CoolLCD products

Since my Zaganu project is already operational I am now looking at the photo side of the project. As I've said in the first post about Zaganu, I intend using this behemoth in aerial photography, and in order to do that I need of course to attach a digital camera to it, and also video a camera with live feed would help. The video camera's purpose is to get a better idea of how the machine is oriented during flight or hover relative to the subject that we want to picture.
 I got the video camera and AV transmitter from HobbyKing and I think it was quite a bargain at a little over 50$. The missing link in this chain was a portable monitor on which to view the live feed. In RC business they usually use video goggles for FPV (First Person View) experiences but this didn't suit my needs and that's partly because I also wanted this monitor for something else. I wanted to use it as a "director's screen" on my DSLR when it comes to shooting video.
 This portable monitor market is quite big and diverse now and it's not so easy to make up your mind. But since I wanted to go cheap on this one and avoid having to spend around 500$ for the monitor alone, I turned my attention to CoolLCD. I found them by google and at first I thought it must be a prank or something. Two weeks after and a lot of googling, my order was on the way.
 I knew it's not going to be high end quality or top features and I was quite afraid of the worse but boy was I wrong. All those good comments from their site weren't for nothing. From start I must say their before-order support is great and the time of delivery unbelievable.

I just got the chance to unwrap the products (as I bought quite a few stuff) and do a video while doing it. More infos will come later as I'll play with them and put them to work.

Till then, here it is:

Zăganu - 04 Trial times

Since spring time is here and I start to become to anxious about it, I decided to take a short cut and by-pass my DIY controller for a while and use the original arduino version. So I got an arduino nano from farnell and start putting it all together. The arduino board was pretty straight forward to connect and program. I used the latest MultiWii version (1_preter7) and carried on with further configs through the USB port and the GUI software.

Almost ready to fly

I'm not so sure about the center plate design so I improvised a lot, using cable ties and duct tape here and there. I didn't want to let everything loose from the start so based on an idea I found on rcgroups.com, I build something like a test bench. It helps with keeping it on the ground while allowing it some degree of free movement.

 



 First try was quite scary because the sensors weren't aligned with the motors and the tunning loop got crazy. Rest of the tries weren't that scary but not successful either. Using the GUI I can see the accelerometers getting correct readings, even though they turn quite noisy once the motors start to spin, the gyro signals are sadly confusing. The magnitude on Y axis is roughly twice as low as on the X axis for the same amount of movement, if judging from the plot even though the numbers seem to match if monitored on the digital read out. Didn't figure out yet if it's a plot issue or a real sensor issue. Also have some troubles  understanding the logic behind the trimming procedure or the software functionality but that can be solved with some reverse engineering on the code.

Hope to get an actual flight till next post but until then, the work must go on

Zăganu - 03 Still alive

Finally back from abroad. Good news is that the project is still alive, during those long cold Russian winter nights I had plenty of time to dive deep into the software side of things. Because it passed some time since I last worked with embedded devices, it took me a little to get back in shape and get familiar with TI's platform. I got a hold of CCS and the Luminary Micro platform which even though is way over the needs of the project is definitely lots of fun to play with.

Starting from the info's from starlino.com I got up and running a 6 DOF IMU. It still needs some tunning but all looks good so far.

I also did some rethinking of the hardware and replaced the FR4 center plate with a 2mm thick 160x160 aluminum plate which is lot easier but stiffer. For now i gave up on the octo configuration since I'm still far away from that point so the center plate is square as I've said and the arms got closer together to shrink things a little.

Got to do some power tests and at full throttle with the frame "bolted down" I only got 8A per motor which was enough to give the frame lift off capability but only half of what the motors can put out so I'm considering bigger props.

Zăganu - 02 Somewhere in between

OK, so most of the materials arrived, I'm almost done with the mechanics but way behind with the software and worst of all I'll have to stop for a couple of weeks because a long mountain trip and a longer foreign trip are coming next. But till then, let me put it down with the progress so far.

 You have in the picture above a view over the base plate and an equipped arm. The plate is 2mm thick FR-4 at a hefty 360gr but I plan to loose some weight by drilling some holes between the arms. As you can see it's octo shaped for the final idea but for now only four arms will be on for easier (and cheaper) operation.

 The arms came out at around 40cm long. Since all I could find locally were 9'' GWS tri-blades I chose to mount them closer to the center plate. This gives a welcomed protection to the propellers on forced landing and I guess it also helps with the dynamics of motion a little. The motors are labeled BL FC2835-10T at 830Kv and at aprox 10V they gave around 120W of power. Too bad I couldn't measure the actual thrust as I fear it might not be enough for the total weight but I'll work on that once I'll be back.

 ESC's are HobbyKing's BlueSeries 30 amps model. I am quite amazed with the quality of these little things and I'm talking here about all the electronics involved in the RC business. It's true I can't do any comparison since I'm a newb in the field.

 Together with the essential  parts for the build I also ordered lots of extra gadgets, to many actually if I think back about it. Well, anyway.. time is short and I'll have to talk some other time about them. I'm still missing the batteries and the charger for them but that's the thing I'll take care first once I'm back at work.

This is what's left from a Wii Motion Plus and a Nunchuk after I hacked them. I can't find any possible use for the joystick and the two buttons but I didn't have the heart to cut them off either.. u never know when they might come in handy. The sensors do their job as expected, communication is working alright but I'm having tons of problems with the MCU and it's IDE. No matter how hard I try to blame myself for all the problems I encounter it keeps pointing out that there's something fishy out there and I can only assume it's because of an early silicon revision of the chip but I didn't have time to dig into it too deep. All in all I hope I'll get over it because I'm eager to get things moving sooner, especially now that good weather's coming up.

That's about it for now, have to run finish my pack and get some sleep also..

Zăganu - 01 Introduction

OK, so after some words in the previous post about all this project wants to be it's time to get into the serious stuff. There are so many things into such a major project that it's hard to put things in order. Spent my last two weeks just surfing the net and trying to assimilate as much info in the field as I could since I'm a newb in all this RC hobby.

Except the documenting phase there's also a lot of acquisitions needed, from the Tx/Rx system, batteries, motors, ESCs, BECs, frame and so on. From all these I'm sure about this:

• I'll make the frame DIY style, using 10x12x1 rectangular aluminum hollow tube for the motor arms and carbon fiber or FR-4 plate for the center part
• I'll go the cheap way with the motors, propellers and ESCs since they are prone to destruction during trials. I've already ordered ESCs from the giant HobbyKing, the props and motors I intend acquiring from local suppliers
• For the flight controller I took the MultiWii path with some modifications. I acquired the original Wii Motion Plus and Nunchuk controllers as to avoid any problems with the cheap replicas. I'll try implementing the actual controller on a LM3S3748 development board I already had. If that doesn't work out then I'll switch to the Arduino approach with the software already available
• for the Rx/Tx system I went for Hitec Aurora 9 which is quite a lot over average but it should make my life a lot easier with all it's bells and bells and whistles. 

 As for some quick links on the subject, here are a few that I really consider essential:

• starlino.com is a great resource on multiple electronics topics but I found it crucial for the following two posts: A Guide To using IMU and Arduino code for simplified Kalman filter
• rcgroups.com is one of the most important forums out there in the field of RC. The Multi Rotor Helis section is packed with topics about the subject
• wiibrew.org is the main place to start when it comes to dealing with Wii controllers
• There are a lot of open source projects out there dealing with multi rotor helis but the ones I found most useful, information wise, and just to name a few, are: KKmulticopter, UAVP, OpenPilot, MikroKopter

So now I've sketched the frame and it's as ready as it can be till I get the rest of the components. I've also hacked the Wii controllers and successfully communicated with them over I2C. That's about it for now, I'll come back with some pictures and details on my work in the next post.

Zăganu - the start of a dream

According to wiki, Zăganu was a species of big eagle that once lived in the mountains of Romania. But I'm not going to talk about this here. Zăganu is just a name i took and gave to my latest project and the only thing that has in common to the bird is it's the flying abilities and the big size.

So.. to cut it short and get on topic, I'm actually talking about a RC multirotor helicopter model. The idea ain't new, neither to myself as I've pondered on it for some time now, and neither to the rest of the world, since there are many projects out there on the subject. Most of them started in the RC model community but the apparent simplicity of the idea made it a wildfire through every hobbyist of one kind or another.

What really got my attention was the photographic opportunity that these machines offer. I first got the idea seeing some BTS movies somewhere on the net with video cameras mounted on RC helicopters. The problem with classic helicopters though is that they're quite exclusivistic in the sense that the hardware involved is quite complicated with lots of moving parts on one side and things that need to be fine tunned on the other, and besides all this, in order to fly a heli you do need some serious skills and practice. The quick way out of this are the multirotor helicopters where all the fancy mechanics and serious skills move to more than one rotor and some sort of controller electronic board.

Most of the multirotor designs involve tri or quad motor designs as they are somewhat simpler and cheaper to build, but when you have and expensive and hefty payload like a DSLR camera then a hex or octo design is best as it is a more stable platform. Since a DSLR is my ultimate goal for such a flying machine I choose starting with a quad design for testing and tuning of the controller and then expanding to octo for the final "product". I'll stop here for now and get back with details as the work continues.