Our H1 drone was finally ready to be tested with new detachable landing gear, 3-axis gimbal and the Gopro camera (powered by an extra 3S-lipo battery). The objective of the test was to test the flight modes (mainly altitude control and position control) via 3DR telemetry connection to an Android phone and the Tower app. It was quite noticeable that the quad needs alot more power to overcome in-ground effects at take-off. This is mainly due to the mass balance with the camera at the nose of the airframe. The altitude control mode worked quite well even at low elevation of 3-4 metres. Unfortunately, at low-battery voltage an automated landing doesn't occur and this resulted in hard-landing (more like a hard crash!). This piece of software will have to be investigated. The manual operation of the Gopro is a bit cumbersome. The alternative of using the WIFI link to operate the camera was investigated but was not deemed a good idea given the potential inteference...

So i took the challenge of setting up the Tarot gimbal not just for inherent stable video footage but also the flexibility of controlling it from the radio control. However, I encountered quite a few challenges which made me aware that I'm not the one only in this battle . It's quite clear that the setup of the Tarot gimbal using its own software is completely different from how it's been described in the Ardupilot/Arducopter webpage and in mission Planner. In Mission Planner and it's associated site makes one believe that it should be done through software, only to realize that in actual fact the setup is more complex than that.  After two evenings of trying various combinations, I realized the getting the pixhawk Aux channels to communicate with the T4 gimbal requires the following steps: - The Pixhawk Pin9 (Aux1) needed to be activated to pass through user-chosen channel from the transmitter. For the Dx6 Gen2 it was the channel 6, which can assigned the ...

So the notion of upgrading my already awesome (if I can say so myself) looking drone to aerial videography using a 3-axis gimbal has been bugging me for a while now. I mean, why not? At least that will get me to fly the drone alot more and use it for other purposes. The fact that I only need a gimbal and a landing gear (given that I already have the awesome Gopro hero 4 silver), should be providential enough to just spend the dollars required to make this happen. But then one get's to think, why I am doing it for? I mean does my research of intelligent flight control ACTUALLY need aerial capability? One could argue that testing your software with a drone representative of an actual commercial drone could only enhance the validation/justification of the research.  But the ultimate question is, how MUCH distraction will this capability introduce to the essence of what the doctoral research is trying to achieve? Will I gain more information given that I've got now no...

Over the course of the past 2-3 weeks I decided to take the plunge of learning a new training algorithm which had quite alot of attention in the academic community but was also well constructed for easier implementation. The work by Peng et al on developing the Continuous Forward Algorithm (CFA) was my subject of attention. The overall premise behind implementing this algorithm was to investigate less memory-intensive machine learning algorithm that will not sacrifice accuracy or robustness. The ability to have a real-time learning system for low-cost electronics (such as the Teensy 3.6 ) has huge implications for the commercialization and affordable access of intelligent drones specifically for developing and even under-developed economies. The far-reaching impact of having technology leveraging efforts of farmers, herders, game rangers, biologists is the next wave of industrialization. This is the essence of this blog. The journey is very exciting and eventual results even mo...

Another succesful 4:30 min of tail-in and side to side hover flight. Accumulated time: 21min. I found it quite difficult with wind to stay at a consistent height, I landed the heli twice and I should have made changes to the throttle/pitch curve or the mixing. It was quite challenging flight in hover in gusty conditions but I'm finding keeping the heli in the air longer much easier. Next is to slowly transition into face in and then nose in (although I feel I'm more comfortable nose-in). In the meantime, I've started working a instrumentation platform that will be integrated between the landing gear and the frame of the heli to hard gathering data. That should bring about more result-orientated fun!

The generation of embedded aero tables from an automated process which uses Digital Datcom has now been checked. The phased approach was used. The longitudinal dynamics were checked first through effectively flying the glider ballistic in the pitch only. Once expected results were achieved, an initial sideslip (over 10 deg) was introduced at the start of the simulation causing the excitation of the lateral and directional aerodynamics. The checking of these was more tricky as one needs to have a good understanding of the geometrical effects of fixed-wing airplane on its aerodynamics. Below show some plots of the angle of attack and sideslip in a disturbed ballistic trajectory whereby all channels of the aircraft are excited. Given that now we have 6DOF simulation model with a complete aerodynamic model, flight control design and introduction of actuator dynamics can now proceed.

So it turns out that I was very optimistic about just using a gain mixing of accelerometer rand gyros than computing a DCM matrix of the aircraft rotation. So I decided to overhaul the code by creating data structures that will hold the information requires for such computation. I must say that at the back of my mind I was really worried about the computational time that these calculations will take in the small Atmega328 micro. To my surprise, provided that one sticks with a minimum of division operands, float arithmetic is actually quite fast even in an 8-bit controller. Given that this application is for high L/D aircraft and who’s mission is mainly waypoint tracking, the slow changing dynamics can be reasonably captured with this environment. The bad part of the implementation was to discover how quickly the gyro drift (especially in the roll channel) hurts the computation of the Euler angles. (See the pics below), even-though all sensor are bias compensated fro...

So I decided to build a new aircraft since my 2m glider only gave me limited flying options. This is was quite a quick project as all was designed in Solid Edge including the electronics. This enabled me to work out the mass and balance throughout the design process. The total weight sits at 250g. This includes autopilot and GPS. It's designed to have external servos and a shifting wing placement since it will have various payloads like a mini VGA camera. The electronics are housed nicely in the fuselage powered by a 850mAh 7.4V battery. I've removed the redundant magnetometer in the autopilot board. Still not sure on the CG placement, but from the crashed maiden test and the fact that the control moment arm is quite small, it's believed that the C.G. needs to be further aft from the wing main spar (which currently sits on the aerodynamic center).

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...