robot4ws_simulations

This package is used to load and run the simulation in Gazebo of the Archimede rover, with (not yet developed) or without the differential.

1. Installation

1.1 Ubuntu

Install Ubuntu 18.04 LTS

1.2 Install main packets

Download .deb from here. sudo apt install git

1.3 ROS

Follow the ROS install guide.

After installation go to ROS tutorial, as per the last step of the guide.

Follow Tutorial 1

1.4 MATLAB

Install matlab from mathworks

1.5 Simulation environment

1.5.1 Installation of the robot environment and model

If robot4ws_simulations exists as a folder in the repository, then copy the folder in catkin_ws. If not, clone this repo directly in catkin_ws.

Clone robot4ws_msgs in catkin_ws/src, then run catkin_make in catkin_ws/

Clone robot4ws_description in catkin_ws/src If using ROS kinetic git checkout kinetic If using ROS melodic git checkout melodic Then run catkin_make in catkin_ws/

Note: if an API error arises, run the following nano ~/.ignition/fuel/config.yaml Change the url from api.ignitionfuel.org to api.ignitionrobotics.org

1.5.2 Dependecies

• gazebo_realsense_plugin: repository
• robot4ws_description: repository
• robot4ws_kinematics: repository
• robot4ws_teleop_keyboard: repository
• robot4ws_teleop_controller: repository
• hector_gazebo_plugins: repository
• (Depends from the forked version of ros-realsense repository) realsense-ros-gazebo repository sudo apt-get install ros-melodic-hector-gazebo-plugins

2. Run environment

2.1 Run simulation environment

Everytime we open a Terminal we should do the following:

• Run source devel/setup.bash in catkin_ws/ to activate the workspace
• Run roslaunch robot4ws_simulations archimede_gazebo_basic.launch include_plugins:=true

2.2 Simulation environment reset

To reset the simulation run rosservice call /gazebo/reset_simulation "{}"

2.3 Extract simulation data from gazebo

The plugin /src/archimede_get_body_pose.cpp (header: /include/archimede_get_body_pose.h) writes on the HDD, at each timestep, the position and velocity data of the bodies specified in robot4ws_description. Data is a CSV file. This can be found usually in src/robot4ws_simulations/data/link_data, unless otherwise specified in robot4ws_description.

3. Robot control

3.1 Robot control variables

The robot is controlled using ROS messages. Some examples are in /src/robot4ws_simulations/.

In the simulation environment *_Secondary are not used. In the physical environment these are used as additional parameters for some types of motor control techniques.

Hub motors

1 - Rear right wheel 2 - Front right wheel 3 - Rear left wheel 4 - Front left wheel

Steer motors

5 - Rear right wheel 6 - Front right wheel 7 - Rear left wheel 8 - Front left wheel

Naming scheme example Hub motor for rear right wheel: One_Primary

3.2 Robot control via ROS in terminal

In /src/robot4ws_simulations/ there are some examples of messages to control the robot.

3.3 Robot control via ROS in MATLAB

Run the rover companion app /RoverMatlab/main.mlapp. At startup, no ROS node is detected. This is normal; press OK when prompted. When controlling hardware, the IP should be specified.

When simulating:

• Specify the namespace, in this case Archimede. When using the hardware robot, this is left blank.
• Check the Simulation checkbox.

Use the Teleop and Experimental testing tabs to control the robot.

To add a subscriber

In the app properties add the variable for the subscriber you want to subscribe to, e.g. gazebo_link_states_subscriber.

In initialize(app), in the simulation mode part of the if, add the subscription function call: app.gazebo_link_states_subscriber = rossubscriber("/gazebo/link_states");