ROS 2 Eloquent Elusor install and use Summary

ROS 2 iterations and update speed is very fast, and ROS 1 has basically been stable development, the latest LTS version as Melodic, 2020 May will be released ROS 1 Redux Noetic Ninjemys.

ROS 2 current LTS version as Dashing, the latest version is Eloquent Elusor. ROS 2 supports simultaneous deployment of multiple release on Ubuntu,

Dashing to the main production program, click here to open the text.

Eloquent Elusor a brief description:

In addition to functional development, also focused on the organization and improvement of tutorials ROS2. We want to try these communities together with Eloquent Elusor tutorials , and where possible provide feedback . The feedback helps the team continue to improve the document.

The following is a look at some of the features highlighted in this release and improvements:

• Supports tag-based startup file (XML / YAML)
• Support for markup-based launch files (XML/YAML)
• Based on the improved release of test 
• Improved launch-based testing
• Key parameters passed on the CLI 
• Passing key-value parameters on CLI
• Support stream recording macros 
• Support stream logging macros
• Each logging node  -  node all stdout / stderr output are recorded in ~ / .ros in 
• Per-node logging - All stdout/stderr output from nodes are logged in ~/.ros
• ros2doctor 
• Improve the performance of the procurement settings file 
• Improved performance of sourcing setup files
• rviz: interactive mark , torque ring , TF message filter 
• rviz: interactive markers, torque ring, tf message filters
• rqt: parameter plug , TF tree plug , robot control widget (the reverse is also ported to Dashing) 
• rqt: parameter plugin, tf tree plugin, robot steering plugin (also backported to Dashing)
• turtlesim (also ported to Dashing) 
• turtlesim (also backported to Dashing)
• RMW implementation:
  • rmw_iceoryx use API for zero-copy message lending
  • FastRTPS 1.9.3
  • A new implementation of the second layer 2: rmw_cyclonedds (also reverse transplanted to Dashing)
  • Environment variables ROS_LOCALHOST_ONLY to limit communicate with a local host
• MacOS Mojave support
• RCL and RCLCPP of tracking instrument

Finally, the plan name next ROS 2 version released in May 2020 as follows:

Foxy Fitzroy

If ROS 2 installed before you install the new version eloquent it is very simple:

$ sudo apt install ros-eloquent-desktop

Then, according to the official website configuration it can be used.

2019-11-14 function package as follows:

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Elusor Eloquent  IS at The Fifth Release of ROS ROS is the fifth version 2. 2

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Setup Locale 

Setting the Locale

Make sure you have a locale which supports UTF-8. If you are in a minimal environment, such as a docker container, the locale may be something minimal like POSIX. We test with the following settings. It should be fine if you’re using a different UTF-8 supported locale.

Ensure that the locale support UTF-8. If the environment is minimal (e.g. docker container), it is possible to minimize the locale as POSIX like. Use the following settings for testing. If you are using UTF-8 support other locales, it should be no problem.

sudo locale-gen en_US en_US.UTF-8
sudo update-locale LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8
export LANG=en_US.UTF-8

Setup Sources 

Installation Source

You will need to add the ROS 2 apt repositories to your system. To do so, first authorize our GPG key with apt like this:

需要在系统中添加ROS 2 apt存储库。为此，请首先使用如下所示的apt授权GPG密钥：

sudo apt update && sudo apt install curl gnupg2 lsb-release
curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -

And then add the repository to your sources list:

然后将存储库添加到源列表中：

sudo sh -c 'echo "deb [arch=amd64,arm64] http://packages.ros.org/ros2/ubuntu `lsb_release -cs` main" > /etc/apt/sources.list.d/ros2-latest.list'

Install ROS 2 packages 

安装ROS 2软件包

Update your apt repository caches after setting up the repositories.

设置存储库后，更新apt存储库缓存。

sudo apt update

Desktop Install (Recommended): ROS, RViz, demos, tutorials.

桌面安装（推荐）：ROS、RViz、演示和教程。

sudo apt install ros-eloquent-desktop

ROS-Base Install (Bare Bones): Communication libraries, message packages, command line tools. No GUI tools.

ROS-Base安装（精简）：通信库、消息包、命令行工具。没有GUI工具。

sudo apt install ros-eloquent-ros-base

See specific sections below for how to also install the ros1_bridge, TurtleBot packages, or alternative RMW packages.

有关如何安装ros1_bridge，TurtleBot软件包或替代RMW软件包的信息，请参见下面的特定部分。

Try some examples 

尝试一些例子

In one terminal, source the setup file and then run a talker:

在一个终端中，更新配置文件，然后运行talker：

. ~/ros2_dashing/install/local_setup.bash
ros2 run demo_nodes_cpp talker

In another terminal source the setup file and then run a listener:

在另一个终端源中，更新配置文件，然后运行listener：

. ~/ros2_dashing/install/local_setup.bash
ros2 run demo_nodes_py listener

You should see the talker saying that it’s Publishing messages and the listener saying I heard those messages. Hooray!

应该看到talker发布it’s Publishing消息同时listener接受并告知I heard这些消息。大功告成！！！

See the demos for other things to try. 请参阅演示以尝试其他案例。

Environment setup 

环境设置

(optional) Install argcomplete 

（可选）安装argcomplete

ROS 2 command line tools use argcomplete to autocompletion. So if you want autocompletion, installing argcomplete is necessary.

ROS 2命令行工具使用argcomplete自动完成。因此，如果要自动补全，则必须安装argcomplete。

sudo apt install python3-argcomplete

Sourcing the setup script  

更新安装配置脚本

Set up your environment by sourcing the following file. 

通过导入以下文件来设置环境。

source /opt/ros/eloquent/setup.bash

You may want to add this to your .bashrc.

如果需要将此添加到.bashrc，使用如下命令：

echo "source /opt/ros/eloquent/setup.bash" >> ~/.bashrc

Install additional RMW implementations 

安装其他RMW实现

By default the RMW implementation FastRTPS is used. If using Ardent OpenSplice is also installed.

默认情况下，使用RMW实现FastRTPS。如果使用Ardent，还将安装OpenSplice。

To install support for OpenSplice or RTI Connext on Bouncy:

在Bouncy上安装对OpenSplice或RTI Connext的支持：

sudo apt update
sudo apt install ros-eloquent-rmw-opensplice-cpp # for OpenSplice
sudo apt install ros-eloquent-rmw-connext-cpp # for RTI Connext (requires license agreement)

By setting the environment variable RMW_IMPLEMENTATION=rmw_opensplice_cpp you can switch to use OpenSplice instead. For ROS 2 releases Bouncy and newer, RMW_IMPLEMENTATION=rmw_connext_cpp can also be selected to use RTI Connext.

通过设置环境变量，RMW_IMPLEMENTATION=rmw_opensplice_cpp可以切换为使用OpenSplice。对于ROS 2版本，Bouncy和更高版本RMW_IMPLEMENTATION=rmw_connext_cpp也可以选择使用RTI Connext。

If you want to install the Connext DDS-Security plugins please refer to this page. 如果要安装Connext DDS-Security插件，请参阅此页面。

University, purchase or evaluation options are also available for RTI Connext. RTI Connext还提供大学，购买或评估选项。

Install additional packages using ROS 1 packages 

使用ROS 1软件包

The ros1_bridge as well as the TurtleBot demos are using ROS 1 packages. To be able to install them please start by adding the ROS 1 sources as documented here. 在ros1_bridge还有TurtleBot演示使用ROS 1包。为了能够安装它们，请首先添加ROS 1源，如此处所述。

If you’re using Docker for isolation you can start with the image ros:melodic or osrf/ros:melodic-desktop (or Kinetic if using Ardent). This will also avoid the need to setup the ROS sources as they will already be integrated.

如果使用Docker进行隔离，则可以从镜像ros:melodic或osrf/ros:melodic-desktop（或Kinetic（如果使用Ardent））开始。这也将避免设置ROS源的需要，因为它们已经被集成。

Now you can install the remaining packages: 

现在，可以安装其余的软件包：

sudo apt update
sudo apt install ros-eloquent-ros1-bridge

The turtlebot2 packages are not currently available in Eloquent. Eloquent目前不支持turtlebot2软件包。

Build your own packages 

建立自定义包

If you would like to build your own packages, refer to the tutorial "Using Colcon to build packages".

如果要构建自定义软件包，请参考教程“使用Colcon来构建软件包”。

Troubleshooting  

故障排除

Troubleshooting techniques can be found here. 故障排除技术可以在这里找到。

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Supported Platforms 

支持的平台

Eloquent Elusor is primarily supported on the following platforms: 

支持Eloquent Elusor主要平台如下：

Tier 1 platforms 第一类:

• Ubuntu 18.04 (Bionic): amd64 and arm64

• Mac OS X 10.12 (Sierra)

• Windows 10 (Visual Studio 2019)

Tier 2 platforms 第二类:

• Ubuntu 18.04 (Bionic): arm32

Tier 3 platforms 第三类:

• Debian Stretch (9): amd64, arm64 and arm32

• OpenEmbedded Thud (2.6) / webOS OSE: arm32 and x86

For more information about RMW implementations, compiler / interpreter versions, and system dependency versions see REP 2000. 有关RMW实现，编译器/解释器版本和系统依赖版本的更多信息，请参见REP 2000。

New features in this ROS 2 release 新功能

During the development the Eloquent meta ticket on GitHub contains an up-to-date state （最新状态）of the ongoing high level tasks （高级任务）as well as references specific tickets with more details （更多详细信息）.

Changes since the Dashing release 

Dashing版本之后的更新

geometry_msgs

The geometry_msgs/msg/Quaternion.msg interface now default initializes to a valid quaternion, with the following values:

现在，geometry_msgs/msg/Quaternion.msg接口默认使用以下值初始化为有效的四元数：

x=0

y=0

z=0

w=1

Here is the pull request for more detail（更多详细信息）: https://github.com/ros2/common_interfaces/pull/74

rclcpp

API Break with get_actual_qos() API中断与get_actual_qos()

Introduced in Dashing, the get_actual_qos() method on the PublisherBase and SubscriptionBase previously returned an rmw type, rmw_qos_profile_t, but that made it awkward to reuse with the creation of other entities. Therefore it was updated to return a rclcpp::QoS instead. 之前使用rmw类型rmw_qos_profile_t，但是在创建其他实体时很难重用，更新为rclcpp::QoS。

Existing code will need to use the rclcpp::QoS::get_rmw_qos_profile() method if the rmw profile is still required. For example:

如果仍然需要rmw配置文件，则现有代码将需要使用如下方式：

void my_func(const rmw_qos_profile_t & rmw_qos);

/* Previously: */
// my_func(some_pub->get_actual_qos());
/* Now: */
my_func(some_pub->get_actual_qos()->get_rmw_qos_profile());

The rationale for breaking this directly rather than doing a tick-tock is that it is a new function and is expected to be used infrequently by users. Also, since only the return type is changing, adding a new function with a different would be to only way to do a deprecation cycle and get_actual_qos() is the most appropriate name, so we would be forced to pick a less obvious name for the method.

API Break with Publisher and Subscription Classes

In an effort to streamline the construction of Publishers and Subscriptions, the API of the constructors were changed.

为了简化发布和订阅的构造，更改了构造函数的API。

It would be impossible to support a deprecation cycle, because the old signature takes an rcl type and the new one takes the NodeBaseInterface type so that it can get additional information it now needs, and there’s no way to get the additional information needed from just the rcl type. The new signature could possibly be backported if that would help contributors, but since the publishers and subscriptions are almost always created using the factory functions or some other higher level API, we do not expect this to be a problem for most users.

Please see the original pr for more detail and comment there if this causes issues （更多详细信息）:

https://github.com/ros2/rclcpp/pull/867

rmw

API Break Due to Addition of Publisher and Subscription Options 由于添加了发布和订阅选项而导致API中断

The rmw_create_publisher() method had a new argument added of type const rmw_publisher_options_t *. This new structure holds options (beyond the typesupport, topic name, and QoS) for new publishers.

The rmw_create_subscription() method had one argument removed, bool ignore_local_publications, and replaced by the new options of type const rmw_subscription_options_t *. The ignore_local_publications option was moved into the new rmw_subscription_options_t type.

In both cases the new argument, which are pointers, may never be null, and so the rmw implementations should check to make sure the options are not null. Additionally, the options should be copied into the corresponding rmw structure.

See this pull request, and the associated pull requests for more details （更多详细信息）:

https://github.com/ros2/rmw/pull/187

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