List of articles

• Remote start ROS node
  • #1 Environmental Science
  • #2 demand
  • #3 Verify the prerequisites
    • #3.1 Verify password free login
    • #3.2 Verify the stand-alone ros Publish subscribe
  • #4 Start
    • #4.1 To configure
      • #4.1.1 pc-master
      • #4.1.2 pc-slave2
    • #4.2 Local host script
    • #4.3 start-up
  • #5 Report errors
    • #5.1 not found in known_hosts
    • #5.2 TypeError: 'NoneType' object is not callable

Remote start ROS node

#1 Environmental Science

Ubuntu 16.04 

Machine configuration :

pc-master 192.168.3.230  Local 
pc-slave2 192.168.3.232  long-range 

Prerequisite :

1. It can be realized on two machines ROS Publish and subscribe

2. Two machines can log in without password

#2 demand

• in application , Different functions will be put on different servers
• You need to subscribe to topic

#3 Verify the prerequisites

#3.1 Verify password free login

---

The two servers can log in to each other without password

Specific password free login tutorial : https://blog.csdn.net/Coxhuang/article/details/106971890

#3.2 Verify the stand-alone ros Publish subscribe

Here we use pc-slave2 Server, for example ( Because the remote startup is also pc-slave2 Nodes on )

talker :

---

listener :

#4 Start

** Next , We will be having pc-master Start the remote server on the server area pc-slave2 Of talker node **

#4.1 To configure

#4.1.1 pc-master

sudo vim /etc/hosts

stay /etc/hosts Add something to the file :

192.168.3.230   pc-master
192.168.3.232   pc-slave2

sudo vim ~/.bashrc

stay ~/.bashrc Add something to :

export ROS_IP="192.168.3.230"
export ROS_HOSTNAME=pc-master
export ROS_MASTER_URI=http://pc-master:11311
export ROSLAUNCH_SSH_UNKNOWN=1

#4.1.2 pc-slave2

sudo vim /etc/hosts

stay /etc/hosts Add something to the file :

192.168.3.230   pc-master
192.168.3.232   pc-slave2

sudo vim ~/.bashrc

stay ~/.bashrc Add something to :

export ROS_HOSTNAME=pc-slave2
export ROS_MASTER_URI=http://pc-master:11311
export ROSLAUNCH_SSH_UNKNOWN=1

sudo vim /opt/ros/kinetic/trunk_evn.sh

newly added trunk_evn.sh file

#!/bin/sh
export ROS_IP=192.168.3.232
export ROS_HOSTNAME=pc-slave2
. /home/trunk/work/test/testworkspace/devel/setup.sh
exec "$@"

sudo chmod 777 trunk_evn.sh

#4.2 Local host script

In the local pc-master Of package Written in launch Script

vim /home/trunk/work/test/testworkspace/src/testpackage/launch/test.launch

<launch>
    <machine name="pc-slave2" address="192.168.3.232" user="trunk" env-loader="/opt/ros/kinetic/trunk_evn.sh"></machine>
    <node machine="pc-slave2" name="talker" pkg="testpackage" type="talker.py" output="screen" ></node>
</launch>

#4.3 start-up

roslaunch testpackage test.launch

#5 Report errors

#5.1 not found in known_hosts

... logging to /home/trunk/.ros/log/84cf4482-b84f-11ea-9d63-000c297ff566/roslaunch-pc-master-3868.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://pc-master:32881/
remote[192.168.3.232-0] starting roslaunch
remote[192.168.3.232-0]: creating ssh connection to 192.168.3.232:22, user[trunk]
/usr/lib/python2.7/dist-packages/Crypto/Cipher/blockalgo.py:141: FutureWarning: CTR mode needs counter parameter, not IV
  self._cipher = factory.new(key, *args, **kwargs)
remote[192.168.3.232-0]: failed to launch on pc-slave2:

Unable to establish ssh connection to [trunk@192.168.3.232:22]: Server u'192.168.3.232' not found in known_hosts

Solutions :

• Log

According to the log error prompt to modify python Bottom source , There is no effect , The log shows , ros It's still running on python2.7 On , Try to ros Running on the Python3 On

1. Default the system to Python Replace with Python3

sudo rm -rf /usr/bin/python
sudo ln -s /usr/bin/python3 /usr/bin/python

2. install ros The basic software package for compiling

sudo apt-get install python3-rosdep python3-rosinstall-generator python3-wstool python3-rosinstall build-essential
sudo pip3 install catkin_pkg

3. Installation package depends on

rosdep install --from-paths src --ignore-src --rosdistro kinetic -y
sudo apt-get install libtbb-dev python3-pyqt5
sudo pip3 install empy numpy defusedxml netifaces
#  Repair  16.04 libboost_python3 Problems that can't be found 
sudo ln -s /usr/lib/x86_64-linux-gnu/libboost_python-py35.so /usr/lib/x86_64-linux-gnu/libboost_python3.so

4. Perfect solution

#5.2 TypeError: ‘NoneType’ object is not callable

modify Python The underlying code