Robotics Development and ROS Overview

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Questions and Answers

What was one major problem in robotics development before the introduction of ROS?

High code reusability

Efficient inter-process communication

Reinventing device drivers (correct)

Standardized algorithms

When was ROS originally developed?

2007 (correct)

2005

2013

2010

Which organization manages ROS since 2013?

Willow Garage

Stanford University

Open Source Robotics Foundation (correct)

Artificial Intelligence Research Lab

What is NOT a standard operating system service provided by ROS?

User interface design Signup and view all the answers

Which of the following best describes the philosophy of ROS?

Peer to peer communication with small programs Signup and view all the answers

What is an example of a common functionality provided by user-contributed packages in ROS?

Visualization tools Signup and view all the answers

Which programming languages currently have client libraries available for ROS?

C++, Python, LISP, and more Signup and view all the answers

What aspect of ROS encourages the creation of stand-alone libraries and packages?

Thin conventions Signup and view all the answers

What must be done after installing ROS to access its commands in a new shell?

Source the setup.*sh file in '/opt/ros/' Signup and view all the answers

Which statement correctly describes a ROS package?

It is the basic unit of build and contains one or more nodes. Signup and view all the answers

Which of the following is true about ROS supported platforms?

Current ROS versions are fully supported on Ubuntu. Signup and view all the answers

In a catkin workspace, which folder is used for compiled binaries?

build Signup and view all the answers

What feature does the rosbash package provide to enhance user experience in the ROS environment?

Enhanced tab-completion for commands. Signup and view all the answers

How can bag files be utilized in ROS?

They can playback to same or different topics. Signup and view all the answers

What file must exist in a ROS package directory?

package.xml Signup and view all the answers

Which of the following best describes the structure of a catkin workspace?

It includes distinct folders for source, build, and development. Signup and view all the answers

What is the primary function of the ROS Master?

Facilitate communication and connection information between nodes Signup and view all the answers

Which of the following correctly describes a ROS service?

A synchronous inter-node transaction that involves a request-response model Signup and view all the answers

What is the purpose of ROS topics?

To allow nodes to publish and subscribe to message streams Signup and view all the answers

Which statement about ROS nodes is true?

Nodes are written using various client libraries for different programming languages Signup and view all the answers

What kind of data is best suited for the Parameter Server in ROS?

Static, non-binary configuration parameters Signup and view all the answers

In the Publish/Subscribe model of ROS, how many nodes can publish messages to a single topic?

Multiple nodes Signup and view all the answers

What type of messages would you expect to be sent on a topic called 'scan'?

LaserScan type messages from a range-finder Signup and view all the answers

Which of the following statements about ROS bags is correct?

They are used for data logging by storing serialized message data Signup and view all the answers

In the context of ROS nodes, what is a likely role of an action?

To manage long-duration tasks that require feedback Signup and view all the answers

Which ROS client library would you use to write a node in Python?

rospy Signup and view all the answers

Study Notes

Robotics Development Before ROS

Lack of standardization and code reusability led to reinventing device drivers and standard algorithms for each new robot.

Robot Operating System (ROS)

An open-source robot operating system.
A collection of software libraries and tools designed to build robot applications across diverse platforms.
Initially developed at Stanford AI Lab in 2007, with further development at Willow Garage.
Maintained by the Open Source Robotics Foundation (OSRF) since 2013.

ROS Main Features

Provides standard operating system services like hardware abstraction, device control, common functionality implementation, inter-process communication, and package management.
Offers a suite of community-contributed packages for common robot functionality such as SLAM, planning, perception, vision, manipulation, etc.

ROS Philosophy

Peer-to-Peer: ROS systems consist of numerous small programs (nodes) that communicate via message exchange.
Tools-based: Emphasizes using numerous generic tools for tasks like visualization, logging, and data plotting.
Multi-Lingual: Accommodates various programming languages (including C++, Python, LISP, Java, JavaScript, MATLAB, Ruby, and more) through client libraries.
Thin: Encourages creating standalone libraries wrapped in a way that allows them to communicate with other ROS modules.
Free & Open Source: Uses community-driven development and relies on repositories.

ROS Key Concepts

Nodes: Individual programs with specific purposes (e.g., sensor drivers, actuator drivers, map building, planning, user interface).
Messages and Topics: Topics are named message streams used for communication between nodes. Messages are strictly-typed data structures for inter-node communication, such as the geometry_msgs/Twist type for expressing velocity commands.
Services: Inter-node transactions for synchronous communication (request and wait for response).
Actions: Enable asynchronous (non-blocking) communication between nodes.
ROS Master: Central hub coordinating node communication and facilitating discovery of information about topics, services, and actions.
Parameters: Shared, multi-variate dictionary accessible via network APIs, primarily used for storing configuration parameters.
Packages and Stacks: A software organization unit, often hosted on GitHub, containing nodes, documentation, and a ROS interface. Packages build upon each other and can be combined into stacks.

ROS Computation Graph Level

Represented using a visual diagram showing the interconnected nodes, messages, services, and actions.

ROS Supported Platforms

Primarily supported on Ubuntu operating systems.
Other platforms like Windows, Mac OS X, and Android are considered experimental.
ROS Kinetic Kame runs on Ubuntu 16.04 (Xenial) and supports Ubuntu 15.10 (Willy).

ROS Environment

Integrates seamlessly with the Linux environment.
The rosbash package, available after installing ROS, enhances the bash shell with useful functions and tab completion for ROS utilities.
The setup.sh files for each ROS version (e.g., /opt/ros/indigo/setup.bash) need to be sourced to enable rosbash and access ROS commands.

ROS Packages

Organize software in a hierarchy, with each package containing one or more nodes, documentation, and a ROS interface.

Catkin Workspace Layout

A set of folders organized for ROS code development:
- Source space: Workspace_folder/src: Contains package source files.
- Build space: Workspace_folder/build: Where compilation happens.
- Development space: Workspace_folder/devel: Stores build outputs.
- Install space: Workspace_folder/install: Final installation location.

ROS Package Files

Inside a catkin workspace, each package folder (e.g., src/my_package) typically follows a structure:
- Source files: Implement nodes, can be written in multiple languages.
- Launch files: Define how nodes are launched individually or in groups.

ROS Community Level

A vibrant community fosters collaboration and development through open-source contributions, forums, and online resources.

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Description

Explore the evolution of robotics before the advent of the Robot Operating System (ROS) and understand its core features. This quiz covers the development history, main functions, and philosophy behind ROS, providing insight into its impact on robotic applications. Test your knowledge of how ROS enhances robotic development.