Overview

Initialization

cd ~/Tasks
catkin_create_pkg noisy_turtle_playback roscpp nav_msgs gtest doxygen
cd noisy_turtle_playback
git init

Installing and setting up Turtlesim3

#Installing dependencies of turtlesim3
sudo apt-get update \
&& sudo apt-get install -y ros-noetic-joy ros-noetic-teleop-twist-joy \
ros-noetic-teleop-twist-keyboard ros-noetic-laser-proc \
ros-noetic-rgbd-launch ros-noetic-rosserial-arduino \
ros-noetic-rosserial-python ros-noetic-rosserial-client \
ros-noetic-rosserial-msgs ros-noetic-amcl ros-noetic-map-server \
ros-noetic-move-base ros-noetic-urdf ros-noetic-xacro \
ros-noetic-compressed-image-transport ros-noetic-rqt* ros-noetic-rviz \
ros-noetic-gmapping ros-noetic-navigation ros-noetic-interactive-markers
#Installing turtlebot3 via Debian packages
sudo apt-get update \
  && sudo apt-get install -y ros-noetic-dynamixel-sdk \
  ros-noetic-turtlebot3-msgs ros-noetic-turtlebot3

Controlling turtlebot3 using ROS and arrow keys

Initially, I didn't know the Keycodes for the arrow keys,
but I knew that this command lets people control the turtle1 in turtlesim using arrow keys:
rosrun turtlesim turtle_teleop_key

So, I checked its source code and found out that the relevant keycodes are:

#define KEYCODE_RIGHT 0x43
#define KEYCODE_LEFT 0x44
#define KEYCODE_UP 0x41
#define KEYCODE_DOWN 0x42
#define KEYCODE_Q 0x71

Now, since the official turtlebot3_teleop package doesn't use the arrow keys,
I cloned it:
git clone https://github.com/ROBOTIS-GIT/turtlebot3/
and created symlink to the package in the src folder of my workspace:
ln -s ~/git/turtlebot3/turtlebot3_teleop

Then edited the turtlebot3_teleop/nodes/turtlebot3_teleop_key file, finally turned it into this and saved it,
rebuilt the package using catkin build turtlebot3_teleop

In order to test it, I installed the following package:
sudo apt install ros-noetic-turtlebot3-simulations

Then, on one terminal I ran roslaunch turtlebot3_teleop turtlebot3_teleop_key.launch (after sourcing devel/setup.bash)
and, in another: roslaunch turtlebot3_gazebo turtlebot3_world.launch
(on both, export TURTLEBOT3_MODEL=waffle needs to be done first)

It worked totally fine

Recording topics into a bag file

Recorded all the topics that were being published using rosbag record --all

Kept recording while driving turtlebot3 for quite a while, and pressed Ctrl+C to finish recording.
The bag file ended up being 12.80 GB for some reason

Adding Gaussian Noise to the velocity of turtlebot3 and publishing it onto a new topic

Implementation Details:

• Odometry Readings (i.e. the /odom topic) have been used to get the velocity of turtlebot3 at a specific time
• while adding Gaussian Noise, all the other dimensions except linear: x and angular: z have been neglected i.e. only 2D Gaussian Noise has been generated and added to the velocity readings
• Parameters of the generated gaussian noise (Variance of $v_x$, $\omega_z$ and the Covariance between them) can be modified in config/config.yaml

Relevant source code can be found in the following files:

include/noisy_turtle_playback/GaussianNoiseGenerator.hpp src/GaussianNoiseGenerator.cpp include/noisy_turtle_playback/NoisyTurtlePlayback.hpp src/NoisyTurtlePlayback.cpp src/noisy_turtle_playback_node.cpp

Mathematical Explanation can be found in the documentation generated by doxygen
in order to view it, open the following file:
doc/html/index.html (requires generating documentation)

Much of the details can be found in the documentation for the generateGaussianNoise() and biVariateStandardNormal() functions of the noisy_turtle_playback::GaussianNoiseGenerator class

Testing

In order to run the gtest(Google Test) tests, run catkin test (or catkin test noisy_turtle_playback to avoid testing all the packages in the Workspace)

The tests were written in the following files:
test/GaussianNoiseGeneratorTest.cpp
test/test_noisy_turtle_playback.cpp

The test that I wrote, verifies that the evaluated Covariance Matrix of the generated noise is as expected (i.e. significantly close to the input Covariance Matrix)

Upon running the tests, the package succeeded

Running

In one terminal, I ran:

catkin build
source devel/setup.bash
roslaunch noisy_turtle_playback noisy_turtle_playback.launch 

In another:

rosbag play --loop --clock 2024-05-15-00-58-12.bag

To verify whether the noisy data was being published correctly, I ran
rostopic echo /noisy_turtle_playback/noisy/cmd_vel
and rostopic echo /odom
in two other terminals

on running, it works totally fine:

Generating Documentation

Doxygen was used to document this package

Here are the instructions to generate the documentation for this package on you local machine

Make sure you have latex installed:

sudo apt install texlive-latex-extra #installs latex
sudo apt install doxygen-latex #installs a few other dependencies

Move to the project's directory and run the following command to generate documentation in the doc folder:

doxygen Doxyfile