Absolute 3D Tracking With EM Fields

[Chris Gunawardena] is still holding his breath on Valve and Facebook surprising everyone by open sourcing their top secret VR prototypes. They have some really clever ways to track the exact location and orientation of the big black box they want people to strap to their faces. Until then, though, he decided to take his own stab at the 3D tracking problems they had to solve. 

While they used light to perform the localization, he wanted to experiment with using electromagnetic fields to perform the same function. Every phone these days has a magnetometer built in. It’s used to figure out which way is up, but it can also measure the local strength of magnetic fields.

Unfortunately to get really good range on a magnetic field there’s a pesky problem involving inverse square laws. Some 9V batteries in series solved the high current DC voltage source problem and left him with magnetic field powerful enough to be detected almost ten centimeters away by his iPhone’s magnetometer.

As small as this range seems, it ended up being enough for his purposes. Using the existing math and a small iOS app he was able to perform rudimentary localization using EM fields. Pretty cool. He’s not done yet and hopes that a more sensitive magnetometer and a higher voltage power supply with let him achieve greater distances and accuracy in a future iteration.

Infrared Targeting On a Small Scale

Sometimes, a person has a reason to track a target. A popular way to do this these days is with a camera, a computer, and software to analyze the video. But, that lends itself more to automated systems, like sentries. What if you want to be able to target something by “painting” it with a laser?

That’s exactly what [Jeremy Leaf] wanted to do, and the results are pretty impressive. He was able to track a .06 milliwatt laser at 2 meters. His design does this using three photodiodes in order to determine the position of a laser spot using triangulation.

Once the location of the laser spot has been determined, it can either simply be reported or it can be tracked. Tracking is achieved with a gimbal setup which updates quickly and accurately. Of course, it can only track the laser if the laser has something to be projected upon. If you need to track something in open 3D space, there are alternatives that would be better suited to the task.

Continue reading “Infrared Targeting On a Small Scale”

Two-Axis Solar Tracker

Solar panels are an amazing piece of engineering, but without exactly the right conditions they can be pretty fickle. One of the most important conditions is that the panel be pointed at the sun, and precise aiming of the panel can be done with a solar tracker. Solar trackers can improve the energy harvesting ability of a solar panel by a substantial margin, and now [Jay] has a two-axis tracker that is also portable.

The core of the project is a Raspberry Pi, chosen after [Jay] found that an Arduino didn’t have enough memory for all of the functionality that he wanted. The Pi and the motor control electronics were stuffed into a Pelican case for weatherproofing. The actual solar tracking is done entirely in software, only requiring a latitude and longitude in order to know where the sun is. This is much easier (and cheaper) than relying on GPS or an optical system for information about the location of the sun.

Be sure to check out the video below of the solar tracker in action. Even without the panel (or the sun, for that matter) the tracker is able to precisely locate the panel for maximum energy efficiency. And, if you’d like to get even MORE power from your solar panel, you should check out a maximum power point tracking system as well.

Continue reading “Two-Axis Solar Tracker”

LEDs Turn This Paper Map into a Tram Tracker

Public transit can be a wonderful thing. It can also be annoying if the trains are running behind schedule. These days, many public transit systems are connected to the Internet. This means you can check if your train will be on time at any moment using a computer or smart phone. [Christoph] wanted to take this concept one step further for the Devlol hackerspace is Linz, Austria, so he built himself an electronic tracking system (Google translate).

[Christoph] started with a printed paper map of the train system. This was placed inside what began as an ordinary picture frame. Then, [Christoph] strung together a series of BulletPixel2 LEDs in parallel. The BulletPixel2 LEDs are 8mm tri-color LEDs that also contain a small controller chip. This allows them to be controlled serially using just one wire. It’s similar to having an RGB LED strip, minus the actual strip. [Christoph] used 50 LEDs when all was said and done. The LEDs were mounted into the photo frame along the three main train lines; red, green, and blue. The color of the LED obviously corresponds to the color of the train line.

The train location data is pulled from the Internet using a Raspberry Pi. The information must be pulled constantly in order to keep the map accurate and up to date. The Raspberry Pi then communicates with an Arduino Uno, which is used to actually control the string of LEDs. The electronics can all be hidden behind the photo frame, out of sight. The final product is a slick “radar” for the local train system.

Track Your Dog With This DIY GPS Harness


Have you ever wondered how far your dog actually runs when you take it to the park? You could be a standard consumer and purchase a GPS tracking collar for $100 or more, or you could follow [Becky Stern’s] lead and build your own simple but effective GPS tracking harness.

[Becky] used two FLORA modules for this project; The FLORA main board, and the FLORA GPS module. The FLORA main board is essentially a small, sewable Arduino board. The GPS module obviously provides the tracking capabilities, but also has built-in data logging functionality. This means that [Becky] didn’t need to add complexity with any special logging circuit. The GPS coordinates are logged in a raw format, but they can easily be pasted into Google Maps for viewing as demonstrated by [Becky] in the video after the break. The system uses the built-in LED on the FLORA main board to notify the user when the GPS has received a lock and that the program is running.

The whole system runs off of three AAA batteries which, according to [Becky], can provide several hours of tracking. She also installed a small coin cell battery for the GPS module. This provides reserve power for the GPS module so it can remember its previous location. This is not necessary, but it provides a benefit in that the GPS module can remember it’s most recent location and therefore discover its location much faster. Continue reading “Track Your Dog With This DIY GPS Harness”

Low-Power Orientation Tracker and an Optimized Math Library for the MSP430

MSP430 Orientation Tracker

Orientation trackers can be used for a ton of different applications: tracking mishandled packages, theft notification of valuables, and navigation are just a few examples! A recent blog post from Texas Instruments discusses how to build a low-cost and low-power orientation tracker with the MSP430.

Based on the MSP430 LaunchPad and CircuitCo’s Educational BoosterPack, the orientation tracker is very simple to put together. It can also be made wireless using any of the wireless BoosterPacks with a Fuel Tank BoosterPack, or by using the BLE Booster Pack with a built in Lithium Battery circuitry. TI provides all the necessary code and design files in their reference application for getting your orientation tracker up and running. Be sure to see the device in action after the break! This project not only involves building a low-power orientation tracker, but also showcases IQmathLib, a library of optimized fixed point math functions on the MSP430. One of the more challenging aspects of using small MCUs such as the MSP430 or Arduino is how inefficient built in math libraries are. Check out the IQmathLib, it greatly improves upon the built in math functions for the MSP430.

It would be interesting to see this project modified to be a DIY pedometer or be used on a self-balancing robot. It would also be interesting to see the IQmathLib ported to other micros, such as the Arduino. Take a look and see how you can use this reference design in your own projects!

Continue reading “Low-Power Orientation Tracker and an Optimized Math Library for the MSP430”

Build a Cheap Airplane ADS-B Radio Receiving Tracking Station

Do you have commercial or general aviation flying over your home or near your home? Would you like to know more about these airplanes: identity, heading, speed, altitude and maybe GPS data along with even more information? Well then [Rich Osgood] has just the project for you and it’s not that expensive to set up. [Rick] demonstrates using a cheap USB dongle European TV tuner style SDR (software defined radio) tuner that you can get for under $30 to listen in on the Automatic Dependent Surveillance-Broadcast (ADS-B) 1090 MHz mode “S” or 978 MHz mode “UAT” signals being regularly transmitted from these aircraft.

He steps us through configuring the radio to use a better antenna for improved reception then walks through detailed software installation and set up to control the radio receiver as well as pushing the final decoded data to mapping software. This looks like a fascinating and fun project if you live near commercial airways. You won’t need a license for this hack because you’re only listening and not transmitting, plus these are open channels which are legal to receive.

There are some frequencies you are not legally allowed to eavesdrop on—private communications for residential wireless telephones and cellular frequencies to name just a few (Code of Federal Regulations Title 47, Part 15.9). So remember you do have to be careful and stay within legal frequencies even if your equipment is not restricted from such reception. Also note that just because you have a legal right to intercept conversations or data on some frequencies it could be illegal to publicly share the intercepted content or any details on the reception or decoding (just saying for the record).

We wonder if [Rick] could partner with [G. Eric Rogers] to upgrade [Eric’s] motorized telescope airplane tracking system to extrapolate the radio telemeter data into vector data so his Arduino can track without relying on a video feed. That merger might just get them both on a short TSA list.

Join us after the break for some extra informational links and to watch the video on setup, installation and usage of this cheap airplane tracking rig.

Continue reading “Build a Cheap Airplane ADS-B Radio Receiving Tracking Station”