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ROS–Unity Integration: Service

Create a simple Unity scene which calls a ROS service with a GameObject's position and rotation to receive a new position to move the GameObject towards.

Setting Up ROS

(Skip to Start the Position service if you already did the ROS–Unity Integration Publisher or Subscriber tutorials.)

Copy the tutorials/ros_packages/robotics_demo folder of this repo into the src folder in your Catkin workspace.
Follow the ROS–Unity Initial Setup guide.
Open a new terminal window, navigate to your ROS workspace, and run the following commands:
```
 source devel/setup.bash
 rosrun robotics_demo server_endpoint.py
```

Once the server_endpoint has started, it will print something similar to [INFO] [1603488341.950794]: Starting server on 192.168.50.149:10000.

Start the Position service

Open a new terminal window, navigate to your ROS workspace, and run the following commands:
```
 source devel/setup.bash
 rosrun robotics_demo position_service.py
```

Setting Up Unity Scene

Generate the C# code for PositionService's messages by going to Robotics -> Generate ROS Messages...
Set the input file path to PATH/TO/Unity-Robotics-Hub/tutorials/ros_packages/robotics_demo, expand the robotics_demo folder and click Build 2 srvs.

The generated files will be saved in the default directory Assets/RosMessages/RoboticsDemo/srv.
Create a script and name it RosServiceExample.cs
Paste the following code into RosServiceExample.cs
- Note: This script can be found at tutorials/ros_unity_integration/unity_scripts.

using RosMessageTypes.RoboticsDemo;
using UnityEngine;
using Unity.Robotics.ROSTCPConnector;

public class RosServiceExample : MonoBehaviour
{
    ROSConnection ros;

    public string serviceName = "pos_srv";

    public GameObject cube;

    // Cube movement conditions
    public float delta = 1.0f;
    public float speed = 2.0f;
    private Vector3 destination;

    float awaitingResponseUntilTimestamp = -1;

    void Start()
    {
        ros = ROSConnection.instance;
        destination = cube.transform.position;
    }

    private void Update()
    {
        // Move our position a step closer to the target.
        float step = speed * Time.deltaTime; // calculate distance to move
        cube.transform.position = Vector3.MoveTowards(cube.transform.position, destination, step);

        if (Vector3.Distance(cube.transform.position, destination) < delta && Time.time > awaitingResponseUntilTimestamp)
        {
            Debug.Log("Destination reached.");

            MPosRot cubePos = new MPosRot(
                cube.transform.position.x,
                cube.transform.position.y,
                cube.transform.position.z,
                cube.transform.rotation.x,
                cube.transform.rotation.y,
                cube.transform.rotation.z,
                cube.transform.rotation.w
            );

            MPositionServiceRequest positionServiceRequest = new MPositionServiceRequest(cubePos);

            // Send message to ROS and return the response
            ros.SendServiceMessage<MPositionServiceResponse>(serviceName, positionServiceRequest, Callback_Destination);
            awaitingResponseUntilTimestamp = Time.time+1.0f; // don't send again for 1 second, or until we receive a response
        }
    }

    void Callback_Destination(MPositionServiceResponse response)
    {
        awaitingResponseUntilTimestamp = -1;
        destination = new Vector3(response.output.pos_x, response.output.pos_y, response.output.pos_z);
        Debug.Log("New Destination: " + destination);
    }
}

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 RosService.
Attach the RosServiceExample script to the RosService GameObject. Drag the cube GameObject onto its cube parameter.
Pressing play in the Editor should start communication with the position_service script, running as a ROS node, causing the cube to move to random positions in the scene.

Please reference networking troubleshooting doc if any errors are thrown.

4.3 KiB 原始文件 文件历史

ROS–Unity Integration: Service

Setting Up ROS

Start the Position service

Setting Up Unity Scene

4.3 KiB

原始文件文件历史