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Best practice for robot control

asked 2018-10-03 06:02:04 -0600

kumpakri gravatar image

I would like to design some control algorithm for a mobile robot in ROS and simulate it with Gazebo.

The goal is to develop such structure of the project to be able to switch the control mechanism from simulation to the real robot. So far I have following project structure:

robot_description
   ├ urdf
   | └ robot.urdf.xacro
   └ meshes
     └ robot_mesh.dae

robot_gazebo
   ├ launch
   | └ robot_world.launch
   ├ plugins
   | └ some_world_plugin
   |   └  SomeWorldPlugin.cc
   └ worlds
     └ robot.world

robot_control
   ├ config
   | └ robot_control.yaml
   └ launch
     └ robot_control.launch

robot_teleop
   ├ resource
   | └ gui_controller.ui
   ├ scripts
   | └ run_gui_controller.py
   └ src
     └ gui_teleop_plugin
       ├ __init__.py
       └ gui_teleop_plugin.py

I omit CMakeLists.txtx and package.xml files in every package in the above listing for simplicity.

The robot_description package contains .urdf model of the robot with all the links and joints defined. The .urdf file also includes a gazebo plugin libgazebo_ros_control.so to handle the <transmission> tags in the urdf model and load appropriate control manager.

The robot_gazebo package contains .world file with the simulation environment defined, a launch file that launches the world, spawns the robot from robot_description package and runs the controller from the robot_control package. It also contains a gazebo world plugin that is loaded in the .world file and publishes some messages to a custom ROS topic /robot/is_in_area (std_msgs::Bool carrying information about the position of the robot - is the robot at some specified position? True or False).

The robot_control package contains the definitions of the joint controllers, its pid and a .launch file that creates a topics for joints state and control commands: /robot/joint_state, /robot/joint1_controller/command etc.

The robot_teleop package contains a QT plugin to rqt. The GUI structure (widget) is defined in the gui_controller.ui file. The Plugin, signals and connections between buttons and functions are defined in the gui_teleop_plugin.py file. The push of the button calls a function which publishes into the /robot/joint1_controller/command topic. And the script for running the plugin is written in the run_gui_controller.py file.

This way I have a robot in my gazebo world simulation that can be controlled via GUI buttons on the screen and a topic that gets an information about whether the robot is at specific area or out of that area (SomeWorldPlugin.cc). This way it works and makes sense to me. If there is a best practice that contradict my structure, please, tell me.

Now I want to make an automatic controller that would move the robot and make decisions based on the state of the world/robot. I was thinking I would create a new package robot_auto or such, that would contain a gazebo model plugin. The model plugin would move the robot by publishing into the /robot/joint1_controller/command topic, just as the GUI does. And that I would read the /robot/is_in_area and change the robot direction when the robot is out of the area. The desired behavior is kind of bouncing off the area borders.

Now I'm not sure if that is the best idea. After all I wand the automatic control to ... (more)

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answered 2018-10-08 19:53:52 -0600

itfanr gravatar image

If you want to train your automatic control algrithm, the most important codes should be in robot_teleop.

Gazebo and real world robot both need joint_states_controllers and some_command_controllers.

And, I think you also need write a sensor model to extract data from gazebo and a hardware package to connect with your real robot.

eg: https://github.com/itfanr/elfin_robot

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Asked: 2018-10-03 06:02:04 -0600

Seen: 62 times

Last updated: Oct 03