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Actuators used with 2d laser scanners to produce 3D images on ROS

asked 2018-05-18 04:00:06 -0600

Mekateng gravatar image

Hi, The acquisition of 3D LIDAR is mainly based on the rotation of the 2D laser scanner around a certain axis. I mean a standard 2D laser scanner and mechanical rotational element are required for 3D scanning on ROS. What are the advantages and disadvantages of the actuators used for this( step, servo and dc motor with encoder)? That's why, which motor should ı use? Why? which motor shouldn't ı use? why? Thanks in advance for your helping.

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answered 2018-05-18 06:27:56 -0600

I have built several 3D LiDAR scanners for our lab using the technique you describe. There are a few factors to consider when choosing an actuator:

  1. It needs to be able to accurately report its position in space and time. You'll need to precisely register each 2D LiDAR scan with the position of the actuator when that scan was captured, so this position feedback is very important however it is achieved.

  2. You'll also want something which already has good ROS support; nobody want to re-invent the wheel.

  3. The actuator also needs to be strong and precise enough to repeatedly follow exactly the same path, so that your 3D scans are consistent.

These requirements can be achieved just as well by a stepper motor system or a DC motor with an encoder, but I would recommend avoiding building something from parts if you can.

We use the FLIR ptu-46 for our 3D LiDAR scanners, there is a ROS driver avilable for this too. It's not the cheapest I have to say but it's strong, reliable and has very good position feedback.

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Thank you for your answer. However, for example, the resolution of the LİDAR we use is 0.352 degree. The resolution of the actuator we use is 0.2. So much higher. What happens when a situation like this happens?

Mekateng gravatar image Mekateng  ( 2018-05-18 06:42:54 -0600 )edit

Those two resolutions describe very different concepts, I would say the difference is not that important. The lidar resolution is the angular distance between samples, and the actuator resolution is the precision it can move itself too.

PeteBlackerThe3rd gravatar image PeteBlackerThe3rd  ( 2018-05-18 06:51:49 -0600 )edit

At the end of the day you probably want the same angular distance between 2D line scans as there is between individual LiDAR samples within each line. It sounds like you can achieve this fine with the 0.2 degree resolution actuator, so this should be fine.

PeteBlackerThe3rd gravatar image PeteBlackerThe3rd  ( 2018-05-18 06:54:27 -0600 )edit

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Asked: 2018-05-18 04:00:06 -0600

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Last updated: May 18 '18