ROS创建workspace跟简单的客户端服务器程序.

首先, 安装就不说了, 戳这里:

http://wiki.ros.org/cn/ROS/Tutorials

中文的哦.

装好后, 第一时间创建一个catkin的workspace:

source /opt/ros/kinetic/setup.bash

执行环境变量的脚本.

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws/src

创建workspace名字叫catkin_ws

对空目录进行初始化:

cd ~/catkin_ws/
catkin_make

看看是否目录是否被成功加入了, 不然的话ros不认识你的包

source devel/setup.bash
echo $ROS_PACKAGE_PATH

会看到workspace被加进去了.

接着是建第一包:

cd ~/catkin_ws/src
catkin_create_pkg beginner_tutorials std_msgs rospy roscpp

把包加进环境变量中:

. ~/catkin_ws/devel/setup.bash

查看包的依赖:

rospack depends1 beginner_tutorials

然后建srv, 这个srv具体是个什么鬼, 我还没搞明白.

roscd beginner_tutorials
mkdir srv

然后从别的地方拷贝一个srv过来:

roscp rospy_tutorials AddTwoInts.srv srv/AddTwoInts.srv

内容其实很简单:

topeet@ubuntu:~/catkin_ws/src/beginner_tutorials/srv$ cat AddTwoInts.srv
int64 a
int64 b
---
int64 sum

接着修改CMakeLists.txt, 增加对message-generation的依赖:

去掉下面的注释:

find_package(catkin REQUIRED COMPONENTS roscpp rospy std_msgs message_generation)

跟这个注释:

add_service_files(
  FILES
  AddTwoInts.srv
)

记得将srv名字改成你需要的srv文件名字.

检查srv内容:

rossrv show <service type>

把这个注释也去掉:

generate_messages(
  DEPENDENCIES
  std_msgs
)

然后重新编译一下:

# In your catkin workspace
$ cd ../..
$ catkin_make
$ cd -

接下来是写服务器端:

cd ~/catkin_ws/src/beginner_tutorials
vi src/add_two_ints_server.cpp

服务器端内容是:

#include "ros/ros.h"
#include "beginner_tutorials/AddTwoInts.h"

bool add(beginner_tutorials::AddTwoInts::Request  &req,
         beginner_tutorials::AddTwoInts::Response &res)
{
  res.sum = req.a + req.b;
  ROS_INFO("request: x=%ld, y=%ld", (long int)req.a, (long int)req.b);
  ROS_INFO("sending back response: [%ld]", (long int)res.sum);
  return true;
}

int main(int argc, char **argv)
{
  ros::init(argc, argv, "add_two_ints_server");
  ros::NodeHandle n;

  ros::ServiceServer service = n.advertiseService("add_two_ints", add);
  ROS_INFO("Ready to add two ints.");
  ros::spin();

  return 0;
}

然后是客户端:

src/add_two_ints_client.cpp

#include "ros/ros.h"
#include "beginner_tutorials/AddTwoInts.h"
#include <cstdlib>

int main(int argc, char **argv)
{
  ros::init(argc, argv, "add_two_ints_client");
  if (argc != 3)
  {
    ROS_INFO("usage: add_two_ints_client X Y");
    return 1;
  }

  ros::NodeHandle n;
  ros::ServiceClient client = n.serviceClient<beginner_tutorials::AddTwoInts>("add_two_ints");
  beginner_tutorials::AddTwoInts srv;
  srv.request.a = atoll(argv[1]);
  srv.request.b = atoll(argv[2]);
  if (client.call(srv))
  {
    ROS_INFO("Sum: %ld", (long int)srv.response.sum);
  }
  else
  {
    ROS_ERROR("Failed to call service add_two_ints");
    return 1;
  }

  return 0;
}

将下面的内容加入到CMakeLists.txt里面:

add_executable(add_two_ints_server src/add_two_ints_server.cpp)
target_link_libraries(add_two_ints_server ${catkin_LIBRARIES})
add_dependencies(add_two_ints_server beginner_tutorials_gencpp)

add_executable(add_two_ints_client src/add_two_ints_client.cpp)
target_link_libraries(add_two_ints_client ${catkin_LIBRARIES})
add_dependencies(add_two_ints_client beginner_tutorials_gencpp)

开始编译:

# In your catkin workspace
cd ~/catkin_ws
catkin_make

运行服务端:

rosrun beginner_tutorials add_two_ints_server

客户端:

rosrun beginner_tutorials add_two_ints_client 1 3

ok, 接下来是建消息服务.