Difference between revisions of "ROS2"

Revision as of 12:41, 10 December 2018

About

Use ROS2 in Elphel single or multi-camera systems. The cameras are 10393 system boards based on Xilinx Zynq, ARM.

Goals

Notes:

Controlling and initializing of multi-camera systems is already implemented using PHP API (autocampars.php), Python and lighttpd.
Using ROS2 is intended to simplify/standardize the above.
Using ROS2 is intended to make cameras compatible with other hardware supported by ROS1/2.

Having ROS2 cross-compiled and installed on each camera:

Initialize cameras in a pre-defined multi-camera system - sync and sequence critical init
Control multiple cameras from any camera of the system - parameters, recording
Control multiple cameras from a PC (with ROS2 for PC installed).
Control multiple cameras from a network device (w/o ROS2 installed, but with a browser) - by accessing a web server running on a camera interfaced with ROS2 of the camera. Can use nodejs or just lighttpd+php.

Status

Development

Interfaces

ROS2 nodes communicate over:

1 GigE LAN or (possibly) wifi (camera1-camera2..N, pc-camera1..N, pc1-pc2..M)
within a single device

Notes:

image sensors, IMS (or GPS & IMU), any other sensors are attached to cameras via a custom interface or USB, with appropriate driver support.
normally cameras in the system are synced with a custom trigger cable - this is setup over network
any device attached to PC?

ROS2 on Zynq

Installation

For Embedded Linux (but not Ubuntu Distro) use meta-ros.git. What about meta-ros2?

TODO: Include meta-ros.git in elphel393 build system.

Include meta-ros to elphel393

Add path to bblayers.conf
Add to "IMAGE_INSTALL_append" of core-image-elphel393.bb:

packagegroup-ros2-world \

Notes

Cross-compilation for ARM
ROS2 for python populates /usr/lib/python3.5/site-packages/ so python scripts can live anywhere.
For command line apps, like ros2 ..., if AMENT_PREFIX_PATH is not set then:

OSError: Environment variable 'AMENT_PREFIX_PATH' is not set or empty

Useful commands (command line):

export AMENT_PREFIX_PATH=/usr

ros2 pkg list
ros2 node list
ros2 srv list
ros2 srv show std_srvs/Trigger
ros2 msg list
ros2 msg show std_msgs/String

Demos

talker-listener cpp

# terminal 1:
export AMENT_PREFIX_PATH=/usr
ros2 run demo_nodes_cpp talker

# terminal 2:
export AMENT_PREFIX_PATH=/usr
ros2 run demo_nodes_cpp listener

Workflow

Use example recipes from meta-ros.git
bitbake package-name, check output and logs in the poky build tree
List package in core-image-elphel393.bb's IMAGE_INSTALL_append

TODO:

Add target-scp and an example empty recipe

ROS2 on PC

Installation

Google and follow the general instructions.

Notes

apt install ros-bouncy-desktop available in 18.04, n/a in 16.04
apt install ros-ardent-desktop available in 16.04
ROS2 will get installed to /opt/ros/<name>, <name>s are ardent, bouncy, crystal, etc.
Terminal setup:

source /opt/ros/bouncy/setup.bash
or
source /opt/ros/bouncy/local_setup.bash

Workflow

Create a workspace
Create some packages inside or clone - they have a vcs tool to clone all repos from a text file.
Install colcon
Then build with colcon
New packages will not get installed to /opt/ros/<name>. They will live in their folders.
To use a package:

source /opt/ros/bouncy/setup.bash
source ~/ros2_ws/some-package/install/local_setup.bash
ros2 pkg list
then run anything in this terminal

Python scripts can live anywhere - just run them from that sourced terminal

ROS2 in Docker

docker pull osrf/ros2:bouncy-desktop
docker run -i -t osrf/ros2:bouncy-desktop 
No network, no colcon, no ament...

ROS2 General Notes

Notes

SROS is Secure ROS or something

Useful links

ErleRobotics Tutorials on ROS2 - very useful

Ament tutorial - build system for new packages
- works and supported in meta-ros
- will not work for PC because repo hashes moved on?

Colcon tutorial - newest build system for new packages
- works for PC, even in 16.04
- not supported in meta-ros (as of 2018/12/07)
- colcon docs

About meta-ros and about meta-ros2 - are they merged?

Networking:

ROS on DDS

... 
if you are concerned about latency, like for soft real-time, you can basically tune DDS to be just a UDP blaster. In another scenario you might need something that behaves like TCP, but needs to be more 
tolerant to long dropouts, and with DDS all of these things can be controlled by changing the QoS parameters.
...

ROS2 Services:

Reference ROS repos

ROS1

Won't build. More info.

@@ Line 39: / Line 39: @@
 ===Notes===
+* Cross-compilation for ARM
 * ROS2 for python populates '''/usr/lib/python3.5/site-packages/''' so python scripts can live anywhere.
 * For command line apps, like ''ros2 ...'', if AMENT_PREFIX_PATH is not set then:
@@ Line 72: / Line 73: @@
 ===Installation===
 * Google and follow the [https://index.ros.org/doc/ros2/ general instructions].
-<font color='green'>'''Notes:'''
+===Notes===
 * '''apt install ros-bouncy-desktop''' available in 18.04, <font color='red'>n/a in 16.04</font>
-* '''apt install ros-ardent-desktop''' available in 16.04</font>
+* '''apt install ros-ardent-desktop''' available in 16.04
+* ROS2 will get installed to '''/opt/ros/<name>''', <name>s are ''ardent'', ''bouncy'', ''crystal'', etc.
-===Workflow===
-* ROS2 will get installed to '''/opt/ros/<name>''', <name> = ardent, bouncy.
 * Terminal setup:
   <font size='2'>''source /opt/ros/bouncy/setup.bash''
@@ Line 83: / Line 83: @@
   ''source /opt/ros/bouncy/local_setup.bash''</font>
+===Workflow===
 * Create a workspace
 * Create some packages inside or clone - they have a [https://github.com/dirk-thomas/vcstool vcs tool] to clone all repos from a text file.
 * Install [https://colcon.readthedocs.io/en/released/user/quick-start.html colcon]
 * Then build with colcon
-* Packages will not get installed to /opt/ros/bouncy/... Instead they will stay in their folders.
+* New packages will not get installed to '''/opt/ros/<name>'''. They will live in their folders.
 * To use a package:
-  source /opt/ros/bouncy/setup.bash
+  <font size='2'>source /opt/ros/bouncy/setup.bash
   source ~/ros2_ws/some-package/install/local_setup.bash
   ros2 pkg list
-  then run anything in this terminal
+  then run anything in this terminal</font>
 * Python scripts can live anywhere - just run them from that sourced terminal
-* [https://erlerobotics.gitbooks.io/erle-robotics-python-gitbook-free/udp_and_tcp/a_simple_tcp_client_and_server.html Good book about UDP?]
+==<font color='blue'>ROS2 in Docker</font>==
+ docker pull osrf/ros2:bouncy-desktop
+ docker run -i -t osrf/ros2:bouncy-desktop
+ No network, no colcon, no ament...
 ==<font color='blue'>ROS2 General Notes</font>==
 ===Notes===
 * SROS is Secure ROS or something
 ===Useful links===
-* [http://docs.erlerobotics.com/robot_operating_system/ros2/tutorials/tutorial_10 Tutorials ErleRobotics]
-* [https://github.com/intel/ros2_intel_realsense Intel RealSense]
+* [http://docs.erlerobotics.com/robot_operating_system/ros2 ErleRobotics Tutorials on ROS2] - very useful
-* [https://index.ros.org/doc/ros2/Ament-Tutorial/ Ament tutorial] - will not work for PC because it's outdated, will work in Yocto
-* [https://index.ros.org/doc/ros2/Colcon-Tutorial/ Colcon tutorial] - this one worked for PC
+* [https://index.ros.org/doc/ros2/Ament-Tutorial/ Ament tutorial] - build system for new packages
-* [https://discourse.ros.org/t/suggestions-for-std-srvs/1079/16 STD-SRVS '''discussion'''] & [https://github.com/ros2/examples/issues/4 ROS2 examples(?)]
+** works and supported in meta-ros
-* [https://discourse.ros.org/search?q=meta-ros%20order%3Alatest About meta-ros]
+** will not work for PC because repo hashes moved on?
+* [https://index.ros.org/doc/ros2/Colcon-Tutorial/ Colcon tutorial] - newest build system for new packages
+** works for PC, even in 16.04
+** not supported in meta-ros (as of 2018/12/07)
+** [https://colcon.readthedocs.io/en/released/user/how-to.html#build-only-a-single-package-or-selected-packages colcon docs]
+* [https://discourse.ros.org/search?q=meta-ros%20order%3Alatest About meta-ros] and [https://discourse.ros.org/search?q=meta-ros2%20order%3Alatest about meta-ros2] - are they merged?
+Networking:
 * [http://design.ros2.org/articles/ros_on_dds.html ROS on DDS]
   <font size='2'>...
@@ Line 114: / Line 130: @@
 * [http://www.eprosima.com/index.php/resources-all/performance/40-eprosima-fast-rtps-performance FastRTPS benchmarks]
 * [http://docs.eprosima.com/en/latest/advanced.html FastRTPS max message size]
+* [https://erlerobotics.gitbooks.io/erle-robotics-python-gitbook-free/udp_and_tcp/a_simple_tcp_client_and_server.html Good book about UDP?]
+ROS2 Services:
 * [https://wiki.ros.org/Services Request-Response is done with '''service''']. Format [https://wiki.ros.org/srv srv]
+* [https://discourse.ros.org/t/suggestions-for-std-srvs/1079/16 STD-SRVS '''discussion'''] & [https://github.com/ros2/examples/issues/4 ROS2 examples(?)]
-===Docker===
+===Reference ROS repos===
- docker pull osrf/ros2:bouncy-desktop
+* [https://github.com/inertialsense/inertial_sense_ros.git inertial_sense_ros.git] - cpp
- docker run -i -t osrf/ros2:bouncy-desktop
+* [https://github.com/intel/ros2_intel_realsense.git ros2_intel_realsense.git] - cpp
- ...no network, no colcon, no ament...
+* [https://github.com/ros-drivers/axis_camera.git axis_camera.git] - python
+* [https://github.com/bmwcarit/meta-ros.git meta-ros.git] - layer for Yocto
 ==<font color='blue'>ROS1</font>==
 <font color='red'>'''Won't build'''</font>. [[ROS1|More info]].

Difference between revisions of "ROS2"

Revision as of 12:41, 10 December 2018

Contents

About

Goals

Status

Interfaces

ROS2 on Zynq

Installation

Include meta-ros to elphel393

Notes

Demos

talker-listener cpp

Workflow

ROS2 on PC

Installation

Notes

Workflow

ROS2 in Docker

ROS2 General Notes

Notes

Useful links

Reference ROS repos

ROS1

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