[gocivici] threatened us with a tutorial on positional astronomy when we started reading his tutorial on a Arduino Powered Star Pointer and he delivered. We’d pick him to help us take the One Ring to Mordor; we’d never get lost and his threat-delivery-rate makes him less likely to pull a Boromir.

As we mentioned he starts off with a really succinct and well written tutorial on celestial coordinates that antiquity would have killed to have. If we were writing a bit of code to do our own positional astronomy system, this is the tab we’d have open. Incidentally, that’s exactly what he encourages those who have followed the tutorial to do.

The star pointer itself is a high powered green laser pointer (battery powered), 3D printed parts, and an amalgam of fourteen dollars of Chinese tech cruft. The project uses two Arduino clones to process serial commands and manage two 28byj-48 stepper motors. The 2nd Arduino clone was purely to supplement the digital pins of the first; we paused a bit at that, but then we realized that import arduinos have gotten so cheap they probably are more affordable than an I2C breakout board or stepper driver these days. The body was designed with a mixture of Tinkercad and something we’d not heard of, OpenJsCAD.

Once it’s all assembled and tested the only thing left to do is go outside with your contraption. After making sure that you’ve followed all the local regulations for not pointing lasers at airplanes, point the laser at the north star. After that you can plug in any star coordinate and the laser will swing towards it and track its location in the sky. Pretty cool.

Laser tripwire security systems can be expensive propositions that don't always work as planned -- just ask Raytheon, which saw its $100 million Perimeter Intrusion Detection System for JFK International Airport undermined by one wayward jet skier. Taking that as a form of dare, Justin Huynh and teammates at Liquidware have devised a much cheaper (if also much smaller) tripwire of their own. Any interruption of a laser pointer's beam is caught by an Arduino light sensor that promptly sends the alert to an Android-running BeagleBoard xM; if a toy like Bruce the shark dares cross the line, the BeagleBoard sends a Twitter message to let the authorities, or at least Huynh, clamp down on the trespasser. The invention won't replace Raytheon's handiwork anytime soon, although Huynh notes that additional or more powerful sensors could theoretically catch real, muscle-bound sharks and not just their plastic counterparts. The supply checklist and source code are waiting on the company's project page below, so those who'd like to ward off miniature invasions can get started today.

Continue reading Liquidware team crafts laser tripwire that tweets intruder alerts, keeps fake sharks at bay (video)

Filed under: Misc. Gadgets

Liquidware team crafts laser tripwire that tweets intruder alerts, keeps fake sharks at bay (video) originally appeared on Engadget on Mon, 20 Aug 2012 19:17:00 EST. Please see our terms for use of feeds.