pluginlib-编写简单的插件

最新推荐文章于 2023-03-29 15:34:39 发布

zhangyang233

最新推荐文章于 2023-03-29 15:34:39 发布

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CC 4.0 BY-SA版权

分类专栏： ROS

本文链接：https://blog.youkuaiyun.com/zhangyang233/article/details/81914708

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1 篇文章

订阅专栏

本文详细介绍如何使用ROS的Pluginlib来创建和使用插件，包括定义基类、实现插件类、注册插件及使用插件的具体步骤。

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来源 http://wiki.ros.org/pluginlib/Tutorials/Writing%20and%20Using%20a%20Simple%20Plugin

代码解释参考https://www.ncnynl.com/archives/201702/1323.html

具体步骤如下

准备

进入工作空间

cd ~/pluginlib_ws/src/

创建pluginlib_tutorials_示例包

catkin_create_pkg pluginlib_tutorials_ roscpp pluginlib

1 创建插件库

1.1 创建基类

vim pluginlib_tutorials_/include/pluginlib_tutorials_/polygon_base.h

基类polygon_base.h代码：

#ifndef PLUGINLIB_TUTORIALS__POLYGON_BASE_H_
#define PLUGINLIB_TUTORIALS__POLYGON_BASE_H_

namespace polygon_base
{
  class RegularPolygon
  {
    public:
      virtual void initialize(double side_length) = 0;
      virtual double area() = 0;
      virtual ~RegularPolygon(){}

    protected:
      RegularPolygon(){}
  };
};
#endif

1.2 创建插件

vim pluginlib_tutorials_/include/pluginlib_tutorials_/polygon_plugins.h
代码如下：

#ifndef PLUGINLIB_TUTORIALS__POLYGON_PLUGINS_H_
#define PLUGINLIB_TUTORIALS__POLYGON_PLUGINS_H_
#include <pluginlib_tutorials_/polygon_base.h>
#include <cmath>

namespace polygon_plugins
{
  class Triangle : public polygon_base::RegularPolygon
  {
    public:
      Triangle(){}

      void initialize(double side_length)
      {
        side_length_ = side_length;
      }

      double area()
      {
        return 0.5 * side_length_ * getHeight();
      }

      double getHeight()
      {
        return sqrt((side_length_ * side_length_) - ((side_length_ / 2) * (side_length_ / 2)));
      }

    private:
      double side_length_;
  };

  class Square : public polygon_base::RegularPolygon
  {
    public:
      Square(){}

      void initialize(double side_length)
      {
        side_length_ = side_length;
      }

      double area()
      {
        return side_length_ * side_length_;
      }

    private:
      double side_length_;

  };
};
#endif

1.3 注册插件

vim pluginlib_tutorials_/src/polygon_plugins.cpp

代码如下：

#include <pluginlib/class_list_macros.h>
#include <pluginlib_tutorials_/polygon_base.h>
#include <pluginlib_tutorials_/polygon_plugins.h>

PLUGINLIB_EXPORT_CLASS(polygon_plugins::Triangle, polygon_base::RegularPolygon)
PLUGINLIB_EXPORT_CLASS(polygon_plugins::Square, polygon_base::RegularPolygon)

构建插件库

在CMakeLists.txt文件中添加

include_directories(include)
add_library(polygon_plugins src/polygon_plugins.cpp)

编译

2 使插件可用于ROS工具链

创建一个XML文件，还需要再包清单中的建立特殊导出行，就可以为ROS工具链提供有关插件的所有必要信息

2.1 创建XML文件

vim pluginlib_tutorials_/polygon_plugins.xml

polygon_plugins.xml位于包的顶层，与CMakeLists.txt和package.xml在一起

代码如下：

<library path="lib/libpolygon_plugins">
  <class type="polygon_plugins::Triangle" base_class_type="polygon_base::RegularPolygon">
    <description>This is a triangle plugin.</description>
  </class>
  <class type="polygon_plugins::Square" base_class_type="polygon_base::RegularPolygon">
    <description>This is a square plugin.</description>
  </class>
</library>

2.2 导出插件

在package.xml中添加

<export>
  <pluginlib_tutorials_ plugin="${prefix}/polygon_plugins.xml" />
</export>

验证是否生效：

rospack plugins --attrib=plugin pluginlib_tutorials_

如果生效，可以看见polygon_plugins.xml文件的完整路径

2.3 使用插件

vim pluginlib_tutorials_/src/polygon_loader.cpp

代码如下

#include <pluginlib/class_loader.h>
#include <pluginlib_tutorials_/polygon_base.h>

int main(int argc, char** argv)
{
  pluginlib::ClassLoader<polygon_base::RegularPolygon> poly_loader("pluginlib_tutorials_", "polygon_base::RegularPolygon");

  try
  {
    boost::shared_ptr<polygon_base::RegularPolygon> triangle = poly_loader.createInstance("polygon_plugins::Triangle");
    triangle->initialize(10.0);

    boost::shared_ptr<polygon_base::RegularPolygon> square = poly_loader.createInstance("polygon_plugins::Square");
    square->initialize(10.0);

    ROS_INFO("Triangle area: %.2f", triangle->area());
    ROS_INFO("Square area: %.2f", square->area());
  }
  catch(pluginlib::PluginlibException& ex)
  {
    ROS_ERROR("The plugin failed to load for some reason. Error: %s", ex.what());
  }

  return 0;
}

3 运行插件

在CMakeLists.txt文件中添加以下行

add_executable(polygon_loader src/polygon_loader.cpp)
target_link_libraries(polygon_loader ${catkin_LIBRARIES})

编译

运行

rosrun pluginlib_tutorials_ polygon_loader

[ INFO] [1534856640.660509344]: Triangle area: 43.30
[ INFO] [1534856640.660569938]: Square area: 100.00

完整工程见 https://github.com/YangFighting/ros_tutorial/tree/master/pluginlib_tutorials_

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