Problem to setup correctly the laser scanner

I am trying to connect via ssh with the robot (pair of raspberry) without success. In particular I am not able to reach this goal:
“1 .Check Husarnet’s DNS resolution of the devices in the group.”
And I am not able to connect with the robot via ssh with
“ssh theconstruct@rpi4-1”
Please, any suggestions are appreciated

Hi @saxosun,

I suppose you have joined the network using the Husarnet Join Code, have you?

If not, please try to join the Husarnet network first, using the JoinCode provided in the notebook.

Once connected, try to ping that robot first, using:

ping rpi4-1 

If it cannot ping, then check if the rpi4 is on /etc/hosts:

cat /etc/hosts

If you cannot see rpi4 there, then the rpi4 is not connected.

If that is the case, maybe @rtellez and @duckfrost2 know better if these Raspberries are online or not.

Hello Ralves,
yes, I joined the network using the JoinCode as described in the lesson. Probably the rpi4-1 is off. I attached the result of the ping and the print of hosts file.

user:~$ ping rpi4-1
PING rpi4-1(rpi4-1 (fc94:b82d:fddc:99d0:4bb1:b92b:ee06:2a1a)) 56 data bytes
--- rpi4-1 ping statistics ---
112 packets transmitted, 0 received, 100% packet loss, time 113661ms
user:~$ cat /etc/hosts       localhost
::1     localhost ip6-localhost ip6-loopback                            r/bin/vife00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodesff02::2 ip6-allrouters      1_xtermfc94:dcb4:606c:1fe2:d046:1842:ef54:66ff 1_xterm # managed by Husarnet
fc94:7c87:33e1:c1e6:19db:f608:b800:15e0 master # managed by Husarnet
fc94:b82d:fddc:99d0:4bb1:b92b:ee06:2a1a rpi4-1 # managed by Husarnet


Yeah the raspberry pies are disconnected because they were not intended to be used outside the workshop

Hi, is this the only exercise that doesn’t work or are there others? I would like to know if this course is profitable if I follow it remotely.
Thank you


The course is profitable in the way that if you have two raspberry pis an dtest this or any other system it will apply with no problem.

The only thing that you don’t have is access to two raspberry pi setup exclusively to help you learn DDS.

I suggest that for example try this on the robot that you want to control and with your own PC to see topics and so on. Its really the objective of the course

Hi @saxosun ,

Here is the answer taken from DDS: QoS: Quality of Service: botbox RViz file does not exist! - #4 by ralves

I see you are facing some problems in the DDS course.

This course is indeed not ready to be followed online. It was created for an In-Person Intensive Training in Barcelona, where at least 20 Raspberry PI were configured for the training, but are not running right now (after the in-person training has finished).

Let’s see what @rtellez says, but I suppose one of the two things will happen:

  1. The course will be disabled because it is not ready to be followed online
  2. The course will be modified to be easily followed online.

I see that the second is better for you and many other members of The Construct.

Ricardo will come up with a solution for this next week, after discussing it with @roalgoal.

Hi Ralves,
I hope the DDS course won’t be disabled because contains important concepts. I am available to buy two raspberry to reproduce the HW here.

Hi @saxosun,

Yes, it’s better if the course is just modified to work online.

Just buying the Raspberry PIs is not enough, since you need instructions on how to setup them, and these instructions may not be right now in the DDS course notebooks.

The same concepts taught using Rapberries could be reproduced using Docker Compose also.

Let’s wait to see what Ricardo decides with Rodrigo.

Hi Ralves,
I hope the DDS course won’t be disabled because contains important concepts. I am available to buy two raspberry to reproduce the HW here.

1 Like

This topic was automatically closed 5 days after the last reply. New replies are no longer allowed.