Hello ROS developers, welcome to the ROS in five minutes video series by
The Construct, your channel for anything ROS. I'm Bayode Aderinola, and in this
video we'll be learning about the ROS parameter server. Of course you can read
about the parameter server topic here, but in this this video we'll be taking the practical
approach and we'll check some things and see them live. Now for this we are
using the ROS Development Studio, a powerful online for pushing your ROS learning in
a practical way. You can create a free account also on this studio and do
exactly what you see here and more. You will find a link to that in the video description. So
let's get started. Create a new project
then we launch it
so as I mentioned we will be doing practical so the first thing we want to do
is: how do interact with the server. It's a parameter server, so let's check the
parameters on the server. rosparam
list. That's the command to see the parameters on the server
Oops what is this?! Unable to communicate with master? Yes, this is correct because
as you will see here it says the ROS parameter server runs
inside of the ROS master and as you can see here we are yet to start the ROS master
so we are going to do the right thing now by starting the ROS master and we do that
with the command roscore
Great! So just from here alone you can see under what is called parameters here
two parameters already listed with their values. rosdistro and rosversion
with their values in front of them. So let's get back to our command here and see
if it works now. Of course it does because we've started the ROS master
and so the parameter server is also working. So the two we saw earlier rosdistro and
rosversion are here, but these two are new. This brings us to the second way
to interact with the parameter server, which is to actually see the value of the
parameters there. So the command is 'rosparam get' so we just want to get
the value of the parameter and this returns for us the value. So now the
other thing about ROS parameters that was explained here is is the way that it exists
in hierarchies, so which means we can get the whole hierarchy or get
part of it. so and we are going to do something similar here so first let's
get ROS..let's use the last command. Let's get up to 'uris' so
you can see that what we have there is a dictionary with hosts and then the value.
We can also get up to roslaunch itself. Now you can see a bigger dictionary here. Sp
that's it! In this video we just covered the basics of the parameter server. In
future videos we might cover more. But before you go remember to visit
the Robotic Ignite Academy our online Academy where you find
practical online ROS courses using simulated robots. No installation required.
You just need your computer and your browser basically. So did you like the video? if you did
please give us a thumbs up and remember to subscribe to our Channel and press the
bell for a new video every day. Whether you liked it or not please leave us your
thoughts and suggestions in the comments area. Peace out ==
O dabo!
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