Part Racing Drone, Part RC Airplane, Part Rocket…all Menace. How else could you describe a quadcopter that shoots off at high speed and is designed for taking down other small quadcopters? The Interceptor Drone by [Aleksey] borrows elements from all of the aforementioned disciplines of flying things.
Built with standard racing drone parts, [Aleksey] assures that no prohibited parts are used in its construction. Instead, the Interceptor Drone relies on a very powerful motors and a light weight frame to keep the power to weight ratio in the “rocketing into the sky” category.
But what Interceptor Drone would be complete without a way to take its target out of the sky? This is where the biggest divergences begin. The motors are all oriented to point away from the center-line of the craft. Upon command, these motors actually detach from the frame, each spreading out and deploying the corner of a net that’s designed to entangle the rotors of the target, causing its battle with gravity to come to a grinding halt.
How does the Interceptor Drone survive the attack? Without its motors, the core of the quadcopter falls to the earth. Arresting the fall is a parachute much like those used in model rocketry. An audio beacon sounds the alarm to help somebody to find it — a move taken straight from the RC aircraft hobby.
There’s certainly a lot of room to discuss legalities in localities, but regardless of opinion about the craft’s intended use, the system looks very slick, and there are some great hacks baked right in. Don’t want to build a drone-killing-drone? Maybe all you need is a pumpkin and good (bad?) timing.
Calculating three-dimensional position from two-dimensional projections are literal textbook examples in geometry, but those examples are the “assume a spherical cow” type of simplifications. Applicable only in an ideal world where the projections are made with mathematically perfect cameras at precisely known locations with infinite resolution. Making things work in the real world is a lot harder. But not only have [Jingtong Li, Jesse Murray et al.] worked through the math of tracking a drone’s 3D flight from 2D video, they’ve released their MultiViewUnsynch software on GitHub so we can all play with it.
Instead of laboratory grade optical instruments, the cameras used in these experiments are available at our local consumer electronics store. A table in their paper Reconstruction of 3D Flight Trajectories from Ad-Hoc Camera Networks (arXiv:2003.04784) listed several Huawei cell phone cameras, a few Sony digital cameras, and a GoPro 3. Video cameras don’t need to be placed in any particular arrangement, because positions are calculated from their video footage. Correlating overlapping footage from dissimilar cameras is a challenge all in itself, since these cameras record at varying framerates ranging from 25 to 59.94 frames per second. Furthermore, these cameras all have rolling shutters, which adds an extra variable as scanlines in a frame are taken at slightly different times. This is not an easy problem.
There is a lot of interest in tracking drone flights, especially those flying where they are not welcome. And not everyone have the budget for high-end equipment or the permission to emit electromagnetic signals. MultiViewUnsynch is not quite there yet, as it tracks a single target and video files were processed afterwards. The eventual goal is to evolve this capability to track multiple targets on live video, and hopefully help reduce frustrating public embarrassments.
Small aircraft with streaming video cameras are now widely available, for better or worse. Making eyes in the sky so accessible has resulted in interesting footage that would have been prohibitively expensive to capture a few years ago, but this new creative frontier also has a dark side when used to violate privacy. Those who are covering their tracks by encrypting their video transmission should know researchers at Ben-Gurion University of the Negev demonstrated such protection can be breached.
The BGU team proved that a side-channel analysis can be done against behavior common to video compression algorithms, as certain changes in video input would result in detectable bitrate changes to the output stream. By controlling a target’s visual appearance to trigger these changes, a correlating change in bandwidth consumption would reveal the target’s presence in an encrypted video stream.
[Battelle], an Ohio-based non-profit R&D firm has just unveiled a device they call the DroneDefender — a long-range anti-drone defense weapon. It almost sounds like they’ve brought the fictional drone hunter’s RF cannon to life. But does it really work?
According to the site, it uses radio frequency disruption to blast unwanted drones out of the sky. Cool concept, but does it actually work? Unlike the hackable MAVLink protocol used by Parrot AR, ArduPilot and a handful of other consumer drones, this weapon uses brute radio signal force to disable any(?) consumer drone.
There’s a video after the break demonstrating a simulated use of the technology, which leaves us a bit confused. They show the drone slowly landing all nicely after being “guided” down by the rifle. If the system is jamming both GPS and the 2.4 GHz control link, the behavior will all depend on the software loaded on the drone. Some will go to a fail-safe mode, which is low throttle or motor power off, assuming the pilot has set fail-safe. Others may attempt to loiter on IMU sensors only.