Home Brew XV-11 style "LIDAR"

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.

Next steps:

• Migrate code to a smaller footprint processor
• Finish the mechanical design of the rotating turret
• Develop absolute encoder system (using my WheelEncoderGenerator program!)
• Mount the laser and adjust triangulation
• Write distance calculation code and calibrate
• Design and build a PCB for the MCU
• Design 'external' interface
• Consider upgrade to a 5mW IR laser (safety issues...)

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.