00:07 Understanding LaserScan data on TurtleBot 01:47 Understanding the structure of the laser scan message 03:09 Understanding the ranges array and angles in LaserScan data 04:37 LaserScan data includes angle increment, angle mean, angle max, coverage, and ranges array 06:31 Understanding LaserScan data ranges array 08:08 Understanding LaserScan data and its values 10:24 Reading LaserScan data values at different angles. 12:04 LaserScan data is read at different angles
1)I think you have just executed the launch file in 9:20 without compiling the package. Is that possible? 2)Another thing why didn't change the CMakeLists.txt ? Maybe when the src file in python you don't need that , idk I have only done the Ros Basics in 5 days (c++) . 3)One more Thing , why the output was a multiple of 720. Is that maybe bacause the callback function is called multiple times? When I look closer later , the value at 90 degrees seems to be changing slightly ,does that means that this is the result in real time and the robot is slightliy moving forward ? If that the case then why would the output comes to an end after a number of outputs? I would appreciate it to have answers. I am a new member of the community of the construct 😄😃 .
Anybody know how to change the angle from -2.356 and 2.356 rad to be equal to 90 degrees? Or how to only print one value with print len(msg.ranges)? Cheers
RLException: Unable to launch [scan_values-1]. If it is a script, you may be missing a '#!' declaration at the top. The traceback for the exception was written to the log file please help me.....
well if we have 720 values, you can divide them equally into 2, but you see that there is no middle element. As we only need approximate reading of what is at front, both 360 and 359 will be fine.
![[ROS Q&A] 040 - How to check the distance to an obstacle using a laser](http://i.ytimg.com/vi/q3Dn5U3cSWk/mqdefault.jpg)
00:07 Understanding LaserScan data on TurtleBot
01:47 Understanding the structure of the laser scan message
03:09 Understanding the ranges array and angles in LaserScan data
04:37 LaserScan data includes angle increment, angle mean, angle max, coverage, and ranges array
06:31 Understanding LaserScan data ranges array
08:08 Understanding LaserScan data and its values
10:24 Reading LaserScan data values at different angles.
12:04 LaserScan data is read at different angles
Very impressive!
Such a great explanation, already thinking to apply for subscription
How would be the program in C++?
how to get the kobuki package
1)I think you have just executed the launch file in 9:20 without compiling the package. Is that possible?
2)Another thing why didn't change the CMakeLists.txt ? Maybe when the src file in python you don't need that , idk I have only done the Ros Basics in 5 days (c++) .
3)One more Thing , why the output was a multiple of 720. Is that maybe bacause the callback function is called multiple times? When I look closer later , the value at 90 degrees seems to be changing slightly ,does that means that this is the result in real time and the robot is slightliy moving forward ? If that the case then why would the output comes to an end after a number of outputs?
I would appreciate it to have answers. I am a new member of the community of the construct 😄😃 .
Anybody know how to change the angle from -2.356 and 2.356 rad to be equal to 90 degrees?
Or how to only print one value with print len(msg.ranges)?
Cheers
How can I get exact location of an obstacle if there is any obstacle like pole or something. How to detect it's coordinates in the ranges.
Thank you
RLException: Unable to launch [scan_values-1].
If it is a script, you may be missing a '#!' declaration at the top.
The traceback for the exception was written to the log file
please help me.....
do not forget to source your workspace
Thanks a lot; what is inf value there? when laser beam does not return back to the sensor, does it show inf value?
Yes exactly it is.
Thank you so much Alberto, it was a very clear presentation which has helped me alot
Hocam merhaba , ben sensörün önüne obje koyduğum halde -inf değer döndürüyor , hatanın çözümünü biliyor musunuz?
Great tutorial thanks
Woud you make another tutorial about how can I read intensity of Lazer scan?
Thank you for making this easy explaining video
Nice video, Thank you for sharing!
hi, i put object in simulation , but laser still gives inf value for the all ranges.Do you know the solution?
Did you provide a to the object model ?
@@TheConstruct I did when you said but still same , i search ros wiki but didnt find out any solution.
Hi, should the value at the middle of the ranges array be 359 instead of 360?
well if we have 720 values, you can divide them equally into 2, but you see that there is no middle element. As we only need approximate reading of what is at front, both 360 and 359 will be fine.
Once you understand all values on the array are "-1" please change 360 to 359 too 😭😭😭
nice, thanks :)