Multi-rotor fixed-pitch aircraft – quad, hexa, octa copters – are the current flavor of the season with hobby and amateur flight enthusiasts. The serious aero-modeling folks prefer their variable-pitch, single rotor heli’s. Defense and military folks, on the other hand, opt for a fixed wing UAV design that needs a launch mechanism to get airborne. A different approach to flight is the ducted fan, vertical take-off and landing UAV. [Armin Strobel] has been working on just such a design since 2001. However, it wasn’t until recent advances in rapid-prototyping such as 3D printing and availability of small, powerful and cheap flight controllers that allowed him to make some progress. His Ducted Fan VTOL UAV uses just such recent technologies.
Ducted fan designs can use either swivelling tilt rotors that allow the craft to transition from vertical flight to horizontal, or movable control surfaces to control thrust. The advantage is that a single propeller can be used if the model is not too big. This, in turn, allows the use of internal combustion engines which cannot be used in multi-rotor craft (well, they’ve proven difficult to use thus far).
[Armin] started this project in 2001 in a configuration where the centre of gravity is located beneath trust vectoring, giving the advantage of stability. Since there were no hobby autopilots available at the time, it was only equipped with one gyroscope and a mechanical mixer to control the vehicle around the vertical axis. Unfortunately, the craft was destroyed during the first flight, after having managed a short flight, and he stopped further work on it – until now. To start with, he built his own 3D printer – a delta design with a big build volume of 400mm3. 3D printing allowed him to build a structure which already included all the necessary mount points and supports needed to fix servos and other components. The in-fill feature allowed him to make his structure stiff and lightweight too.
Intending to build his own auto-pilot, he experimented with a BeagleBone Black connected to a micro controller to interface with the sensors and actuators. But he wasn’t too happy with initial results, and instead opted to use the PixHawk PX4 auto-pilot system. The UAV is powered by one 3-cell 3500mAh LiPo. The outside diameter of the duct is 30cm (12”), the height is 55cm (22”) and the take-off weight is about 1.2kg (2.6 pound). It has not yet been flown, since he is still waiting for the electronics to arrive, but some bench tests have been conducted with satisfactory results. In the meantime, he is looking to team up with people who share similar interests, so do get in touch with him if this is something up your alley.
If you want to look at other interesting designs, check this UAV that can autonomously transition from quadcopter flight to that of a fixed-wing aircraft or this VTOL airplane / quadcopter mashup.
Quadcopters are useful little flying machines. They can be used in all sorts of applications, from mapping, to inspecting long pipelines, to border surveillance, or simply for fun. They all have one thing in common, however – a relatively short battery life. Because quadcopters use brute force to churn through the air, they require a lot of energy. More energy for longer flights means more batteries. More batteries means more weight to carry, which requires even more energy. If you want longer flight times, something has to change. Or does it?
A small start-up company called Horizon Unmanned Systems based out of Singapore claims their quadcopter can fly for up to four hours on a single charge, or up to two and a half hours carrying a 2.2 pound load. They claim to be able to pull this off with a novel approach. First, they fill the hollow frame of the quadcopter with hydrogen gas. They use that gas to power a cute little miniaturized fuel cell LiPo battery hybrid gizmo. And that’s about it. The rest is just standard quadcopter stuff.
The secret to all of this is the miniaturized fuel cell, and how it works. Unfortunately, this is as close as we’re going to get (pdf) for a datasheet. Fuel cells are nifty devices that take hydrogen and oxygen and convert them into water, along with electricity. While that sounds simple, making one is not. And making a miniature one light enough for a quadcopter is down right hard.
How would you increase the flight time of quadcopters? Fuel cells are a great idea, but is this technology within the reach of the modern hacker? We’ve seen people make them from scraps out of a junkyard, but how would you miniaturize it and make it light enough to be used as a practical power supply for a quadcopter?
Thanks to [Joseph Rautenbach] for the tip!
A team at the École Polytechnique Fédéral de Lausanne has developed and built a quadcopter with arms that unfold just before takeoff. The idea is that you can fold the device back up when you’re done with it, making it possible to store a bunch more of the quads in your backpack for instance.
The unfolding mechanism relies on the torque of the rotors spinning up to swing the arms into place. Once fully extended, a spring-loaded flap folds up, catches on some magnets, and forms an L-shaped structure that won’t re-fold without human intervention.
Under normal flying conditions, quads have a two left-handed propellers and two right-handed ones and the motors spin in opposite directions. In order to do the unfolding, two of the motors need to run essentially in reverse until the frame has clicked into place. They use a sensor (Hall effect?) to detect the arm locking, and then the rotors quickly switch back to their normal rotation before the quad hits the floor. In the video, they demonstrate that they’ve got this so well tuned that they can throw it up into the air to launch. Wow.
Everything’s still in prototype phase, and one of the next goals is “strengthening the arms so they can withstand crashes”, so don’t expect to see these in your local hobby store too soon. In the mean time, you’ll be able to see them in the flesh if you head up to the IEEE International Conference on Robotics and Automation in Seattle that started today and runs through Friday. If anyone goes, take more video and post in the comments?
Continue reading “Foldable Quadrotor is Origamilicious”
[Geir] has created a pretty neat device, it’s actually his second version of an autonomous boat that maps the depths of lakes and ponds. He calls it the Sea Rendering. The project is pretty serious as the hull was specially made of fiberglass. The propulsion is a simple DC motor and the rudder is powered by an RC servo. A light and flag adorn the top deck making the small craft visible to other larger boats that may be passing by. Seven batteries are responsible for all of the power requirements.
The craft’s course is pre-programmed in Mission Planner and uses ArduPilot loaded on an Arduino to steer to the defined way points. An onboard GPS module determines the position of the boat while a transducer measures the depth of the water. Both position and depth values are then saved to an SD card. Those values can later be imported into a software called Dr Depth that generates a topographic map of the water-covered floor.
[Geir] has sent this bad boy out on an 18 km journey passing through 337 way points. That’s pretty impressive! He estimates that the expected run time is 24 hours at a top speed of 3 km/h, meaning it could potentially travel 72 km on a single charge while taking 700 depth measurements during the voyage.
Continue reading “Project Sea Rendering Autonomously Renders Sea Bottoms”
When [Ian Wood] accidentally broke the camera on his fancy-pants FPV quadrotor he was a little bit upset. But out of all things we break, we hack something new. [Ian] decided to strap on some RGB LEDs to the drone and turn it into a UFO to scare his neighbors!
Now we know what you’re thinking: RGB LEDs? That hardly constitutes a hack! You’re right — but [Ian] didn’t just simply strap some LEDs on and call it a day. Oh no. He’s using a Teensy micro-controller and the NazaCANDecoder to listen to the CAN bus for RC stick positions, flight mode, altitude, battery data, etc. This means the LEDs are actually responding to the way he flies the drone. And since there was a spare channel on his Futaba RX controller, he’s also got an animation mode that can be controlled from the ground to do whatever he wants. He also got rid of the standard indicator LEDs on the quad and wired them into his new setup. They’re all being controlled by a FastLED library on the Teensy. Check it out in the clip after the break.
Continue reading “Roswell Eat Your Heart Out”
With more than five years down the road in this successful hack, [Alexinparis] and his pioneering Nintendo controller hack have been taking eager enthusiasts to the skies with homebrew multicopters armed with MultiWii firmware.
The MultiWii firmware, like most other glorious moments that gloss these pages, was as a hack, and a darn good one. By harvesting the (I²C-based) accel-gyro sensor package in a Nintendo Wii MotionPlus, [Alexinparis] developed control firmware for an Arduino Pro Mini, and, thus: the MultiWii Controller Board was born. With a successful WiiMotion Plus pcb extraction, an Arduino Pro Mini, and some help from the forums, the dedicated hobbyist could build their own flying platform with customizable firmware enabling bi, tri, quad, hex, octo, Y6, and Y4 propeller configurations.
With a working flight controller, [Alexinparis] sent his firmware skyward in a tricopter built from scratch. For a light-but-sturdy shell, he opted for a lost-foam cast hull made from fiberglass and carbon fiber tow. This hull houses most of the electronics safely inside the hollow shell while maintaining the strength to sustain heavy blows from crashes. (The version shown above features additional carbon fiber reinforcement in the center.)
More than five years later, MultiWii is a mature open-source project with firmware and wiki under constant update. If you’ve ever considered getting started with multicopters, this project stands as a tested-and-tried road to success. In fact, even RC vendor HobbyKing offers low-cost Multiwii PCBs compatible with the firmware. For more details on the project’s humble beginnings, head on over to the RC Groups thread and followup documentation thread.
We’ve seen MultiWii countless times in the past as the firmware in numerous multicopter builds. It’s about time we give [Alexinparis] some well-deserved credit for paving the way.
Continue reading “Multicopters and their MultiWii Beginnings”
Is it a quadcopter? A plane? No, it’s both! [Daniel Lubrich] is at it again with a vertical take off and landing transformer he calls the SkyProwler.
The SkyProwler uses a switch blade type mechanism to move from quadcopter mode to plane mode. The wings can be detached to make it a normal quad that has all the typical bells and whistles. It can follow you around with GPS, fly autonomously via way points, and has this cool gimbal mechanism that keeps the GoPro stable as the drone pitches in flight, allowing for a better video experience.
[Dan’s] ultimate goal is a full size passenger model called the SkyCruiser, which uses the same switchblade transformation mechanism as his much smaller SkyProwler. Be sure to check out the video below if you haven’t already, and let us know of any quadcopter / plane hybrids of your own.
Correction: We previously associated [Daniel Lubrich] with the ATMOS program. This was in error and has been removed from the article. The ATMOS UAV is a separate project which we previously covered.
Continue reading “Quadcopter Plane Transformer is Awesome”