ROS快速入门第三讲——ROS的Subscriber订阅者

Lucas在澳洲

优质创作者: python技术领域

2022-08-01 14:50:31

ROS的Subscriber订阅者

什么是订阅者

接收信息，通过ROS Topic接收来自其它Node的信息，并通过回调函数处理

通常用于监测系统状态，如当机器人关节到达限位位置时触发运动中断

ROS Topic示例

Topic通信过程为：

Publisher节点和Subscriber节点分别在Master进行注册
Publisher发布Topic
Subscriber在Master指挥下订阅Topic，从而建立起Pub-Sub之间的通信

Publisher Node Demo

#!/usr/bin/env python
#-- coding:UTF-8 --
import rospy
from std_msgs.msg import String

def push_msgs():
    rospy.init_node("push_node", anonymous=False)
    push_pub = rospy.Publisher("push", String, queue_size=10)
    rate = rospy.Rate(100)

    while not rospy.is_shutdown():
        msg = "hello world"
        push_pub.publish(msg)
        rospy.loginfo("send message %s", msg)
        rate.sleep()


if __name__ == "__main__":
    push_msgs()

Subscriber Node Demo

#!/usr/bin/env python
#-- coding:UTF-8 --
import rospy
from std_msgs.msg import String

def stringSubscriberCallback(data): #data的数据类型与Subscriber接收的Topic对应的消息类型一致
    rospy.loginfo('The contents of simple_topic: %s', data.data)

def stringSubscriber():
    rospy.init_node('sub_node', anonymous = False) #初始化ROS节点
    rospy.Subscriber('push', String, stringSubscriberCallback) #定义Subscriber对象

    rospy.spin()


if __name__ == "__main__":
    stringSubscriber()