Tracking a car like it were a computer mouse

optical-mouse-sensor-tracks-vehicle-motion

This is [Paul Mandel’s] Ground-truth velocity sensor. That’s a fancy name for a device which tracks the movement of a vehicle by actually monitoring the ground its travelling over. This differs from simply measuring wheel rotation (which is how traditional odometers work) in that those systems are an indirect measurement of motion. For us the interesting part is the use of an ADNS-3080 single-chip optical mouse sensor on the left. It’s cheap, accurate, and only needs to be ruggedized before being strapped to the bottom of a car.

[Paul] designed a case that would protect the electronics and allow the sensor to mount on the uneven underbelly of a vehicle. The optical chip needs to be paired with a lens, and he went with one that cost about ten times as much as the sensor. Data is fed from the sensor to the main system controller using the PIC 18F2221. One little nugget that we learned from this project is to poll a register that always returns a default value as a sanity check. If you don’t get the expected value back it signals a communications problem, an important test for hardware going into the vibration-hell that is automotive technology.

Lightsaber color selector

[George Hadley] developed a nice setup to control the color of a replica Lightsaber. A small PCB houses a PIC 18F2221 and three switching transistors for the colors. A powerful LED resides in the tip of the handle, lighting up the diffuser that makes up the blade. But our favorite part is the control scheme. He’s embedded a small RGB LED in the handle, giving feedback as to which color of light can currently be adjusted (red, green, or blue). One button scrolls through the colors and a slide potentiometer adjusts that them.

We wouldn’t go as far as calling this a Halloween prop, we think it’s better suited for serious replica builds. But it would make an amazing addition to the little one’s costume. See it in action after the break.

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