Improving Flying Drones By Mimicking Flying Squirrels

With the ability to independently adjust the thrust of each of their four motors, quadcopters are exceptionally agile compared to more traditional aircraft. But in an effort to create an even more maneuverable drone platform, a group of South Korean researchers have studied adding flying squirrel tech to quadcopters. Combined with machine learning, this is said to significantly increase the prototype’s agility in an obstacle course.

Flying squirrels (tribe Pteromyini)) have large skin flaps (patagium) between their wrists and ankles which they use to control their flight when they glide from tree to tree, along with their fluffy squirrel tail. With flights covering up to 90 meters, they also manage to use said tail and patagium to air brake, which prevents them from smacking with bone jarring velocities into a tree trunk.

By taking these principles and adding a similar mechanism to a quadcopter for extending a patagium-like membrane between its rotors, the researchers could develop a new controller (thrust-wing coordination control, TWCC), which manages the extending of the membranes in coordination with thrust from the brushless motors. Rather than relying on trial-and-error to develop the controller algorithms, the researchers trained a recurrent neural network (RNN) which was pre-trained prior to first flights using simulation data followed by supervised learning to refine the model.

During experiments with obstacle avoidance on a test-track, the RNN-based controller worked quite well compared to a regular quadcopter. A disadvantage is of course that the range of these flying squirrel drones is less due to the extra weight and drag, but if one were to make flying drones that will perch on surfaces between dizzying feats of agility in the air, this type of drone tech might just be the ticket.

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Why Not Build Your Quadcopter Around An Evaluation Board?

Quadcopters are flying machines. Traditionally, that would mean you’d optimize the design for lightweight and minimum drag, and you’d do everything in a neat and tidy fashion. The thing is, brushless motors and lithium batteries are so power-dense that you really needn’t try so hard. A great example of that is this barebones quadcopter build from [hebel23] all the way back in 2015.

The build is based around the STM32F4 Discovery Board, which [hebel23] scored as a giveaway at Electronica in Munich way back when. It’s plopped on top of a bit of prototyping board so it can be hooked up to the four controllers driving the motors at each corner. The frame of the quadcopter similarly uses cheap material, in the form of alloy profiles left over from an old screen door. Other equipment onboard includes a GY-273 electronic compass module, a MPU6050 3-axis gyroscope and accelerometer to keep the thing on the straight and level, and the Fly Sky R9B RC receiver for controlling the thing.

It might look crude, but it gets off the ground just fine. We’ve seen quadcopters using the STM32 in more recent years with more refined designs, but there’s something amusingly elegant about lacing one together with an evaluation board and some protoboard in the middle. If you’re working on your own flying projects, don’t hesitate to notify the tipsline!

Modular Multi-Rotor Flies Up To Two Hours

Flight time remains the Achilles’ heel of electric multi-rotor drones, with even high-end commercial units struggling to stay airborne for an hour. Enter Modovolo, a startup that’s shattered this limitation with their modular drone system achieving flights exceeding two hours.

The secret? Lightweight modular “lift pods” inspired by bicycle wheels using tensioned lines similar to spokes. The lines suspend the hub and rotor within a duct. It’s all much lighter than of traditional rigid framing. The pods can be configured into quad-, hex-, or octocopter arrangements, featuring large 671 mm propellers. Despite their size, the quad configuration weighs a mere 3.5 kg with batteries installed. From the demo-day video, it appears the frame, hub, and propeller are all FDM 3D printed. The internal structure of the propeller looks very similar to other 3D-printed RC aircraft.

The propulsion system operates at just 1000 RPM – far slower than conventional drones. The custom propellers feature internal ring gears driven by small brushless motors through a ~20:1 reduction. This design allows each motor to hover at a mere 60 W, enabling the use of high-density lithium-ion cells typically unsuitable for drone applications. The rest of the electronics are off-the-shelf, with the flight controller running ArduPilot. Due to the unconventional powertrain and large size, the PID tuning was very challenging.

We like the fact this drone doesn’t require fancy materials or electronics, it just uses existing tech creatively. The combination of extended flight times, rapid charging, and modular construction opens new possibilities for applications like surveying, delivery, and emergency response where endurance is critical.

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Transforming Drone Drives And Flies

Vehicles that change their shape and form to adapt to their operating environment have long captured the imagination of tech enthusiasts, and building one remains a perennial project dream for many makers. Now, [Michael Rechtin] has made the dream a bit more accessible with a 3D printed quadcopter that seamlessly transforms into a tracked ground vehicle.

The design tackles a critical engineering challenge: most multi-mode vehicles struggle with the vastly different rotational speeds required for flying and driving. [Michael]’s solution involves using printed prop guards as wheels, paired with lightweight tracks. An extra pair of low-speed brushless motors are mounted between each wheel pair, driving the system via sprockets that engage directly with the same teeth that drive the tracks.

The transition magic happens through a four-bar linkage mounted in a parallelogram configuration, with a linear actuator serving as the bottom bar. To change from flying to driving configuration the linear actuator retracts, rotating the wheels/prop guards to a vertical position. A servo then rotates the top bar, lifting the body off the ground. While this approach adds some weight — an inevitable compromise in multi-purpose machines — it makes for a practical solution.

Powering this transformer is a Teensy 4.0 flight controller running dRehmFlight, a hackable flight stabilization package we’ve seen successfully adapted for everything from VTOLs to actively stabilized hydrofoils. Continue reading “Transforming Drone Drives And Flies”

Dog Poop Drone Cleans Up The Yard So You Don’t Have To

Sometimes you instantly know who’s behind a project from the subject matter alone. So when we saw this “aerial dog poop removal system” show up in the tips line, we knew it had to be the work of [Caleb Olson].

If you’re unfamiliar with [Caleb]’s oeuvre, let us refresh your memory. [Caleb] has been on a bit of a dog poop journey, starting with a machine-learning system that analyzed security camera footage to detect when the adorable [Twinkie] dropped a deuce in the yard. Not content with just knowing when a poop event has occurred, he automated the task of locating the packages with a poop-pointing robot laser. Removal of the poop remained a manual task, one which [Caleb] was keen to outsource, hence the current work.

The video below, from a lightning talk at a conference, is pretty much all we have to go on, and the quality is a bit potato-esque. And while [Caleb]’s PoopCopter is clearly still a prototype, it’s easy to get the gist. Combining data from the previous poop-adjacent efforts, [Caleb] has built a quadcopter that can (or will, someday) be guided to the approximate location of the offending package, home in on it using a downward-looking camera, and autonomously whisk it away.

The retrieval mechanism is the high point for us; rather than a complicated, servo-laden “sky scoop” or something similar, the drone has a bell-shaped container on its belly with a series of geared leaves on the open end. The leaves are open when the drone descends onto the payload, and then close as the drone does a quick rotation around the yaw axis. And, as [Caleb] gleefully notes, the leaves can also open in midair with a high-torque yaw move in the opposite direction; the potential for neighborly hijinx is staggering.

All jokes and puns aside, this looks fantastic, and we can’t wait for more information and a better video. And lest you think [Caleb] only works on “Number Two” problems, never fear — he’s also put considerable work into automating his offspring and taking the awkwardness out of social interactions.

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Full-Scale Flying DeLorean Gets Closer To Liftoff

These days, even hobbyist multi-rotor aircraft are capable of carrying considerable payloads. For example, the test rig that [Brian Brocken] recently put together should be able to loft more than 80 pounds (36 kilograms) without breaking a sweat. That would be a whole lot of camera gear or other equipment, but in this case, he’s planning on carrying something a bit more interesting: a full-scale foam DeLorean.

We first covered this project in December of last year, when [Brian] started using a massive robotic arm to carefully cut the body and individual parts of the car out of expanded polystyrene foam. He estimated at the time the body should weigh in at less than 30 lbs (14 kg), so he’d need to build a quadcopter with a maximum lift of roughly twice that much to keep the performance where he wanted it.

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New Quadcopter Speed World Record Set At Nearly 500 Km/h

Making a quadcopter go fast would seem to be quite simple: just strap on powerful motors, aim the quadcopter roughly at where you want it to go fast, and let ‘er rip. Because of aerodynamics and other pesky physical laws there are a few complications to this, of course, but this didn’t deter [Luke Bell] and his father [Mike Bell] from nailing the Guinness World Record for remote-controlled quadcopters on April 21, 2024. During the official run, a top speed of 480.23 km/h was recorded, making it considerably faster than the first version they made, which hit a measly 400 km/h.

For this second iteration of the ‘got to go fast’ quadcopter, the design was scaled up, with more powerful motors and associated electronics added. Naturally, when you’re pushing brushless motors and their ESCs to their limits, stuff can get a bit hot due to the immense currents flowing through the system. This resulted in a number of battery, wire and other fires. Fortunately, the worrying aspect of in-flight stability got addressed pretty well courtesy of a professional drone trainer, and ultimately the world record attempt went off without a hitch.

An endurance test was also attempted, which reached 7.5 km at 180 km/h, and with the clear canopy in from of the camera removed, visual performance was pretty stunning, while still easily reaching 400 km/h. This might make it the perfect high-speed chase camera system.

Thanks to [Craig] for the tip.

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