ROS2学习

前言

本篇文章属于ROS2humble的学习笔记，来源于B站鱼香ROSup主。下面是这位up主的视频链接。本文为个人学习笔记，只能做参考，细节方面建议观看视频，肯定受益匪浅。

《ROS 2机器人开发从入门到实践》课程介绍_哔哩哔哩_bilibili

一、项目一（下载小说，并通过话题间隔5s发送一行）

（1）创建工作空间

在终端中输入：

mkdir -p topic_ws/src

（2）在src目录下创建软件包

处于src目录下，在终端中输入：

ros2 pkg create demo_python_topic --build-type ament_python --dependencies rclpy example_interfaces --license Apache-2.0

回到topic_ws目录下，再输入：

colcon build                 构建文件

 （3）在有__init__.py文件的目录下创建节点文件novel_pub_node.py，节点代码部分如下

import rclpy
from rclpy.node import Node
import requests
from example_interfaces.msg import String
from queue import Queue

class NovelNode(Node):
    def __init__(self, node_name):
        super().__init__(node_name)
        self.get_logger().info(f'{node_name},启动！')
        self.novel_queue = Queue()  #创建队列
        self.novel_publisher = self.create_publisher(String, 'novel', 100)
        self.create_timer(5, self.timer_callback)

    def timer_callback(self):
        if self.novel_queue.qsize()>0:
            line = self.novel_queue.get()
            msg = String()
            msg.data = line
            self.novel_publisher.publish(msg)
            self.get_logger().info(f'发布了：{msg}')

    def download(self, url):
        responese = requests.get(url)
        responese.encoding = 'utf-8'
        text = responese.text
        self.get_logger().info(f'下载{url},{len(text)}')
        for line in text.splitlines():
            self.novel_queue.put(line)


def main():
    rclpy.init()
    node = NovelNode('novel_pub')
    node.download('https://fanqienovel.com/reader/7173216089122439711?enter_from=page')
    rclpy.spin(node)
    rclpy.shutdown()

（4）执行代码

先找到

entry_points={

'console_scripts': [

],

},

改为

entry_points={

        'console_scripts': [

                'novel_pub_node=demo_python_topic.novel_pub_node:main'

],

},

等号左边是可执行文件的名字，等号右边是软件包名和节点名

然后回到 topic_ws目录下，再输入：

colcon build                 构建文件

再在终端中输入source install/setup.bash

修改一下环境变量

再运行即可：ros2 run demo_python_topic novel_pub_node

二、项目二（订阅小说并合成语音）

import espeakng
import rclpy
from rclpy.node import Node
from example_interfaces.msg import String
from queue import Queue
import threading
import time

class NovelSubNode(Node):
    def __init__(self, node_name):
        super().__init__(node_name)
        self.get_logger().info(f'{node_name},启动！')
        self.novel_queue = Queue()
        self.create_subscription(String, 'novel', self.novel_callback, 10)
        self.speech_thread_ = threading.Thread(target=self.speaker_thread)
        self.speech_thread_.start()

    def novel_callback(self, msg):
        self.novel_queue.put(msg.data)
        pass

    def speaker_thread(self):
        speaker = espeakng.Speaker()
        speaker.voice = 'zh'

        while rclpy.ok():   #检测ROS当前上下文是否ok
            if self.novel_queue.qsize()>0:
                text = self.novel_queue.get()
                self.get_logger().info(f'朗读：{text}')
                speaker.say(text)       #说
                speaker.wait()        #等说完
            else:
                #让当前线程休眠1s
                time.sleep(1)

def main():
    rclpy.init()
    node = NovelSubNode('novel_sub')
    rclpy.spin(node)
    rclpy.shutdown()

espeakng为朗读引入的库

注意当前线程休眠1s的操作很关键，这能降低CPU功耗