So I had a brainwave the past two days in how to test various aspects of the autopilot modes without having to land and flash new software. It became very frustrating that for each morning, I had to land the aircraft 5-6 times and increase the risks crashing and even worse loosing the instrumentation on board the glider. This approach could potentially allow me to analyze various options of flight modes and optimize which one best suited for that function. The ultimate goal is of course, the speed at which each flight modes can tested. So I manage to devise a method that allows me to use a switching mechanism such that I can switch between each programmed flight modes by using transmitter only. The code was tested and seems to work just fine. Now it's just a matter of testing in flight.

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Due to the past 2-3 months of bad rainy weather and gusty winds, I've decided that it was time that I invested in a tool that will be able to give me preliminary understanding the flight control is a scientific way . That means I will have to acquire a mathematical model of the airframe and use the current hardware to form a In-The-Loop Simulation (HILS). My approach for this will be to use DATCOM to derive aerodynamics parameters then coding the equations in C. This will then be flashed unto a separate Atmega microcontroller and will talk to the the rest of the hardware via the serial interface . The accelerometers and gyroscope values (superimposed with errors and biases) will be then form part of the output from the airframe model which in turn will exercise the flight controller and mission controller. What's not sure yet is how to test completely the waypoint tracking algorithm without using the GPS hardware. One way was to have a simulated GPS module as part of t...

This one is going to be quite short. Yesterday was the turn of the heading error algorithm to be tested. This heading error is calculated based on the heading the between two waypoints and heading measurement from the GPS module. This error will then be fed into a the roll controller as an input for roll command to reduce it to zero. But for the roll controller to work accordingly, the input must be right and within certain bounds. Same as the previous ground test, waypoints were loaded unto the autopilot and serial debug data was monitored using my Asus TF101 Tablet. It's worth saying that I managed to get serial data output straight from the LINUX command line . So the command line integration with VIM is complete. So it takes approximately under 10sec to upload and start debugging data of the autopilot. Sweet! Anyway, it was found that the GPS accuracy should be considered at 10-12m. Anything less than that and you'll be running for trouble. That is not a real conc...

So after a period of absence of over a month (feel depressed everytime I say it), I got back into the groove of things. Decided not to wait to get back on the field to test the pitch and roll autopilot and decided to start working on the waypoint tracking algorithm . The advantage of having your own home with a garden is that you no longer struggle to get a GPS lock (There's no more concrete flats surrounding us yeah!!!). So got familiar with my gear again. Also decided to buy a piezo buzzer that could be used as a replacement of the serial monitor. The aim was to increase the intensity of sound as you got closer to the next waypoint. In such a way you will know if you're going the correct way. Decided to use GPS Visualizer to get waypoints on the property. Re-formatted the points into the code uploaded it onto the controller. It must add that I managed to successfully run arduino from the linux command line and use the program screen as a serial monitor. Not only is it m...

deadband diagram (Photo credit: Wikipedia ) Managed to squeeze another flight test on Sunday morning (the usual madness occurred afterwards). Had about 7 - 8 hand launches to test the pitch autopilot with the gyro measurements integrated in the PID loop . It was quite that some adjustment to the how these inputs are being used was needed. So after each landing, adjustment to the gains was made. The erratic nature of the control requires a deadband filter approach which would enable the airframe to settle on a particular flight path naturally (restoring motion). A crude logic was implemented and tested and seemed to work although further test will need to confirm such approach. From a kinematics point of view, it makes sense and prevents excessive servo control usage which decreases the life of the part dramatically. Once confirmation that the logic is sound, the same approach will be made on the roll and speed autopilots which will allow us in the next 2-3 weeks move towards...

We've been having quite bad (windy) weather that It has been almost impossible to get the glider up in the air to gather more flight data . But nonetheless, I managed to analyse the data that I have come to some interesting conclusion on the behaviour of the aircraft in flight. The post-filtering of the IMU euler angles prior to controller design only add approximately 4/10th of the second in lag (guestimate). The servo limiter which I set on all channels is which what a normal flight actuation is experienced (considering wind factors). It's quite clear from the graphs that GPS velocity is expected to change with aircraft pitch although the nature of the sensitivity over a 1Hz update was not expected. The noise factor in launch in both roll and pitch channels shows that an alternative method needs to be established for a take-off and landing autopilot mode. There seems to be a considerable lag in pitch servo input and pitch change. This makes sense for the fact that t...

So I got some flight time under my belt yesterday. I must say there's nothing better than seeing your flying skills improve with time ( I can't wait to get more batteries so I can get my heli in the air as well). Anyway, back to the glider autopilot . Managed to get the roll autopilot to stabilize the aircraft which was a great feat. Although because the glider is inherently unstable during banking (due to the battery pack sitting on top of the wing) the roll autopilot relies heavily in controlling the rates produced by the aircraft. This is still a problem as roll rate doesn't yet have a strong influence in the control loop . The same can be said about the pitch controller (which I had to land the aircraft, upload new code and launch again). Due to the lack of control on the pitch rate, the phugoid mode of the aircraft is activated and the aircraft goes into an unstable dives which eventually would cause a crash. The use of the safety switch mechanism logic has ...

Depicts a traditional PID controller. (Photo credit: Wikipedia ) I'm such an exciting right now. It's been over a year of putting this UAV glider with custom autopilot and electronics together and now we're at the pivotal stage. In-flight testing of autopilot and GPS waypoint tracking!! Decided to go for a flight test on Sunday morning before church (around 7am) eventhough I was performing the church band that morning (crazy I know). It was bitter cold but decided to push through. I must say that I realised that I need a small collapse table/stool to setup the instruments instead of the wet/moist ground. I was great to see that the transmitter code works as expected. There was no lag in the transmission of signals from transmitter -> autopilot -> servos. The turning of aircraft with rudder and elevator control was smooth and consistent. It was refreshing to see that the filtering algorithm worked well. Decided to test the roll autopilot first, this...

An aircraft separation incident between an unmanned aerial vehicle and crop duster highlights the challenges with having a diverse mix of aircraft operating in the same airspace. On 12 September 2013 the pilot of an Ayres S2R commenced aerial agricultural spraying operations on a property near Horsham, Victoria. At about the same time, the operator of a UAV, Sensefly eBee 178, arrived at ‘Iluka Echo’ (Echo) mine site to conduct an aerial photography survey of the site. After completing his pre-flight preparation and risk assessment of the operation, the operator heard an aircraft operating about 1 – 1.5 km away on a neighbouring property.

If you want to use my graphic outside Wikipedia, and its resolution or license doesn't satisfy you, write to me: 100px (Photo credit: Wikipedia ) The radian glider took a real beating at the last crash. Although it had a 'soft' landing eventually, going through the trees was not pleasant the foamy airframe . since it wasn't covered, indentations can be seen all over the aircraft.

The Dx4e transmitter (currently that's what I'm using) creates alot of noise when used with arduino. It's quite clear that the receiver has a tuned low pass filter that needed to be emulated for the code. A low pass filter was implemented with a stategy of using a the gradient of 3 values to determine whether allow input to the servo signal stream or not. Here's the pseudo code below:

Although it was a bittersweet moment when the Radian glider took off (my own airframe had a disastrous crash), it felt really good seeing that glider gracefully fly through the skies. After the repairs I had to make on it, I realise that motor has a pitch up moment on the airframe causing the glider to quickly gain altitude but loosing forward speed. That will have to be remedied.

FAA can't regulate small RC aircraft as "drones," judge rules NTSB judge strikes down $10,000 fine against man for unlicensed "commercial use." Raphael Pirker prepares to launch his " FPV " remote controlled plane in New York City in a video he posted in 2010. http://vimeo.com/17351140 In 2011, Raphael Pirker used a RiteWing Zephyr II  remote-controlled flying wing to record aerial video of a hospital campus for use in a television advertisement. That act resulted in the Federal Aviation Administration issuing a fine to Pirker of $10,000 for that commercial use of an unmanned aircraft. But now an administrative judge with the National Transportation Safety Board has struck down that fine , contending that FAA regulations can't be applied to the styrofoam drone Pirker flew.

Shinden by Bryan Hebert (Photo credit: Wikipedia ) Hi all, I came across this spreadsheet containing rough estimates of common building materials used for scratchbuild of RC airplanes . Use it, don't use it. Here it is. What it doesn't have, is a updated list on LIPO batteries and common brushless motors but besides that it's pretty decent. Enjoy! Click the link below: https://docs.google.com/viewer?url=http%3A%2F%2Fwww.flyelectric.ukgateway.net%2Fweights.xls

I Although I now have a Radian glider. It's quite difficult to find open places where you're able to practice your flying. So i decided to design a new airframe that will be able to keep my flight hours up without having to travel far. The aim was to make a cheap. light and yet strong powered plane that, if needed, would be able to carry the autopilot board. The airframe was made of foam core , 160gsm board paper, packaging tape and dowel sticks.

The inevitable had to come... Introducing the Radian Glider. This will be used as the ultimate airframe to put my autopilot to the test... But for now, I will have to get my flight skills up with a self made trainer ( with foldable prop). I will have to make use of a public park for now until I'm ready to join a flying club. Let the games begin!