A-Star Path Planning - Turtlebot3 (Gazebo)

Project - 03 (Phase 02, Part-02) for the course, 'ENPM661 - Planning for Autonomous Robots' at the University of Maryland, College Park.

Implementation of the A-star algorithm for path planning of the Turtlebot3 robot with a Non-Holonomic action set in Gazebo.

Team Members:

• Kumara Ritvik Oruganti (117368963)
• Adarsh Malapaka (118119625)

Required Libraries:

• cv2 : To add lines or circles in the map at the desired coordinates.
• time: To calculate the running time for the Dijkstra algorithm.
• numpy: To define the obstacle map matrix
• heapq: Heap Queue to store opened_list nodes
• rospy: To import ROS functionalities into the code
• geometry_msgs.msg: To define Twist() velocity messages

Note: Make sure TurtleBot3 packages are installed in your catkin workspace.

Test Case:

Video Link: https://youtu.be/QSFRc_03UiY

[co-ordinates with respect to bottom left corner origin of the map in the PPT (scaled by 100)]

Note: The origin in Gazebo is in the center whereas the origin defined in the PPT is in the bottom-left corner.

Start-Node: (50, 50)   ---> Gazebo Map Coordinates: (-4.5, -4.5)

Goal-Node:  (600, 300)   ---> Gazebo Map Coordinates: (1.0, -2.0)

Robot Clearance: 10

RPM1: 50 

RPM2: 100

Initial Heading Angle: 0

Running the Code:

The code accepts the start and goal positions from the user through the command-line interface as mentioned below. Add the package into your the src directory of your catkin workspace and run catkin_make

Format/Syntax:

'roslaunch <package-name> <launch-file> <x_pos> <y_pos> <z_pos>'

Here: x_pos, y_pos, z_pos are optional arguments. Default: -4.5,-4.5, 0

Note: The map is scaled by 100. So, while giving the optional arguments, the user has to account for the start co-ordinates. For ex: (-4.5, -4.5) ---> (50, 50) (-4,-4) ---> (100, 100)

Test Case:

 ```
 roslaunch proj3_phase2_okritvik_amalapak turtlebot3_661_proj3.launch x_pos:=-4.5 y_pos:=-4.5 z_pos:=0.0
 
 Enter the robot's clearance: 10
 Enter Left Wheel Velocity in RPM: 200
 Enter Right Wheel Velocity in RPM: 300
 Enter the X Coordinate of the Start Node: 50
 Enter the Y Coordinate of the Start Node: 50
 Enter the X Coordinate of the Goal Node: 600
 Enter the Y Coordinate of the Goal Node: 300
 Enter the Initial Head Angle: 0 
 ```