【RK3399Pro学习笔记】九、ROS客户端Client的编程实现

平台：华硕 Thinker Edge R 瑞芯微 RK3399Pro
固件版本：Tinker_Edge_R-Debian-Stretch-V1.0.4-20200615

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记录自【古月居】古月·ROS入门21讲 | 一学就会的ROS机器人入门教程 —— 古月居GYH P13 13.客户端Client的编程实现

如何实现一个客户端

1. 初始化ROS节点；
2. 创建一个Client实例；
3. 发布服务请求数据；
4. 等待Server处理之后的应答结果。

C++

创建功能包

cd ~/catkin_workspace/src
catkin_create_pkg learning_service roscpp rospy std_msgs geometry_msgs turtlesim

编写程序

nano ~/catkin_workspace/src/learning_service/src/turtle_spawn.cpp

/***********************************************************************
Copyright 2020 GuYueHome (www.guyuehome.com).
***********************************************************************/

/**
 * 该例程将请求/spawn服务，服务数据类型turtlesim::Spawn
 */

#include 
#include 

int main(int argc, char** argv)
{
    // 初始化ROS节点
	ros::init(argc, argv, "turtle_spawn");

    // 创建节点句柄
	ros::NodeHandle node;

    // 发现/spawn服务后，创建一个服务客户端，连接名为/spawn的service
	ros::service::waitForService("/spawn");
	ros::ServiceClient add_turtle = node.serviceClient<turtlesim::Spawn>("/spawn");

    // 初始化turtlesim::Spawn的请求数据
	turtlesim::Spawn srv;
	srv.request.x = 2.0;
	srv.request.y = 2.0;
	srv.request.name = "turtle2";

    // 请求服务调用
	ROS_INFO("Call service to spwan turtle[x:%0.6f, y:%0.6f, name:%s]", 
			 srv.request.x, srv.request.y, srv.request.name.c_str());

	add_turtle.call(srv);

	// 显示服务调用结果
	ROS_INFO("Spwan turtle successfully [name:%s]", srv.response.name.c_str());

	return 0;
};

配置CMakeLists.txt

nano ~/catkin_workspace/src/learning_service/CMakeLists.txt

添加

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

编译并运行

cd ~/catkin_workspace
catkin_make

# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roscore
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun turtlesim turtlesim_node 
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_service turtle_spawn 

python

创建并编写脚本

cd ~/catkin_workspace/src/learning_service
mkdir scripts
cd ~/catkin_workspace/src/learning_service/scripts
nano turtle_spawn.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

########################################################################
####          Copyright 2020 GuYueHome (www.guyuehome.com).          ###
########################################################################

# 该例程将请求/spawn服务，服务数据类型turtlesim::Spawn

import sys
import rospy
from turtlesim.srv import Spawn

def turtle_spawn():
	# ROS节点初始化
    rospy.init_node('turtle_spawn')

	# 发现/spawn服务后，创建一个服务客户端，连接名为/spawn的service
    rospy.wait_for_service('/spawn')
    try:
        add_turtle = rospy.ServiceProxy('/spawn', Spawn)

		# 请求服务调用，输入请求数据
        response = add_turtle(2.0, 2.0, 0.0, "turtle2")
        return response.name
    except rospy.ServiceException, e:
        print "Service call failed: %s"%e

if __name__ == "__main__":
	#服务调用并显示调用结果
    print "Spwan turtle successfully [name:%s]" %(turtle_spawn())

运行

sudo chmod +x ~/catkin_workspace/src/learning_service/scripts/turtle_spawn.py

# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roscore
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun turtlesim turtlesim_node 
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_service turtle_spawn.py