ROS与C++入门教程-nodelet-Node封装为Nodelet

ROS与C++入门教程-nodelet-Node封装为Nodelet

说明：

• 介绍如何将节点封装为Nodelet

处理过程

• 查阅nodelet_tutorial_math例子
• 添加必要的#includes
• 去掉int main（）
• 继承子类 nodelet::Nodelet
• 将代码从构造函数移动到onInit()
• 添加PLUGINLIB_EXPORT_CLASS宏或PLUGINLIB_DECLARE_CLASS宏
• 在包manifest.xml或package.xml中对nodelet添加<build_depend> 和 <run_depend>依赖项。
• 请在包manifest.xml或package.xml部分中添加项
• 创建.xml文件以将nodelet定义为插件
• 对CMakeLists.txt进行必要的更改（注释掉一个rosbuild_add_executable，添加一个rosbuild_add_library）

代码库：

• https://github.com/ncnynl/example_pkg

最小的Nodelet

• 创建包example_pkg

cd ~/catkin_ws/src
catkin_create_pkg  example_pkg 

• 创建MyNodeletClass.h文件

cd ~/catkin_ws/src/example_pkg/
mkdir -p include/example_pkg
touch include/example_pkg/MyNodeletClass.h
vim include/example_pkg/MyNodeletClass.h

• 代码：

#include <nodelet/nodelet.h>
namespace example_pkg
{

    class MyNodeletClass : public nodelet::Nodelet
    {
        public:
            virtual void onInit();
    };

}

• 创建MyNodeletClass.cpp文件

cd ~/catkin_ws/src/example_pkg/
mkdir src
touch src/MyNodeletClass.cpp
vim src/MyNodeletClass.cpp

• 代码：

// this should really be in the implementation (.cpp file)
#include <ros/ros.h>
#include <pluginlib/class_list_macros.h>
#include <example_pkg/MyNodeletClass.h>


namespace example_pkg
{
    void MyNodeletClass::onInit()
    {
        NODELET_DEBUG("Initializing nodelet...");
        ROS_INFO("Nodelet is Ok for test!!");
    }
}

// watch the capitalization carefully
PLUGINLIB_DECLARE_CLASS(example_pkg, MyNodeletClass, example_pkg::MyNodeletClass, nodelet::Nodelet)

• 成功则输出"Nodelet is Ok for test!!"

• 创建nodelet_plugins.xml文件

cd ~/catkin_ws/src/example_pkg/
mkdir plugins
touch plugins/nodelet_plugins.xml
vim plugins/nodelet_plugins.xml

• 代码：

<library path="lib/libexample_pkg">
  <class name="example_pkg/MyNodeletClass" type="example_pkg::MyNodeletClass" base_class_type="nodelet::Nodelet">
  <description>
  This is my nodelet.
  </description>
  </class>
</library>

• 修改package.xml文件，增加：

cd ~/catkin_ws/src/example_pkg/
vim package.xml

• 代码：

  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>nodelet</build_depend>
  <build_depend>roscpp</build_depend>

  <run_depend>nodelet</run_depend>
  <run_depend>roscpp</run_depend>


  <!-- The export tag contains other, unspecified, tags -->
  <export>
    <!-- Other tools can request additional information be placed here -->
    <nodelet plugin="${prefix}/plugins/nodelet_plugins.xml" />
  </export>

• 修改CMakeLists.txt

cd ~/catkin_ws/src/example_pkg
vim  CMakeLists.txt 

• 内容：

cmake_minimum_required(VERSION 2.8.3)
project(example_pkg)

## 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 nodelet roscpp)
find_package(Boost REQUIRED)

catkin_package(
   INCLUDE_DIRS include
   LIBRARIES ${PROJECT_NAME}
   CATKIN_DEPENDS nodelet roscpp
)

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
  include
  ${catkin_INCLUDE_DIRS}
  ${Boost_INCLUDE_DIRS}
)

## Declare a C++ library
add_library(${PROJECT_NAME}  src/MyNodeletClass.cpp)

add_dependencies(${PROJECT_NAME} 
   ${${PROJECT_NAME}_EXPORTED_TARGETS} 
   ${catkin_EXPORTED_TARGETS}
)

target_link_libraries(${PROJECT_NAME}
   ${catkin_LIBRARIES}
)
                                          

• 创建mynodelet.launch文件

cd ~/catkin_ws/src/example_pkg/
mkdir launch
touch launch/mynodelet.launch
vim  launch/mynodelet.launch

• 代码：

<launch>
  <node pkg="nodelet" type="nodelet" name="standalone_nodelet"  args="manager" output="screen"/>

  <node pkg="nodelet" type="nodelet" name="MyNodeletClass" args="load example_pkg/MyNodeletClass standalone_nodelet" output="screen">
  </node>                 
</launch>

• 编译：

cd ~/catkin_ws/
catkin_make
rospack profile

测试：

• 新终端，运行roscore

$ roscore

• 新终端，运行launch

$ rosluanch examples_pkg mynodelet.launch

• 效果：

SUMMARY
========

PARAMETERS
 * /rosdistro: indigo
 * /rosversion: 1.11.16

NODES
  /
    MyNodeletClass (nodelet/nodelet)
    standalone_nodelet (nodelet/nodelet)

ROS_MASTER_URI=http://192.168.0.88:11311

core service [/rosout] found
process[standalone_nodelet-1]: started with pid [23420]
process[MyNodeletClass-2]: started with pid [23421]
[ INFO] [1488697612.246845992]: Loading nodelet /MyNodeletClass of type example_pkg/MyNodeletClass to manager standalone_nodelet with the following remappings:
[ INFO] [1488697612.289895137]: waitForService: Service [/standalone_nodelet/load_nodelet] has not been advertised, waiting...
[ INFO] [1488697612.521288394]: Initializing nodelet with 1 worker threads.
[ INFO] [1488697612.553078141]: waitForService: Service [/standalone_nodelet/load_nodelet] is now available.
[ INFO] [1488697612.831934104]: Nodelet is Ok for test!!
[ INFO] [1488697626.013265094]: Bond broken, exiting
[MyNodeletClass-2] process has finished cleanly
log file: /home/ubu/.ros/log/e1cb7ac4-0156-11e7-9599-1002b594fceb/MyNodeletClass-2*.log

• 输出[ INFO] [1488697612.831934104]: Nodelet is Ok for test!!