Hackaday Prize 2023: Hearing Sirens When Drivers Can’t

May 25, 2023 by 25 Comments

[Jan Říha]’s PionEar device is a wonderful entry to the Assistive Tech portion of the 2023 Hackaday Prize. It’s a small unit intended to perch within view of the driver in a vehicle, and it has one job: flash a light whenever a siren is detected. It is intended to provide drivers with a better awareness of emergency vehicles, because they are so often heard well before they are seen, and their presence disrupts the usual flow of the road. [Jan] learned that there was a positive response in the Deaf and hard of hearing communities to a device like this; roads get safer when one has early warning.

Deaf and hard of hearing folks are perfectly capable of driving. After all, not being able to hear is not a barrier to obeying the rules of the road. Even so, for some drivers it can improve awareness of their surroundings, which translates to greater safety. For the hearing impaired, higher frequencies tend to experience the most attenuation, and this can include high-pitched sirens.

The PionEar leverages embedded machine learning to identify sirens, which is a fantastic application of the technology. Machine learning, after all, is a way to solve the kinds of problems that humans are not good at figuring out how to write a program to solve. Singling out the presence of a siren in live environmental audio definitely qualifies.

We also like the clever way that [Jan] embedded an LED light guide into the 3D-printed enclosure: by making a channel and pouring in a small amount of white resin intended for 3D printers. Cure the resin with a UV light, and one is left with an awfully good light guide that doubles as a diffuser. You can see it all in action in a short video, just under the page break.

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Cornering The Antenna Market

May 17, 2023 by 21 Comments

Sometimes antennas can seem like black magic. However, when you see things like a dish antenna, it sort of makes sense, right? Just like a mirror focuses light, the parabola of a dish focuses RF energy. But [IMSAI Guy] shows another common-sense antenna arrangement: a corner reflector dipole. He had built one years ago and decided to do a bit of research and make another one.

In a clever use of copper-clad board, he was able to make a reasonable reflector by soldering together three boards and an RF connector. A single wire makes the “driven element,” and by bending it to just the right position, you can change the characteristic impedance for matching.

The antenna, in this case, is essentially a quarter-wave antenna with a ground plane and reflector arrangement. After the obligatory chalk talk, he breaks out the vector network analyzer and shows how well it matches. He didn’t, however, measure the gain or directional selectivity due to the reflector.

Intuitively, you’d think this kind of antenna would be good for direction finding purposes. In fact, hams that use handy talkies for direction finding often use their bodies to block signals, much like these reflectors should.

The [IMSAI Guy] reflector is pretty small, but you can easily make bigger ones. Using PCB material for antennas isn’t anything new, either, but we still enjoyed this simple corner reflector build.

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Hackaday Prize 2023: Eye-Tracking Wheelchair Interface Is A Big Help

May 14, 2023 by 2 Comments

For those with quadriplegia, electric wheelchairs with joystick controls aren’t much help. Typically, sip/puff controllers or eye-tracking solutions are used, but commercial versions can be expensive. [Dhruv Batra] has been experimenting with a DIY eye-tracking solution that can be readily integrated with conventional electric wheelchairs.

The system uses a regular webcam aimed at the user’s face. A Python script uses OpenCV and a homebrewed image segmentation algorithm to analyze the user’s eye position. The system is configured to stop the wheelchair when the user looks forward or up. Looking down commands the chair forward. Glancing left and right steers the chair in the given direction.

The Python script then sends the requisite commands via a TCP connection to an ESP32, which controls a bunch of servos to move the wheelchair’s joystick in the desired manner. This allows retrofitting the device on a wheelchair without having to modify it in an invasive manner.

It’s a neat idea, though it could likely benefit from some further development. A reverse feature would be particularly important, after all. However, it’s a great project that has likely taught [Dhruv] many important lessons about human-machine interfaces, particularly those beyond the ones we use every day. 

This project has a good lineage as well — a similar project, EyeDriveOMatic won the Hackaday prize back in 2015.

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Giving A Tinge Of Color To The Mars Map Courtesy Of The UAE’s Hope Orbiter

May 9, 2023 by No comments

Since the United Arab Emirates’ Hope (“Al-Amal”) orbiter made it safely into orbit around Mars on February 9, 2021, it’s been busy using its onboard instruments to measure everything it could about not only the planet’s atmosphere but also its surface and how both change seasonally. The first months of results of these detailed captures of Mars have now been released in the form of the full-color Mars Atlas website, and a pretty well made PDF version of the Atlas that can be downloaded from the website.

Although the Emirates Mars Mission is not the first to capture the surface or seasons of Mars — with the Mars Reconnaissance Orbiter (MRO)’s Context Camera  (CTX) having gifted us the result of many thousands of captures in a massive monochrome mosaic of Mars’ surface — it’s good to remember that Hope is only just getting started. The current atlas is the result of about 3,000 captures from the Emirates eXploration Imager (EXI) multi-band camera (with better than 8 km spatial resolution), with new images in the pipeline.

Hope has transitioned from a low 1,072 km orbit to a higher, science orbit on March 29, which gives the orbiter a good view of the seasonal transitions on the Red Planet. Along with data from other current Mars orbiters, we should be able to piece together the most detailed atlas yet, even before more helicopters will zip along Mars’ surface.

LoRa Goes To The Moon

May 3, 2023 by 12 Comments

LoRa is a communications method that allows for long range radio contacts to be made using typically low-powered devices. This shouldn’t be surprising given that LoRa is short for “long range” which typically involves distances on the order of a few kilometers. However, a group of students are taking the “long range” moniker to the extreme by attempting to send and receive a signal with a total path of around 768,000 kilometers by using some specialized equipment to bounce a LoRa signal off of the moon and receive it back on Earth.

Earth-Moon-Earth (EME) communications are typically done by amateur radio operators as a hobby, since the development of communications satellites largely rendered other uses of this communication pathway obsolete. A directional antenna and a signal typically on the order of 1 kW are often used to compensate for the extremely high path losses. Using LoRa, which makes use of chirp spread spectrum modulation, they hope to reduce this power requirement significantly. The signals are being generated and received on a set of HackRF One devices fed into a series of amplifiers, and the team is also employing a set of large dish antennas, one in New Jersey and another in Alaska, to send and receive the messages.

The software used is the open-source SDRAngel which is useful for controlling the HackRF and moving the LoRa signal up to 1296 MHz. Normally LoRa is operated on an unlicensed band, but this method allows for finer control of not only frequency but also bandwidth, which helps reduce the impacts of path loss. Right now they have not yet completed their contacts with the Alaska station (partially due to that antenna being covered in snow) but we hope to hear more news in the future. In the meantime, take a look at some more traditional long-range communications using this protocol with more manageable-sized antennas.

Image courtesy of NASA, Public domain, via Wikimedia Commons

Leonardo Da Vinci’s Visualization Of Gravity As A Form Of Acceleration

April 26, 2023 by 20 Comments

Although we take a lot of scientific knowledge for granted today, each of the basics – whether it be about light, gravity, mass or the shape of the Earth – had to be theorized and experimentally verified. In the case of gravity, as far back as around 500 BCE the Ionian Greek philosopher Heraclitus theorized on the balance created by what we came to call ‘gravity’. Later, the Greek philosopher Aristotle coined his own postulations and Greek physicist Archimedes did research that led him to discover the center of mass. Centuries later, the Roman engineer and architect Vitruvius argued for the concept of specific gravity rather than mass alone.

Da Vinci’s sketch and the Caltech experiment replicating it.

Although scientific pursuits in this area ground to a halt in Europe during medieval times, the Renaissance saw a renewed interest in the topic, with newly published research performed on Leonardo da Vinci‘s notes showing that he appears to – unsurprisingly – have also created a number of experiments aimed at determining the properties of gravity. One of the major limitations of the 15th century was that many of the basic scientific tools we have come to rely on since the 19th century such as accurate clocks, along with many other products of advanced alloys and metallurgy simply did not exist. Da Vinci’s experiment in this context is nothing if not ingenious in its simplicity.

By the time of the European Renaissance, the Aristotelian concept of gravity as solely a factor of an object’s mass was dismissed by many in favor of a model that saw the motion of an object affected by its velocity and mass, also influenced by works published by Persian scholars. When Da Vinci set up his experiment, he focused specifically on the acceleration of the falling objects by pouring a large number of granules or possibly water droplets from a pitcher which was being pulled along a straight path. He theorized that if the pitcher was being accelerated at the same rate as the objects are accelerating due to gravity, it’d create a isosceles right triangle.

When the researchers ran his experiment and compared Da Vinci’s notes on the results, they realized that although he had made a mistake in his model, at the small scale this would not have affected the results, making it valid and an early precursor to what later be published by Isaac Newton in the 17th century.

Ambrosianus L 99 sup., p. 190, ll. 14–23, UV fluorescence image by Lumière Technology. Upside-down Latin overtext in dark brown and Greek undertext in light brown.

Reading Ptolemy’s Treatise On The Meteoroscope On Palimpsests After Centuries Of Recovery Attempts

April 25, 2023 by 12 Comments

During the Middle Ages much of Ancient Greek and Roman scientific, legal and similarly significant texts written on parchment were commonly erased, mostly because of the high cost of new parchment and the little regard given to these secular texts. Although recovery attempts of the remaining faint outlines of the old text has been attempted since at least the 19th century, these often involved aggressive chemical means. Now researchers have managed to recover the text written by Ptolemy on a parchment that suffered such a previous recovery attempt.

The term for a parchment and similar on which the existing text was washed or scraped off is a palimpsest, via Latin from  Ancient Greek παλίμψηστος (palímpsēstos, from παλίν + ψαω = ‘again’ + ‘scrape’). In the case of this particular treatise, it is part of L 99 sup which is kept at the Biblioteca Ambrosiana in Milan, Italy. This collection contains fifteen palimpsest parchment leaves previously used for three Greek scientific texts: a text of unknown authorship on mathematical mechanics and catoptrics, known as the Fragmentum Mathematicum Bobiense (three leaves), Ptolemy’s Analemma (six leaves), and a so far unidentified astronomical text on six leaves.

Outermost six rings of the meteoroscope, not to scale. Nh, Sh, Eh, and Wh are cardinal points of the horizon; Ne and Se are the north and south celestial poles; Nz and Sz are the north and south poles of the ecliptic; and Z is the zenith. (Gysembergh et al., 2023)

It is this last text that has now been identified, courtesy of work by Victor Gysembergh and colleagues. Whereas 19th century palimpsest recovery attempts by Angelo Mai involved reagents, during the 20th century ultraviolet illumination became the preferred method, followed by similar non-destructive analysis methods. For this study UV fluorescence and multispectral reflectance imaging was employed, which allowed for significant more of the original Greek text to be uncovered. Most notable, this revealed Ptolemy’s treatise on the Meteoroscope, which is an instrument for measuring the position, length, and direction of the apparent path of a shooting star.

This new recovery builds upon text previously recovered by other researchers since Mai’s attempts, and fills in more details, although it must be noted that not all of the text has been recovered. It’s hoped that in future imaging sessions more can be recovered of this irreplaceable text, that like so many of its kind nearly got destroyed during Europe’s darkest era.

(Top image: Ambrosianus L 99 sup., p. 190, ll. 14–23, UV fluorescence image by Lumière Technology. Upside-down Latin overtext in dark brown and Greek undertext in light brown.)