Combine Broken Drone Propellers For A Second Spin

May 6, 2020 by Danie Conradie 8 Comments

If you’ve ever flown or watched anyone fly a racing drone for any length of time, you know that crashes are just part of the game and propellers are consumables. [Adam] knows this all to well, decided to experiment with combining multiple broken propellers into one with a 3D printed hub.

A damaged propeller will often have one blade with no damage, still attached to the hub. [Adam] trimmed the damaged parts of a few broken props, and set about designing a 3D printed hub to attach the loose blades together. The hubs were designed let the individual blades to move, and folding out as the motors spin up, similar to the props on many photography drones.

Once [Adam] had the fit of the hubs dialed in, he mounted a motor on a piece of wood and put the reborn propellers through their paces. A few hubs failed in the process, which allowed [Adam] to identify weak points and optimise the design. This sort of rapid testing is what 3D printing truly excels at, allowing test multiple designs quickly instead of spending hours in CAD trying to foresee all the possible problems.

He then built a test drone from parts he had lying around and proceeded with careful flight testing. The hubs were thicker than standard propellers so it limited [Adams] motor choices to ones with longer shafts. Flight testing went surprisingly well, with a hub only failing after [Adam] changed the battery from a 3 cell to a 4 cell and started with some aerobatics. Although this shows that the new props are not suitable for the high forces from racing or aerobatics/freestyle flying, they could probably work quite well for smoother cruising flights. The hubs could also be improved by adding steel pins into the 3D printed shafts, and some carefully balancing the assembled props.

Continue reading “Combine Broken Drone Propellers For A Second Spin” →

The Drone That Can Play Dodgeball

March 23, 2020 by Rich Hawkes 10 Comments

Drones (and by that we mean actual, self-flying quadcopters) have come a long way. Newer ones have cameras capable of detecting fast moving objects, but aren’t yet capable of getting out of the way of those objects. However, researchers at the University of Zurich have come up with a drone that can not only detect objects coming at them, but can quickly determine that they’re a danger and get out of the way.

The drone has cameras and accompanying algorithms to detect the movement in the span of a couple of milliseconds, rather than the 20-40 milliseconds that regular quad-copters would take to detect the movement. While regular cameras send the entire screens worth of image data to the copter’s processor, the cameras on the University’s drone are event cameras, which use pixels that detect change in light intensity and only they send their data to the processor, while those that don’t stay silent.

Since these event cameras are a new technology, the quadcopter processor required new algorithms to deal with the way the data is sent. After testing and tweaking, the algorithms are fast enough that the ‘copter can determine that an object is coming toward it and move out of the way.

It’s great to see the development of new techniques that will make drones better and more stable for the jobs they will do. It’s also nice that one day, we can fly a drone around without worrying about the neighborhood kids lobbing basketballs at them. While you’re waiting for your quadcopter delivered goods, check out this article on a quadcopter testbed for algorithm development.

Lego Drone Finally Takes Off

January 15, 2020 by Al Williams 7 Comments

We were concerned when we saw [Brick Experiment Channel] test a drone propulsion pod made with Lego. After all, the thrust generated was less than the weight of the assembly. But a few tweaks got enough lift to overcome the assembly weight, as you can see in the video below.

The next step was to build three more pods and add some lightweight avionics and a battery. The first flight was a little dicey because the sensor orientation was off. Then there was some more software tuning before things really got airborne.

Continue reading “Lego Drone Finally Takes Off” →

3D Pens Can Make Ugly Drone Parts That Almost Work

January 5, 2020 by Donald Papp 23 Comments

Small hobby aircraft and light plastic parts go hand in hand, and a 3D printing pen makes lightweight plastic things without the overhead of CAD work and running a 3D printer. So could a 3D pen create useful plastic bits for small quadcopters? [Michael Niggel] decided to find out by building his drone parts with a 3D pen loaded with ABS plastic. He mostly discovered that the created objects could politely be said to look like they were sketched by a toddler, but that’s not all he learned.

He found that in general creating an object was harder than the marketing materials implied. As soon as the filament exits the pen’s nozzle, the thin little molten line of plastic cools rapidly and does two things: it has a tendency to curl, and loses its desire to stick to things. [Michael] found the whole affair worked much less like ‘drawing in thin air’ and rather more like piping frosting, or caulking.

An almost functional micro quad frame. The arms aren’t rigid enough to hold the motors vertical when under power.

Nevertheless, [Michael] sought to discover whether a 3D pen could be used to make quick and dirty parts of any use. He created two antenna brackets and one micro quad frame. All three are chaotic messes, but one antenna bracket was perfectly serviceable. The 3D pen was indeed able to create a strangely-shaped part that would have been a nightmare to CAD up. The other antenna part worked, but didn’t do anything a zip tie wouldn’t have done better. The rapid cooling of the plastic from the 3D pen has an advantage: extrusions don’t “droop” like a glob of hot glue does before it hardens.

By now, [Michael] agreed that the best way to create a plastic part of any complexity whatsoever seemed to be to draw sections flat, build them up in layers, then use the pen to weld the pieces together and add bulk. The micro quad frame he made in this way doesn’t look any nicer than the other attempts, but it did hold the parts correctly. Sadly, it would not fly. Once the motors powered up, the arms would twist and the flight controller was unable to compensate for motors that wouldn’t stay straight. This could probably be overcome, but while the end result was dirty it certainly wasn’t quick. The 3D pen’s niche seems restricted to simple, unstressed parts that aren’t permitted to gaze up themselves in a mirror.

If you have a 3D pen, we’d like to remind you of this mini spool design whose parts are welded together with the pen itself. For bigger jobs, a high-temperature hot glue gun can be used to dispense PLA instead.

Tiny Drones Navigate Like Real Bugs

November 6, 2019 by Danie Conradie 14 Comments

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” →

Flying Batteries For Drones

October 12, 2019 by Al Williams 22 Comments

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.

Continue reading “Flying Batteries For Drones” →

The UK Drone Community Fights Back, Gains FOI Admission Of No Tangible Drone Evidence

June 4, 2019 by Jenny List 33 Comments

Regular Hackaday readers will have noted a succession of stories following the reports of drones in the air over British airports and in proximity to aircraft. We’ve consistently asked for a better quality of investigation and reporting into these cases, because so far the absence of reported tangible evidence of a drone being present casts doubt on the validity of the official reaction. For too long the official records of air proximity incidents have relied upon a shockingly low standard of proof when apportioning blame to drone operators, and this situation has contributed to something of a panic over the issue.

It seems that some members of the British drone flying community are on the case though. Airprox Reality Check are a group analysing air proximity reports and linking them to contemporary ADS-B and weather records to identify possible explanations. They have devised a rating system based upon a number of different metrics in an attempt to quantify the reliability of a particular report, and they are tabulating their analysis of air proximity reports on a month by month basis. This includes among many analyses such gems as Airprox Report #2019046, in which an Embraer 170 flying at 9000 feet and 20 km offshore reported a drone in close proximity. The Airprox Reality Check analysis points out that no known drone could manage that feat, and refers to a passing Boeing 737 revealed through ADS-B data as a more likely culprit.

Their latest news is that they have made a Freedom of Information request to the Air Proximity Board, asking for what evidence the Board has of a drone having been involved in any of the over 350 incidents in UK airspace having been reported as involving drones. The official response contains the following quote:

in all cases UKAB has no confirmation that a drone has flown close to an aircraft other than the report made by the pilot(s). Similarly, other than from the report of the pilot(s), UKAB has no confirmation that a drone was involved.

This confirms the view of the multirotor and drone community that has been reported by Hackaday in the past, that the whole British drone panic has been based upon unreliable and uncorroborated reports from eyewitnesses with little direct experience of multirotors. If any irresponsible drone operator is flying into close proximity with aircraft or otherwise into protected airspace then it goes without saying that they should be prosecuted, yet it seems that the community is being punished as though this had happened when the reality is that no such acts are proven to have occurred.