Ros Cc 1 Intro

7/31/2019 Ros Cc 1 Intro

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ROS Crash-Course, Part I

Introduction to ROS distribution, build system and infrastructure

Jonathan BohrenWith some information and figures adapted from http: //www.ros.org

and the COTESYS-ROS School 2010 presentation given by Radu Rusu
http://www.ros.org/http://www.ros.org/


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Outline

1 Introduction

Jonathan Bohren (JHU LCSR) ROS Crash-Course, Part I: Introduction 2 / 30


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Outline

1 IntroductionHigh-Level



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Outline

1 IntroductionHigh-LevelThe ROS Ecosystem



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Outline

1 IntroductionHigh-LevelThe ROS EcosystemROS Community



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Outline


2 ROS as a Communication Platform



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Outline


2 ROS as a Communication PlatformThe ROS Network Graph



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Outline


2 ROS as a Communication PlatformThe ROS Network GraphRunning and Connecting Nodes



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2 ROS as a Communication PlatformThe ROS Network GraphRunning and Connecting NodesAnalyzing the System at Runtime



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Outline



3 ROS as a Build Platform



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3 ROS as a Build PlatformDistribution & Package Management System



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3 ROS as a Build PlatformDistribution & Package Management SystemBuild System


Introduction


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Outline (revisted)





Introduction High-Level


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What is ROS?More than just middleware

A meta operating system for robots




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A collection of packaging, software building tools




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An architecture for distributed* inter-process/inter-machinecommunication and configuration




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Development tools for system runtime and data analysis




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Open-source under permissive BSD licenses (ros core libraries)




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A language-independent architecture (c++, python, lisp, java, andmore)




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A scalable platform (ARM CPUS to Xeon Clusters)




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A scalable platform (ARM CPUS to Xeon Clusters)

With the intent to enable researchers to rapidly develop new robotic

systems without having to reinvent the wheel through use of

standard tools and interfaces.




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What is ROS not?No confusion

Anactual

operating system




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An actual operating system

A programming language




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A programming environment / IDE




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A programming environment / IDE

A hard real-time architecture*


Introduction The ROS Ecosystem


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What does ROS get you?All levels of development




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Introduction ROS Community


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The ROS CommunityResearchers using common tools to enable collaboration

79 Institutional ROS Repositories, all over the world (July, 2011)(jhu-lcsr-ros-pkg would make 80)




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www.ros.org - The ROS HubA centralized location for ROS users and developers




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answers.ros.org - ROS Questions & AnswersCommunity-supported help for ROS users




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code.ros.org - Willow Garage, Inc CodeHosting and project management for official packages




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ros mailing listsGetting in touch with the developer community

ROS Users - for general ROS-related discussionshttps://code.ros.org/mailman/listinfo/ros-users

ROS Developers - for ROS core developmenthttps://code.ros.org/mailman/listinfo/ros-developers

Other Lists & List Archiveshttp://code.ros.org/lurker


ROS as a Communication Platform

l ( )
https://code.ros.org/mailman/listinfo/ros-usershttps://code.ros.org/mailman/listinfo/ros-developershttp://code.ros.org/lurkerhttp://code.ros.org/lurkerhttps://code.ros.org/mailman/listinfo/ros-developershttps://code.ros.org/mailman/listinfo/ros-users


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Outline (revisted)





ROS as a Communication Platform The ROS Network Graph

ROS C


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ROS CoreWhere it all comes together

Thr ROS core is a set of the only three programs that are necessary for theROS runtime. They include:

ROS Master



ROS C


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ROS Master

A centralized XML-RPC server



ROS C


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ROS Master

A centralized XML-RPC serverNegotiates communication connections



ROS C


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ROS Master

A centralized XML-RPC serverNegotiates communication connectionsRegisters and looks up names for ROS graph resources



ROS C


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ROS Master


Parameter ServerStores persistent configuration parameters and other arbitrary data



ROS Core


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ROS Master


Parameter ServerStores persistent configuration parameters and other arbitrary data

rosoutEssentially a network-based stdout for human-readable messages



ROS Graph Abstraction


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ROS Graph AbstractionNamed network resources

The ROS runtime designates several classes of named ROS graphresources. These resources can exist in namespaces to reduce namingcollisions, and fall into the following categories:





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nodesRepresent processes distributed across the ROS network. A ROS nodeis a source and sink for data that is sent over the ROS network.





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parametersPersistent (while the core is running) data such as configuration &initialization settings, stored on the parameter server.





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topicsAsynchronous many-to-many communication streams.





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topicsAsynchronous many-to-many communication streams.

servicesSynchronous one-to-many network-based functions.



ROS Graph


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ROS Graphrxgraph: communication network visualization


ROS as a Communication Platform Running and Connecting Nodes

Creating and Running ROS Nodes


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Creating and Running ROS NodesDistributing computation with ROS

ROS provides a mechanism for simultaneously configuring and launchingcollections of ROS nodes. This is done with lightweight xml files and theroslaunch program.

Launch files enable users to:

Associate a set of parameters and nodes with a single file





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Hierarchically compose collections of other launch files





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Automatically re-spawn nodes if they crash





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g gDistributing computation with ROS






Change node names, namespaces, topics, and other resource nameswithout recompiling





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g gDistributing computation with ROS






Change node names, namespaces, topics, and other resource nameswithout recompiling

Easily distribute nodes across multiple machines



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ROS Communication Protocols


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Connecting nodes over the network

ROS supports a growing number of communication capabilities that enabledistributing computation in a robotic system. These capabilities arecurrently built entirely on two high-level communication APIs:

ROS Topics





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ROS Topics

Asynchronous stream-like communication



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ROS Topics


TCP/IP or UDP TransportStrongly-typed (ROS .msg spec)





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ROS Topics


TCP/IP or UDP TransportStrongly-typed (ROS .msg spec)Can have one or more publishers





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ROS Topics


TCP/IP or UDP TransportStrongly-typed (ROS .msg spec)Can have one or more publishersCan have one or more subscribers





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ROS Topics



ROS Services



ROS Communication ProtocolsC d h k


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ROS Topics



ROS Services

Synchronous function-call-like communication



ROS Communication ProtocolsC i d h k


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ROS Topics



ROS Services

Synchronous function-call-like communicationTCP/IP or UDP Transport



ROS Communication ProtocolsC ti d th t k


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ROS Topics



ROS Services

Synchronous function-call-like communicationTCP/IP or UDP TransportStrongly-typed (ROS .srv spec)



ROS Communication ProtocolsC ti d th t k


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ROS Topics



ROS Services

Synchronous function-call-like communicationTCP/IP or UDP TransportStrongly-typed (ROS .srv spec)Can have only one server



ROS Communication ProtocolsConnecting nodes over the network


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ROS Topics



ROS Services

Synchronous function-call-like communicationTCP/IP or UDP TransportStrongly-typed (ROS .srv spec)Can have only one serverCan have one or more clients



Asynchronous Distributed* CommunicationROS TCP Topics


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ROS TCP Topics





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ROS TCP Topics





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ROS TCP Topics





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ROS TCP Topics





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ROS TCP Topics





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p





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p





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Jonathan Bohren (JHU LCSR) ROS Crash-Course, Part I: Introduction 18 / 30 ROS as a Communication Platform Running and Connecting Nodes



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Jonathan Bohren (JHU LCSR) ROS Crash-Course, Part I: Introduction 18 / 30 ROS as a Communication Platform Analyzing the System at Runtime

rosout Messagingstdout on steroids


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ROS provides mechanisms in all languages for specifying different levels ofhuman-readable log messages. The five default levels are:

fatal

error

warninfo

debug

Jonathan Bohren (JHU LCSR) ROS Crash-Course Part I: Introduction 19 / 30 ROS as a Communication Platform Analyzing the System at Runtime

rosout Messagingstdout on steroids


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ROS provides mechanisms in all languages for specifying different levels ofhuman-readable log messages. The five default levels are:

fatal

error

warninfo

debug

These enable a user to add printfs to their code for debugging, andselectively enable and disable them at runtime without a large

performance hit. For example, useful debug messages that might benecessary to diagnose a problem could be left in the code and re-enabledat a critical time.


ROS Graph IntrospectionNo more wireshark


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ROS provides several tools for analyzing the data flowing over ROScommuncation resources:

rosnode

Gives a user infomation about a node: publications, subscriptions, etc




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rosnode


rostopic

Gives datarate, actual data, publishers, subscribes




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rosnode


rostopic


rosservice

Enables a user to call a ROS Service from the command line




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rosnode


rostopic


rosservice

Enables a user to call a ROS Service from the command line

roswtf (wire trouble finder)Diagnoses problems with a ROS network


ROS GUI ToolsThere are lots. . .


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Jonathan Bohren (JHU LCSR) ROS Crash Course Part I: Introduction 21 / 30 ROS as a Communication Platform Analyzing the System at Runtime



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rviz - 3D VisualizationModular state and sensor visualization


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Jonathan Bohren (JHU LCSR) ROS Crash Course Part I: Introduction 22 / 30 ROS as a Build Platform

Outline (revisted)

1 Introduction


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1 Introduction

High-LevelThe ROS EcosystemROS Community

2 ROS as a Communication Platform

The ROS Network GraphRunning and Connecting NodesAnalyzing the System at Runtime

3 ROS as a Build Platform

Distribution & Package Management SystemBuild System

Jonathan Bohren (JHU LCSR) ROS Crash Co rse Part I Introd ction 23 / 30 ROS as a Build Platform Distribution & Package Management System

ROS Stacks & PackagesHow to organize code in a ROS ecosystem


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ROS code is grouped at two different levels:

Packages

A named collection of software that is built and treated as an atomicdependency in the ROS build system.

StacksA named collection of packages for distribution.

J th B h (JHU LCSR) ROS C h C P t I I t d ti 24 / 30 ROS as a Build Platform Distribution & Package Management System

ROS DistributionsDelivering ROS packages to the masses


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ROS as a Build Platform Distribution & Package Management System



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ROS as a Build Platform Build System

ROS Meta-FilesystemIncreasing codebase flexibility


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The minimal representation of a ROS package is a directory in the$ROS_PACKAGE_PATH which contains a single file:

manifest.xml





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manifest.xml

Contains package metadata (author, license, url, etc)





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manifest.xml


Specifies system and package dependencies





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manifest.xml


Specifies system and package dependenciesSpecifies language-specific export flags





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manifest.xml



CMakeLists.txt

Contains ROS build rules (executables, libraries, custom build flags,etc)





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manifest.xml



CMakeLists.txt

Contains ROS build rules (executables, libraries, custom build flags,etc)

Makefile

Just a proxy to build this package



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ROS Meta-Filesystem


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This meta-filesystem allows ROS (rospack, specifically) to locate anypackage in the designated path, be it at compile time or runtime.

Since ROS can find any package at any time, it enables packages to bemoved aoround in the actual filesystem and greater codebase flexibility.



Building Code with ROSEasier CMake


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While ROS uses CMake (www.cmake.org) internally to compile and linkcode, the ROS build system it adds several useful features that make iteasier to build ROS code.



http://www.cmake.org/http://www.cmake.org/


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rosbuild pulls compile and linker flags out of ROS package manifests,

so compiling against other ROS code is as easy as specifying thepackage name





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rosdep can be used to install system dependencies specified in apackages manifest.xml





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rosdep can be used to install system dependencies specified in apackages manifest.xml

ROS CMake macros enable rapid building of executables, libaries, andautomated regression tests




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Thank you!


http://www.ros.org/wiki/ROS/Tutorials


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Thank you!Now proceed to the ROS Beginner Tutorials!http://www.ros.org/wiki/ROS/Tutorials

http://www.ros.org/wiki/ROS/Tutorialshttp://www.ros.org/wiki/ROS/Tutorials

Ros Cc 1 Intro

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