Instructions

Initial steps:

1. Download comprobfall2018-hw3.zip

2. Unzip the folder inside $HOME/catkin_ws/src

3. Run the following commands to compile and source the setup script:

$ cd $HOME/catkin_ws
$ catkin_make
$ source devel/setup.bash

You might have to do rosdep update and rosdep install.

Running the software:

1. Open a terminal and run the following commands:

$ roscore &
$ rosparam set scan_noise <std.deviation of scan noise>
$ rosparam set rotation_noise <std.deviation of angular noise>
$ rosparam set translation_noise <std.deviation of linear noise>
$ export ROBOT_INITIAL_POSE="-x <x of start position> -y <y of start position>" 
$ roslaunch turtlebot_gazebo turtlebot_world.launch world_file:=<absolute path to world_x.world>

If you are running the experiment corresponding to map_x.txt, you must provide the absolute path to the world file world_x.world. The world files are located in folder $HOME/catkin_ws/src/comprobfall2018-hw3/turtlebot_simulator/turtlebot_gazebo/worlds.

2. In a separate terminal, run the controller service server by running:

   $ rosrun turtlebot_ctrl turtlebot_control.py
   

Subscribing to topics:

Topic: turtlebot_scan

/turtlebot_scan is a ROS topic that is published to by the node turtlebot_scan_handler, which is provided by us. The message description is defined by turtlebot_ctrl/TurtleBotScan.msg.

$ rosmsg show turtlebot_ctrl/TurtleBotScan

To see the messages getting published to the topic:

$ rostopic echo /turtlebot_scan

The message has one component: a float32 array called "ranges" of size 54. It contains range data within angle -30 degrees to +30 degrees.

Communicating with service:

Service: turtlebot_control

turtlebot_control is a ROS service provided by us, which uses the service description defined by turtlebot_ctrl/TurtleBotControl.srv.

$ rossrv show turtlebot_ctrl/TurtleBotControl

The srv file is divided into two parts, separated by a − − −. The top part of the srv file is the request, while the bottom part of the srv file is the response.

Generating trajectories:

1. Execute all the steps mentioned in the section "Running the software".

2. In a separate terminal, run the client:

   $ rosrun turtlebot_ctrl generate_data.py

3. Follow the instructions on the terminal to rotate/displace the turtlebot. ( Notice that when you press any rotation key, the turtlebot doesn't translate but rotates in its current position, and so this might not be visible. )

4. In the end when you press the key 's', a file called trajectories.txt will be generated in the current folder.

5. Sample trajectories are provided in https://github.com/rajanya/comprobfall2018-hw3/tree/master/turtlebot_maps/trajectories, where trajectories_x.txt corresponds to map_x.txt for x = 1,2,3,4,5,6,7. Here, scan_noise, rotation_noise, translation_noise are set to 0.0

Part B World: