Turtle Boundary Controller — Assignment 2

A ROS2 package that makes a turtlesim turtle autonomously draw the boundaries of its domain. The behavior is interruptible: press SPACE at any time to take manual control via teleop.

Architecture

A Finite State Machine (FSM) drives the turtle through these states:

State	Description	Pen
MOVE_TO_BOUNDARY	Drives straight toward the nearest wall	UP
FOLLOW_BOUNDARY	Traces the perimeter rectangle counter-clockwise	DOWN
RETURN_HOME	Navigates back to initial position	UP
IDLE	Done — turtle stops	—
MANUAL	Teleop mode (entered/exited via SPACE)	unchanged

Nodes

• draw_boundaries_node — Main FSM controller. Subscribes to /turtle1/pose and /keyboard_input, publishes to /turtle1/cmd_vel, calls /turtle1/set_pen.
• keyboard_listener — Captures spacebar presses from terminal, publishes toggle_manual on /keyboard_input.
• turtlesim_node — Standard turtlesim.
• turtle_teleop_key — Standard turtlesim teleop for manual control.

Installation & Build

cd ~/robotics/ROS-TP2
colcon build
source install/setup.bash

Running

Launch everything at once

ros2 launch turtle_boundary_controller draw_boundaries.launch.py

This opens:

• The turtlesim window
• An xterm for the keyboard listener (press SPACE here to toggle manual mode)
• An xterm for turtle_teleop_key (use arrow keys when in manual mode)

Launch options

Option	Default	Description
speed	2.0	Maximum linear/angular speed
boundary_margin	0.5	Distance from wall edge defining the boundary

Example:

ros2 launch turtle_boundary_controller draw_boundaries.launch.py speed:=1.5 boundary_margin:=1.0

Usage

1. Launch the system — the turtle automatically starts moving toward the nearest wall
2. When it reaches the boundary, pen goes down and it traces the full perimeter counter-clockwise
3. After completing the rectangle, pen goes up and the turtle returns to its starting position
4. At any time, press SPACE in the keyboard listener terminal to enter manual mode
5. In manual mode, use arrow keys in the teleop terminal to move the turtle
6. Press SPACE again to resume autonomous boundary-following from the current position

Dependencies

• ROS2 Jazzy
• turtlesim
• xterm (for the launch file to open separate terminal windows)

Install xterm if needed:

sudo apt install xterm