Skip to content

Latest commit

 

History

History
57 lines (30 loc) · 3.52 KB

part3_ros.md

File metadata and controls

57 lines (30 loc) · 3.52 KB

Part 3: ROS

This part includes how to add ROS communication scripts and set up the ROS node to communicate with robots in Unity.

To communicate between Unity and ROS, we need to define subscribers and publishers C# scripts, and launch an endpoint on the ROS side.

On the ROS side

  • Copy all the folders under ROS folder of this repository, and paste them to your catkin workspace. Build your catkin workspace again with catkin_make. Please note that if you don't find any files under ROS-TCP-Endpoint or teleop_twist_joy, you didn't correctly clone the repository. Remember to clone it with --recurse-submodules.

  • You don't necessarily need to change the IP adress in launch file, but you have to do that if you are using ports other than 10000.

  • Now you could launch ROS node by

    roslaunch freight_endpoint server.launch

On the Unity side

  • click Robotics in the menu bar and click ROS Settings. Change the IP Address to your IP. You can get the IP of your machine by hostname -I. This will generate a ROSConnectionPrefab in Assets/Resources, drag it to the Scene hierarchy.
  • With the nodes launched, run Unity, hit connect in the hub, and you should be able to see they are connected successfully.

To send and receive messages from ROS, we will still need some subscribers and publishers scripts to send and receive messages. Some of the codes are originated from ros-sharp and are modified to work with the new ROS-Unity framework.

Let's create a new empty game object called ROS under Freight to store ROS-related scripts, or you could also add the scripts to Freight/Plugins as the previous ones.

  • Now in Freight/ROS, Add Component, and search Subscriber and add Twist Subscriber. This script subscribes the twist message from the ROS side and send the control signal to the wheel controller to move the robot. Now drag and drop the Freight/Plugins into Wheel Controller slot, and set the maximum linear and angular speed. As we are using control command from ROS side now, don't forget to disable the Keyboard Control in Freight/Plugins.

    Run the Unity simulation and launch the ROS node, send commands to topic cmd_vel with packages like teleop_twist_joy. The robot should be able to follow your command.

image

  • In terms of publishers, in Freight/ROS, Add Component, search Publisher and add publishers: ROS Clock Publisher, ROS Transform Tree Publisher, Image Publisher, Laser Scan Publisher, Joint State Publisher, Pose Stamped Publisher and Twist Stamped Publisher, based on your need. Don't forget to drag and drop proper game objects and parameters (e.g. publish rate) after adding scripts.

image

  • You can view the sent image by

    rosrun image_view image_view image:=/camera/color/image_raw

    There are a few known issues with the camera publisher

    • This render mode does NOT support linear color space.
    • The renderer and encoder will slow down the frame rate dramatically. Disable it if you are not using it.

  • You can view the laser scan with Rviz. Add a laser scan, select the base_scan topic and change the global fixed frame to freight/base_link.

image

  • For the others, you could echo them to check if they are sent and received properly.

By now, you finish setting up a mobile robot demo, and you should have the same setup as the Scene RobotROS.

Proceed to Part 4: ROS Navigation