Personal UAV’s are becoming ubiquitous these days, but there is still much room for improvement. Researchers at [Modlab] understand this, and they’ve come up with a very unique method of controlling pitch, yaw, and roll for a coaxial ‘copter using only the two drive motors.
In order to control all of these variables with only two motors, you generally need a mechanism that adjusts the pitch of the propeller blades. Usually this is done by mounting a couple of tiny servos to the ‘copter. The servos are hooked up to the propellers with mechanical linkages so the pitch of the propellers can be adjusted on the fly. This works fine but it’s costly, complicated, and adds weight to the vehicle.
[Modlab’s] system does away with the linkages and extra servos. They are able to control the pitch of their propellers using just the two drive motors. The propellers are connected to the motors using a custom 3D printed rotor hub. This hub is specifically designed to couple blade lead-and-lag oscillations to a change in blade pitch. Rather than drive the motors with a constant amount of torque, [Modlab] adds a sinusoidal component in phase with the current speed of the motor. This allows the system to adjust the pitch of the blades multiple times per rotation, even at these high speeds.
Be sure to watch the demonstration video below. Continue reading “UAV Coaxial Copter Uses Unique Drive Mechanism”
One of the major design challenges when it comes to building an efficient quadcopter is weight. The idea here is that the more you can trim down the weight of the frame, motors, and circuitry, the longer the batteries will last. Or, in [dalbyman]’s case, the more beer it can carry.
[Dalbyman]’s housemate built the actual quadcopter, but then [dalbyman] got a little inebriated and decided that, while the quadcopter was exciting on its own, it would be even better with this modification. The actual device is a modified Pringles can with two servo motors on the bottom with arms that hold the beer. A parachute is attached to the beverage can and the assembly is loaded in. With a simple press of a button, the servos turn the arms and the beer falls out of the tube. Hopefully the parachute deploys and gently (and accurately) floats the beer to the thirsty person on the ground!
This project is a simple step that goes a long way towards a beer delivery system even Amazon could be proud of, and also shows off the capabilities of quadcopters in general. Perhaps the next step could be to automate the beer delivery system!
Just a few years ago, palm sized radio controlled toys were nothing more than a dream. Today, you can find them at every mall, toy store, and hobby shop. [Alvaro] couldn’t resist the tiny Estes Proto X quadcopter. While he enjoyed flying the Proto X, he found that the tiny controller left quite a bit to be desired. Not a problem for [Alvaro], as he embarked on a project to reverse engineer the little quad.
Inside the quadcopter and its lilliputian radio, [Alvaro] found a STM8 based processor and an Amiccom A7105 2.4G FSK/GFSK Transceiver radio. The A7105 is well documented, with datasheets easily obtained on the internet. The interface between the processor and the radio chip was the perfect place to start a reverse engineering effort.
With the help of his Saleae logic analyzer, [Alvaro] was able to capture SPI data from both the quadcopter and the transmitter as the two negotiated a connection. The resulting hex files weren’t very useful, so [Alvaro] wrote a couple of Python scripts to decode the data. By operating each control during his captures, [Alvaro] was able to reverse engineer the Proto X’s control protocol. He tested this by removing the microcontroller from the remote control unit and wiring the A7105 to a STM32F4 dev board. Connecting the STM32 to his computer via USB, [Alvaro] was able to command the quad to take off. It wasn’t a very graceful flight, but it did prove that his grafted control system worked. With basic controls covered, [Alvaro] knocked up a quick user interface on his computer. He’s now able to fly the quadcopter around using keyboard and mouse. Not only did this prove the control system worked, it also showed how hard it is to fly a real aircraft (even a tiny model) with FPS controls.
The Estes Proto X is actually manufactured by Hubsan, a China based manufacturer best known for the x4 series of mini quadcopters. Since the Proto X and the x4 share the same communication protocol, [Alvaro’s] work can be applied to both. With fully computer controlled quads available for under $30 USD, we’re only a few cameras (and a heck of a lot of coding) away from cooperative drone swarms akin to those found in the University of Pennsylvania GRASP Lab.
Continue reading “Reverse Engineering the Proto X Quadcopter Radio”
[Ioannis Kedros] claims to be rather new to the game of building multi-rotor drones. You’d never know it looking at his latest creation. Yes, we’re talking about the quadcopter seen here, but it’s the core of the machine that’s so interesting. He came up with a PCB hub that allows multiple orientations to be used with the same board. These include tri-copter, and quadcopter with different strut angles for different applications.
The silk screen of the PCB has dotted lines showing the different angles possible for one pair of motor supports. One set makes a perfect “X” for traditional quadcopter flight. Another reduces the angle between front and back struts for higher-performance quad flight, while the last set is intended for a tricopter setup.
We’d recommend taking a look at [Ioannis’] project writeup whether this particular application interests you or not. His design techniques go through all possible manner of checks before placing the PCB order. There is no substitute for this process if you want to avoid getting burnt by silly mistakes.
Continue reading “Modular Multicopter Core Flies in Multiple Orientations”
Flying RC aircraft with a first person view is the latest and greatest thing in the hobby. In a fact that I’m sure will be shocking to 90% of people, you don’t need to buy a Phantom quad fly FPV. The guys at Flite Test show how you can build a tiny 5.8GHz FPV transmitter for under $100.
The parts used for this build are pretty much jelly bean parts at this point, but [Peter] at Flite Test is going for extremely lightweight parts for this build. He found an NTSC board camera that only weighs 1g and added a wide-angle lens. The transmitter is a tiny 200mW module that only weighs about 2g.
Why are the Flite Test crew going for small and light FPV setups? They just launched a new line of planes that can be built from a single piece of foam board. If you have a small micro quad, you can easily add FPV to it with this rig.
[Ioannis] is like anyone else who has a quadcopter or other drone. Eventually you want to sit in the cockpit instead of flying from the ground. This just isn’t going to happen at the hobby level anytime soon. But the next best option is well within your grasp. Why not decouple your eyes from your body by adding a first-person video to your quad?
There are really only four main components: camera, screen, and a transceiver/receiver pair to link the two. [Ioannis] has chosen the Sony Super HAD CCTV camera which provides excellent quality at the bargain basement price of just $25 dollars. A bit of patient shopping delivered a small LCD screen for just $15. The insides have plenty of room as you can see. [Ioannis] connected the screen’s native driver board up to the $55 video receiver board. To boost performance he swapped out the less-than-ideal antenna for a circular polarized antenna designed to work well with the 5.8 GHz radio equipment.
It seems that everything works like a dream. This all came in under $100 which is half of what some other systems cost without a display. Has anyone figured out a way to connect a transmitter like this to your phone for use with Google Cardboard?
Commercial R/C aircraft have been getting smaller and smaller with each passing year. In the early 2000’s, a palm-sized plane or helicopter was the dream of many an R/C enthusiast. Today, you can pick them up for around $20 USD at the local mall. The smallest models however, are still built by an elite group of modelers. Weighing in at a mere 3 grams, [Martin Newell’s] P-51D mustang model certainly puts him into that group. While the P-51’s 11.6 cm wingspan may not make it the smallest plane in the world, its many functions make it incredible.
The Mustang is an 8 channel affair, with elevator, throttle, rudder, ailerons, flaps, navigation lights, working retracts, and flashing cannon lights. That’s Wright, we did say retracts, as in retractable landing gear on a 3 gram model.
All the Mustang’s flight surfaces feature fully proportional control. However, there are no closed loop servos involved. The flight surfaces use magnetic actuators, consisting of a tiny neodymium magnet surrounded by a coil of magnet wire. We’re not sure if the signals to these actuators is straight PWM or if [Martin] is varying the frequency, but the system works. The retracts use heat-sensitive Nitinol “muscle wire” along with a bellcrank system to make sure the landing gear is up and locked after takeoff, and comes down again before a landing.
We don’t have any in-flight video of the Mustang, but we do have footage of an even smaller 1.2 gram plane [Martin] has been flying lately. Click past the break to check it out!
Continue reading “Tiny R/C P-51D Mustang Tips the Scales at 3 Grams”