Tiny Drones Navigate Like Real Bugs

When it comes to robotic navigation, the usual approach is to go as technically advanced and “smart” as possible. Yet the most successful lifeforms that we know of follow a completely different approach. With limited senses and cognitive abilities, the success of invertebrates like ants and honeybees lie in cooperation in large numbers. A joint team of researchers from TU Delft, University of Liverpool and Radboud University of Nijmegen, decided to try this approach and experimented with a simple navigation technique to allow a swarm of tiny flying robots to explore an unknown environment.

The drones used were of-the-shelf Crazyflie 2.0 micro quadcopters with add-on boards. Sensors consisted of it’s onboard IMU, simple range finding sensors on a Multi-ranger deck for obstacle detection, and a down pointing optical flow sensor, on a Flow deck, to keep track of the distance travelled.  To navigate, the drones used a “swarm gradient bug algorithm” (SGBA).  Each drone in has different preferred direction of travel from takeoff. When an obstacle encountered, it follows the contour of the obstacle, and then continues  in the preferred direction once the path is clear.  When the battery drops to 60%, it returns to a wireless homing beacon. While this technique might not be the most efficient, it has the major advantage of being “lightweight” enough to implement on a cheap microcontroller, an STM32F4 in this case. The full research article is available for free, and is a treasure trove of information.

The main application researchers have in mind is for search and rescue. A swarm of drones can explore an unstable or dangerous area, and identify key areas to focus rescue efforts on.  This can drastically reduce wasted time and risk to rescue workers. It is always cool to see complex problems being solved with simple solution, and we are keen to see where things go. Check out the video after the break. Continue reading “Tiny Drones Navigate Like Real Bugs”

Autonomous Air Boat Vs Lake Washington

Autonomous vehicles make a regular appearance around here, as does [Daniel Riley] aka [rctestflight]. His fascination with building long-endurance autonomous vehicles continues, and this time he built an autonomous air boat.

This craft incorporates a lot of the lessons learnt from his autonomous boat that used a plastic food container. One of the biggest issues was the submerged propellers kept getting tangled in weeds. This led [Daniel] to move his props above water, sacrificing some efficiency for reliability, and turning it into an air boat. The boat itself is catamaran design with separate 3D printed hulls connected by carbon fibre tubes. As with the tupperware boat, autonomous control is done by the open source Ardupilot software.

During testing [Daniel] had another run in with his old arch-nemesis, seaweed. It turns out the sharp vertical bow is a nice edge for weeds to hook on to, create drag, and screw up the craft’s control. [Daniel]’s workaround involved moving the big batteries to the rear, causing the bows lift almost completely out of the water.

With a long endurance in mind right from the start of the project, [Daniel] put it to the test with a 13 km mission on Lake Washington very early one morning. For most of the mission the boat was completely on its own, with [Daniel] stopping at various points along the lake shore to check on its progress. Everything went smoothly until 10 km into the mission when the telemetry showed it slowing down and angling off course, after which is started going in circles. Lucky for Daniel he was offered a kayak by a lakeside resident, and he managed to recover the half sunken vessel. He suspects the cause of the failure was a slowly leaking hull. [Daniel] is already working on the next version, and were looking forward to seeing what he comes up with. Check out the video after the break. Continue reading “Autonomous Air Boat Vs Lake Washington”

These Maple Pod Inspired Drones Silently Carry Payloads

Researchers from the Singapore University of Technology and Design (SUTD) recently released a video showing their nature-inspired drone that is capable of breaking out into five separate smaller drones. The drones each have auto-rotating wings that slow their rate of descent, similar to seed pods from a maple tree. Due to their design, the drones are only made to be used for a one-way trip, with the five components each carrying a separate payload. The drones are designed to detach within a specified distance from their destination, allow the collective body to safely spiral downwards towards land.

In their paper published on the same subject, the researchers discuss how they optimized the balsa wood wings with servos, a LiPo battery, and a receiver attached to a 3D-printed body. Four are equipped with just these components, while the fifth also holds a 3-axis magnetometer, a Teensy 3.5 board, a GPS module, and a Pixracer controller.

They experimented with several motion capture setups and free-flight drop tests to verify their simulations on the models for the drones. Apart from simply detaching, they are also designed to cater to different mission profiles based on the environment they are dropped in.

We’ll admit that the implementation and design of the drones does seem fairly dystopian, especially when you wonder what could possibly be the payloads these drones are designed to carry. But in terms of nature-inspired robotics, the maple seed pod idea is pretty interesting.

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Planting 20 Million Trees, Using Drones, Cannons, And More Unconventional Ways

When YouTuber MrBeast hit 20 million subscribers, it kicked off the promise to plant 20 million new trees by 2020. While seeming rather mad for a single person to attempt such a feat, the channel has begun an organized effort under the banner of ‘Team Trees‘. With many famous and less famous YouTubers and other online personalities pitching in, along with a number of companies and organizations, it seems like it’s not as far-fetched of an idea as it first seemed.

We’ve embedded MrBeast’s video after the break where you’ll also find a video by Mark Rober, who teamed up a company called DroneSeed, who use large flying drones to distribute seeds contained in nutrition pods over large areas. Their focus is on reforestation after large wildfires and other events that leave the land devoid of trees. Of course, this being seeds, it will take quite a while for results to become visible.

The impatient Canadians over at Linus Media Group figured that they’d rather plant tree seedlings at a breakneck pace, cobbling together a nitrogen cannon that fires a nutrition pellet into the soil, creating the hole for the seedling, or alternately firing the pellet and seedling into the soil in one go from the breach-loading cannon. Obviously the results from the latter method are decidedly more questionable, taking a bit chunk out of the about 300 seedlings they were planning to add to the local nature.

Regardless of the method chosen, any significant reforestation around the world could be a crucial part of reducing the global increase of atmospheric CO2, and the climate challenges this creates.  With sources putting the total number of trees in the world today at about 3 trillion, 20 million more doesn’t seem like a lot, yet techniques we’re learning today to speed up the process of reforestation might play a major role in the near future.

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A Drone Sprouts Wings

While there are some fixed-wing drones in the hobby world, most of us around here think of the quadcopter when this word is mentioned. There have been some fixed-wings around, and lots of multi-rotors, but not much of a mix of the two. [Paweł] wanted to see what would happen if he mixed these two together, and created a quadcopter drone with retractable wings, essentially just to see what would happen.

This isn’t something that can convert from fixed-wing flight to helicopter-style hovering like a V22 Osprey or Harrier, either. The lift and thrust is entirely generated by the rotors, and the “wings” are essentially deployable air brakes that allow the drone to slow down quickly without consuming as much energy under propeller power alone. The air brake wings are designed to automatically deploy as a function of throttle position, too, so there’s a lot that could be built on this idea in the future, in theory.

[Paweł] notes that this design is somewhat controversial, and although few of us are in the drone racing community we can imagine how a functional change like this might impact in an arena such as that. He also only saw marginal performance increases and isn’t planning on perusing this idea much further. If you’re interested in a drone with “true” wings, though, check out this one which gets fired out of a grenade launcher.

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Military Gliders Are Making A Comeback, This Time In Unmanned Form

Sun Tzu said, “The line between disorder and order lies in logistics.” This is as true in the modern world as it was 2500 years ago, and logistics have helped win and lose many wars and battles over the centuries. To this end, Logistical Gliders Inc. is developing one-time use, unmanned delivery gliders, for the US Military.

Reminiscent of the military gliders used in WW2, the gliders are designed to be dropped from a variety of aircraft, glide for up to 70 miles and deliver supplies to troops in the field. Specifically intended to be cheap enough to be abandoned after use, the gliders are constructed from plywood, a few aluminum parts for reinforcement and injection molded wing panels. There are two versions of the glider, both with huge payloads. The LG-1K, with a payload capacity of 700 lbs/320 kg and the larger LG-2K, with a payload capacity of 1,600 lbs/725 kg. Wings are folded parallel to the fuselage during transport and then open after release with the help of gas springs. The glider can either do a belly landing in an open area or deploy a parachute from the tail at low altitude to land on the crushable nose.

Gliders like these could be used to deliver supplies after natural disasters, or to remote locations where road travel is difficult or impossible while reducing the flight time required for conventional aircraft. Powered UAVs could even be used to carry/tow a glider to the required release point and then return much lighter and smaller, reducing the required fuel or batteries.

Drones are already used to deliver medical supplies in Rwanda and Ghana, and it’s possible to build your own autonomous unmanned glider. Check out the video after the break to see the big boys in action. Continue reading “Military Gliders Are Making A Comeback, This Time In Unmanned Form”

Flying Batteries For Drones

Power is the bane of drone pilots. You’d like to fly longer which means a bigger battery. But a bigger battery will weigh more which leads to less flight time. You have to strike a balance and for most consumer drones that balance is about 20 minutes of flight time, more or less. Researchers at Berkeley have a different idea: don’t use a bigger battery, but simply replace the battery in flight.

The idea isn’t completely new. After all, many planes refuel in flight — a technically sophisticated operation, but it occurs every day. The scheme here is to have a primary battery and a secondary battery. When the secondary battery is low, the drone ejects it while running on the primary battery. Another secondary battery flies to the drone and docks with it becoming the new main power source.

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