TurtleBot lidar

Course Support ROS Basics In 5 Days (C++)
1

Hello,
last week I booked robot for check my final quiz is working (ros basic 5 days c++). In simulations everything works but on real robot I had problem with laser, I checked that /scan node didnt publish any data. Everything else was working.
Also your banner also broke off and was partially lying on the track, but its not big deal.

Mateusz

2

Did you bring up your real TurtleBot?

3

We don’t expect everything to work out of the box when you connect to the Real Robot.

In fact, we included the Real Robot bit so you can learn what will happen when you develop your program with a simulation and then try to use it on a real robot.

Things you should consider for the Real Robot:

  • The topic names might be different from that of the simulation.
  • The range of the laser scan might be different.
  • The robot might have a speed limit that was not present in the simulation.
  • When you publish once in the simulation, the robot keeps moving. It might not be so for the real robot.
4

Thank You for answer.
The name of topics I think was fine, robot was moving. /scan topic exist but robot didnt publish any data, on rviz there also wasn’t any data from lidar. Other topics was working and return some data.
Its wasn’t problem in my code (at this point) because robot didn’t return any data from lidar, there was no message it was empty. So we don’t talk at this point about wrong moving, speed, something wrong in algorithm. Maybe robot has some error, I don’t know.

5

I see. If the robot had any error, that would be temporary, because it’s the same robot used by everyone.

Could you please try again?

6

Yes of course I will try again, maybe tomorrow.

7

I checked it yesterday and now its workig. Now I have problem in my soft. Maybe I can ask You sometthing else. In service client node to find wall i subscribe data from lidar and publish data to odometry. Service is bloking other subscriber and publisher so to do this task I use “ros::AsyncSpinner spinner(0);” in simulation its wroking but on real robot not exacly. How many threads is avaiable in turtlebot ? Its looks like working service + pub odom or service + sub lidar.
Ofcourse I could make some bug by myself.

8

Please create a new topic for this subscription/service problem, and I’ll get one of our experts to have a look.

9

ok, thank you. Tomorrow I create new topic.