An introduction to inertial navigation systems


Long before ships relied on GPS to determine their location – and even before radio navigation systems such as LORAN, vessels relied on a still impressively sophisticated means of determining their position: inertial navigation. The theory is simple: if you keep a few very accurate gyroscopes and accelerometers on board, you’ll be able to calculate where you are relative to your previous position. Since electronic gyros and accelerometers are all over the place, [Sebastian] thought he would have a go at creating his own inertial navigation system.

The difficulty in using this method is that every gyroscope invariably has some error. Since the measurements from the gyros and accelerometers are integrated together, the error is also integrated, resulting in an increasing positioning error as time goes on. With a few clever algorithms and very good sensors, it’s possible to minimize this error.

[Sebastian] doesn’t have really great hardware – he’s only working with a accelerometer/gyro breakout board that’s good enough for experimental purposes. After reading the accelerometer data with an Arduino, he’s able to capture all the sensor data and read it into a Python script.

The next steps are to figure out a decent algorithm to integrate all the sensor data, and possibly add a barometer and magnetic compass for better compensation for errors. The project is still in the early phases, but seeing as how an inertial navigation system is one of the engineering triumphs of the early 20th century, we’re eagerly awaiting any progress updates.

Raspberry Pi replaces a Volvo nav system


[Reinis] has a Volvo S80. One of the dashboard features it includes is a 6.5″ LCD screen which periscopes up to use as a navigation system. The problem is that Volvo stopped making maps for it around five years ago and there are no maps at all for Latvia where he lives. So it’s worthless… to you’re average driver. But [Reinis] is fixing it on his own by replacing the system with a Raspberry Pi.

That link leads to his project overview page. But he’s already posted follow-ups on hardware design and initial testing. He’s basing the design around a Raspberry Pi board, but that doesn’t have all the hardware it needs to communicate with the car’s systems. For this he designed his own shield that uses an ATmega328 along with a CAN controller and CAN transceiver. The latter two chips patch into the CAN bus on the car’s On Board Diagnostic system. We didn’t see much about the wiring, but the overview post mentions that the screen takes RGB or Composite inputs so he must be running a composite video cable from the trunk to the dashboard.


Make Your Own GPS Receiver!

GPS receivers may be available for well under $100 these days, but what’s the fun in buying one when you can build it yourself? According to [Andrew], the creator of this device, he was inspired by Matjaž Vidmar who developed a GPS receiver from scratch over 20 years ago. His article can be found here and includes some nicely hand-drawn diagrams as well as a lot of theory.

However, [Andrew’s] article is a bit more up-to-date and features plenty of theory itself. He explains how he built his four-channel GPS receiver, able to track four satellites at the same time. This is the minimum number of satellites needed to track your position using such a device.

GPS technology is quite incredible, and the amount of soldering as well as the understanding of the theory behind it required to build such a device is astonishing. Interestingly (sadly?), it seems we are beyond the time of LORAN hacks, but if you have an old one to share, be sure to send it in! For something a bit easier, maybe one could try making a GPS “cateye” to track what your pet does all day!

jGPX keeps the bachelor party moving in the right direction, regardless of BAC


[Davy] and his friend [Chris] were tasked with putting together a bachelor party for their friend [J], and had a little more in mind than the standard drunken revelry. To earn the privilege of partying his brains out, they decided that [J] would have to fulfill a series of tasks and challenges before joining up with the rest of his friends for the evening’s events. [Davy] didn’t specify what these tasks were, lest he spoil the surprise, but he did let us in on a little device that he and [Chris] built to help guide the bachelor through his day.

They were a bit worried that the bachelor would get sidetracked during his journey if he happened to imbibe along the way, so they built a device called jGPX that would ensure [J] stayed on track and on time. jGPX is a custom GPS navigator consisting of an Arduino, a GPS module with built-in antenna, and a compass.  The pair created a set of routes in Google Earth, exporting the data to KML for interpretation by their device. The jGPX is meant to guide [J] along via a small LCD screen that shows him the distance to his target as well as the proper direction of travel to get there.

It looks like [J’s] friends put a lot of effort into his party, and although there are no details as to how things went, we’re sure it was a blast!

Forearm-mounted GPS uses LEDs to light the way home


While some people can rely solely on memory and landmarks to find their way home, others need a bit more help. Consider Instructables user [_macke_] for instance.

Like other screenless GPS navigation devices we have seen, his “Find Home Detector” uses a GPS module to obtain his location, guiding the way home via a set of alternate indicators. In this case, he uses LEDs which are laid out like a compass rose. When [_macke_] is aimed toward his destination, the LED nearest to his fingertips lights up, letting him know he is on the right path. As he turns away from home, the other LEDs light, indicating the direction in which he should turn.

His forearm-mounted GPS navigator uses a LilyPad Arduino to control the system, much like others we have seen. It is connected to a GPS sensor and a compass module that work in concert to guide him home. The compass is responsible obtaining his heading information, and while it might look as if the LEDs that surround the module are pointing North, they are in fact indicating the heading of his destination instead.

It’s a cool little creation, and we can imagine it would be quite helpful if you happen to be walking home after a long night of drinking.

Be sure to check out the video below for a quick demonstration.

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Haptic GPS sneakers for the visually impaired


The world can be a pretty difficult place to navigate when you lack the ability to see it. There are many visually impaired people across the globe, with some figures claiming up to 40 million individuals affected. While walking canes and seeing-eye dogs can be a huge help, [Anirudh] of Multimodal Interactions Group, HP Labs India, and some students at the College of Engineering in Pune, India (COEP) have been hard at work constructing a haptic navigation system for the blind.

[Anirudh Sharma and Dushyant Mehta] debuted their haptic feedback shoe design during an MIT Media Lab Workshop hosted at COEP. In its current form, Google Maps and GPS data is sourced from an Android device, which is fed to an Arduino via Bluetooth. The Arduino then activates one of four LEDs mounted on a shoe insert that are used to indicate which direction the individual should travel in order to safely reach their destination. While the current iteration uses LEDs, they will be swapped out for small vibrating motors in the final build.

We’re always fans of assistive technology hacks, and we think this one is great. The concept works well, as we have seen before, so it’s just a matter of getting this project refined and in the hands shoes of those who need it.

Stick around for a quick video about the project filmed at the MIT/COEP event.

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GPS-enabled bag allows for carefree city roaming


[Josh] was looking for a way to enjoy exploring the city of Chicago safely, and hacked together a messenger bag navigation system to ensure he always knew where he was going.

While riding, he wanted to embrace the idea of Dérive, but he felt that he was being too overly conscious of time as well as his location, which took all the fun out of his unplanned excursions. Having recently been “doored” by a car, he was also looking for a way to help him navigate the city streets without being overly distracted with finding his way around.

His “Map Bag” solves both of these problems for him, without being obtrusive. He fit a messenger bag with a LilyPad Arduino and a GPS receiver for keeping track of his location. The Arduino can constantly monitor speed, heading, and location, directing [Josh] to his destination by vibrating one of 8 shaftless motors that are installed throughout the bag’s chest strap. Now while he rides, he can take in the city’s atmosphere while also knowing that he will get exactly where he needs to – on time.

He does not have any source code or schematics on his site as of yet, but we hope to see some in the near future. If you are interested, check out the videos of the bag’s construction embedded below.

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