No one noticed the two men in the alley as the darkness of midnight approached – their long, black trench coats acting like a soldier’s camouflage.
“You got the goods?”
“Yeah, these are hot man…super fast..check this…”
The bark of a police siren broke their whispered conversation like a shattering glass, causing the two men to briefly freeze in their steps.
“Johnny B. got busted last week…did you hear?”
“No way man! What he get busted for?”
“Drone racing man…drone racing.”
Deep within the shadows of abandoned warehouses and dilapidated factories on the outskirts of Australian suburbia, the telltale buzz of numerous drones can be heard. Zipping to and fro at speeds upwards of 60km/h, these drones are not just flying. They’re racing each other. The operators use specialized FPV goggles that allow them to see the raceway in real time. This method, unfortunately, puts them on the wrong side of the law.
The dated laws governing drones in Australia are similar to those in the US, which were written for the radio controlled plane industry. While they technically forbid any flying outside of line-of-site, the Australian Civil Aviation Authority seems to be OK with the drone racing so long as it’s done indoors and poses no risk to people or property.
Know of any drone racing in your country? Is it legal? Do people do it anyway? Let us know in the comments.
Last April, graffiti artist [KATSU] strapped a can of red spray paint to a Phantom quadcopter, flew it up against one of the largest billboards in New York City, and pressed a button. Now, [KATSU], [Dan Moore], and Adafruit’s [Becky Stern] are trying to perfect a flying can of spraypaint, and they’ve met with some success and surely many broken props.
The team used an Iris+ for this project instead of the Phantom used by [KATSU] earlier this year, but the principle of the entire endeavor remains the same: fly up against a wall, flick a switch, and watch paint come out of a spray gun. To get the can spraying paint, they modified a can gun to accept a micro servo. This servo is connected to the trigger mechanism of the can gun, and the entire unit is slung under the quad.
Getting a quadcopter to put paint exactly where you want it is hard, even indoors. Luckily, the Pixhawk inside the Iris has sensor inputs and an ‘altitude hold’ mode that can accept a sonar sensor and can be programmed to stay a set distance away from a wall. These sensors are susceptible to interference, and a proper, shielded cable had to be made, but the sensor did work.
Flying the quad did not go as smoothly. The swinging can of paint changes the center of gravity of the quad, and even flying indoors proved difficult. Still, if you’d like to give it a go, [Becky] put up the instructions for their build. You can see the hover attempts in the video below.
Continue reading “The Trials Of Quadcopter Graffiti”
Normal WiFi is not what you want to send video from your quadcopter back to the first-person-view (FPV) goggles strapped on your head, because it’s designed for 100% correct, two-way transmission of data between just two radios. Transmission of analog video signals, on the other hand, is lossy, one-way, and one-to-many, which is why the longer-range FPV flights all tend to use old-school analog video transmission.
When you’re near the edge of your radios’ range, you care much more about getting any image in a timely fashion than about getting the entire video sequence correctly after a delay. While WiFi is retransmitting packets and your video is buffering, your quadcopter is crashing, and you don’t need every video frame to be perfect in order to get an idea of how to save it. And finally, it’s just a lot easier to optimize both ends of a one-way transmission system than it is to build antennas that must receive and transmit symmetrically.
And that’s why [Befinitiv] wrote wifibroadcast: to give his WiFi FPV video system some of the virtues of analog broadcast.
Continue reading “Wifibroadcast Makes WiFi FPV Video More Like Analog”
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”