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ctu-mrs / mrs_uav_system

The entry point to the MRS UAV system.
https://ctu-mrs.github.io/
BSD 3-Clause "New" or "Revised" License
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Question about lidar sensor. #38

Closed Gaoyuan-Liu closed 3 years ago

Gaoyuan-Liu commented 3 years ago

Hey Mrs team, I notice you integrated a laser scanner called "rplidar" in the drones (F550), I'm recently using it to detect obstacles. My question is what is the real-world lidar sensor you are using onboard? Since we are trying to build a counterpart real-world drone as the simulation.

Thanks for your help! : )

Gaoyuan

DanHert commented 3 years ago

http://letmegooglethat.com/?q=rplidar

But jokes aside, it is a rplidar A3 - https://www.slamtec.com/en/Lidar/A3

Gaoyuan-Liu commented 3 years ago

Hey Dan, Sorry about the silly question. Yes, I also googled that but wanted to make sure ;) And could you please also give some information about what sensor/camera you are using currently to achieve obstacle avoidance, I also saw a long list in the urdf file about sensor/camera, but which one (or combinations for data fusion maybe) you will recommend using on a real-world drone (let's say F450 this time)? And what's the consideration of your preference?

Thanks again!

DanHert commented 3 years ago

On our F450s, we use the rplidar for obstacle avoiodance. It is only a planar sensor, but that is enough in some enviroments. In more cluttered environments, we are using 3D lidars (mostly Ouster OS0), complemented by stereocameras (Intel Realsense).

Dan H.

Gaoyuan-Liu commented 3 years ago

Hey Dan, I'm trying to use octomap to do mapping and path planning. Is there any camera/sensor plugin written in urdf can generate /sensor_msgs/PointCloud2 data?

Thanks for your help.

DanHert commented 3 years ago

Hello! You can use a 3D lidar in the simulation (add "--enable-velodyne" into the spawn command in simulation session file). It will output PointCloud2 directly. Alternatively, you can use a simulated stereocamera ("--enable-realsense-front" other orientations available) which will give you a depth image, but that can be converted to PC2 with http://wiki.ros.org/depth_image_proc The LaserScan data from rplidar can be also converted to PC2, with http://wiki.ros.org/laser_geometry

cheers, Dan H.

Gaoyuan-Liu commented 3 years ago

Hey Dan, Thanks a lot for your response! I just tried "--enable-velodyne", indeed, it can give a PC2 topic but there is an error in rviz: "Message Data size (333750 bytes) does not match width (0) times height (1) times point_step (25). Dropping message."

Maybe I also need some configuration before I use it directly?

Thanks!

DanHert commented 3 years ago

Yeah, looks like we have some bug there. Switch to "--enable-ouster" instead of velodyne, that one should work normally.

Cheers, Dan H.

WingRS commented 3 years ago

Hi all, @DanHert have you been able to test the velodyne in RviZ?

petrapa6 commented 3 years ago

Hi,

velodyne was fixed in 297f0ba.

ZhiWei20011 commented 3 years ago

Hi, after adding the "--enable-realsense-front" to the simulation command, how can I see the image from rviz? Do I need to change some settings in rviz? Appreciate any answers. Thank you.

petrapa6 commented 3 years ago

Hello, you definitely need to add manually all the data you want to visualize in RVIZ on your own. I believe using the RVIZ GUI is intuitive and straightforward, and does not need any more explanation. I can point you to http://wiki.ros.org/rviz for more information.

If you have an unrelated question to this issue, please either open a new issue or use discussions. Closed issues and PRs are no place for unrelated questions.

Best, Pavel