网站建设与管理课程标准,怎样创作网站,网络营销的主要形式有建设网站,网站外链要怎么做1 param介绍
类似C编程中的全局变量#xff0c;可以便于在多个程序中共享某些数据#xff0c;参数是ROS机器人系统中的全局字典#xff0c;可以运行多个节点中共享数据。 全局字典 在ROS系统中#xff0c;参数是以全局字典的形态存在的#xff0c;什么叫字典#xff1f;…1 param介绍
类似C编程中的全局变量可以便于在多个程序中共享某些数据参数是ROS机器人系统中的全局字典可以运行多个节点中共享数据。 全局字典 在ROS系统中参数是以全局字典的形态存在的什么叫字典就像真实的字典一样由名称和数值组成也叫做键和值合成键值。或者我们也可以理解为就像编程中的参数一样有一个参数名 然后跟一个等号后边就是参数值了在使用的时候访问这个参数名即可。 可动态监控 在ROS2中参数的特性非常丰富比如某一个节点共享了一个参数其他节点都可以访问如果某一个节点对参数进行了修改其他节点也有办法立刻知道从而获取最新的数值。这在参数的高级编程中大家都可能会用到。
2 param编码示例
这里创建功能包名为learning05_param
2.1 parameter.cpp
/*** file parameters.cpp** brief A node to declare and get parameters* Here the parameters are the message data for two publisher* Its possible to change them at run time using the commad line* ros2 param set /set_parameter_node vehicle_speed 100* ros2 param set /set_parameter_node vehicle_type car* or using a launch file** author Antonio Mauro Galiano* Contact: https://www.linkedin.com/in/antoniomaurogaliano/**/#include chrono
#include string
#include rclcpp/rclcpp.hpp
#include std_msgs/msg/string.hpp
#include std_msgs/msg/int16.hppusing namespace std::chrono_literals;class MySetParameterClass: public rclcpp::Node
{
private:int velocityParam_;std::string typeVehicleParam_;rclcpp::TimerBase::SharedPtr timer_;rclcpp::Publisherstd_msgs::msg::String::SharedPtr pubString_;rclcpp::Publisherstd_msgs::msg::Int16::SharedPtr pubInt_;void TimerCallback();public:MySetParameterClass(): Node(set_parameter_node){// here are declared the parameters and their default valuesthis-declare_parameterstd::string(vehicle_type, bike);this-declare_parameterint(vehicle_speed, 10);pubString_ this-create_publisherstd_msgs::msg::String(/vehicle_type, 10);pubInt_ this-create_publisherstd_msgs::msg::Int16(/vehicle_speed, 10);timer_ this-create_wall_timer(1000ms, std::bind(MySetParameterClass::TimerCallback, this));}
};void MySetParameterClass::TimerCallback()
{// here the params get their value from outside// such as a set command or a launch filethis-get_parameter(vehicle_type, typeVehicleParam_);this-get_parameter(vehicle_speed, velocityParam_);std_msgs::msg::String messageString;messageString.datatypeVehicleParam_;std_msgs::msg::Int16 messageInt;messageInt.datavelocityParam_;RCLCPP_INFO(this-get_logger(), Publishing two messages - vehicle type %s\tVehicle speed %d,typeVehicleParam_.c_str(), velocityParam_);pubInt_-publish(messageInt);pubString_-publish(messageString);
}int main(int argc, char** argv)
{rclcpp::init(argc, argv);auto node std::make_sharedMySetParameterClass();rclcpp::spin(node);rclcpp::shutdown();return 0;
}2.2 CMakeLists.txt
cmake_minimum_required(VERSION 3.5)
project(learning05_param)# Default to C99
if(NOT CMAKE_C_STANDARD)set(CMAKE_C_STANDARD 99)
endif()# Default to C14
if(NOT CMAKE_CXX_STANDARD)set(CMAKE_CXX_STANDARD 14)
endif()if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES Clang)add_compile_options(-Wall -Wextra -Wpedantic)
endif()# find dependencies
find_package(ament_cmake REQUIRED)
find_package(rclcpp REQUIRED)
find_package(std_msgs REQUIRED)if(BUILD_TESTING)find_package(ament_lint_auto REQUIRED)# the following line skips the linter which checks for copyrights# uncomment the line when a copyright and license is not present in all source files#set(ament_cmake_copyright_FOUND TRUE)# the following line skips cpplint (only works in a git repo)# uncomment the line when this package is not in a git repo#set(ament_cmake_cpplint_FOUND TRUE)ament_lint_auto_find_test_dependencies()
endif()add_executable(parameters src/parameters.cpp)
ament_target_dependencies(parameters rclcpp std_msgs)install(TARGETSparametersDESTINATION lib/${PROJECT_NAME})ament_package()
2.3 package.xml
?xml version1.0?
?xml-model hrefhttp://download.ros.org/schema/package_format3.xsd schematypenshttp://www.w3.org/2001/XMLSchema?
package format3namelearning05_param/nameversion0.0.0/versiondescriptionExample node to handle parameters/descriptionmaintainer emailfoofoo.fooAntonio Mauro Galiano/maintainerlicenseTODO: License declaration/licensebuildtool_dependament_cmake/buildtool_dependdependrclcpp/dependtest_dependament_lint_auto/test_dependtest_dependament_lint_common/test_dependexportbuild_typeament_cmake/build_type/export
/package
3 编译运行
# 编译
colcon build# source环境变量
source install/setup.sh# 运行parameters节点
ros2 run learning05_param parameters可以看到 再开一个终端 这里set了vehicle_speed值为12可以看到运行的程序中vehicle_speed的值从10 变为了12
4 param常用指令
查看列表参数
ros2 param listros2 param list /set_parameter_node: use_sim_time vehicle_speed vehicle_type 查看描述
ros2 param describe /set_parameter_node use_sim_timeros2 param describe /set_parameter_node use_sim_time Parameter name: use_sim_time Type: boolean Constraints: 获取参数值
ros2 param get /set_parameter_node use_sim_time
Boolean value is: False设置参数值
ros2 param set /set_parameter_node use_sim_time true
Set parameter successful将一个节点所有的param写在一个yaml文件中
ros2 param dump /set_parameter_node
Saving to: ./set_parameter_node.yaml修改上面的yaml文件通过下面指令直接生效
ros2 param load /set_parameter_node set_parameter_node.yaml
Set parameter use_sim_time successful
Set parameter vehicle_speed successful
Set parameter vehicle_type successful
