首页 资讯 应用 高压 设计 行业 低压 电路图 关于


旗下栏目: 物联网 机器人 新技术 仪器仪表


机器人 | 发布时间:2017-10-08 | 人气: | #评论# | 本文关键字:ROS
摘要:Hello World from Windows Description: How to publish information to a ROS master from windows using rosserial_windows. Keywords: rosserial, windows, rosserial_windows Tutorial Level: INTERMEDIATE 目录 Introduction Generating the ros_lib I

Hello World from Windows

Description: How to publish information to a ROS master from windows using rosserial_windows.

Keywords: rosserial, windows, rosserial_windows

Tutorial Level: INTERMEDIATE 

  1. Introduction

  2. Generating the ros_lib

    1. Installing rosserial_windows

    2. Generate ros_lib

  3. Add ros_lib to Visual Studio Project

    1. Create a new Win32 Console Application

    2. Copy ros_lib into the project

    3. Add ros_lib to project

  4. Add code to main for Hello World

  5. Start ROS and rosserial_server

  6. Run the app

  7. Robot Doughnuts


Windows machines can do all kinds of thing that are difficult to do in other environments: interface an MYO, displays for end users, and working with Windows-only software. Working with a ROS master from Windows can be difficult. The rosserial_windows package makes it much easier to send and receive ROS messages from Windows. This package generates all of the coded needed to drop into a Visual Studios Solution. The workflow is generally:

  1. From the ROS based system, generate the ros_lib code

  2. Drop the ros_lib code into a Visual Studios Solution

  3. Write code to use ros_lib to connect to the ROS master and send/receive messages

  4. Run rosserial_server socket on ROS master

  5. Compile and run Windows app

This tutorial will guide you through those steps to be up and running with your own project.

Generating the ros_lib

Installing rosserial_windows

Install rosserial_windows and the rosserial server:

sudo apt-get install ros-hydro-rosserial-windows sudo apt-get install ros-hydro-rosserial-server

Generate ros_lib

This step will generate the code that will be needed in the Visual Studio project to talk to the ROS master. You will need to supply the name of the folder into which to copy the finished files.

rosrun rosserial_windows my_library

This will place the ros_lib folder in the folder my_library.

Add ros_lib to Visual Studio Project

NB: This tutorial assumes Visual Studio 2013 Express Desktop.

Create a new Win32 Console Application

  1. Open Visual Studio

  2. File -> New Project

  3. Find the Win32 Console Application under Installed -> Templates -> Visual C++ -> Win32

  4. Give your project a name. We'll use rosserial_hello_world

  5. You will probably want to turn off precompile headers. The project should work with them enabled, but precompiled headers have caused problems in the past.

Copy ros_lib into the project

Copy the ros_lib folder into the rosserial_hello_world project folder. The folder structure should look like:

  • rosserial_hello_world/

    • ReadMe.txt

    • rosserial_hello_world.cpp

    • rosserial_hello_world.vcxproj

    • rosserial_hello_world.vcxproj.filters

    • stdafx.cpp

    • stdafx.h

    • targetver.h

    • ros.h

    • WindowsSocket.cpp

    • ... all of the rosserial generated code, including folders for all of the message packages

    • ipch/

    • ros_lib/

    • rosserial_hello_world/

    • rosserial_hello_world.opensdf

    • rosserial_hello_world.sdf

    • rosserial_hello_world.sln

    • rosserial_hello_world.v12.suo

Add ros_lib to project

Add all of the files in the ros_lib folder that aren't in subfolders to your project. As of writing this, those are:

  • ros.h

  • duration.cpp

  • time.cpp

  • WindowsSocket.h

  • WindowsSocket.cpp

Then add the ros_lib folder to your includes path by:

  1. Right-click on the rosserial_hello_world project in the Solution Explorer and go to Properties

  2. Under C/C++, add "../ros_lib" to the Additional Include Directories property

Add code to main for Hello World

Since we're commanding a robot, why not send a command instead of just a string? Here we'll send the cmd_vel message to command a robot to go forward and spin around. You'll need to change the IP address to match the address of your ROS master.


   1 // rosserial_hello_world.cpp : Example of sending command velocities from Windows using rosserial    2 //    3 #include "stdafx.h"    4 #include <string>    5 #include <stdio.h>    6 #include "ros.h"    7 #include <geometry_msgs/Twist.h>    8 #include <windows.h>    9    10 using std::string;   11    12 int _tmain (int argc, _TCHAR * argv[])   13 {   14   ros::NodeHandle nh;   15   char *ros_master = "";   16    17   printf ("Connecting to server at %s\n", ros_master);   18   nh.initNode (ros_master);   19    20   printf ("Advertising cmd_vel message\n");   21   geometry_msgs::Twist twist_msg;   22   ros::Publisher cmd_vel_pub ("cmd_vel", &twist_msg);   23   nh.advertise (cmd_vel_pub);   24    25   printf ("Go robot go!\n");   26   while (1)   27   {   28     twist_msg.linear.x = 5.1;   29     twist_msg.linear.y = 0;   30     twist_msg.linear.z = 0;   31     twist_msg.angular.x = 0;   32     twist_msg.angular.y = 0;   33     twist_msg.angular.z = -1.8;   34     cmd_vel_pub.publish (&twist_msg);   35    36     nh.spinOnce ();   37     Sleep (100);   38   }   39    40   printf ("All done!\n");   41   return 0;   42 }

A few notes on this code:

  • A "node handle" is the equivalent to a ROS node. You'll send everything through that handle

  • Use "init_node" to connect to your ROS master. The format is "hostname:port". The default port is 11411 if none is specified

  • The include files are organized by "package/msg.h" so that they match what you would expect from ROS

  • To publish a message, you first need to make a publisher and then advertise that you're publishing a message

  • finally, you can fill in the message data structure and use the publisher to send it

  • Spin once is used for both receiving messages and for any admin on the port, including keeping your connection alive

  • Beware of a precompile headers. They tend to break building the project.

Start ROS and rosserial_server

In order for rosserial_windows to communicate with the ROS master, a server socket is needed to connect. This tutorial uses a TCP socket, but in theory it is also possible to use a serial port. On the ROS master, start the ROS core:


In a separate terminal, start the rosserial server

rosrun rosserial_server socket_node

In a third terminal, use rostopic to see what your app sends

rostopic echo /cmd_vel

Run the app

Go back to your windows machine and run the app. You should see command velocities start appearing in the rostopic terminal on your ROS master.

Robot Doughnuts

If you set up a robot simulation in Gazebo, you can then see your robot move based on your commands from Windows. For example, if you follow the ROS 101 Drive a Husky tutorial, you can use this to make the Husky do doughnuts. Here's how to set up that simulation.

In one terminal, launch the husky simulator in an empty world:

roslaunch husky_gazebo husky_empty_world.launch

In another terminal, start the rosserial_server with the command velocity topic remapped to where the Husky expects it.

rosrun rosserial_server socket_node cmd_vel:=/husky/cmd_vel

Now run your app again, and watch the Husky spin around!


Receiving Messages in rosserial_windows

Description: An example of receiving messages in rosserial_windows

Keywords: rosserial, windows, rosserial_windows

Tutorial Level: INTERMEDIATE 


  1. Introduction

  2. Using a Callback Function

  3. Receiving Messages

  4. Example

  5. Running it all together

  6. Class-based Approach



By now you've learned how to say Hello World with rosserial_windows. But what about if you want to receive a message? This tutorial will guide you through receiving messages in rosserial_windows

Using a Callback Function


Receiving a message is a little more complicated than sending, but only slightly. You'll need to tell the node handle what to do when you receive a message. Specifically, we'll use a callback function that gets called when a message is received.

Let's say that you want to receive the estimated pose of the robot. Whenever that happens, you'll want to print out the pose. Here's a function that might do that.


   1 void estimated_pose_callback (const geometry_msgs::PoseWithCovarianceStamped & pose)    2 {    3   printf ("Received pose %f, %f, %f\n", pose.pose.pose.position.x,    4           pose.pose.pose.position.y, pose.pose.pose.position.z);    5 }


That is an example of a callback function. It handles a new pose, in this case by printing to the screen. The next question is how do you get this called when receiving a new message? Assuming that you've already connected to the ROS master and have a NodeHandle called nh, here's how you would do that:


   1 ros::Subscriber < geometry_msgs::PoseWithCovarianceStamped >     2   poseSub ("estimated_pose", &estimated_pose_callback);    3 nh.subscribe (poseSub);


Receiving Messages


Now you have a callback and you've subscribed, but if you don't actually give rosserial a chance to process messages you won't receive anything. Fortunately, we've been doing that all along. That's what this bit of code does:


   1 while (1)    2 {    3   nh.spinOnce ();    4   Sleep (100);    5 }


All this does is give rosserial a chance to process messages and then sleep for a bit. The sleep is optional, though I don't recommend just calling spinOnce(). If you have other elements that you need to call that block for short periods, put them in this loop. Otherwise, beware that going too long between calling spinOnce() will produce disconnects.



Here's the full example of how to receive messages.


   1 #include "stdafx.h"    2 #include <string>    3 #include <stdio.h>    4 #include "ros.h"    5 #include <geometry_msgs/PoseWithCovarianceStamped.h>    6 #include <windows.h>    7     8 using std::string;    9    10 void estimated_pose_callback (const geometry_msgs::PoseWithCovarianceStamped & pose)   11 {   12   printf ("Received pose %f, %f, %f\n", pose.pose.pose.position.x,   13           pose.pose.pose.position.y, pose.pose.pose.position.z);   14 }   15    16 int _tmain (int argc, _TCHAR * argv[])   17 {   18   ros::NodeHandle nh;   19   char *ros_master = "";   20    21   printf ("Connecting to server at %s\n", ros_master);   22   nh.initNode (ros_master);   23    24   ros::Subscriber < geometry_msgs::PoseWithCovarianceStamped >    25     poseSub ("estimated_pose", &estimated_pose_callback);   26   nh.subscribe (poseSub);   27    28   printf ("Waiting to receive messages\n");   29   while (1)   30   {   31     nh.spinOnce ();   32     Sleep (100);   33   }   34    35   printf ("All done!\n");   36   return 0;   37 }


Running it all together


Again, assuming the Husky/Gazebo simulation from ROS 101 Drive a Husky, here's how to receive the pose from odometry:

In one terminal, launch the husky simulator in an empty world:

roslaunch husky_gazebo husky_empty_world.launch


In another terminal, start the rosserial_server with the estimated_pose topic remapped to the odometry result from robot EKF:

rosrun rosserial_server socket_node estimated_pose:=/robot_pose_ekf/odom


Now run the app, and you should be receiving pose messages. If not, check that the mapping is correct, using rostopic if necessary.

Class-based Approach


It's possible to subclass the Subscriber class for a more object-oriented approach. In that case, instead of registering with the call back above simply instantiate the new class and pass that in to the subscribe call.

首页 | 电气资讯 | 应用技术 | 高压电器 | 电气设计 | 行业应用 | 低压电器 | 电路图 | 关于我们 | 版权声明

Copyright 2017-2018 电气自动化网 版权所有 辽ICP备17010593号-1

电脑版 | 移动版 原创声明:本站大部分内容为原创,转载请注明电气自动化网转载;部分内容来源网络,如侵犯您的权益请发送邮件到[email protected]联系我们删除。