Discussion Mikrokopter / UAVP / quadrocopter / quadrotor build

[Arthur P.]

Come now. Swedish is more difficult

The only site offering fully populated MK boards is www.quattrocopter.com but currently on hold until software (and hardware) is updated including I think for the upgraded ESCs. But you could contact Frank to see if and when he expects to have boards ready again.

Actually soldering those 1-3mm large surface mount resistors really isn't that hard once you've got accustomed to them. I found the ICs tricker but even those are not really difficult if you have the right materials on hand.

Depending upon how nice you wan to make it, the frame may be more work. Been experimening a bit with plywood for the motormounts this evening. Have decided how I-m going to do those so that they are minimum work and still efficient and aestetically OK. Will also do the central hub this weekend and progress the TowerPro ESC. I do have to fess up that I have also ordered the upgraded FETs and already have the small parts for 4 upgraded Holger ESCs so that one of the two MKs will probably fly with those once the PCBs are available again (and probably TowerPro originated A20-20L motors). I also have the small parts for the 2nd MK PCB (the partially assembled one). So lots to do this weekend....

[airfoto.se]

How about the manuals, i noticed that that they are only avalible in german, that makes it kind of hard for us non german speaking, or have you seen translations?

How much weight do you think that your mk can carry with thoose Tower pro motors?

Swedish and german have some word that are close, so some understanding can be done

[Pigs dont fly]

Look at the MikroKopter 'Wiki' using Google translate Hit translate on the MK site then go to the Wiki..


http://www.mikrokopter.de/


Most of it is in there, also check out the thread on ApLanding.com
http://aplanding.com/smf/index.php/topic,470.0.html

Hope this helps a little.

[airfoto.se]

I never looked at the wiki, translated to eng and i found a lot of interesting reading


thanks

[waterzak]

@Arthur

Hi,

I finally got my MK working again after the crash in Cologne.
1st I had to wait for a new Roxxy motor (never ever buy them again )
Then I had some trouble building a new frame, which, by the way can be fold in! (sort of... ) And last week I ran out of spare FET's.
I will try to post some pictures of my latest MK in a few days.

What do you think of the motormounts that Quattrocopter.com is offering?
If You or some other dutchie orders parts from quattrocopter, I like to participate!


Jacques

[Arthur P.]

Hi Jaques,

Very interested to see your folding solution. Build myself a testframe yesterday from light-ply from the DIY store. It's a bit too heavy without any lightening areas, but is close to where I see the first version going. I-ll post some pics later. But short description:
- Central part is a 10cm radius half-ball with
== A bottom section which is 4cm high and allows 1 or 2 batteries of up to 3S 5000mAh to be inserted comfortably. Space on both sides next to the battery for the main power connection.
== A top part which is anther 4.5cm high and has an open area between the 7-8 vertical formers of about 10.5x10.5cm. This of course very easilly takes the MK control board but will also allow a 10x10cm experiment board with the Q4Arm7 controler when that is ready for testing. GPS, compass and RX fit partially in the open area, partialy between the vertical formers.
== has a 1cm high bottom most layer with 4 slots for the arms.
- 25cm long arms of 10x10mm aluminum with an 8mm carbon rod glued in with gorilla glue. Haven't finished a locking mechanism yet. But most likely I-ll go for some click-lock mechanism.
- tear-shaped motormounts made of 3mm model-building plywood mounted to the end of the arms with 3 small bolts and predrilled so that the TowerPro A20-22L motors can be mounted above or below the mount to use the normal axle with prop saver or the rear prop mount. I had also looked at the plastic mounts you mention (also available from Unitedhobbies, by the way) and at aluminum stick mounts. But all would require a 90degree stick mount at the end of the arms. This is simpler at less than 10grams per mount, and should allow for a breaking point on too fast landings which may help prevent damage to arms and frame. In addition they can be home-made, don't require any significant space in the field box, and can be replaced very quickly at the field.

Total axis end to end is 60cm as the ply plates prolong the arms a bit and they are 3cm apart in the central hub. This allows for prop sizes of up to 12 inches with enought room to spare. Removing the arms will require loosening the powerlines, ESC control line and LED power lines. But this will only be needed to take the machine along in a small case on foreign trips. For normal transport in a car there should be no need to disassemble. Despite the rather large central part this would still result in the smallest package for travelling. Foldable arms with the 20cm diameter central part would require a thicker case for transport.

The 20cm diameter is dictated by the battery size which is dictated by the consideration to eventually move up to up to 12x6 props and heavier motors. In fact the 3s 3650mAh (approx 300grams) batteries as advised for the UAVP, are just marginally shorter, a bit thinner than the 5000mAhs (approx450grams). With the current battery area I could go as far as 10000 mAh although that would result in a 900gram battery load.... but an RTF weight of about 2kg max for the heavy motor version (aiming at 1.2-1.5kg max for the A20-22L version) which would be about 1.5kg less then a Logo 14. Wonder what flighttimes that will end me up with.... Looking at data for amp draws of the different MK's for 'hover" they seem to be around 1A per 100gram weight. So 2kg should be about 20A which, if I-m right, would be 10-15min on a small battery, more than 40min on the 2x 5000mAh.... Might be a bit too optimistic, but that should allow for quite some RCAP on a charge.

Of course this all assumes I can keep the camera carrier weight low enough to have a payload of about 500g including the cam carrier. Will be prototyping that today / tomorrow. And I also still have to create a landing gear. Most likely will keep that simple with 4 legs pointing down and out, possibly using some lightweight model car shock absobers (14g a piece), or just some silicone tubing, to cushion landings a bit.

Landing gear and camera carrier will also have to be easy to disassemble for transport.

[Arthur P.]

A very productive day today. Started working on an updated circuit, as proposed my Mr Cam-Man, to reconstitute a proper PPM signal off of the AR7000. Managed to get 8 diodes, a 16pin DIL chip, 3 condensators, several resistors, and 13 wire connectors all wired up to a 3.5x3cm piece of prototyping board. Not bad imho. Sadly however first tests showed a flatliner at 5V :=( But just now I followed further advice of Mr Cam-Man to power the circuit with 3V and indeed that showed improvement. Still not fully there as the rudder channel (7) is still missing, but another little step in the right direction.

Put together the 2nd mikrokopter controler, this time using a partially assembled board (CPU, linear accel sensor, opamp and a small number of small parts pre-installed, and software already writen to CPU). That worked like a charm. Also immediately introduced two changes. I mounted both the buzzer and the jaw gyro topside. That reduces the bottom clearance needs very significantly. But it does require that the buzzer legs be kept as long as possible --and make sure the resistors and caps below it are properly installed before installing the buzzer--, and the wiring for the gyro is a bit more difficult as it is a bit reversed. For fixing the gyro to the PCM I used some double sided tape, for fear of the epoxy used on the previous build maybe playing a role in the failure of that gyro. Seems to be sufficiently fixated this way. Needed two resistors to get the amplificcation correct. But this one was 100% up and running on the first powerup

After that I moved the beeper on the first controler board topside as well and replaced the jaw gyro. On powerup this MK nr 1 also was now fully operational

After that I decided to also wire up the two compasses which meant first removing the row of preinstalled prints. While looking at this it surprised me that the MK is using the PWM output of the compass --which only counts 357 degrees0-- and not the I2C output. Decided to be future-proof and wire it up to provide both the I2C channels and the PWM channel. In both cases perfect operation straight off (although I didn't really check whether North is truly North).

After all of this some cleaning of the working area was in order and no time for further work on the frame or the ESCs....

Some pics:

[Yimmy]

Keep up the good work arthur! This build is fascinating.

[Hogster]

Fascinating work Arthur I'm very much enjoying this thread and seeing your progress


David

[Arthur P.]

One more little step.... As suggested by Mr Cam Man I corrected an error in the original schematic and pulled pin 11 up to 5V. Still no 7th channel, but pin 5 does show a very narrow positive pulse where the end pulse of the 7th channel should be. So we're 99% there

[Pigs dont fly]

Wow you've put a ton of effort into getting 2.4ghz to work Arthur, well done!

I have not looked into the Rx breakout as of yet, as I've spent most of my time messing around with my sick Atmega644, and sorting out the FET's for the uprated ESC's> How do the extra channels for cam control breakout? Does it have to all go through the MK control board, or can you use any or the original RX connections?

Keep up the great work
Ian

Ps If you go the whole hog and get a PCB etched, any chance of selling a few ?

[Arthur P.]

Actually with this setup I expect to have both options (directly from Rx or through the MK controler).

Going to try the changed solution Mr.Cam man just advised to the above diagram later this evening:
* Pin 1 to GND,
* Pin 5 through a diode back into the collected PWM inputs to Pin 2.

To me being able to use the 2.4GHz system for main control is really important. I wouldn't mind a 2nd compact FM based Tx and Rx for camera control if need be. But the aircraft control really has to have the lowest possible chance of interference as I tend to fly in the bussies part of the Netherlands in the wierdest places. When flying with FM I tended to often have short hits in some locations, and once had some very serious interference with a lucky good ending. That was with an EasyStar which crashed a foamy wing into a car at full throttle. It was my own car, no damage other than wing torn apart (easlly repaired). But really don't want to repeat anything like that with a MK. That would definitly cause a significant dent.... I-ll even accept no or low quality image downlink to stick with the 2.4Ghz system.

[jesolins]

Great work Arthur on both the frame and the 2.4 solution! You said 330g is too much weight. What target weight are you trying to achieve? Have you considered DIY CF?
Cheers,
Jim

[Arthur P.]

One more step: the amended circuit provides a nice 7 channel PPM signal. And the MK controler sees that signal and properly recognizes the different channels Great thanks to Mr.Cam-Man !!!

Still not completely out of the woods. The center point is about 22 points off, the range of all controls going from approx. -97 to +145. But most likely that can be corrected by some parameters at the side of the MK controler or trimming at the side of the TX. However that will have to wait for a bit as I-m off for a couple of days of leave...

Target weight.... Most standard MKs seem to have RTF weights of 600-800 grams with 3S 2100-2500mAh batteries. The heavier ones range from about 1100 tot 1500 grams with 3S 3650mAh batteries. I would hope to stay in that range with:
* Battery 3S 5000mAh 410g
* Panasonic camera 265g
* Motors 4x 60 to 90g 350g
* Aluminium arms + mounts 4x 44g 180g
== Subtotal approx. 1200g

So hub, controler, landing gear and camera carrier have about 300g to share among them if aiming for 1500g max.

Of course with the heavier motors and 5A battery I could probably go to 12x6 props and allow the weight to kreep up to about 2kg RTF on this battery. But with the current motors I may choose to go for the lighter camera (Casio 180g vs Panasonic 280g) and 3650mAh 3S battery (approx. 300g), which wins me 200g for hub, cam carrier and LG.

I may eventually go for carbon, but for now the aluminium and multiplex will have to do for reasons of cost. Look on the bright side. Once the design has proven itsself in heavy materials, think of the weight savings on then going for carbon

[waterzak]

Arthur,

Wow, you are realy building an impresive MikroKopter. Good work! 1st time right I guess!?
As promised here are some pictures of my MK. Considering myselve still as a beginner, but I'm having lots of fun flying my own Mikrokopter.

Lets start with my plans:


The smaller board with the 2 black patterns is the top mounting PCB for distributing power to the regulators.

After removing 2 screws of the left and right arm + unscrewing 2 triangle brackets you can fold-in the frame. Only the left and right arm need to be folded in.



My actual MK:


a closeup:


Frame fold-in:


Regarding the motor mounts:
During a crash it is most likely that one of the arms is hitting the ground first. Are you not worried that your type of mount will tear or damage the motor?
The next picture shows the dirt after an crash. But the motor survived the impact.



1st I have to improve my skills of flying and then start to improve the MK.

Good luck with your Mikrokopter!


Jacques