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aciton 是 ROS 中异步通信的一种形式。 操作客户端向操作服务器发送目标请求。 动作服务器将目标反馈和结果发送给动作客户端。
将需要上一个 教程创建操作action_tutorials_interfaces中定义的包和接口。Fibonacci.action
cd ~/ros2_study/src
ros2 pkg create --dependencies action_tutorials_interfaces rclcpp rclcpp_action rclcpp_components -- action_tutorials_cpp
为了使该包能够在 Windows 上编译并运行,我们需要添加一些“可见性控制”。实验阶段可忽视
打开action_tutorials_cpp/include/action_tutorials_cpp/visibility_control.h,并输入以下代码:
#ifndef ACTION_TUTORIALS_CPP__VISIBILITY_CONTROL_H_ #define ACTION_TUTORIALS_CPP__VISIBILITY_CONTROL_H_ #ifdef __cplusplus extern "C" { #endif // This logic was borrowed (then namespaced) from the examples on the gcc wiki: // https://gcc.gnu.org/wiki/Visibility #if defined _WIN32 || defined __CYGWIN__ #ifdef __GNUC__ #define ACTION_TUTORIALS_CPP_EXPORT __attribute__ ((dllexport)) #define ACTION_TUTORIALS_CPP_IMPORT __attribute__ ((dllimport)) #else #define ACTION_TUTORIALS_CPP_EXPORT __declspec(dllexport) #define ACTION_TUTORIALS_CPP_IMPORT __declspec(dllimport) #endif #ifdef ACTION_TUTORIALS_CPP_BUILDING_DLL #define ACTION_TUTORIALS_CPP_PUBLIC ACTION_TUTORIALS_CPP_EXPORT #else #define ACTION_TUTORIALS_CPP_PUBLIC ACTION_TUTORIALS_CPP_IMPORT #endif #define ACTION_TUTORIALS_CPP_PUBLIC_TYPE ACTION_TUTORIALS_CPP_PUBLIC #define ACTION_TUTORIALS_CPP_LOCAL #else #define ACTION_TUTORIALS_CPP_EXPORT __attribute__ ((visibility("default"))) #define ACTION_TUTORIALS_CPP_IMPORT #if __GNUC__ >= 4 #define ACTION_TUTORIALS_CPP_PUBLIC __attribute__ ((visibility("default"))) #define ACTION_TUTORIALS_CPP_LOCAL __attribute__ ((visibility("hidden"))) #else #define ACTION_TUTORIALS_CPP_PUBLIC #define ACTION_TUTORIALS_CPP_LOCAL #endif #define ACTION_TUTORIALS_CPP_PUBLIC_TYPE #endif #ifdef __cplusplus } #endif #endif // ACTION_TUTORIALS_CPP__VISIBILITY_CONTROL_H_
动作服务器需要完成 一下 6 个操作:
模板化操作类型名称:Fibonacci。
将操作添加到的 ROS 2 节点
实例化 动作名称:‘fibonacci’.
用于处理目标的回调函数:handle_goal
用于处理取消的回调函数:handle_cancel。
用于处理目标accept:的回调函数handle_accept。
打开action_tutorials_cpp/src/fibonacci_action_server.cpp,并输入以下代码:
#include <functional> #include <memory> #include <thread> #include "action_tutorials_interfaces/action/fibonacci.hpp" #include "rclcpp/rclcpp.hpp" #include "rclcpp_action/rclcpp_action.hpp" #include "rclcpp_components/register_node_macro.hpp" #include "action_tutorials_cpp/visibility_control.h" namespace action_tutorials_cpp { class FibonacciActionServer : public rclcpp::Node { public: using Fibonacci = action_tutorials_interfaces::action::Fibonacci; using GoalHandleFibonacci = rclcpp_action::ServerGoalHandle<Fibonacci>; ACTION_TUTORIALS_CPP_PUBLIC explicit FibonacciActionServer(const rclcpp::NodeOptions & options = rclcpp::NodeOptions()) : Node("fibonacci_action_server", options) { using namespace std::placeholders; this->action_server_ = rclcpp_action::create_server<Fibonacci>( this, "fibonacci", std::bind(&FibonacciActionServer::handle_goal, this, _1, _2), std::bind(&FibonacciActionServer::handle_cancel, this, _1), std::bind(&FibonacciActionServer::handle_accepted, this, _1)); } private: rclcpp_action::Server<Fibonacci>::SharedPtr action_server_; rclcpp_action::GoalResponse handle_goal( const rclcpp_action::GoalUUID & uuid, std::shared_ptr<const Fibonacci::Goal> goal) { RCLCPP_INFO(this->get_logger(), "Received goal request with order %d", goal->order); (void)uuid; return rclcpp_action::GoalResponse::ACCEPT_AND_EXECUTE; } rclcpp_action::CancelResponse handle_cancel( const std::shared_ptr<GoalHandleFibonacci> goal_handle) { RCLCPP_INFO(this->get_logger(), "Received request to cancel goal"); (void)goal_handle; return rclcpp_action::CancelResponse::ACCEPT; } void handle_accepted(const std::shared_ptr<GoalHandleFibonacci> goal_handle) { using namespace std::placeholders; // this needs to return quickly to avoid blocking the executor, so spin up a new thread std::thread{std::bind(&FibonacciActionServer::execute, this, _1), goal_handle}.detach(); } void execute(const std::shared_ptr<GoalHandleFibonacci> goal_handle) { RCLCPP_INFO(this->get_logger(), "Executing goal"); rclcpp::Rate loop_rate(1); const auto goal = goal_handle->get_goal(); auto feedback = std::make_shared<Fibonacci::Feedback>(); auto & sequence = feedback->partial_sequence; sequence.push_back(0); sequence.push_back(1); auto result = std::make_shared<Fibonacci::Result>(); for (int i = 1; (i < goal->order) && rclcpp::ok(); ++i) { // Check if there is a cancel request if (goal_handle->is_canceling()) { result->sequence = sequence; goal_handle->canceled(result); RCLCPP_INFO(this->get_logger(), "Goal canceled"); return; } // Update sequence sequence.push_back(sequence[i] + sequence[i - 1]); // Publish feedback goal_handle->publish_feedback(feedback); RCLCPP_INFO(this->get_logger(), "Publish feedback"); loop_rate.sleep(); } // Check if goal is done if (rclcpp::ok()) { result->sequence = sequence; goal_handle->succeed(result); RCLCPP_INFO(this->get_logger(), "Goal succeeded"); } } }; // class FibonacciActionServer } // namespace action_tutorials_cpp RCLCPP_COMPONENTS_REGISTER_NODE(action_tutorials_cpp::FibonacciActionServer)
#include 的前几行包含我们需要编译的所有标头。
主要三部分:c++ 库,ros2 库,以及我们自定义的action 实体类
接下来我们创建一个类,它是以下类的派生类rclcpp::Node:
class FibonacciActionServer : public rclcpp::Node
该类的构造函数FibonacciActionServer将节点名称初始化为fibonacci_action_server:
explicit FibonacciActionServer(const rclcpp::NodeOptions & options = rclcpp::NodeOptions())
: Node("fibonacci_action_server", options)
构造函数还实例化一个新的操作服务器:
this->action_server_ = rclcpp_action::create_server(
this,
“fibonacci”,
std::bind(&FibonacciActionServer::handle_goal, this, _1, _2),
std::bind(&FibonacciActionServer::handle_cancel, this, _1),
std::bind(&FibonacciActionServer::handle_accepted, this, _1));
处理新目标的回调开始:
rclcpp_action::GoalResponse handle_goal(
const rclcpp_action::GoalUUID & uuid,
std::shared_ptr<const Fibonacci::Goal> goal)
{
RCLCPP_INFO(this->get_logger(), "Received goal request with order %d", goal->order);
(void)uuid;
return rclcpp_action::GoalResponse::ACCEPT_AND_EXECUTE;
}
此实现仅接受所有目标。
接下来是处理取消的回调:
rclcpp_action::CancelResponse handle_cancel(
const std::shared_ptr<GoalHandleFibonacci> goal_handle)
{
RCLCPP_INFO(this->get_logger(), "Received request to cancel goal");
(void)goal_handle;
return rclcpp_action::CancelResponse::ACCEPT;
}
此实现只是告诉客户端它接受取消。
最后一个回调接受一个新目标并开始处理它:
void handle_accepted(const std::shared_ptr<GoalHandleFibonacci> goal_handle)
{
using namespace std::placeholders;
// this needs to return quickly to avoid blocking the executor, so spin up a new thread
std::thread{std::bind(&FibonacciActionServer::execute, this, _1), goal_handle}.detach();
}
由于执行是一个长时间运行的操作,因此我们生成一个线程来完成实际工作并handle_accepted快速返回。
execute 执行方法,所有进一步的处理和更新都在新线程的方法中完成:
void execute(const std::shared_ptr<GoalHandleFibonacci> goal_handle) { RCLCPP_INFO(this->get_logger(), "Executing goal"); rclcpp::Rate loop_rate(1); const auto goal = goal_handle->get_goal(); auto feedback = std::make_shared<Fibonacci::Feedback>(); auto & sequence = feedback->partial_sequence; sequence.push_back(0); sequence.push_back(1); auto result = std::make_shared<Fibonacci::Result>(); for (int i = 1; (i < goal->order) && rclcpp::ok(); ++i) { // Check if there is a cancel request if (goal_handle->is_canceling()) { result->sequence = sequence; goal_handle->canceled(result); RCLCPP_INFO(this->get_logger(), "Goal canceled"); return; } // Update sequence sequence.push_back(sequence[i] + sequence[i - 1]); // Publish feedback goal_handle->publish_feedback(feedback); RCLCPP_INFO(this->get_logger(), "Publish feedback"); loop_rate.sleep(); } // Check if goal is done if (rclcpp::ok()) { result->sequence = sequence; goal_handle->succeed(result); RCLCPP_INFO(this->get_logger(), "Goal succeeded"); } }
该工作线程每秒处理一个斐波那契数列的序列号,并为每个步骤发布一个反馈更新。当处理完成后,它将标记goal_handle为成功并退出。
首先,我们需要设置 CMakeLists.txt 以便编译操作服务器。打开action_tutorials_cpp/CMakeLists.txt,并在调用后添加以下内容find_package:
add_library(action_server SHARED src/fibonacci_action_server.cpp) target_include_directories(action_server PRIVATE $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include>) target_compile_definitions(action_server PRIVATE "ACTION_TUTORIALS_CPP_BUILDING_DLL") ament_target_dependencies(action_server "action_tutorials_interfaces" "rclcpp" "rclcpp_action" "rclcpp_components") rclcpp_components_register_node(action_server PLUGIN "action_tutorials_cpp::FibonacciActionServer" EXECUTABLE fibonacci_action_server) install(TARGETS action_server ARCHIVE DESTINATION lib LIBRARY DESTINATION lib RUNTIME DESTINATION bin)
具体位置看如下截图:
现在我们可以编译这个包了。转到 的顶层ros2_study ,然后运行:
现在我们已经构建了操作服务器,我们可以运行它了
ros2 run action_tutorials_cpp fibonacci_action_server
通过查看action fibonacci已经有一个服务起来了
在 action_tutorials_cpp/src 下新建 fibonacci_action_client.cpp,具体代码如下:
#include <functional> #include <future> #include <memory> #include <string> #include <sstream> #include "action_tutorials_interfaces/action/fibonacci.hpp" #include "rclcpp/rclcpp.hpp" #include "rclcpp_action/rclcpp_action.hpp" #include "rclcpp_components/register_node_macro.hpp" namespace action_tutorials_cpp { class FibonacciActionClient : public rclcpp::Node { public: using Fibonacci = action_tutorials_interfaces::action::Fibonacci; using GoalHandleFibonacci = rclcpp_action::ClientGoalHandle<Fibonacci>; explicit FibonacciActionClient(const rclcpp::NodeOptions & options) : Node("fibonacci_action_client", options) { this->client_ptr_ = rclcpp_action::create_client<Fibonacci>( this, "fibonacci"); this->timer_ = this->create_wall_timer( std::chrono::milliseconds(500), std::bind(&FibonacciActionClient::send_goal, this)); } void send_goal() { using namespace std::placeholders; this->timer_->cancel(); if (!this->client_ptr_->wait_for_action_server()) { RCLCPP_ERROR(this->get_logger(), "Action server not available after waiting"); rclcpp::shutdown(); } auto goal_msg = Fibonacci::Goal(); goal_msg.order = 10; RCLCPP_INFO(this->get_logger(), "Sending goal"); auto send_goal_options = rclcpp_action::Client<Fibonacci>::SendGoalOptions(); send_goal_options.goal_response_callback = std::bind(&FibonacciActionClient::goal_response_callback, this, _1); send_goal_options.feedback_callback = std::bind(&FibonacciActionClient::feedback_callback, this, _1, _2); send_goal_options.result_callback = std::bind(&FibonacciActionClient::result_callback, this, _1); this->client_ptr_->async_send_goal(goal_msg, send_goal_options); } private: rclcpp_action::Client<Fibonacci>::SharedPtr client_ptr_; rclcpp::TimerBase::SharedPtr timer_; void goal_response_callback(const GoalHandleFibonacci::SharedPtr & goal_handle) { if (!goal_handle) { RCLCPP_ERROR(this->get_logger(), "Goal was rejected by server"); } else { RCLCPP_INFO(this->get_logger(), "Goal accepted by server, waiting for result"); } } void feedback_callback( GoalHandleFibonacci::SharedPtr, const std::shared_ptr<const Fibonacci::Feedback> feedback) { std::stringstream ss; ss << "Next number in sequence received: "; for (auto number : feedback->partial_sequence) { ss << number << " "; } RCLCPP_INFO(this->get_logger(), ss.str().c_str()); } void result_callback(const GoalHandleFibonacci::WrappedResult & result) { switch (result.code) { case rclcpp_action::ResultCode::SUCCEEDED: break; case rclcpp_action::ResultCode::ABORTED: RCLCPP_ERROR(this->get_logger(), "Goal was aborted"); return; case rclcpp_action::ResultCode::CANCELED: RCLCPP_ERROR(this->get_logger(), "Goal was canceled"); return; default: RCLCPP_ERROR(this->get_logger(), "Unknown result code"); return; } std::stringstream ss; ss << "Result received: "; for (auto number : result.result->sequence) { ss << number << " "; } RCLCPP_INFO(this->get_logger(), ss.str().c_str()); rclcpp::shutdown(); } }; // class FibonacciActionClient } // namespace action_tutorials_cpp RCLCPP_COMPONENTS_REGISTER_NODE(action_tutorials_cpp::FibonacciActionClient)
#include 部分为项目依赖引入
#include <functional>
#include <future>
#include <memory>
#include <string>
#include <sstream>
#include "action_tutorials_interfaces/action/fibonacci.hpp"
#include "rclcpp/rclcpp.hpp"
#include "rclcpp_action/rclcpp_action.hpp"
#include "rclcpp_components/register_node_macro.hpp"
新增类FibonacciActionClient 继承 ros 的node
class FibonacciActionClient : public rclcpp::Node
构造FibonacciActionClient 类 初始化一个节点,并命名fibonacci_action_client
explicit FibonacciActionClient(const rclcpp::NodeOptions & options)
: Node("fibonacci_action_client", options)
初始化一个新的action 对象
this->client_ptr_ = rclcpp_action::create_client<Fibonacci>(
this,
"fibonacci");
aciton 客户端 主要定义以下几个主要步骤:
定义一个时间定时方法
this->timer_ = this->create_wall_timer(
std::chrono::milliseconds(500),
std::bind(&FibonacciActionClient::send_goal, this));
当时间过期就是调用send_goal 方法,接下来让我们来实现send_goal 方法中分内容
void send_goal() { using namespace std::placeholders; this->timer_->cancel(); if (!this->client_ptr_->wait_for_action_server()) { RCLCPP_ERROR(this->get_logger(), "Action server not available after waiting"); rclcpp::shutdown(); } auto goal_msg = Fibonacci::Goal(); goal_msg.order = 10; RCLCPP_INFO(this->get_logger(), "Sending goal"); auto send_goal_options = rclcpp_action::Client<Fibonacci>::SendGoalOptions(); send_goal_options.goal_response_callback = std::bind(&FibonacciActionClient::goal_response_callback, this, _1); send_goal_options.feedback_callback = std::bind(&FibonacciActionClient::feedback_callback, this, _1, _2); send_goal_options.result_callback = std::bind(&FibonacciActionClient::result_callback, this, _1); this->client_ptr_->async_send_goal(goal_msg, send_goal_options); }
以上代码主要实现:
当action server 收到 参数请求后,它会发送一个反馈给客户端,这个反馈就 进入到这个方法中goal_response_callback
void goal_response_callback(const GoalHandleFibonacci::SharedPtr & goal_handle)
{
if (!goal_handle) {
RCLCPP_ERROR(this->get_logger(), "Goal was rejected by server");
} else {
RCLCPP_INFO(this->get_logger(), "Goal accepted by server, waiting for result");
}
}
当action server 进入开始处理,它会发松反馈给客户端,这个反馈就进入到feedback_callback
这个方法中
void feedback_callback(
GoalHandleFibonacci::SharedPtr,
const std::shared_ptr<const Fibonacci::Feedback> feedback)
{
std::stringstream ss;
ss << "Next number in sequence received: ";
for (auto number : feedback->partial_sequence) {
ss << number << " ";
}
RCLCPP_INFO(this->get_logger(), ss.str().c_str());
}
当action server 服务处理完成后,就会将结果 反馈给客户端,结果由result_callback
来处理;
void result_callback(const GoalHandleFibonacci::WrappedResult & result) { switch (result.code) { case rclcpp_action::ResultCode::SUCCEEDED: break; case rclcpp_action::ResultCode::ABORTED: RCLCPP_ERROR(this->get_logger(), "Goal was aborted"); return; case rclcpp_action::ResultCode::CANCELED: RCLCPP_ERROR(this->get_logger(), "Goal was canceled"); return; default: RCLCPP_ERROR(this->get_logger(), "Unknown result code"); return; } std::stringstream ss; ss << "Result received: "; for (auto number : result.result->sequence) { ss << number << " "; } RCLCPP_INFO(this->get_logger(), ss.str().c_str()); rclcpp::shutdown(); } };
首先,我们需要设置 CMakeLists.txt 以便编译操作客户端。打开action_tutorials_cpp/CMakeLists.txt,将下面的配置贴到 之前配置服务端的下面
add_library(action_client SHARED src/fibonacci_action_client.cpp) target_include_directories(action_client PRIVATE $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include>) target_compile_definitions(action_client PRIVATE "ACTION_TUTORIALS_CPP_BUILDING_DLL") ament_target_dependencies(action_client "action_tutorials_interfaces" "rclcpp" "rclcpp_action" "rclcpp_components") rclcpp_components_register_node(action_client PLUGIN "action_tutorials_cpp::FibonacciActionClient" EXECUTABLE fibonacci_action_client) install(TARGETS action_client ARCHIVE DESTINATION lib LIBRARY DESTINATION lib RUNTIME DESTINATION bin)
现在我们可以编译这个包了。转到 的顶层ros2_study,然后运行:
colcon build
3.3 运行客户端
ros2 run action_tutorials_cpp fibonacci_action_client
运行后效果如下:
有多种方法可以用 C++ 编写操作服务器和客户端;查看ros2官方示例 ros2/examples存储库中的minimal_action_server和软件包minimal_action_client。
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