Oguz's Shrediquette

Here is another Shrediquette, built by Oğuz. He experimented with a fixed motor and some control surfaces to enable yaw control.

Although the propellers are too heavy to allow an efficient stabilization, his tricopter seems to fly pretty good:


Tricopter test flight from Oguz on Vimeo.

Edit: Here is another outdoor video of Oguz:


Tricopter Stability from Oguz on Vimeo.

Finished I²C to PWM converter and TriGUIDE mini

The last nights were a bit shorter for me, since the PCBs I ordered at bilex-lp.com arrived. They look really good and seem to be of high quality (I ordered a different "solder resist" colour, well, I like bright colors, but anyway... ).
So I had the opportunity to do my very first SMD solderings. This really seems to be comfortable... I will completely switch to SMD I think.
The I²C to PWM converters work! Here are the features:

• Weight under 1 g
• Works with (most likely many) standard ESCs (currently tested: HK SS 18-20A, ...)
  
• I²C address selectable via solder jumpers (4 standard mikrokopter addresses dec 82, 84, 86, 88)
• Refresh rate selectable via solder jumpers (417 Hz, 292 Hz, 155 Hz, 49 Hz)
• Pulse width (I²C 0-255): 990µS - 2010µS
  
• Pulse width at startup (3 s): 920µS
  
• Motor off when no I²C connection longer than 256ms
• Motor off when microcontroller crashes (veeeery unlikely)
• Powered by the BEC of the ESC, or by an external 5V source (prepared as well)
• Very easy to connect: plug the servo cable of your ESC to the converter, connect the converter to your TriGUIDE via a two-wired I²C cable
• Does also support standard servos
  

I could test the converters today together with three unmodified Hobbyking SuperSimple 18-20A ESCs (@Dave: thank you very much!!) in flight. These ESCs work with 417Hz (probably like many other ESCs). I couldn't notice any difference in stability or noise or anything compared to my modified I²C-ESCs ("Quax" firmware) or compared to the "Holger-Regler" with my tricopter. Different refresh rates were also tried. 292Hz doesn't feel different to 417Hz; 155Hz is a bit more nervous when flying in the ground effect and doesn't "lock" that well when releasing the sticks after a fast manoeuvre. 50Hz isn't possible without changing the settings of the tricopter. The gain of the gyros has to be decreased about 50%. After adjustment, flying around is possible without problems. But the reactions are generally less precise.

Eagle schematics & layout, source code are available here:
I²C->PWM converter files (updated with jumper description)
Edit:
I could successfully test the following ESCs on the ground with 417Hz:
Turnigy Plush - 60A, Turnigy Plush - 40A, Turnigy Plush - 25A, Turnigy Plush - 10A, Turnigy Plush - 6A

Second news: My SMD version of the TriGUIDE is finished. I could also test it and it works (phew...!). I added the Eagle files to the existing Eagle zip archive. The software doesn't have to be modified. Weight is 13g.

Updated manual & tricopter firmware

Interestingly, the first thing that people try when they flashed the firmware to the Arduino, is to connect to my GUI. But the GUI would only work if receiver and sensors were connected to the board. This seemed to cause some confusion.

Tonight, I updated the firmware and the manual. Now, the connection to my GUI should even work if the receiver & transmitter isn't set up correctly. I also introduced a "special LED flashing code" that will show you if the tricopter is ready for a GUI connection (see the manual for details). It is different from the regular "in flight flashing code".

As this will probably not be the last time that I am modifying the source code, I put a text file into the zip that contains the firmware. This textfile ("_changes.txt") will track all modifications.

Most likely, I will not announce every change in the source code. Just have a look at the top right corner: Everytime I changed anything, the timestamp will be updated.

Receiver tool released etc.

I released a simple tool that allows you to check if the serial connection of TriGUIDE works, and if your receiver can be read out correctly. This tool (actually it is a firmware for the arduino) is included in the source code zip-archive (you'll still find it at the top right corner of this blog). I also put some short instructions on how to use it in the archive.

The PCBs for my I²C->PWM converter should arrive within one week. I will of course instantly test them in flight as soon as I put them together. I will post any news on this very soon. Here is a picture of the latest layout:

I also made a smaller version of the TriGUIDE controller PCB. It will arrive together with the converter PCB's. The new TriGUIDE mini will not have a MAX232 on board any more. The ISP-connector has also been removed (transferring the firmware will be done via the serial connection). The LEDs are not driven with external transistors any more, they are connected directly to the controller. Current is limited to 10-15 mA.

Eric's Shrediquette

Eric from France made a video that nicely shows the stability of Shrediquette when set up properly.
In the end he also shows a nice low-altitude 180° flip and he demonstrates that multicopters with fixed pitch can't hover in inverted flight... ;-D

tricopter test de stabilité from erictrex on Vimeo.

I2C -> PWM converters

I2C to PWM converters will make it possible to use standard ESCs with my tricopter design (and other multicopters) without modifying anything. Each converter has it's own I2C address and will deliver one PWM signal for one ESC. The refresh rate will be selectable via solder jumpers (50 to 400 Hz). The final PCB for the converters will have a size of about 20x20mm (0.8x0.8'').
After some setbacks while trying to build a converter with a tiny45, I finally decided to take an ATmega8 (TQFP) instead. This controller features a 16bit timer and I know how to talk to it via I2C...

I put the circuit on a breadboard (with larger electronic components...) and it already works with a servo. I am optimistic that it will also work with ESCs and in flight. I'll try to make the PCB soon...

New brushless motors

As some of you might know, I am using Scorpion S-2212-26 motors for quite a while now. I am extremely happy with these motors.
Short time ago, SCORPION POWER SYSTEM LTD offered to provide three recently developed motors (prototypes of the SII-2212-960KV) for tests with my tricopter . Of course I didn't say no...!! I had the opportunity to test them recently, and these motors are absolutely great! They seem to be even more efficient and powerful than the S-2212-26 I used before. These motors stay absolutely cold (prop: EPP 10x4.5'') even if I do aerobatics with my copter. I am not a real expert with motors, but if no heat is produced, all the available energy should be converted to mechanical energy/ thrust... And that is also what it feels like :-D . So, I would absolutely recommend to use these motors with my tricopter!
And last but not least, they look pretty nice...