topic_demo by roscpp
参考中国大学MOOC课程《机器人操作系统入门》
第一步:建立文件夹
cd catkin_ws/src
cd ..
catkin_make
第二步:
添加文件。pylistener.py, pytalker.py等
#pylistener.py
#!/usr/bin/env python
#coding=utf-8
import rospy
import math
#导入mgs到pkg中
from topic_demo.msg import gps
#回调函数输入的应该是msg
def callback(gps):
distance = math.sqrt(math.pow(gps.x, 2)+math.pow(gps.y, 2))
rospy.loginfo('Listener: GPS: distance=%f, state=%s', distance, gps.state)
def listener():
rospy.init_node('pylistener', anonymous=True)
#Subscriber函数第一个参数是topic的名称,第二个参数是接受的数据类型 第三个参数是回调函数的名称
rospy.Subscriber('gps_info', gps, callback)
rospy.spin()
if __name__ == '__main__':
listener()
然后是pytalker.py
#pytalker.py
#!/usr/bin/env python
#coding=utf-8
import rospy
#倒入自定义的数据类型
from topic_demo.msg import gps
def talker():
#Publisher 函数第一个参数是话题名称,第二个参数 数据类型,现在就是我们定义的msg 最后一个是缓冲区的大小
#queue_size: None(不建议) #这将设置为阻塞式同步收发模式!
#queue_size: 0(不建议)#这将设置为无限缓冲区模式,很危险!
#queue_size: 10 or more #一般情况下,设为10 。queue_size太大了会导致数据延迟不同步。
pub = rospy.Publisher('gps_info', gps , queue_size=10)
rospy.init_node('pytalker', anonymous=True)
#更新频率是1hz
rate = rospy.Rate(1)
x=1.0
y=2.0
state='working'
while not rospy.is_shutdown():
#计算距离
rospy.loginfo('Talker: GPS: x=%f ,y= %f',x,y)
pub.publish(gps(state,x,y))
x=1.03*x
y=1.01*y
rate.sleep()
if __name__ == '__main__':
talker()
把这两个文件放在scripts文件夹里
在src文件夹下面,建立CMakeLists文件夹(虽然py文件是脚本文件,可以直接运行,但是要生成topic_demo.msg还是需要添加依赖项与包等。
cmake_minimum_required(VERSION 2.8.3)
project(topic_demo)
## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)
## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTS
message_generation
roscpp
rospy
std_msgs
)
## Generate messages in the 'msg' folder
add_message_files(
FILES
gps.msg
# Message2.msg
)
## Generate added messages and services with any dependencies listed here
generate_messages(
DEPENDENCIES
std_msgs
)
###################################
## catkin specific configuration ##
###################################
## The catkin_package macro generates cmake config files for your package
## Declare things to be passed to dependent projects
## INCLUDE_DIRS: uncomment this if you package contains header files
## LIBRARIES: libraries you create in this project that dependent projects also need
## CATKIN_DEPENDS: catkin_packages dependent projects also need
## DEPENDS: system dependencies of this project that dependent projects also need
catkin_package(
# INCLUDE_DIRS include
# LIBRARIES publish_subscribe_demo
CATKIN_DEPENDS roscpp rospy std_msgs message_runtime
# DEPENDS system_lib
)
###########
## Build ##
###########
## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
include
${catkin_INCLUDE_DIRS}
)
添加package.xml文件,添加模板即可。
<?xml version="1.0"?>
<package>
<name>topic_demo</name>
<version>0.0.0</version>
<description>The publish_subscribe_demo package</description>
<!-- One maintainer tag required, multiple allowed, one person per tag -->
<!-- Example: -->
<!-- <maintainer email="[email protected]">Jane Doe</maintainer> -->
<maintainer email="[email protected]">davidhan</maintainer>
<!-- One license tag required, multiple allowed, one license per tag -->
<!-- Commonly used license strings: -->
<!-- BSD, MIT, Boost Software License, GPLv2, GPLv3, LGPLv2.1, LGPLv3 -->
<license>BSD</license>
<!-- Url tags are optional, but multiple are allowed, one per tag -->
<!-- Optional attribute type can be: website, bugtracker, or repository -->
<!-- Example: -->
<!-- <url type="website">http://wiki.ros.org/publish_subscribe_demo</url> -->
<!-- Author tags are optional, multiple are allowed, one per tag -->
<!-- Authors do not have to be maintainers, but could be -->
<!-- Example: -->
<!-- <author email="[email protected]">Jane Doe</author> -->
<!-- The *_depend tags are used to specify dependencies -->
<!-- Dependencies can be catkin packages or system dependencies -->
<!-- Examples: -->
<!-- Use build_depend for packages you need at compile time: -->
<!-- <build_depend>message_generation</build_depend> -->
<!-- Use buildtool_depend for build tool packages: -->
<!-- <buildtool_depend>catkin</buildtool_depend> -->
<!-- Use run_depend for packages you need at runtime: -->
<!-- <run_depend>message_runtime</run_depend> -->
<!-- Use test_depend for packages you need only for testing: -->
<!-- <test_depend>gtest</test_depend> -->
<buildtool_depend>catkin</buildtool_depend>
<build_depend>message_generation</build_depend>
<build_depend>roscpp</build_depend>
<build_depend>rospy</build_depend>
<build_depend>std_msgs</build_depend>
<run_depend>roscpp</run_depend>
<run_depend>rospy</run_depend>
<run_depend>std_msgs</run_depend>
<run_depend>message_runtime</run_depend>
<!-- The export tag contains other, unspecified, tags -->
<export>
<!-- Other tools can request additional information be placed here -->
</export>
</package>
最后,catkin_make
并且rosrun topic_demo listener.py
另开一个终端:rosrun topic_demo talker.py