MARCO Construction

Below are some pictures of the physical experimental MARCO optical array.  The whole module is about 14x14x17 cm, and weighs a little less than a kilogram, however these proportions are not to be expected on an actual vehicle.  The whole setup is built on .25in plate aluminum, which gave me an excellent, sturdy, stable construction surface, but also adds a great deal of unnecessary weight to the setup.

Additionally, components like batteries, LIDAR modules, cameras, and processors are already present on most autonomous vehicles, meaning that much of the required hardware can simply be temporarily repurposed to MARCO for docking operations.
The business end of MARCO, you can see the two LIDAR barrels up top, the LED bulbs on either side in the middle, and the camera with its IR-pass filter on the bottom.  I left the center open in case I get the chance to build and mount a docking mechanism later.

The guts of MARCO, again the LIDAR module is in the top center.  Directly to the left of the LIDAR you can see the array of transistors MARCO uses as relays to power the lights.  On the bottom left is the ubiquitous Raspberry Pi, to its right is the 11.1V drone battery, and in front of the battery is a voltage regulator feeding the Pi.  From this angle you can't see the camera or the filter actuator, which are obscured behind the battery and the camera's white ribbon cable.



This is the filter actuator, a physical electromagnetic switch that flicks the camera between the visible and infrared spectra.  The large bulbous cylinders on either side are big solenoids in series and the piece in the middle, called the filter shuttle, houses and protects the filters in the middle.  When activated, current in the solenoids produces a strong magnetic field that pulls and pushes on magnets on each end of the filter shuttle, flicking the entire shuttle to the left or right and placing the desired filter in front of the camera.  This assembly is operated by the Pi's GPIO pins.
An early cut of the optical array surface, the camera and LIDAR holes were drilled with a drill press, and the LED slots on either side were painstakingly cut with a few of the adorable little dremel cutting wheels.  I know it's not pretty, and it's gotten uglier after drilling the holes to mount the instruments.  It holds the hardware in place, and that's all I really need it to do.  It's not an art project.



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