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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

(You can skip this 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 RosMessageGeneration -> AutoGenerateServices -> Single Service...
Set the input file path to PATH/TO/Unity-Robotics-Hub/tutorials/ros_packages/robotics_demo/srv/PositionService.srv and click GENERATE!
- The generated files will be saved in the default directory Assets/RosMessages/srv
Create a script and name it RosServiceExample.cs
Paste the following code into RosServiceExample.cs
Note Script can be found at tutorials/ros_unity_integration/unity_scripts

using System;
using RosMessageTypes.RoboticsDemo;
using UnityEngine;
using Debug = UnityEngine.Debug;

public class RosServiceExample : MonoBehaviour
{
    public 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()
    {
        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.");

            PosRot cubePos = new PosRot(
                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
            );

            PositionServiceRequest positionServiceRequest = new PositionServiceRequest(cubePos);

            // Send message to ROS and return the response
            ros.SendServiceMessage<PositionServiceResponse>(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(PositionServiceResponse response)
    {
        awaitingResponseUntilTimestamp = -1;
        destination = new Vector3(response.output.pos_x, response.output.pos_y, response.output.pos_z);
        Debug.Log("New Destination: " + destination);
    }
}

Create an empty GameObject, name it RosConnection, and attach the Plugins/TCPConnection/ROSConnection script to it. (Or, if you're reusing the same scene from the previous tutorials, you can just keep the existing RosConnection object.)
In the Inspector window of the Editor change the Host Name variable on the RosConnection GameObject to the ROS IP.
Create another empty GameObject and name it RosService.
Attach the RosServiceExample script to the RosService GameObject. Drag the cube GameObject onto its cube parameter and the RosConnection GameObject onto its Ros 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.

4.4 KiB 原始文件 文件历史

ROS–Unity Integration: Service

Setting Up ROS

Start the Position service

Setting Up Unity Scene

4.4 KiB

原始文件文件历史