The repository shows how to generate a simple exploring behavior on turtlebot. It uses laser scan messages being published to check if there is something in its vicinity. If there is then it rotates until it finds a free space and then goes again to explore the environment.
The dependencies of this repository are:
* Ubuntu 16.04
* ROS Kinetic Kame
* Turtlebot Packages
Before proceedigng to install ROS, ensure that version of Ubuntu is 16.04. To install ROS follow the steps given below:
$ sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'
$ sudo apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-key 421C365BD9FF1F717815A3895523BAEEB01FA116
$ sudo apt-get update
$ sudo apt-get install ros-kinetic-desktop-full
After installation of ROS, the next step is to initialize and install its dependencies using following commands:
$ rosdep init
$ rosdep update
The next step is to setup ROS environment which can be done using following commands:
$ echo "source /opt/ros/kinetic/setup.bash" >> ~/.bashrc
$ source ~/.bashrc
Following the environment setup, next step is to create the workspace.
$ cd <path where workspace needs to be created>
$ mkdir -p <name of workspace>
$ cd <workspace>
<workspace>$ catkin_make
Just like the path of the ROS was sourced in .bashrc file, same needs to be done for the workspace by writing source <path to workspace>/devel/setup.bash at the end of the .bashrc file.
This avoids the need to source every time one needs to use workspace's packages.
Other dependency for this repository is turtlebot packages which allow the use of turtlebot in gazebo. Please follow the instructions given below to install the packages:
<home> sudo apt-get install ros-kinetic-turtlebot-*
The command above installs all turtlebot packages instead of cherry picking them.
The code can be built by cloning the repository and executing following steps:
<home>$ cd <workspace>/src
<workspace>/src$ git clone https://github.com/nr-parikh/808X_week12_walker.git
<workspace>/src$ cd ..
<workspace>$ catkin_make
After cloning the repository and building it, there are two ways to run the code using rosrun or roslaunch commands. The steps to run using both of them are given below.
Please ensure that rosmaster is running before executing following steps. rosmaster can be started by following command.
<home>$ roscore
Before starting the node, it is necessary to launch the world in gazebo. This can be done as follows:
<home>$ roslaunch turtlebot_gazebo turtlebot_world.launch
To start the turtlebot_walker node follow the steps given below:
<home>$ rosrun 808X_week12_walker walker_node
The launch file in this repository launches two things viz. turtlebot_world and the walker_node.
<home>$ roslaunch 808X_week12_walker turtlebot_walker.launch
Please note here that it is not mandatory to start rosmaster node while using launch file. It starts when the file is launched if it is not running. The command above will launch the node with default string in the launch file.
turtlebot_walker launch file of this package accepts a flag record that can be used to record the bag file which will record all the data that is being published. By default, the launch file will not record a bag file. It will save the file in results directory. This can be done using following commands:
<home>$ roslaunch 808X_week12_walker turtlebot_walker.launch record:=true
The launch file also accepts a flag which can be used to set how much duration should the bag file record. The flag is duration. The default value of this flag is 45 seconds however it can be changed as follows:
<home>$ roslaunch 808X_week12_walker turtlebot_walker.launch record:=true duration:=30
This command will record the bag file for 30 seconds.
A sample bag file is included in the results directory. The info of this bag file which can be obtained using rosbag info <../808X_week12_walker/results/turtlebot_walker.bag> looks like below:
path: results/turtlebot_walker.bag
version: 2.0
duration: 44.9s
start: Dec 31 1969 19:00:00.29 (0.29)
end: Dec 31 1969 19:00:45.17 (45.17)
size: 17.4 MB
messages: 33827
compression: none [23/23 chunks]
types: bond/Status [eacc84bf5d65b6777d4c50f463dfb9c8]
dynamic_reconfigure/Config [958f16a05573709014982821e6822580]
dynamic_reconfigure/ConfigDescription [757ce9d44ba8ddd801bb30bc456f946f]
gazebo_msgs/LinkStates [48c080191eb15c41858319b4d8a609c2]
gazebo_msgs/ModelStates [48c080191eb15c41858319b4d8a609c2]
geometry_msgs/Twist [9f195f881246fdfa2798d1d3eebca84a]
nav_msgs/Odometry [cd5e73d190d741a2f92e81eda573aca7]
rosgraph_msgs/Clock [a9c97c1d230cfc112e270351a944ee47]
rosgraph_msgs/Log [acffd30cd6b6de30f120938c17c593fb]
sensor_msgs/Imu [6a62c6daae103f4ff57a132d6f95cec2]
sensor_msgs/JointState [3066dcd76a6cfaef579bd0f34173e9fd]
sensor_msgs/LaserScan [90c7ef2dc6895d81024acba2ac42f369]
std_msgs/String [992ce8a1687cec8c8bd883ec73ca41d1]
tf2_msgs/TFMessage [94810edda583a504dfda3829e70d7eec]
topics: /clock 4492 msgs : rosgraph_msgs/Clock
/cmd_vel_mux/active 1 msg : std_msgs/String
/cmd_vel_mux/input/navi 448 msgs : geometry_msgs/Twist
/cmd_vel_mux/parameter_descriptions 1 msg : dynamic_reconfigure/ConfigDescription
/cmd_vel_mux/parameter_updates 1 msg : dynamic_reconfigure/Config
/depthimage_to_laserscan/parameter_descriptions 1 msg : dynamic_reconfigure/ConfigDescription
/depthimage_to_laserscan/parameter_updates 1 msg : dynamic_reconfigure/Config
/gazebo/link_states 4486 msgs : gazebo_msgs/LinkStates
/gazebo/model_states 4486 msgs : gazebo_msgs/ModelStates
/gazebo/parameter_descriptions 1 msg : dynamic_reconfigure/ConfigDescription
/gazebo/parameter_updates 1 msg : dynamic_reconfigure/Config
/joint_states 4373 msgs : sensor_msgs/JointState
/laserscan_nodelet_manager/bond 88 msgs : bond/Status (2 connections)
/mobile_base/commands/velocity 437 msgs : geometry_msgs/Twist
/mobile_base/sensors/imu_data 4373 msgs : sensor_msgs/Imu
/mobile_base_nodelet_manager/bond 176 msgs : bond/Status (3 connections)
/odom 4370 msgs : nav_msgs/Odometry
/rosout 48 msgs : rosgraph_msgs/Log (9 connections)
/rosout_agg 31 msgs : rosgraph_msgs/Log
/scan 433 msgs : sensor_msgs/LaserScan
/tf 5578 msgs : tf2_msgs/TFMessage (2 connections)
/tf_static 1 msg : tf2_msgs/TFMessage
NOTE: The launch file doesn't record any data related to camera.
The provided sample bag file or any recorded bag file using the instructions provided above can be played by following the commands given below:
<home>$ cd <worskpace>/src/808X_week12_walker/results
<../results>$ rosbag play turtlebot_walker.bag
One will see the output similar to the sample output given below.
nrparikh@ubuntu:~/catkin_ws/src/808X_week12_walker$ rosbag play results/turtlebot_walker.bag
WARNING: Catkin package name "808X_week12_walker" does not follow the naming conventions. It should start with a lower case letter and only contain lower case letters, digits, and underscores.
[ INFO] [1511244506.044792480]: Opening results/turtlebot_walker.bag
Waiting 0.2 seconds after advertising topics... done.
Hit space to toggle paused, or 's' to step.
[RUNNING] Bag Time: 2.890364 Duration: 2.600364 / 44.880000 44506.03
One can use, space key to toggle between pause and play. Pressing s key will skip to the next nearest second value.
While playing the bag file, one can echo a topic to see what is being published on the that topic and to analyze the behavior of the robot. To do this, please ensure that the bag file is being played. In other terminal execute the following command:
<home>$ rostopic echo <topic which needs to be checked>
For example, if one wants to check the topic /cmd_vel_mux/input/navi this can be one as follows after running the bag file:
<home>$ rostopic echo /cmd_vel_mux/input/navi
NOTE: Please note that Gazebo should not be running while playing the bag file.