Unity-Robotics-Hub/tutorials/ros_unity_integration/unity_service.md

ROS–Unity Integration: UnityService

Create a simple Unity scene which runs a Service in Unity that takes a request with a GameObject's name and responds with the GameObject's pose (position and orientation) in the ROS coordinate system.

Setting Up ROS

• Follow the ROS–Unity Initial Setup guide if you haven't already done so.

Setting Up the Unity Scene

• Create a new C# script and name it RosUnityServiceExample.cs
• Paste the following code into RosUnityServiceExample.cs
  • (Alternatively, you can drag the script file into Unity from tutorials/ros_unity_integration/unity_scripts).

using RosMessageTypes.UnityRoboticsDemo;
using UnityEngine;
using Unity.Robotics.ROSTCPConnector;
using Unity.Robotics.ROSTCPConnector.ROSGeometry;

/// <summary>
/// Example demonstration of implementing a UnityService that receives a Request message from another ROS node and sends a Response back
/// </summary>
public class RosUnityServiceExample : MonoBehaviour
{
    ROSConnection ros;

    [SerializeField]
    string m_ServiceName = "obj_pose_srv";

    void Start()
    {
        // register the service with ROS
        ros = ROSConnection.instance;
        ros.RegisterUnityService<ObjectPoseServiceRequest>(m_ServiceName);
        ros.ImplementService<ObjectPoseServiceRequest>(m_ServiceName, GetObjectPose);
    }

    /// <summary>
    ///  Callback to respond to the request
    /// </summary>
    /// <param name="request">service request containing the object name</param>
    /// <returns>service response containing the object pose (or 0 if object not found)</returns>
    private ObjectPoseServiceResponse GetObjectPose(ObjectPoseServiceRequest request)
    {
        // process the service request
        Debug.Log("Received request for object: " + request.object_name);

        // prepare a response
        ObjectPoseServiceResponse objectPoseResponse = new ObjectPoseServiceResponse();
        // Find a game object with the requested name
        GameObject gameObject = GameObject.Find(request.object_name);
        if (gameObject)
        {
            // Fill-in the response with the object pose converted from Unity coordinate to ROS coordinate system
            objectPoseResponse.object_pose.position = gameObject.transform.position.To<FLU>();
            objectPoseResponse.object_pose.orientation = gameObject.transform.rotation.To<FLU>();
        }

        return objectPoseResponse;
    }
}

• From the main menu bar, open Robotics/ROS Settings, and change the ROS IP Address variable to the ROS IP.
• Create an empty GameObject and name it UnityService.
• Attach the RosUnityServiceExample script to the UnityService GameObject.
• Pressing play in the Editor should start running as a ROS node, waiting to accept ObjectPose requests. Once a connection to ROS has been established, a message will be printed on the ROS terminal similar to Connection from 172.17.0.1.

Start the Client

• On your ROS system, open a new terminal window, navigate to your ROS workspace, and run the following commands:

   source devel/setup.bash
   rosrun unity_robotics_demo object_pose_client.py Cube
  

  • If using ROS2, the command is:

     source install/setup.bash
     ros2 run unity_robotics_demo object_pose_client Cube
    

• This wil print an output similar to the following with the current pose information of the game object (note that the coordinates are converted to the ROS coordinate system in our Unity Service):

  Requesting pose for Cube
  Pose for Cube:
  position:
    x: 0.0
    y: -1.0
    z: 0.20000000298023224
  orientation:
    x: 0.0
    y: -0.0
    z: 0.0
    w: -1.0
  

You may replace Cube with the name of any other GameObject currently present in the Unity hierarchy.

• Alternatively you may also call the ROS service using rosservice call:

  rosservice call /obj_pose_srv Cube
  

  • If using ROS2, the command is:

     ros2 service call obj_pose_srv unity_robotics_demo_msgs/ObjectPoseService "{object_name: Cube}"
    

   object_pose:
    position:
      x: 0.0
      y: -1.0
      z: 0.20000000298023224
    orientation:
      x: 0.0
      y: -0.0
      z: 0.0
      w: -1.0