ROS 命令以及相关内容学习（二）

在上一节中我们已经学习了package node topic message 这些的运行方式，下面我们去理解service 的运行方式。

1.sevice

#命令
rosservice list         print information about active services
rosservice call         call the service with the provided args
rosservice type         print service type
rosservice find         find services by service type
rosservice uri          print service ROSRPC uri
#例子
rosservice list
/clear
/kill
/reset
/rosout/get_loggers
/rosout/set_logger_level
/spawn
/teleop_turtle/get_loggers
/teleop_turtle/set_logger_level
/turtle1/set_pen
/turtle1/teleport_absolute
/turtle1/teleport_relative
/turtlesim/get_loggers
/turtlesim/set_logger_level
#另一个例子
rosservice type [service]

rosservice type /clear  #你会发现这个命令是没有什么东西，

 1.1 rosservice call [service] [args]

当你运行着一条的 
$ rosservice call /clear  
就可以清空小乌龟的轨迹哦。
运行着一条的时候
rosservice call /spawn 2 2 0.2 ""   
你会发现另一只小乌龟出现啦！

2 rosparam list查看参数

rosparam set [param_name]  #设置参数
rosparam get [param_name]  #得到参数
rosparam set /background_r 150  #把参数设置成150
rosparam get /background_g  #获得G的参数
rosparam get /  #获得所有参数

2.1  rosparam dump and rosparam load

rosparam dump [file_name] [namespace]  #将参数写进 。yaml文件中
rosparam load [file_name] [namespace]

rosparam dump params.yaml

rosparam load params.yaml copy
 rosparam get /copy/background_b

3. Using rqt_console and roslaunch 

rqt _console  and rqt_logger_level  是调试的可视化界面。

roslaunch  是一次性打开多个 节点

rosrun rqt_console rqt_console
rosrun rqt_logger_level rqt_logger_level

http://wiki.ros.org/ROS/Tutorials/UsingRqtconsoleRoslaunch#CA-21ef414cf4c910bb1286ff2aedfe349a32a099b9_1

先打开这两个界面然后就，打开node  就可以调试啦！。不懂就去参考wik 吧。

 

创建一个roslaunch文件，你可以在  之前建的工作空间，src/beginner… 中建一个lanunch 文件（这个文件的名字其实是随便取的。反正要存放的你的lanunch文件）之后我们来写一个launch文吧。

 1 cd ~/catkin_ws
 2  source devel/setup.bash
 3  roscd beginner_tutorials
 4 mkdir launch
 5  cd launch
 6 touch turtlemimic.launch 
 7 vi turtlemimic.launch 
 8 
 9 文件内容
10 <launch>                 #嘛 告诉你这是个lanunch 文件
11 
12   <group ns="turtlesim1">
13     <node pkg="turtlesim" name="sim" type="turtlesim_node"/>   #嘛 定义以下这个节点的名字呀，sim ，类型呀。
14   </group>
15 
16   <group ns="turtlesim2">                                      #第二个节点
17     <node pkg="turtlesim" name="sim" type="turtlesim_node"/>
18   </group>
19 
20   <node pkg="turtlesim" name="mimic" type="mimic">           #第三个节点，命令文件，可以让小乌龟跑哦。
21     <remap from="input" to="turtlesim1/turtle1"/>
22     <remap from="output" to= 　　"turtlesim2/turtle1"/>           # 运行之后，你能想想到，节点之间是怎么  传递 订阅消息哦的吗？
23   </node>
24 
25 </launch>

这样你运行  roslaunch beginner_tutorials turtlemimic.launch  你就会发现两只小乌龟出现啦！

然后你发不一条命令 rostopic pub /turtlesim1/turtle1/cmd_vel geometry_msgs/Twist -r 1 -- '[2.0, 0.0, 0.0]' '[0.0, 0.0, -1.8]'   两只小乌龟就可以动啦!

 

4.rosed [package_name] [filename] ROS 里面的vim。

5.Creating a ROS msg and srv

$ roscd beginner_tutorials
$ mkdir msg
$ echo "int64 num" > msg/Num.msg   #以上是创建msg 并且将int64 写入，也可以用其他方式写  

in package.xlm   make sure      #以下是告诉package，xml 以及 camke 我们要创建msg 
  <build_depend>message_generation</build_depend>
  <run_depend>message_runtime</run_depend>
in CMakeLists.txt  make sure 
find_package(catkin REQUIRED COMPONENTS
   roscpp
   rospy
   std_msgs
   message_generation
)
catkin_package(
  ...
  CATKIN_DEPENDS message_runtime ...
  ...)
add_message_files(
  FILES
  Num.msg
)
generate_messages(
  DEPENDENCIES
  std_msgs
)

查看一个信息。。
rosmsg show XX

PS：roscp [package_name] [file_to_copy_path] [copy_path]  ros 里买你的复制example：roscp rospy_tutorials AddTwoInts.srv srv/AddTwoInts.srv

然后去 工作空间下catkin_make install  就可以ˊ啦。就会生成相应的 msg srv 源码。你可以在以下路径下查看，py 跟cpp

~/catkin_ws/devel/lib/python2.7/dist-packages/beginner_tutorials/msg.

 ~/catkin_ws/devel/share/common-lisp/ros/beginner_tutorials/msg/. 

6.Writing the Publisher Node

$ wget https://raw.github.com/ros/ros_tutorials/kinetic-devel/rospy_tutorials/001_talker_listener/talker.py
$ chmod +x talker.py  #将下载的东西弄成可执行

#!/usr/bin/env python
# license removed for brevity
import rospy            
from std_msgs.msg import String

def talker():
    pub = rospy.Publisher('chatter', String, queue_size=10) #节点发送了chatter topic 以 msg type string 的形式
    rospy.init_node('talker', anonymous=True) # rospy.init_node(NAME)  是非常重要的，告诉了rospy 节点的名字，这样roscore 才可以管理
    rate = rospy.Rate(10) # 10hz 一中非常好的方法，可以循环。因为是没有 十分之一秒的/
    while not rospy.is_shutdown():
        hello_str = "hello world %s" % rospy.get_time()
        rospy.loginfo(hello_str)
        pub.publish(hello_str)
        rate.sleep()          #这段loop 是为你没有crlt+c 的时候，你可以一直保持稳定的运行。

if __name__ == '__main__':　　
    try:
        talker()
    except rospy.ROSInterruptException:
        pass

6.Writing the Subscriber Node

$ roscd beginner_tutorials/scripts/
$ wget https://raw.github.com/ros/ros_tutorials/kinetic-devel/rospy_tutorials/001_talker_listener/listener.py

#!/usr/bin/env python
import rospy
from std_msgs.msg import String

def callback(data):
    rospy.loginfo(rospy.get_caller_id() + "I heard %s", data.data)
    
def listener():

    # In ROS, nodes are uniquely named. If two nodes with the same
    # node are launched, the previous one is kicked off. The
    # anonymous=True flag means that rospy will choose a unique
    # name for our 'listener' node so that multiple listeners can
    # run simultaneously.
    rospy.init_node('listener', anonymous=True)

    rospy.Subscriber("chatter", String, callback)

    # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()

if __name__ == '__main__':
    listener()

 注意: 其实写  订阅以及 发送也是一个节点， 可以直接运行，你去运行试试吧。

7.Writing a Service Node

# Create the scripts/add_two_ints_server.py file within the beginner_tutorials package and paste the following inside it: 

#!/usr/bin/env python

from beginner_tutorials.srv import *
import rospy

def handle_add_two_ints(req):
    print "Returning [%s + %s = %s]"%(req.a, req.b, (req.a + req.b))
    return AddTwoIntsResponse(req.a + req.b)   #表示加法的
#实现发布 service
def add_two_ints_server():
    rospy.init_node('add_two_ints_server')
    s = rospy.Service('add_two_ints', AddTwoInts, handle_add_two_ints)
    print "Ready to add two ints."
    rospy.spin()    # 确保在没有结束这段程序之前，他就一直运行。

if __name__ == "__main__":
    add_two_ints_server()

 上面的  发布的，我们来写一个客户

#!/usr/bin/env python

import sys
import rospy
from beginner_tutorials.srv import *

def add_two_ints_client(x, y):
    rospy.wait_for_service('add_two_ints')  #等待 服务。
    try:
        add_two_ints = rospy.ServiceProxy('add_two_ints', AddTwoInts)
        resp1 = add_two_ints(x, y)
        return resp1.sum
    except rospy.ServiceException, e:
        print "Service call failed: %s"%e

def usage():
    return "%s [x y]"%sys.argv[0]

if __name__ == "__main__":
    if len(sys.argv) == 3:
        x = int(sys.argv[1])
        y = int(sys.argv[2])
    else:
        print usage()
        sys.exit(1)
    print "Requesting %s+%s"%(x, y)
    print "%s + %s = %s"%(x, y, add_two_ints_client(x, y))