The goal of this assignment is the development of a simulation in a 3D enviroment via Coppelia Simulator of a mobile robot.

In particular we have used the Pioneer P3DX as the model of the robot.

The package rt2_assignment1 was given. It contains four nodes and three custom services. It is used to get a random point in the space and control the robot to get it to that point. This package also contains two launch files. The first one sim.launch was given and it implements robot simulation in RViz and Gazibo. The second one is sim_coppelia.launch and it starts the four Ros nodes.

The second package is simExtROS. It is used to customize the Coppelia-Ros integration. However, all the messages needed from Coppelia are not custom ones and so they were already implemented in the package.

Regarding the simulation we have create a Coppelia's scene rt2_assignment1.ttt. Inside it we have deleted the default sensors of the P3DX, since there are no obstacles in the enviroment. We have also resized the floor because it was too small and the robot fell sometimes. In the script of the robot we have created a publisher to the topic /odom, which is used to publish the current position of the robot, and a subscriber to the topic /cmd_vel, which is used to receive the linear and angular velocities. The callback of the subscriber transforms the angular and linear velocities (from geometry_msgs/Twist message) to the differential velocities related to the two wheels of the P3DX and set them for the two motors (left and right). In the sysCall_actuation we get the Pose (Position plus Orientation) of the robot and we insert it in a nav_msgs/Odometry message. After that, we publish the message and wait (via the sleep function) 100 ms before restart the actuation function.

This project is developed and tested with ROS Noetic, it may not work properly with other ROS versions.

Linux:

Copy the two ROS packages (rt2_assignment1 and simExtROS) into your ROS workspace and build your workspace with the command catkin_make in the shell.

Linux:

First run the ros simulation:

roslaunch rt2_assignment1 sim_coppelia.launch

Run the Coppelia Sim (in your Coppelia's folder):

./coppeliaSim.sh

Open the Coppelia's scene rt2_assignment1.ttt

Riccardo Parosi – [email protected]

https://github.com/Parosi/github-link