Extrinsic Motivation: Smart Antenna Tracker for R/C Aircraft

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Long distance FPV (First Person View) flying can be a handful. Keeping a video feed alive generally requires a high gain directional antenna. Going directional creates the chore of keeping the antenna pointed at the aircraft. [Brandon's] smart antenna tracker is designed to do all that automatically. What witchcraft is this, you ask? The answer is actually quite simple: Telemetry! Many flight control systems have an optional telemetry transmitter. [Brandon] is using the 3DRobotics APM or PixHawk systems, which use 3DR’s 915 MHz radios.

The airborne radio sends telemetry data, including aircraft latitude and longitude down to a ground station. Equipped with a receiver for this data and a GPS of its own, the smart antenna tracker knows the exact position, heading and velocity of the aircraft. Using a pan and tilt mount, the smart antenna tracker can then point the antenna directly at the airborne system. Since the FPV antenna is co-located on the pan tilt mount, it will also point at the aircraft and maintain a good video link.

One of the gotchas with a system like this is dealing with an aircraft that is flying directly overhead. The plane or rotorcraft can fly by faster than the antenna system can move. There are a few commercial systems out there that handle this by switching to a lower gain omnidirectional whip antenna when the aircraft is close in. This would be a great addition to [Brandon's] design.

Droning On: Maiden Flights

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When we last left off, the Hackaday Drone Testbed was just a box of parts on workbench. Things have changed quite a bit since then! Let’s get straight to the build.

With the arms built and the speed controls soldered up, it was simply a matter of bolting the frame itself together. The HobbyKing frame is designed to fold, with nylon washers sliding on the fiberglass sheets. I don’t really need the folding feature, so I locked down the nylock nuts and they’ve stayed that way ever since. With the arms mounted, it was finally starting to look like a quadcopter.

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Using the correct screws, the motors easily screwed into the frames. I did have to do a bit of filing on each motor plate to get the motor’s screw pattern to fit. The speed controls didn’t have a specific mount, so I attached them to the sides of the arms with double-sided tape and used some zip ties to ensure nothing moved. In hindsight I should have mounted them on the top of the arms, as I’m planning to put LED light strips on the outside of edges of the quad. The LEDs will help with orientation and ensure a few UFO sightings during night flights.

Power distribution is a major issue with multicopters. Somehow you have to get the main battery power out to four speed controls, a flight controller, a voltage regulator, and any accessories. There are PCBs for this, which have worked for me in the past. For the Hackaday Testbed, I decided to go with a wiring harness. The harness really turned out to be more trouble than it was worth. I had to strip down the wires at the solder joint to add connections for the voltage regulator. The entire harness was a bit longer than necessary. There is plenty of room for the excess wire between the main body plates of the quad, but all that copper is excess weight the ‘bench’ doesn’t need to be carrying. The setup does work though. If I need to shed a bit of weight, I’ll switch over to a PCB.

Click past the break to read the rest of the story.

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R/C Plane Flies with a Cockpit View

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That’s not a jet jockey making a low altitude turn up there. In fact, the pilot has his feet planted firmly on the ground. [Reliku] has built a radio controlled BAE Hawk which is flown via First Person View (FPV). FPV models often have a small camera mounted on the exterior of the craft. This camera gives a great field of view, but it isn’t exactly how full scale planes are flown.

[Reliku] took it to the next level by creating a scale cockpit for his plane. The cockpit is accurate to the real BAE Hawk T2, and features back lit simulated screens. Even the pilot got the FPV treatment. Micro servos move the pilot’s right hand in response to aileron and elevator inputs from the radio control system. The pilot’s head has been replaced with the FPV camera, which is mounted on a pan tilt unit. Pan and tilt are controlled by a head tracking system attached to [Reliku's] video goggles. The entire experience is very immersive.

All this is built into a Hobbyking BAE Hawk Electric Ducted Fan (EDF) model, so space is at a premium. Even with the Hawk’s relatively large cockpit, [Reliku] found he was tight on space. While attempting to keep the cockpit scale from the pilot’s view, he found he was barely able to fit a single seat cockpit into a space designed for two! Adding all these modifications to a plane and still keeping the model flyable was not easy, as displayed by [Reliku's] earlier attempt with an F-16.

The ends do justify the means though, as the final model looks great. We’d love to see those static cockpit displays replaced with small LCD or OLED panels for an even more realistic experience!

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Quadruped Robot Thinks it’s a Puppy

puppybotBack at New York MakerFaire 2012, we noticed an amazing little steampunk quadruped robot walking around in the crowd outdoors. The robot was amazingly well executed, and had a unique ability to draw children over with it’s puppy like animations. It turns out this is [Drew’s] Little Walking Robot (AKA Puppy Bot).

Puppy Bot has actually been around for quite a while. He was born from the spare parts [Drew] had left over after competing in Robot Wars and Battlebots. The robots in these competitions were often controlled by Radio Control plane or car transmitters. Most of these systems are sold as packs for an RC car or plane. In addition to the transmitter and receiver, the pack usually included a battery and 3 or 4 servos. Standard RC servos were much too weak for use in battle robots, so they remained in his parts box.

On what [Drew] calls a slow weekend, he started putting the servos together, and ended up with a basic robot that could crawl around the room. After that the robot took on a life of its own. [Drew] improved the battery system, and added a microcontroller to automate the various gaits and animations. He brought the robot along with him to one of his battlebot competitions, and it took home the “Coolest Robot” award – even though it wasn’t actually competing!

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Hackaday Links: August 15, 2012

An Octopart for RC equipment

When [Zach] started building a quadcopter he found it very difficult to source the required parts. Thus was born CompareRC, an aggregation of several online RC retailers. There’s over 150,000 parts in the database, all searchable and sortable by lowest price.

Segway iPad Skype teleconferencing robot

It’ll be a while until robots completely eliminate the need for any human interaction, but until then there’s Double. It’s a two-wheeled balancing robot with an iPad dock, controllable via a remote iPad.

Free electronic design

In case you weren’t aware, Fedora has an electronic design distro that includes just about everything needed to build electronic circuits called Fedora Electronic Lab. FEL has PCB designers, circuit simulators, editors for just about everything, and support for PICs, AVRs, and 8051 micros. Thanks for sending this in, [Simon].

Make your own Megadrive ROMs

Last month, [Lee] sent in a build where he connected an Arduino Mega to an old Sega Genesis/Megadrive cartridge. He’s figured out how to read the contents of the cartridge now, allowing you to preserve your 100% complete Sonic & Knuckles / Sonic 3 save for time immemorial.

A surprising amount of graphics tutorials

Khan Academy, every autodidacts best friend, is now teaching computer science. Right now, there is a heavy focus on drawing graphics, and everything is coded in the browser (using Javascript…), but at least it’s a start. The fundamentals of programming are platform and language agnostic, so this looks to be a great way to learn programming.

Here’s a blog post from the lead dev of the Khan CS project.

Home automation with RC wall plugs and Raspberry Pi

[Jake] took some cheap hardware and figured out a way to use it as a huge home automation network. He’s chose a Raspberry Pi board to connect the radio controlled power outlets to his network. He wrote about his project in two parts, the first is hacking the RC outlet controller and the second is using the Raspberry Pi to manipulate it.

These RC outlets are a pass-through for appliances that connect to mains (lamps, consumer electronics, christmas trees, etc). Often the protocol used by the cheap-as-dirt remote is difficult to work with, but [Jake] really hit it out of the part on this one. In addition to simulating button presses for up to fifteen devices on the remote, he replaced the DIP switch package. This lets him change the encoding, essentially allowing the one device to control up to 32 sets of outlets. Theoretically this lets him command 480 devices from the Raspberry Pi. Since that board is a web server it’s just a matter of coding an interface.

Some of the inspiration for this hack came from the whistle-controlled appliance hack.

7 foot long flying dragon breathes fire

What do you have to do to win best of show at an R/C event in Toledo? Build a 7 foot long fire breathing radio controlled dragon of course! [Rick Hamel] stuffed his electronics, a turbine engine, a kerosene tank, and a stun gun into a home built body shaped like a dragon. You can see a few construction pics that show how he is able to steer. It looks like it flies just like any r/c airplane. This one, however could burn down a village and keep going. Check out the videos after the break to see it flying and testing out its fire breathing mechanism.

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