Assignment2-ROS

This package is build on ROS-Melodic. This package has a urdf for a crawling robot (Snake inspired). This crawling robot is similar to serial manipulators without base in the way of construction.

The initial robot has 5 revolute joints and their position controllers. The robot's joints and link can be extended by modifing snake.urdf.xacro and adding <xacro:extra_link num="idx" parent="idx_parent"/>

The robot is controlled with position controllers, and there is a node that publish to the topics of the controllers with values that is from scaled and shifted sin function in order to perform an oscilation move to make the snake move. The advanced way to control the snake inspired robots is by using CPG (Central Pattern Generator) that is one of the methods that was inspired from animals in both invertebrate and vertebrateanimals for locomotion control, it is widely used in Crawling locomotion and can be used here for serpentine gait for snake-inspired robot. Also, there is Serpenoid Curve Control function, this function is used to generatethe joint rythm in order to control the snake-inspiredrobot to perform serpentine locomotion.

Requirements:

If ros-melodic-effort-controllers is not installed, you should install it:

    sudo apt install ros-melodic-effort-controllers

How to use it?

• To run only the robot in rviz

    roslaunch assignment2_ros rviz.launch model:=snake.urdf.xacro

• To run only the robot in Gazebo without controller

    roslaunch assignment2_ros gazebo.launch model:=snake.urdf.xacro

• To run the robot in rviz and Gazeob and use the poition controller

    roslaunch assignment2_ros snake.launch

Notes:

• In order to use nodes, in python you should make the files executable:

    chmod +x snake.py

• To clone the repo in different directory thann catkin_ws, you should link it to catkin_ws in order to compile the project:

    ln -s ~/repos/FoR_Fall20IU/assignment2_ros ~/catkin_ws/src/assignment2_ros

• In order to generate urdf tree from xacro files:

    rosrun xacro xacro -o snake.urdf snake.urdf.xacro
    check_urdf snake.urdf
    urdf_to_graphiz snake.urdf
    xdg-open snake.pdf

• In order to compile and make the catkin_ws:

    cd ~/catkin_ws
    catkin_make && source devel/setup.zsh