SICK Laser Rangefinder (LIDAR) Disassembled

I've always wanted to pull apart a SICK laser rangefinder (LIDAR).  However, the $6k price-tag (and advisor repercussions) have always been a sufficient deterrent.  Well, Kyle Vogt of MIT has disassembled what looks to be a SICK LMS-210 -- perhaps his was already broken?  Anyway, the internal design is surprisingly simple.  It's interesting to look at the internals of such iconic piece of robotics hardware.  Read on for more images.

Laser rangefinders have had a tremendous impact on robotics, and the SICK series of laser rangefinders is perhaps the most recognizable (SICK LMS 210, LMS 291, and PLS 100/200 pictured below).

SICK LMS 200 Laser Rangefinder (LIDAR)  SICK LMS 291 Laser Rangefinder (LIDAR)  SICK PLS 100/200 Laser Rangefinder (LIDAR)

They're a common fixture on many robotic platforms, especially DARPA Grand Challenge vehicles.  Of course, the SICK is not the only lidar around; numerous competitors have popped up, such as the Velodyne (below left) and a number of capable Hokuyo laser rangefinders (the four pictured below on the right available from Acroname).  Generally my preferences have drifted toward the Hokuyo line, which are lower-cost, better form-factor, and have lower power requirements, but the SICK line is steadily re-gaining ground.

Velodyne Laser Rangefinder (LIDAR)   Hokuyo URG-04LX Laser Rangefinder (LIDAR)  Hokuyo UTM-30LX Laser Rangefinder (LIDAR)  Hokuyo UHG-08LX Laser Rangefinder (LIDAR)  Hokuyo UBG-04LX-F01 Laser Rangefinder (LIDAR)

OK, OK... enough talk.  Here are Kyle Vogt's SICK internals!

 SICK LMS210 Laser Rangefinder (LIDAR) with back cover off This is the SICK with it's cover off.  You can clearly see the motor (copper colored piece) that spins the primary mirror.  This mirror scans the laser beam, coming from the laser module positioned in the middle of the "U-shaped" PCB, across the environment to obtain time-of-flight (TOF) ranges.
 SICK LMS210 Laser Rangefinder (LIDAR) Mirror rotation assembly Here is another angle of the SICK internals.  This image is taken along the plane of the scan.  Now the laser module is a little more clearly visible.
 SICK LMS210 Laser Rangefinder (LIDAR) Optical Encoder Assembly Here, you can see the optical encoder assembly.  I'm actually rather surprised that they've used such a simple "slotted-switch" assembly rather than a quality (high-res) encoder on the motor shaft.  Oh well, the guys at SICK probably have a good reason (cost or robustness).
 SICK LMS210 Laser Rangefinder (LIDAR) ASIC and FPGA Finally, here is a look at (one of) the circuit boards.  Based on Kyle's comments, the Infineon chip is an ASIC, and the Xilinx part is (clearly) an FPGA.  Apparently these units are not produced in large enough quantities to justify a full VLSI solution.  This makes me think that the day of the super low-cost (hobbyist) laser rangefinder may not be as far away as I imagined!

 

Well, those are the most telling pictures, though there are more images of the PCBs and the laser diode module on Kyle's website.


Oh, and if anyone has internal pictures of the other laser rangefinder models, please do let me know in the comments.

 

Comments

Hey Travis, glad you liked my pictures.  This was an LMS291-S06 I believe, and it was working when I took it apart (and when it went back together).
—Kyle

Hey Kyle,

Wow, I really admire your courage to open up a functional SICK... 

I was basing my model number prediction on the blue color of the SICK in the photo on your website.  I thought the LMS291 was universally a beige color (I have one sitting on my desk), and that the LMS200 was typically blue. But upon closer inspection, the SICK parts shown above have the characteristic beige color, so I do believe your part number is correct -- this is a LMS 291.

Either way,  I definitely enjoyed the pictures -- here in our lab we've been talking about doing something similar for some time, but no one was willing to risk it...

 

—Travis Deyle

Fantastic lineup of LIDAR systems!  

I want to recommend you also add ibeo to your  lineup.  I don't have any internal photos but I did do a write-up of it back home at RobotCentral (http://robotcentral.com/2007/11/15/sensor-technology-may-optimize-driving/).  The interview and photos were conducted at the DARPA Urban Challenge.  Ibeo has a complete system built on top of their unit and it's ready-to-go for application developers and each unit is expected to cost right around $300 when it hits mass production.

ZMP Inc (a Japanese company) recently introduced a Car Robotics Platform that includes a laser rangefinder.  What's interesting is that the entire platform, including the rangefinder, is priced at about  $5.5KUSD.    It's unclear whether their embedded LRF sweeps or not.

I just discovered your blog today and immediately added it to the top of my RSS list.

This is how a blog is done!  Kudos on the completeness of your articles!

Hey Ray,

Thanks for the pointers --  I am (vaguely) familiar with the Ibeo line of laser rangefinders, but have yet to actually see one in operation.  I was previously unfamiliar with ZMP, but will check it out too.  In my experience, most of the academic LRFs are from the SICK LMS series or of the Hokuyo variety. 

I'd certainly be very excited to see some quality LIDARs in the sub-$500 range; then I might be able to justify purchasing a few for personal use!  This reminds me of a paper at ICRA 2008 about a sub-$30 laser range finder being developed by Silicon Valley robotics startup Neato Robotics. I'd really like to learn more about their plans and aspirations for their laser range finder...

Oh, and thanks for the kind words about Hizook.  I also appreciate your work at Robot Central, which is included in my (excessively large) list of RSS feeds.

 

—Travis Deyle

Very cool. My Lidar bought in 1991 for robot guidance cost $120,000 and ran on the VME bus inside a $90,000 SGI 310 VGX. We used it for robot guidance generating 3D imagery for differetial geometry based path generation. This is a good old technology that can be widely used if cheap and safe. My Lidar was strong enough to damage eyes. Hope the mirror stability goes up and the costs continue to go down. I question the safety of a device that can be used for meaningful robot guidance over a several meter ambiguity interval.

Still very cool, my last robot: http://myrobotworld.spaces.live.com

 

 

—George Giles

Hi ,

Some pics and a video of my lidar that I opened up to share with you guys (Lidar Model : STI os3100).  This is the lidar I used for the Techx 2008 competition held in singapore:

http://www.facebook.com/album.php?aid=2018431&id=1211301187&l=a7489

http://www.facebook.com/v/1108663716075

—Yue Khing

Thanks Yue.  I've written a new blog post on the STI OS3100, here.

 

—Travis Deyle

Hi,

Do you know the Rockwell laser sensor, the SAFEZONE™ MULTIZONE SAFETY LASER SCANNER?

http://www.ab.com/en/epub/catalogs/3377539/5866177/3377569/6388297/3383633/3383653/

Has it ever been used in robotics?

—Rafael Vasconcelos
Does anyone know where I can get a CAD model of the sick lidar?
—Kelly

@ Kelly,

A quick Google search for "site:sick.com cad model" leads to the SICK parterns program, where they state:

Engineering and Consulting Services: SICK provides a variety of consulting services to help its customers meet the needs of their demanding customers, including machine efficiency reviews, customized data sheets, CAD drawings and 3D models, along with many other services.  

It looks like you might try contacting them directly. 

—Travis Deyle

Hello,

I know the SICK LMS is mainly used in robotic applications. What could be the price for a LMS200, a new old stock 6 or 7 years old ? It's complete and totally brand new in appearance, in its original box. Thanks in advance for your help. Regards, Gilles

—Gilles

I want disassembly for  SICK NAV200/300 of optics

—Shail

Are these lasers really eye-safe ?  Has there been any thrust towards higher wavelengths ?  Is there a worry that with large groups of robots and cars using LIDAR, that the summed laser energy moving around could cause an issue ?

—Anonymous

@Anonymous,  I've wondered the same thing... Looking at the actual LRFs, I don't recall seeing standard laser pointer "warning" labels (though I never really looked that hard).  I'm not sure how meaningful that is though.  I've speculated with other roboticists (not authoritative optics folks)... and the best explanation we could produce:

Laser safety standards use power (joules / second) delivered into the eye (right?).  Since the laser ranefinder rotates the laser at (say) 10Hz, it's only hitting your eye for a few microseconds -- too short a time to deliver much power to your eye?

Honestly... I still don't know the answer to that question.  In particular: what happens if the laser rangefinder breaks (quits spinning) and the laser is now fixed.  That could definitely be dangerous, right?!  And of course... these are infrared lasers, so you're not even aware when it's hitting you.

—Travis Deyle

As the product manager for SICK's Lidar devices, I would be happy to address @Anonymous' question.  It is true that the SICK LMS devices use a massively powerful laser to cut through rain, snow, and fog while still obtaining a 40m range on black objects.  This laser would unquestionably cause eye damage at long exposure times, especially since it's infrared so there is no blink reflex involved.  This is one of the reasons we don't recommend opening up the case, KYLE!  :)

However, Travis Deyle's speculation is correct:  The reason we're able to obtain a Class 1 - Eye Safe rating is that our pulse length is too short to deliver a dangerous amount of energy.  To clarify, the LMS5xx device spins anywhere from 25Hz to 100Hz and has a resolution (angular distance between pulses) of as little as an eighth of a degree.  On top of that, during each send-receive cycle, most of the time is spent waiting for the response and processing the data.  I can't divulge our actual pulse length but, if you consider the information above, you can reasonably assume that it's an extremely short amount of time.

To address your concerns about fault conditions, the internal control mechanisms of the LMS devices constantly monitor rotation and won't allow the laser to fire if it doesn't detect movement of the mirror.  If we assume the worst case scenario where the mirror has stopped spinning and the laser somehow gets stuck "on", the PSU & laser systems aren't built to deliver more than the standard pulse and would release the magic smoke almost instantly.

I hope this information helps...thanks for the cool pictures of the now-obsolete LMS2xx.  For something more up to date, check out our latest LMS5xx:  http://www.sick.com/us/en-us/home/products/product_portfolio/laser_measurement_systems/pages/outdoor_laser_measurement_technology.aspx

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