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The recent Open LIDAR bounty for hacking the XV-11 LIDAR inspired me to try and cook up a home brew proof-of-concept LIDAR with a similar design. The XV-11 spins an infrared laser and a very high speed camera to achieve 1 degree resolution and 360 degree field of view with a 5Hz update rate, which means the camera must be effectively capturing 1800 frames per second!!
The initial concept design is based on a Wiimote infrared camera which incorporates blob tracking firmware and reports the x,y positions of 4 infrared light sources via I2C protocol. That simplifies the design and coding considerably but at a cost of $40 for a Wii controller.
A 1mW infrared laser module provides the blob to track, and will be mounted similarly to the XV-11 design, to provide triangulation for distance calculation. The range of the system will most likely be around 24-36 inches, probably limited by the very low power laser.
The processor, initially, is an NXP mbed, a DIP-40 packaging of an ARM Cortex M3 (interfacing details here) but I will soon migrate to a smaller device, possibly an ATtiny2313 or MSP430G2.
After prototyping on a breadboard, I designed a PCB to house the camera. I've fabricated several PCBs at home but this time I wanted to push my limits.
First by attempting to create a PCB with 16 mil traces (32 mil was my prior smallest trace). Second by using a variety of SMD components -- 0805 passives, SOT-223, and 3x6mm crystal.
I discovered to my great happiness that it is in fact possible to transfer 16 mil traces to a PCB using the magazine paper / laser printer method. Etching went perfectly.
To install the SMD components I tinned the pads with fine gauge solder and my WE51 station, and then I used my brand new hot plate skillet... aka Reflow Skillet. The parts reflowed in minutes and while I had to manually fix a couple of components while the solder was hot, otherwise the process was easy as pie. I'll be doing more SMD work in the future! That was $40 well-spent.
If the proof-of-concept works well enough I'll probably install it on my Trinity-style Firefighting Robot, Pokey as the robot needs an upgraded wall / object detection system.
Beyond the proof-of-concept if it seems worthwhile, I'll explore the use of a fast line scan sensor or other alternatives to increase the frame rate to match the XV-11 design.
I'll update this page as I progress.