Second assignment for ME 495: Embedded Systems in Robotics, Northwestern University, Fall 2020.

This package contains nodes that accomplish two tasks:

1. Cause a TurtleBot to follow a configurable figure 8 trajectory. One has the option to run this code in real-life or in a Gazebo simulation. Either way it is accompanied by an RViz visualization.

2. Visualize a 2R arm that follows a trajectory where its y-position remains constant.

• turtlebot3

TurtleBot RVIz: https://youtu.be/BLI5nBEQBdw
TurtleBot IRL: https://youtu.be/CagvXUCvS04
Arm RViz: https://youtu.be/47MknIazwUA

1. Create a new workspace and clone this repositiory.

# Create a new workspace
mkdir -p ws/src

# clone the demonstration code
cd ws/src
git clone https://github.com/ME495-EmbeddedSystems/homework02-ctsaitsao turtlebot3_figure_eight

# return to ws root
cd ../

2. Build the workspace and activate it.

catkin_make install
. devel/setup.bash

3. To run the TurtleBot code in real life, create these three terminals:

   1. In the first one, create a ROS Master.

   roscore

   2. In the second one, SSH into a TurtleBot machine and run the startup launch file.

   ssh [email protected]
   roslaunch turtlebot3_bringup turtlebot3_robot.launch

   3. In the third, export the TurtleBot model (if this hasn't been done before) and run the main launch file.

   export TURTLEBOT3_MODEL=burger
   roslaunch turtlebot3_figure_eight figure_eight.launch

4. The 2R arm code runs two main nodes, arm_traj (which commands the arm trajectory) and arm_marker (which draws markers at the end-effector of the arm). To run the 2R arm code, run:

roslaunch turtlebot3_figure_eight arm_traj.launch

• TurtleBot configuration options:

  • Add the launch_gazebo:=True option to run the TurtleBot code in the Gazebo simulation.
  • Add the launch_rqt_plot:=True option to graph the x and y positions of the robot over time.
  • Add the launch_rviz=False option to not run RViz.

• 2R arm configuration options:

  • Add the display_markers:=False option to not display the markers at the end-effector frame of the arm.
  • The 2R arm can be manually controlled (without a trajectory) by running:

    roslaunch turtlebot3_figure_eight view_arm.launch launch_gui:=True

    This launch file is included in arm_traj.launch and runs the rviz, joint_state_publisher_gui, and robot_state_publisher nodes.

Handwritten calculations for the TurtleBot control velocity inputs v and w as well as the TurtleBot's trajectory parametric equations can be found in the doc folder.