Screenshot of the SDR software in action, with decoded data in a terminal, and a map that shows the location received from the decoded data

Loudmouth DJI Drones Tell Everyone Where You Are

March 26, 2023 by Arya Voronova 43 Comments

Back when commercial quadcopters started appearing in the news on the regular, public safety was a talking point. How, for example, do we keep them away from airports? Well, large drone companies didn’t want the negative PR, so some voluntarily added geofencing and tracking mechanisms to their own drones.

When it comes to DJI, one such mechanism is DroneID: a beacon on the drone itself, sending out a trove of data, including its operator’s GPS location. DJI also, of course, sells the Aeroscope device that receives and decodes DroneID data, declared to be for government use. As it often is with privacy-compromising technology, turns out it’s been a bigger compromise than we expected.

Questions started popping up last year, as off-the-shelf quadcopters (including those made by DJI) started to play a part in the Russo-Ukrainian War. It didn’t take long for Ukrainian forces to notice that launching a DJI drone led to its operators being swiftly attacked, and intel was that Russia got some Aeroscopes from Syria. DJI’s response was that their products were not meant to be used this way, and shortly thereafter cut sales to both Russia and Ukraine.

But security researchers have recently discovered the situation was actually worse than we expected. Back in 2022, DJI claimed that the DroneID data was encrypted, but [Kevin Finisterre]’s research proved that to be a lie — with the company finally admitting to it after Verge pushed them on the question. It wouldn’t even be hard to implement a worse-than-nothing encryption that holds up mathematically. However, it seems, DroneID doesn’t even try: here’s a GitHub repository with a DroneID decoder you can use if you have an SDR dongle.

Sadly, the days of companies like DJI standing up against the anti-copter talking points seem to be over, Now they’re setting an example on how devices can subvert their owners’ privacy without reservation. Looks like it’s up to hackers on the frontlines to learn how to excise DroneID, just like we’ve done with the un-nuanced RF power limitations, or the DJI battery DRM, or transplanting firmware between hardware-identical DJI flight controller models.

Continue reading “Loudmouth DJI Drones Tell Everyone Where You Are” →

Stranded Motorist Effects Own Rescue Using A Drone And A Cell Phone

March 8, 2023 by Dan Maloney 79 Comments

If you’re looking for a good excuse to finally buy a drone, you probably can’t do better than claiming it can save your life.

Granted, you may never find yourself in the position of being stuck in a raging snowstorm in the middle of the Oregon wilderness, but if you do, this is a good one to keep in mind. According to news stories and the Lane County Sheriff Search and Rescue Facebook page, an unnamed motorist who was trying to negotiate an unmaintained road through the remote Willamette National Forest got stuck in the snow. This put him in a bad situation, because not only was he out of cell range, but nobody knew where he was or even that he was traveling, so he wouldn’t be missed for days.

Thankfully, the unlucky motorist played all his cards right. Rather than wandering off on foot in search of help, he stayed with his vehicle, which provided shelter from the elements. Conveniently, he also happened to have a drone along with him, which provided him with an opportunity to get some help. After typing a detailed text message to a friend describing his situation and exact location, he attached the phone to his drone and sent it straight up a couple of hundred feet — enough to get a line-of-sight connection to a cell tower. Note that the image above is a reenactment by the Search and Rescue team; it’s not clear how the resourceful motorist rigged up the drone, but we’re going to guess duct tape was involved.

When he brought the drone back down a few minutes later, he found that the queued text had been sent, and the cavalry was on the way. The Search and Rescue unit was able to locate him, and as a bonus, also found someone else nearby who had been stranded for days. So it was a win all around thanks to some clever thinking and a little technology.

Renaissance-Style Drone Would Make Da Vinci Proud Four Times Over

February 1, 2022 by Dan Maloney 7 Comments

For as much of a genius as Leonardo da Vinci obviously was, modern eyes looking upon his notebooks from the 1400s tend to see his designs as somewhat quaint. After all, his concept of a vehicle armored with wood would probably only have survived the archers and pikemen of a Renaissance battlefield, and his curious helicopter driven by an Archimedes screw would certainly never fly, right?

Don’t tell that to [Austin Prete] and his team from the University of Maryland, who’ve built a da Vinci-style quadcopter that actually flies. Called the “Crimson Spin”, the quad is based on a standard airframe and electronics. Details are sparse — the group just presented the work at a vertical flight conference — but it appears the usual plastic props are replaced with lightweight screws made from wire and some sort of transparent plastic membrane. Opposing pairs of screws have the opposite handedness, which gives the quad yaw control. There’s a video embedded in the link above that shows the quad being tested both indoors and out, and performing surprisingly well. We’d imagine that Crimson Spin might not do so well on a windy day, given the large wind cross-section those screws present, but the fact it got off the ground at all is cool enough. It kind of makes you wonder where we’d be today if da Vinci had access to BLDCs.

For as fanciful as da Vinci’s designs can be, we’ve seen a fair number of attempts to recreate them in modern materials. His cryptex is a perennial favorite for hackers, and his bizarre piano-esque “viola organista” has been attempted at least once.

Thanks to [Peter Ryseck] for this tip.

Inverted Pendulum Balanced On A Drone

November 25, 2021 by Dave Rowntree 9 Comments

[Nicholas Rehm] works during the day at the Applied Physics Laboratory at Johns Hopkins, Maryland, so has considerable experience with a variety of UAV applications. The question arose about how the perseverance mars rover landing worked, which prompted [Nicholas] to hang a rock under his drone, attached via a winch. This proved to be interesting. But what is more interesting for us, is what happens when you try to attach an inverted pendulum to the top of a drone in flight? (video embedded, below)

This is a classic control theory problem, where you need to measure the angle of the pendulum with respect to the base, and close the loop by calculating the necessary acceleration from the pendulum angle. Typically this is demonstrated in one dimension only, but it is only a little more complicated to balance a pendulum with two degrees of freedom.

[Nicholas] first tried to derive the pendulum angle by simply removing the centering springs from an analog joystick, and using it to attach the pendulum rod to the drone body. As is quite obvious, this has a big drawback. The pendulum angle from vertical is now the sum of the joystick angle and the drone angle, which with the associated measurement errors, proved to be an unusable setup. Not to be discouraged, [Nicholas] simply added another IMU board to the bottom of the pendulum, and kept the joystick mechanism as a pivot only. And, as you can see from the video after the break, this indeed worked.

The flight controller is [Nicholas’] own project, dRehmFlight (GitHub), which is an Arduino library intended for the Teensy 4.0, using the ubiquitous MPU6050 6-DOF IMU. [Nicholas] also made an intro video for the controller, which may prove instructive for those wishing to go down this road to build their own VTOL aircraft. The code for pendulum experiment is not available at the time of writing, perhaps it will hit the GitHub in the future?

Continue reading “Inverted Pendulum Balanced On A Drone” →

VTOL Tailsitter Flies With Quadcopter Control Software

August 2, 2021 by Danie Conradie 11 Comments

Quadcopters are great for maneuverability and slow, stable flight, but it comes at the cost of efficiency. [Peter Ryseck]’s Mini QBIT quadrotor biplane brings in some of the efficiency of fixed-wing flight, without all the complexity usually associated with VTOL aircraft.

The Mini QBIT is just a 3″ mini quadcopter with a pair of wings mounted below the motors, turning it into a “tailsitter” VTOL aircraft. The wings and nosecone attach to the 3D printed frame using magnets, which allows them to pop off in a crash. There is no need for control surfaces on the wings since all the required control is done by the motors. The QBIT is based on a research project [Peter] was involved in at the University of Maryland. The 2017 paper states that the test aircraft used 68% less power in forward flight than hovering.

(Editor’s Note: [Peter] contacted us directly, and he’s got a newer paper about the aircraft.)

Getting the flight controller to do smooth transitions from hover to forward flight can be quite tricky, but the QBIT does this using a normal quadcopter flight controller running Betaflight. The quadcopter hovers in self-leveling mode (angle mode) and switches to acro mode for forward flight. However, as the drone pitches over for forward flight, the roll axis becomes the yaw axis and the yaw axis becomes the reversed roll axis. To compensate for this, the controller set up to swap these two channels at the flip of a switch. For FPV flying, the QBIT uses two cameras for the two different modes, each with its own on-screen display (OSD). The flight controller is configured to use the same mode switch to change the camera feed and OSD.

[Peter] is selling the parts and STL files for V2 on his website, but you can download the V1 files for free. However, the control setup is really the defining feature of this project, and can be implemented by anyone on their own builds.

For another simple VTOL project, check out [Nicholas Rehm]’s F-35 which runs on his dRehmFlight flight control software. Continue reading “VTOL Tailsitter Flies With Quadcopter Control Software” →

Get Some Close Air Support With A Nerf Drone

July 26, 2021 by Danie Conradie 12 Comments

Working from home has the major advantage of spending more time with loved ones, but it all that time can sometimes lead to friction. [Cory] found that Nerf battles with his kids is an effective way to blow off some steam, but felt he was getting a bit too much exercise in the process. Instead, he equipped an FPV quadcopter with a 3D printed Nerf gun to take his place.

Since manually reloading the Nerf gun after every shot wasn’t an option, he needed to create an autoloader. The darts are propelled by a pair of brushless drone motors mounted side-by-side, with just enough space for a dart the squeeze between. The motors are allowed to spin up, and then a dart is loaded servo-operated plunger, out of an off-the-shelf Nerf magazine. The motors ESCs and servo is controlled by an Arduino Nano, which receives the fire command from one of the spare outputs on the drone’s flight controller. To nerf gear is easily removable from the drone, so [Cory] to also fly the drone on more peaceful missions. See the video of one of the battles after the break. [Cory] might need to find an alternative control location to prevent himself being used as cover by his adversaries.

Nerf guns are a fun and harmless way to live out your sci-fi warfare fantasies, especially with the technology we have available these days. From FPV sentry guns to auto-aiming rifles, and heavy artillery, anything is possible.

Continue reading “Get Some Close Air Support With A Nerf Drone” →

Taking Reverse Engineering To The Skies: Cheap Drone Gets PX4 Autopilot

April 24, 2021 by Stephen Ogier 3 Comments

Sometimes bad software is all that is holding good hardware back. [Michael Melchior] wanted to scavenge some motors and propellers for another project, so he bought an inexpensive quadcopter intending to use it for parts. [Michael] was so surprised at the quality of the hardware contained in his $100 drone that he decided to reverse engineer his quadcopter and give the autopilot firmware a serious upgrade.

Upon stripping the drone down, [Michael] found that it came with a flight management unit based on the STM32F405RG, an Inertial Measurement Unit, magnetic compass, barometric pressure sensor, GPS, WiFi radio, camera with tilt, optical flow sensor, and ultrasonic distance sensor, plus batteries and charger! The flight management unit also had unpopulated headers for SWD, and—although the manufacturer’s firmware was protected from reading—write protection hadn’t been enabled, so [Michael] was free to flash his own firmware.

We highly recommend you take a look at [Michael]’s 10 part tour de force of reverse engineering which includes a man-in-the-middle attack with a Raspberry Pi to work out its WiFi communication, porting the open-source autopilot PX4 to the new airframe, and deciphering unknown serial protocols. There are even amusing shenanigans like putting batteries in the oven and freezer to help figure out which registers are used as temperature sensors. He achieves liftoff at the end, and we can’t wait to see what else he’s able to make it do in the future.

Of course, [Michael] is no stranger to hacking imported quadcopters, and if you’re interested in PX4 but want something quieter than a quadcopter, take a look at this autopilot-equipped glider.