ROS2时间同步(python)

乎语百科 117 0

最近1周一直研究ROS2的时间同步,翻越很多博客,很少有人使用ROS2进行时间同步的代码,无奈不断尝试与源码阅读,终于将其搞定,

为此,本博客将介绍基于python的ROS2的时间同步方法。

本博客内容结构为话题发布代码,话题订阅与时间同步代码,代码文件夹结构及结果显示图片。本博客假设2个publisher和一个scribe,同步是在scibe中完成。

一.话题发布代码

发布1为第二个发布者,可理解为某传感器

publisher1代码如下:

#!/usr/bin/env python3
import rclpy
from rclpy.node import Node
from std_msgs.msg import String,Float32,Int32
import cv2
# from std_msgs.msg import Header
import time
class NodePublisher(Node):
    def __init__(self,name):
        super().__init__(name)
        self.get_logger().info("大家好,我是%s!" % name)
        self.num=0
        self.command_publisher1 = self.create_publisher(Int32,"command1", 10)
        self.timer = self.create_timer(0.4, self.timer_callback)  #
        # self.inputdata1()
    def inputdata1(self):
        msg = Int32() #String()
        period=0.5
        print("publisher1-周期",period)
        self.get_logger().info(f'发布了指令:{msg.data}')    #打印一下发布的数据
        num=0
        while True:
            num=num+1
            msg.data = num #str(num)

            self.command_publisher_.publish(msg)
            # time.sleep(period)
            self.get_logger().info(f'发布了指令:{msg.data}')    #打印一下发布的数据
    def timer_callback(self):
        msg = Int32() #String()
        self.num+=1
        msg.data = self.num #str(num)
        self.command_publisher1.publish(msg)
        self.get_logger().info(f'发布了指令:{msg.data}')    #打印一下发布的数据
def main(args=None):
    rclpy.init(args=args) # 初始化rclpy
    node = NodePublisher("topic_publisher1")  # 新建一个节点
    rclpy.spin(node) # 保持节点运行,检测是否收到退出指令(Ctrl+C)
    rclpy.shutdown() # 关闭rclpy

发布2为第二个发布者,可理解为某传感器

publisher2代码如下:

#!/usr/bin/env python3
import rclpy
from rclpy.node import Node
from std_msgs.msg import String,Float32,Int32
import time
class NodePublisher(Node):
    def __init__(self,name):
        super().__init__(name)
        self.get_logger().info("大家好,我是%s!" % name)
        self.num=0
        self.command_publisher2= self.create_publisher(Int32,"command2", 10)
        self.timer = self.create_timer(0.2, self.timer_callback)  #
    def timer_callback(self):
        msg = Int32() #String()
        self.num+=1
        msg.data = self.num #str(num)
        self.command_publisher2.publish(msg)
        self.get_logger().info(f'发布了指令:{msg.data}')    #打印一下发布的数据
def main(args=None):
    rclpy.init(args=args) # 初始化rclpy
    node = NodePublisher("topic_publisher2")  # 新建一个节点
    rclpy.spin(node) # 保持节点运行,检测是否收到退出指令(Ctrl+C)
    rclpy.shutdown() # 关闭rclpy

二.话题订阅及时间同步代码

订阅发布者信息,并将其同步,可理解为同步不同传感器

scriabe代码如下:

#!/usr/bin/env python3
import rclpy
from rclpy.node import Node
import message_filters
from std_msgs.msg import String,Float32,Int32
import message_filters
from sensor_msgs.msg import Image, CameraInfo
def callback(image_sub,info_sub):
    res=int(info_sub.data)-int(image_sub.data)
    print("publisher1:\t{}\tpubsher2:\t{}\t{}".format(str(image_sub.data),str(info_sub.data),res))
def main(args=None):
    rclpy.init(args=args) # 初始化rclpy
    scribe_node=Node('scribe_time')

    image_sub = message_filters.Subscriber(scribe_node, Int32,'command1')
    info_sub = message_filters.Subscriber(scribe_node, Int32,'command2')

    ts = message_filters.ApproximateTimeSynchronizer([image_sub, info_sub], 10, 0.1, allow_headerless=True) # allow_headerless=True,可以不使用时间戳
    # ts = message_filters.TimeSynchronizer([image_sub, info_sub], 10) # 这个需要时间戳才可调用
    ts.registerCallback(callback)
    rclpy.spin(scribe_node)
    rospy.spin()
    

三.参数配置及文件格式

setup.py设置如下:

from setuptools import setup
package_name = 'topic_time'
setup(
    name=package_name,
    version='0.0.0',
    packages=[package_name],
    data_files=[
        ('share/ament_index/resource_index/packages',
            ['resource/' + package_name]),
        ('share/' + package_name, ['package.xml']),
    ],
    install_requires=['setuptools'],
    zip_safe=True,
    maintainer='root',
    maintainer_email='root@todo.todo',
    description='TODO: Package description',
    license='TODO: License declaration',
    tests_require=['pytest'],
    entry_points={
        'console_scripts': [
        "publisher1_node = topic_time.publisher1:main",
        "publisher2_node = topic_time.publisher2:main",
        "subscribe_node = topic_time.subscribe:main",
        "subscribe2_node = topic_time.subscribe2:main"

        ],
    },
)

文件格式如下:

ROS2时间同步(python)

通过以上代码将可看到同步的scribe中发布1时间无间隔,发布2时间间隔为4,恰好与设置周期同等,结果显示如下:

ROS2时间同步(python)

标签: # python

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