car safety

3 Articles

Why You Probably Shouldn’t DIY A Car Airbag

May 10, 2026 by 13 Comments

Car airbags are both a very simple concept and a marvel of engineering, replacing the bone-shattering impact of unforgiving plastic and steel with a relatively soft landing in a funky-smelling air cushion. This deceptively simple concept requires that the gas generator activates only when there is a crash and finishes filling the airbag in the milliseconds before the squishy human’s cranium with its soft filling attempts to occupy the same space as said airbag. This makes mad Aussie bloke [Turnah81]’s attempt at DIY-ing a car airbag a most daring proposition.

Rather than messing about with an IMU and microprocessors, he went low-tech with an inertial fuel cut-off switch. These are mechanical switches that hold a steel ball in place with a magnet until a sufficiently large force — like a crash — dislodges the ball and triggers an event. Usually, a switch like this cuts off the fuel pump.

After a bit of fun with a crash-test rig and the airbag of a salvaged steering wheel, a DIY airbag was assembled using a compressed-gas cylinder instead of the fancy gas generator, along with an electrically triggered valve. Here, you can already see why modern airbags use a gas generator, as it is simply far more compact.

For the bag itself, a pillow case was adapted, with the subsequent crash test — as pictured above — going about as well as you can imagine. After this, he tried a few improvements, like using a bin liner and detonating some fuel, but it seems that the gas generator is very hard to beat for producing a large amount of gas in very little time.

Meanwhile, the inertial cut-off switch turned out to be more than sufficient for this purpose, and it was also used to trigger the original airbag. Of course, with how cheap those off-the-shelf airbag units are and are tested to be fit for purpose, you’d never DIY them for actual use in a car unless you were stark raving mad.

Airbags have a checkered history. There are some places you shouldn’t try to save costs.

Continue reading “Why You Probably Shouldn’t DIY A Car Airbag” →

How Safe Are Old Airbags, Anyway?

February 23, 2026 by 56 Comments

Automotive airbags are key safety devices that aim to reduce injuries and mortality in the event of motor vehicle accidents. These rapidly-inflating cushions act to soften the blow of an impact, catching occupants of the vehicle and preventing them from hitting hard parts of the vehicle’s interior.

Airbags are rigorously tested to perform as faultlessly as possible under all conditions. However, no system is perfect, and every automotive component has an expected service life. The question is—how old is too old when it comes to airbags? The answer is not exactly straightforward.
Continue reading “How Safe Are Old Airbags, Anyway?” →

Using Smartphone Cameras To Make Sure Drivers Are Looking At The Road

May 3, 2020 by 25 Comments

Most of us are probably quite aware of the damage that a car can inflict when driven by a distracted driver. In an ideal world, people who are driving a car would not allow something like their phone to distract them from their primary task of being the primary navigation system for the 1+ metric ton vehicle which they are controlling.

Many smartphone apps as well as in-car infotainment systems have added features over the years that try to prevent a driver from using them, but they run into the issue that it’s hard to distinguish between passenger and driver. As it turns out, asking the human driver whether they are the driver doesn’t always get the expected result. This is where [Rushil Khurana] and his team at Carnegie Mellon University (CMU) have come up with a more fool-proof approach.

In their paper (PDF), they cover the algorithm and software implementation that uses the smartphone’s own front (selfie) and back cameras to determine from the car’s interior which side of the car the user is sitting in, and deducing from that whether the user is sitting in the driver’s seat or not.  From there it is a fairly safe assumption to make that if the user is sitting in the driver’s seat, and the car is moving, that this user should not be looking at the phone’s screen.

In a test involving 16 different cars and 33 users, they achieved an overall accuracy of 94% with the phone held in the hand, and 92.2% while docked. This is more reliable than the other approaches covered in the paper, and as a benefit does not require any extra hardware. Who knows, upcoming smartphones may include a feature like this, so that apps can easily determine what feature set should be made available to a driver, if any.

Continue reading “Using Smartphone Cameras To Make Sure Drivers Are Looking At The Road” →