Turtlebot Programming

• Start the Turtlebot simulator by following the steps from the previous lab.
• Download either approach.py or approach_oo.py .
• Execute the file by typing:

  python approach.py
  

  or

  python approach_oo.py
  

  inside the directory that contains the file. If all is well, the simulated robot should approach the wall in front of it.
• Make a copy of your file named wander.py and open it in your favorite text editor. (If you use gedit, make sure to configure it to insert spaces instead of tabs: Edit->Preferences->Editor-> Tab width 4, Insert spaces instead of tabs.)
• Modify the resulting file so that it allows the Turtlebot to wander around without colliding with obstacles. Feel free to use any strategy you like, but I suggest the following algorithm as a simple starting point:
• Move forward until the distance to the nearest obstacle is too small.
• Move a few inches backward, then turn a few degrees to the left.
• Repeat.
The Python time module can be used to determine the current system time in seconds:

import time
time.time()  # returns current time. 

This may be helpful in writing code that allows the robot to execute some operation for a fixed amount of time. For example: moving backward for exactly .4 seconds.
• Test and debug your program until it works to your satisfaction

Testing on a Real Robot

• Close down the simulator and obtain a Turtlebot.
• Plug in both USB cables and then type the following command in a terminal:

  roslaunch turtlebot_bringup minimal.launch
  

  If all goes well, the terminal should fill with notification messages and the robot should make a pleasant electronic start-up sound.
• Type the following in a separate terminal:

  roslaunch turtlebot_bringup 3dsensor.launch depth_registration:=false
  

  Ignore the warnings about missing calibration files.
• You should now be able to test both approach.py and wander.py on the real robot.
• Once you are satisfied with your wander.py, submit it through Canvas. Each group should only submit one file. Make sure the names of all group members are stored in the file.

Command-Line ROS

• Complete the Tutorials Understanding ROS Nodes and Understanding ROS Topics. Skip any steps in the tutorials that ask you to install software.