Experimental Drone Flies Like A Bird

Most RC planes follow a simple control scheme: elevators for pitch, rudder for yaw, and ailerons for roll. This one-to-one mapping keeps things straightforward, and fewer actuators means less weight. But nature has other ideas. Birds achieve flight control through complex, coordinated movements where different body parts can affect multiple degrees of freedom simultaneously. Now, researchers at EPFL have brought this biological approach to robotics with the LisEagle, a drone featuring morphing wings and tail that demonstrate remarkable stability.

All the control surfaces and actuators
All the actuators!

The LisEagle packs seven different actuation methods alongside its nose-mounted motor. Three of these control the bird-like wingtips and spreading tail, while the remaining actuators handle more conventional controls: independently twisting wing bases (similar to ailerons) and a tail assembly that combines elevator and rudder functions in its vertical stabilizer.

Testing took place in controlled indoor conditions, with the maintaining position in front of an open wind tunnel. Optical position tracking provided closed-loop feedback and power was provided via a tether to minimize weight. A PID flight controller orchestrated all seven actuators in concert, achieving impressive stability even when faced with induced turbulence or being poked with a stick. In a demonstration of redundancy, the researchers deliberately disabled the twisting wing mechanisms, and the aircraft maintained control using just its wingtips and tail.

The team went further, employing Bayesian optimization to find the most efficient actuator combinations. This revealed potential energy savings of up to 11%, with optimal configurations varying based on airspeed as lift requirements changed.

While research into the flight mechanisms of bees, bats and birds might not immediately translate to practical applications, it deepens our understanding of flight control principles. Don’t be surprised if morphing wings become a more common sight in future aircraft designs.

Continue reading “Experimental Drone Flies Like A Bird”

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”

Automated Weed Spraying Drone Needs No Human Intervention

Battling weeds can be expensive, labor intensive and use large amounts of chemicals. To help make this easier [NathanBuilds] has developed  V2 of his open-source drone weed spraying system, complete with automated battery swaps, herbicide refills, and an AI vision system for weed identification.

The drone has a 3D printed frame, doubling as a chemical reservoir. V1 used a off-the-shelf frame, with separate tank. Surprisingly, it doesn’t look like [Nathan] had issues with leaks between the layer lines. For autonomous missions, it uses ArduPilot running on a PixHawk, coupled with RTK GPS for cm-level accuracy and a LiDAR altimeter. [Nathan] demonstrated the system in a field where he is trying to eradicate invasive blackberry bushes while minimizing the effect on the native prairie grass. He uses a custom image classification model running on a Raspberry Pi Zero, which only switches on the sprayers when it sees blackberry bushes in the frame. The Raspberry Pi Global Shutter camera is used to get blur-free images.

At just 305×305 mm (1×1 ft), the drone has limited herbicide capacity, and we expect the flights to be fairly short. For the automated pit stops, the drone lands on a 6×8 ft pad, where a motorized capture system pulls the drone into the reload bay. Here a linear actuator pushes a new battery into the side of the drone while pushing the spend battery one out the other side. The battery unit is a normal LiPo battery in 3D-printed frame. The terminal are connected to copper wire and tape contacts on the outside the battery unit, which connect to matching contacts in the drone and charging receptacles. This means the battery can easily short if it touches a metal surface, but a minor redesign could solve this quickly. There are revolving receptacles on either side of the reload bay, which immediately start charging the battery when ejected from the drone.

Developing a fully integrated system like this is no small task, and it shows a lot of potential. It might look a little rough around the edges, but [Nathan] has released all the design files and detailed video tutorials for all the subsystems, so it’s ready for refinement.

Continue reading “Automated Weed Spraying Drone Needs No Human Intervention”

Amazon Receives FAA Approval For MK30 Delivery Drone

It’s been about a decade since Amazon began to fly its delivery drones, aiming to revolutionize the online shopping experience with rapid delivery of certain items. Most recently Amazon got permission from the FAA to not only start flying from its new Arizona-based location, but also to fly beyond-visual-line-of-sight (BVLOS) missions with the new MK30 drone. We reported on this new MK30 drone which was introduced earlier this year along with the news of the Amazon Prime Air delivery service ceasing operations in California and moving them to Arizona instead.

This new drone has got twice the range as the old MK27 drone that it replaces and is said to be significantly quieter as well. The BLOS permission means that the delivery drones can service areas which are not directly visible from the warehouse with its attached drone delivery facility. With some people within the service range of the MK27 drones having previously complained about the noise levels, we will see quickly enough whether the MK30 can appease most.

As for the type of parcels you can have delivered with this service, it is limited to 2.27 kg (~5 lbs), which is plenty for medication and a range of other items where rapid delivery would be desirable.

Custom Drone Software Searches, Rescues

When a new technology first arrives in people’s hands, it often takes a bit of time before the full capabilities of that technology are realized. In much the same way that many early Internet users simply used it to replace snail mail, or early smartphones were used as more convenient methods for messaging and calling than their flip-phone cousins, autonomous drones also took a little bit of time before their capabilities became fully realized. While some initially used them as a drop-in replacement for things like aerial photography, a group of mountain rescue volunteers in the United Kingdom realized that they could be put to work in more efficient ways suited to their unique abilities and have been behind a bit of a revolution in the search-and-rescue community.

The first search-and-rescue groups using drones to help in their efforts generally used them to search in the same way a helicopter would have been used in the past, only with less expense. But the effort involved is still the same; a human still needed to do the searching themselves. The group in the UK devised an improved system to take the human effort out of the equation by sending a drone to fly autonomously over piece of mountainous terrain and take images of the ground in such a way that any one thing would be present in many individual images. From there, the drone would fly back to its base station where an operator could download the images and run them through a computer program which would analyse the images and look for outliers in the colors of the individual pixels. Generally, humans tend to stand out against their backgrounds in ways that computers are good at spotting while humans themselves might not notice at all, and in the group’s first efforts to locate a missing person they were able to locate them almost immediately using this technology.

Although the system is built on a mapping system somewhat unique to the UK, the group has not attempted to commercialize the system. MR Maps, the software underpinning this new feature, has been free to use for anyone who wants to use it. And for those just starting out in this field, it’s also worth pointing out that location services offered by modern technologies in rugged terrain like this can often be misleading, and won’t be as straightforward of a solution to the problem as one might think.

Tiny Drones Do Distributed Mapping

Sending teams of tiny drones to explore areas and structures is a staple in sci-fi and research, but the weight and size of sensors and the required processing power have long been a limiting factor. In the video below, a research team from [ETH Zurich] breaks through these limits, demonstrating indoor mapping with a swarm of tiny drones without dependence on any external systems.

The drone is the modular Crazyflie platform, which uses stackable PCBs (decks) to expand capabilities. The team added a Flow deck for altitude control and motion tracking, and a Loco positioning deck with a UWB module determining relative distances between drones. On top of this, the team added two custom decks. The first mounts four VL53L5CX 8×8 pixel TOF sensors for omnidirectional LIDAR scanning. The final deck does handles all the required processing with a GAP9 System-on-Chip, which features 10 RISC-V cores running on just 200 mW of power.

Of course the special sauce of this project lies in the software. The team developed a lightweight collaborative Simultaneous Localization And Mapping (SLAM) algorithm which can be distributed across all the drones in the swarm. It combines LIDAR scan data and the estimated position of the drone during the scan, and then overlays the data for the scans for each location across different drones, compensating for errors in the odometry data. The team also implemented inter-drone collision avoidance, packet collision avoidance and optimizing drones’ paths. The code is supposed to be available on GitHub, but the link was broken at the time of writing.

The Crazyflie platform has been around for more than a decade now, and we’ve seen it used in several research projects, especially related to autonomous navigation. Continue reading “Tiny Drones Do Distributed Mapping”

Single Rotor Drone Spins For 360 Lidar Scanning

Multiple motors or servos are the norm for drones to achieve controllable flight, but a team from MARS LAB HKU was able to a 360° lidar scanning drone with full control on just a single motor and no additional actuators. Video after the break.

The key to controllable flight is the swashplateless propeller design that we’ve seen a few times, but it always required a second propeller to counteract self-rotation. In this case, the team was able to make that self-rotation work so that they could achieve 360° scanning with a single fixed LIDAR sensor. Self-rotation still needs to be slowed, so this was done with four stationary vanes. The single rotor also means better efficiency compared to a multi-rotor with similar propeller disk area.

The LIDAR comprises a full 50% of the drone’s weight and provides a conical FOV out to a range of 450m. All processing happens onboard the drone, with point cloud data being processed by a LIDAR-inertial odometry framework. This allows the drone to track and plan its flight path while also building a 3D map of an unknown environment. This means it would be extremely useful for indoor or underground environments where GPS or other positioning systems are not available.

All the design files and code for the drone are up on GitHub, and most of the electronic components are off-the-shelf. This means you can build your own, and the expensive lidar sensor is not required to get it flying. This seems like a great platform for further experimentation, and getting usable video from a normal camera would be an interesting challenge. Continue reading “Single Rotor Drone Spins For 360 Lidar Scanning”