# Velodyne Lidar sensor system for collision avoidance detection

Hi, I am designing collision avoidance detection system for my dissertation using Ubuntu 18-04 and ros-melodic but since I couldn't find complete answers to my problems I will explain here for some help:

I am designing a system that should be mounted on a deck on a landing station for research vessels and boats. I will use RViz and either the sensor Velodyne Puck or the HDL-64E which seems to be specific for maritime applications. Both technical sheets can be found here for the Puck and here for the HDL-64E

The green line represents the edge of the vessel that is approaching the deck from a particular side or heading. If the points are not returned by the lidar nothing will show.

Below I am attaching a small example of the system:

The questions I have are:

1) Would that be possible to show the whole contour line (the green line) that is detected by the lidar system? If so, how could that be done?

2) Would that be possible to show the points related to stern and bow all the time?

3) Do I need to have some sample data to post-process to make sure that the system is working as expected on real-time? (e.g. reading all the files and store them into a rosbag and from there create all the necessary messages to receive?)

4) Would that be possible to provide a live feed of the lidar data to visually show the orientation and distances of the approaching vessel in relation to the deck? (I think it is possible but need to be careful with reference systems correct?)

5) I think I don't need geo-reference of latitude and longitude if I put everything in the reference frame of the deck?

6) Would that be possible to show both trajectory and velocity of the vessel? or do I have to have a GPS to have those information?

7) I am also evaluating the possibility to use 2 lidar sensors mounted as shown in the drawing below but I don't know how beneficial would that be in relation to what I am trying to do.

8) Would that be possible to look both at my laptop in the lab and at another laptop on the deck?

Thank you all very much for all the help and guidance you can provide on these doubts I have. It will be possible for me to have both the SolidWorks model of some research vessel and the deck if that is useful for better understanding. I have a good understanding of RViz and reference systems if that is also useful to anyone and hope to deliver in the next 2-3 months the first copy of my dissertation. Thank you all for the help!

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