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ROS–Unity Integration: Server Endpoint

A walkthrough of the important components of a ROS TCP endpoint script using the robotics_demo package as a example.

The following is an example of a server endpoint Python script that:

Gets parameters from rosparam
Creates corresponding ROS Publisher, Subscriber, and Service objects to interact with topics and services running in in ROS network
Starts TCP Server process to handle incoming and outgoing connections

#!/usr/bin/env python

import rospy

from tcp_endpoint.RosTCPServer import TCPServer
from tcp_endpoint.RosPublisher import RosPublisher
from tcp_endpoint.RosSubscriber import RosSubscriber
from tcp_endpoint.RosService import RosService

from robotics_demo.msg import PosRot, UnityColor
from robotics_demo.srv import PositionService


def main():
	 # Get variables set in rosparam used for 
	 # server/node communication 
    ros_tcp_ip = rospy.get_param("/ROS_IP")
    ros_tcp_port = rospy.get_param("/ROS_TCP_PORT")

    ros_node_name = rospy.get_param("/TCP_NODE_NAME", 'TCPServer')

    unity_machine_ip = rospy.get_param("/UNITY_IP")
    unity_machine_port = rospy.get_param("/UNITY_SERVER_PORT")

    rospy.init_node(ros_node_name, anonymous=True)
    rate = rospy.Rate(10)  # 10hz

    # Create ROS communication objects dictionary for routing messages
    source_destination_dict = {
        'pos_srv': RosService('position_service', PositionService),
        'pos_rot': RosPublisher('pos_rot', PosRot, queue_size=10),
        'color': RosSubscriber('color', UnityColor, unity_machine_ip, unity_machine_port),
    }

    # Start the Server Endpoint
    tcp_server = TCPServer(ros_tcp_ip, ros_tcp_port, ros_node_name, source_destination_dict)
    tcp_server.start()
    rospy.spin()


if __name__ == "__main__":
    main()

Import Statements for Services and Messages

# TCP Endpoint package imports to enable ROS communication
from tcp_endpoint.RosTCPServer import TCPServer
from tcp_endpoint.RosPublisher import RosPublisher
from tcp_endpoint.RosSubscriber import RosSubscriber
from tcp_endpoint.RosService import RosService

# Import specific ROS Messages and Services
from robotics_demo.msg import PosRot, UnityColor
from robotics_demo.srv import PositionService

Instantiate the ROS Node

    rospy.init_node(ros_node_name, anonymous=True)
    rate = rospy.Rate(10)  # 10hz

ROS Publisher

A ROS Publisher requires three components:

Topic name
ROS message class generated from running catkin_make command
Queue size

RosPublisher('pos_rot', PosRot, queue_size=10)

ROS Subscriber

A ROS Subscriber requires four components:

Topic name
ROS message class generated from running catkin_make command
IP address of machine running Unity
Corresponding TCP port of machine running Unity

RosSubscriber('color', UnityColor, unity_machine_ip, unity_machine_port)

ROS Service

A ROS Service requires two components:

Service name
ROS Service class generated from running catkin_make command

RosService('position_service', PositionService)

Source Destination Dictionary

Create a dictionary keyed by topic or service with the corresponding ROS communication class as the value. The dictionary is used by the TCP server to direct messages to and from the ROS network.

    source_destination_dict = {
        'pos_srv': RosService('position_service', PositionService),
        'pos_rot': RosPublisher('pos_rot', PosRot, queue_size=10),
        'color': RosSubscriber('color', Color, unity_machine_ip, unity_machine_port),
    }

Starting the Server

Requires:

IP of machine the script will be executing on
The port to open for incoming connections
The ROS node name
Dictionary of service or topic names to corresponding class

    tcp_server = TCPServer(ros_tcp_ip, ros_tcp_port, ros_node_name, source_destination_dict)
    tcp_server.start()
    rospy.spin()

These values can be hardcoded, but for the sake of portability, we recommend setting the parameters using the rosparam set command, or a rosparam YAML file.

    ros_tcp_ip = rospy.get_param("/ROS_IP")
    ros_tcp_port = rospy.get_param("/ROS_TCP_PORT")

    ros_node_name = rospy.get_param("/TCP_NODE_NAME", 'TCPServer')

    unity_machine_ip = rospy.get_param("/UNITY_IP")
    unity_machine_port = rospy.get_param("/UNITY_SERVER_PORT")

Note: Read more about the ROS Parameter Server here.

Launch File

An example launch file that will set the appropriate ROSPARAM values required for a parameterized TCP Endpoint script.

<launch>

    <env name="ROS_IP" value="192.168.1.116"/>
    <env name="ROS_HOSTNAME" value="$(env ROS_IP)"/>
    
    <param name="ROS_IP" type="str" value="$(env ROS_IP)" />
    <param name="ROS_TCP_PORT" type="int" value="10000" />
    <param name="TCP_NODE_NAME" type="str" value="TCPServer" />

    <param name="UNITY_IP" type="str" value="192.168.1.105" />
    <param name="UNITY_SERVER_PORT" type="int" value="5005" />

	<group ns="position_service_and_endpoint">
	       <node pkg="robotics_demo" name="position_service" type="position_service.py"/>
	       <node pkg="robotics_demo" name="server_endpoint" type="server_endpoint.py"/>
	</group>
</launch>

5.2 KiB 原始文件 文件历史