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).
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.
|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.
|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.|
|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).
|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.