring())
print("\n3. Waiting for map to complete (or timing out after 30s)...")
# Blocks while frontier exploration runs autonomously
map_finished = bot.wait_for_map_complete(timeout=30.0)
print("Exploration map complete status:", map_finished)
print("\n4. Halting autonomous exploration...")
bot.stop_explore()
print("Is exploration active after stop?", bot.is_exploring())
print("5. Saving complete map to robot storage...")
bot.save_map()Expected Output
Click to see expected output
Visual Output
Terminal Output
🤖 Connected to BonicBot at 192.168.29.52:9090
1. Configuring system for autonomous exploration mode...
2. Launching autonomous frontier exploration...
Is autonomous exploration active?: True
3. Waiting for map to complete (or timing out after 30s)...
Exploration map complete status: True
4. Halting autonomous exploration...
Is exploration active after stop?: False
5. Saving complete map to robot storage...
🔌 Disconnected from BonicBot🔧 Under the Hood
How ExploreController runs frontier mapping in autonomous.py
ExploreController runs frontier mapping in autonomous.pyExploreController in autonomous.py interfaces with ROS 2 explore_lite frontier exploration nodes. It monitors OccupancyGrid frontiers, selects target frontier goals, commands Nav2 trajectories, and detects when no unmapped frontiers remain.
Student Challenge
Challenge 1 — Python Only
Write a frontier detection decision function has_unmapped_frontiers(grid_data, threshold=5) that returns True if the count of unknown cells (-1) adjacent to free cells (0) exceeds threshold.
Click to see solution
def has_unmapped_frontiers(grid_data, threshold=5):
unknown_count = sum(1 for cell in grid_data if cell == -1)
return unknown_count >= threshold
sample_grid = [0, 0, -1, -1, -1, -1, -1, -1]
print("Frontiers remain:", has_unmapped_frontiers(sample_grid, 5))Challenge 2 — Robot
Create a complete autonomous mapping program: setup for exploration, launch exploration for 45 seconds, halt exploration, save the generated map file, and bookmark the final robot pose as "dock".
Click to see solution
import time
from bonicbot_bridge import BonicBot
with BonicBot(host="192.168.0.188") as bot:
print("Initializing autonomous frontier mapping pipeline...")
bot.setup_for_exploration()
bot.start_explore()
print("Exploring unmapped frontiers for 45 seconds...")
time.sleep(45.0)
print("Stopping exploration worker...")
bot.stop_explore()
print("Saving completed map file...")
bot.save_map()
print("Bookmarking final robot pose as 'dock'...")
bot.save_location("dock")
print("Autonomous mapping complete!")Quick Reference
Exploration Methods
| Method | Return Type | Description |
|---|---|---|
bot.setup_for_exploration() | bool | Configure system for autonomous frontier mapping |
bot.start_explore() | bool | Launch ROS 2 explore_lite frontier navigation worker |
bot.stop_explore() | bool | Terminate active autonomous exploration |
bot.is_exploring() | bool | Check if autonomous exploration worker is running |
bot.wait_for_map_complete(timeout) | bool | Block until no unexplored frontiers remain |
Reflection Questions
How does autonomous frontier exploration differ from manual teleop mapping or static waypoint navigation?
What safety mechanisms are active during start_explore() to prevent the robot from colliding with obstacles while seeking new frontiers?