robotont_simple_simulator

A minimalistic simulator package for the Robotont robot, providing basic navigation capabilities with naive physics integration. This package includes a simple driver for basic movement and a navigator for goal-based navigation.

Installation

Prerequisites

• ROS2 Jazzy
• Colcon build tools

Install Dependencies

# Install required ROS2 packages
sudo apt update
sudo apt install ros-jazzy-nav2-msgs \
                 ros-jazzy-tf2-geometry-msgs \
                 ros-jazzy-teleop-twist-keyboard

# Install rosdep if not already installed
sudo apt install python3-rosdep

# Initialize rosdep (only needed once)
sudo rosdep init
rosdep update

Clone and Build

# Navigate to your ROS2 workspace src directory
cd ~/your_workspace/src

# Clone the repository
git clone https://github.com/robotont/robotont_simple_simulator

# Install package dependencies using rosdep
cd ~/your_workspace
rosdep install --from-paths src --ignore-src -r -y

# Build the package
colcon build --packages-select robotont_simple_simulator

# Source the workspace
source install/setup.bash

Package Components

This package provides two main components:

1. Simple Driver

A basic driver that integrates velocity commands into odometry using naive kinematic integration. When commanded to move at 1 m/s for 1 second, it will publish odometry confirming 1 meter translation.

2. Simple Navigator

A goal-based navigation node that accepts NavigateToPose actions and drives the robot to specified positions and orientations using simple proportional control.

Usage

Simple Driver

Launch the simple driver:

ros2 launch robotont_simple_simulator simple_driver.launch.py

Test with keyboard teleop:

# In a separate terminal
ros2 run teleop_twist_keyboard teleop_twist_keyboard

The driver will:

• Subscribe to /cmd_vel for velocity commands
• Publish to /odom with integrated odometry
• Broadcast TF transforms between odom and base_link

Simple Navigator

Launch the simple navigator with default parameters:

ros2 launch robotont_simple_simulator simple_navigator.launch.py

Launch with custom speed parameters:

# Launch with faster speeds
ros2 launch robotont_simple_simulator simple_navigator.launch.py linear_speed:=0.8 angular_speed:=1.5

# Launch with slower, more precise speeds
ros2 launch robotont_simple_simulator simple_navigator.launch.py linear_speed:=0.1 angular_speed:=0.3

# Override just one parameter
ros2 launch robotont_simple_simulator simple_navigator.launch.py linear_speed:=0.5

Test with action commands:

# Send a navigation goal to position (1.0, 2.0) with default orientation
ros2 action send_goal /navigate_to_pose nav2_msgs/action/NavigateToPose '{pose: {header: {frame_id: "map"}, pose: {position: {x: 1.0, y: 2.0, z: 0.0}, orientation: {w: 1.0}}}}'

# Send a goal with specific orientation (90 degrees rotation)
ros2 action send_goal /navigate_to_pose nav2_msgs/action/NavigateToPose '{pose: {header: {frame_id: "map"}, pose: {position: {x: 2.0, y: 1.0, z: 0.0}, orientation: {x: 0.0, y: 0.0, z: 0.707, w: 0.707}}}}'

The navigator will:

• Accept NavigateToPose action goals
• Drive the robot to the specified position
• Rotate to match the goal orientation
• Provide feedback during navigation
• Report success/failure upon completion

Topics and Services

Simple Driver

Subscribed Topics:

• /cmd_vel (geometry_msgs/Twist) - Velocity commands

Published Topics:

• /odom (nav_msgs/Odometry) - Robot odometry

TF Broadcasts:

• odom → base_link

Simple Navigator

Subscribed Topics:

• /odom (nav_msgs/Odometry) - Robot odometry for navigation

Published Topics:

• /cmd_vel (geometry_msgs/Twist) - Velocity commands to drive the robot

Action Servers:

• /navigate_to_pose (nav2_msgs/action/NavigateToPose) - Navigation goals

Parameters

Simple Navigator

• linear_speed: Maximum linear velocity (default: 0.2 m/s)
• angular_speed: Maximum angular velocity (default: 0.5 rad/s)

Navigation Behavior

The simple navigator uses a two-phase approach:

1. Phase 1: Navigate to the goal position while roughly facing the target
2. Phase 2: Once at position, rotate to match the exact goal orientation

The navigation uses simple proportional control with configurable speed limits and tolerance thresholds.

Limitations

This is a simple simulator with the following limitations:

• Naive kinematic integration (no physics simulation)
• No obstacle avoidance
• No path planning
• Basic proportional control only
• No sensor simulation

Contributing

When contributing to this package, please:

• Follow ROS2 coding standards
• Test both components thoroughly
• Update documentation as needed
• Maintain the simplicity principle

Credits

The simple_navigator_node was originally conceived and implemented by Märten Mikk as part of Robotics Technology course at the University of Tartu in 2025 spring semester.