RPLIDAR A2 - The Thinest LIDAR - 360 Laser Scanner

I bought this for a personal project that I am working on. This 'lidar' is actually a structured light sensor but works in a roughly equivalent manner. I have heard from others that this device has some variability in the range measurements based on possibly temperature. In my application that doesn't matter at all though and this sensor worked great. They list this as having a range of 6m but it is greater in my experience. I believe that we were getting range measurements up to about 12 meters. Probably the 6 meter spec is where they hold the 2% range spec and beyond that it is more. I noticed that at long distances, this module had a lot of noise in the reported ranges. Despite that, I was able to have a robot traverse a path roughly 70 to 80 meters in length through a building and using only this module's range measurements was able to have the start and end points of the map come to just over a half meter of the actual ground truth. The software that I wrote could have been improved further so don't read this as a fundamental limitation of this module. I would definitely use this module again for other projects.

I bought this slick-looking little unit in March to make static curved interior measurements. It works as advertised, but be aware of a few software issues (not sure if they've been addressed as of early May, 2017):1) The "frame_grabber" program only records a maximum of one revolution of data (0-360 degrees)2) The faster the rotation rate (default is 10 revs/sec), the fewer data points you get. At the default you'll maybe get 200-300 data points.3) You can slow the rotation to get more data points, but when it drops to around 2 revs/sec or below, it records about 1200 data points, then just cuts off data gathering before making a complete rotation.4) Dumped measurements are in polar coordinates - degrees & mms. Would be nice if we could select units (e.g. inches or cms since that's what Fusion 360 imports likes), and also toggle between polar and cartesian coordinates. Might also be nice if we could input a static height ("Z") coordinate to dump out as well. I'm currently having to write a post-processing python script to tenderize all the numbers so the CAD program can digest them.5) The dumped data files has a third status(?) number, "47" on each line. Nothing in the documentation to tell you what the hell that is or if it has any practical use.6) Would be nice if it could optionally add commas between the columns in the data dump file for CSV file digestibility.7) Would also be nice to be able to optionally leave off the opening text lines for the same reason.8) To really impress us, they could add a high-resolution mode that time-averages the scans for more precise static measurements, perhaps allowing us to specify how many points or the distances we want between points.On the hardware side, I found the following issues:1) It seems that some combinations of angles, surface textures/materials and angle-of-incidence fail to properly reflect, even at fairly close ( under 30cm) distance, leaving me with a few unexpected gaps in my perimeter scan.2) Would also be nice if the base had a line showing where 0-degrees is. Spoiler - It's 180 degrees from the center of the rear cord.3) They should also include a protective case for the small USB adapter PCB board. Had to pad & shrink-tube it to adequately protect it. Better yet, they should abandon the 4-pin connector and just put the USB port in the unit since that's pretty much the universal connector these days.I'm working around the issues, and this is by far the most economical way to get 2D planar distance scans, at least until cheap solid-state auto LIDAR chips become available. It works at both short & medium distance, and works will. Most of the issues are in the JMOS ("Just a Matter Of Software). Kudos to the team for making this available to geeks like us.

My unit came very unbalanced, so unbalanced that it caused my robot to think it was going in circles on a turtlebot2 base (the gyro caught the momentum, which I don't blame it, the whole robot shook with each rev). Took weeks to find out.EDIT: I originally had this review as a 1 star, but I updated it to three as I was able to balance it myself with a weight placed inside the head. I updated it to three as it's a decent design IMO. It's pretty rad how they communicate the top and the bottom.

Finally a lidar built to last and not 1k$. Every 2d 360 lidar I have used has a slip ring to pass data from the spinning top to the base - they wear really quickly add some dust and it's junk in a week (scanse sweep). Rplidar has opto to pass data and wireless power pretty slick. The update rate isn't bad either. I use this on a rover through ROS there is a robopeak GitHub with a few things to get development started.