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Only weeks left

  2013-01-22  |     |    9 Comments

Who knew that it was possible to discuss product descriptions for almost a whole evening… Since the release is getting really close now we actually have finalize the product description and it turns out that we didn’t all agree on everything. One thing that’s good about being three people in this project is that we can have a lot of discussions that gives (hopefully) good results and the bad thing is that there’s a lot of discussions which takes a lot of time :-)

Another night without any flying at all, just administrative stuff… But if everything is goes according to plan the pre-order should start within the two next weeks!

Merry Christmas!

  2012-12-24  |     |    Leave a comment

Even though it’s Christmas Eve we managed to sneak away from the celebrations to post the regular Monday post. Unfortunately there’s not much progress to report this week, but we are continuing the planning for the release of the Crazyflie Dev Kit. More and more stuff is being sorted and soon all the details will be in place. As soon as we have a timeplan we feel that we can commit to we will release more information.

Finally we want to wish everyone a Merry Christmas!!

Crazyflie piloted by Raspberry Pi

  2012-11-05  |     |    18 Comments

Last week we received one of the new raspberry pi and we wanted to start doing something useful with it. One idea that came directly in mind was to control the copter with it. As it has 2 USB port it should be possible to use one for the gamepad and one for the Crazyradio dongle.

The Raspberry pi running Debian the operation ended up being surprisingly easy: Just apt-get install python, pygame and pyUSB and we where able to run our old script. By adding pyQT we where even able to run the GUI out of the box (it is still a bit heavy though as the GUI is not yet very optimized when receiving fast log informations). So we just made a “headless” version of the control software, launched it automatically with a udev rule when the radio is inserted and it was done!

We can power the Raspberry pi with a USB battery and we now have a small portable ground station for the Crazyflie. We have also proven that our PC software tools are easily portable to other architecture thanks to Python and all its libs. Currently the software is tested on Windows and Linux (x86 and ARM), but it should also work on MAC.

Raspberry PI controlling the Crazyflie

Protective frame prototype

  2012-10-29  |     |    4 Comments

While we are waiting for the pre-series to arrive, which hopefully will be within 4-5 weeks, we have tested this idea we have had for a while. On the Crazyflie PCB we placed mounting holes in each corner for the possibility to add e.g. a landing gear, canopy or maybe a protective frame. The holes are about 0.9mm and plated so it is possible to solder something in it and a protective frame made of piano wire would be a good candidate.

We bought a couple of 0.8 mm thick 1m long piano wires at a nearby hobby store and got to work. On the first try we bend the wires into the shape solely by hand and it didn’t look or work well at all. We figured there must be some better way! And after searching the net we found this site explaining how to make your own DIY springs of different types. We however needed a circle with a much bigger diameter than normal springs use so it took us a while to find a tube with the right diameter to bend it around to get the right size. We found out that when bending the piano wire around a tube with the diameter of 20mm it ended up at about 55mm which was close enough to the 60mm we needed. Piano wire is a bit hard to solder but with plenty of solder flux it works well. We are pretty pleased with the result!

The piano wire frame itself weights about 3.5-4g so it is within the acceptable payload limit. The flight characteristics is changed a bit making it more controllable but less agile which is perfect for beginners. We have tested throwing it in the ground and crashing it several times and the Crazyflie just bounces so it works great. It might even be possible to go to a smaller piano wire diameter to save weight because now the frame is very stiff. Next step would be to come up with a design that could be attached/detached without soldering. It should also be cheap and easy to manufacture.

Crazyflie presentation at Øredev!

  2012-10-22  |   

This week we decided to do our weekly meeting at the local pub. Why? We needed some beer to calm our nerves and to get some expert advice from Martin, one of our collegues, that has presented at a lot of conferances. The reason for this is that in about two weeks we are presenting the Crazyflie project at the annual Øredev developer conference in Malmo, Sweden.

The presentation will be a mix of the project history, some tech details and of course a demo (hopefully a successful one without any injuries ;-) ).

So if you are attending Oredev drop by our presentation on the 7th of November at 15:40 in the Nyan Cat room and we will do our best to give you an interesting 50 minutes.

Another key-chain camera hack

  2012-10-15  |     |    11 Comments

We discovered a new key-chain video camera which is called the 808#16. It had gotten a pretty good review so we decided to give the video camera add-on hack yet another try. A while ago we tried it with a 808#14 but it didn’t work that well when we where running it directly from the Crazyflie battery. It shut down as soon as we used to much throttle and using a separate battery made it to heavy. We didn’t have to high hopes for the 808#16 either and when we discovered that the bare camera weight, no battery nor case, was about 9g we knew it would be at the maximum of what the Crazyflie could carry.  With high hopes we connected the camera directly to the Crazyflie battery terminal and gave it a try.

It worked! The camera didn’t shut down but as you can see the stability is pretty bad during take-off. Once in the air it is controllable but only barely. We haven’t tested the full flight time but it probably wont be more then 2-3 minutes. We are thinking of doing a test where we add 4 more motors “mirrored” directly underneath the existing ones to increase the payload capability. Would be nice to have that option and it should be fairly simple to do.

We are pretty impressed with the video of the 808#16 which still is very cheap. We bought the 808#16 camera with the D-lens which is a wide angle lens and that’s why the video has a bit of a fish-eye.

Pre-series ordered!

  2012-10-08  |     |    29 Comments

We just finished the top level BOM, test plan, fabrication files, etc… which mean everything required to order the pre-series of the Crazyflie. The pre-series  is meant to be last version before the first real production batch and the idea of it is so that we can test the manufacturing and verify that it is manufactured with good quality.

One of the last minute changes we made for the pre-series has been to power the motors directly from the battery instead of through the power management chip. This should gives us up to 8% more power and efficiency due to power management mosfet on-resistance losses. It should also reducing the voltage drop which causes disturbances to the other circuits. The only drawback is that the Crazyflie consume a bit more power when OFF, because of the leakage current through the motor mosfets, but it is still within acceptable limits (a full battery will still take more than 2 years to be depleted by our electronics). Also the battery can now be swapped/disconnected for storage as we have added a connector.

Our target is to have the Crazyflie DIY kit availible for X-mas. It is very tight and it will be hard but what would life be without challenges :-)

Inductive charging hack

  2012-09-24  |     |    21 Comments

After the LED hack we are back with an inductive charging hack!

The idea of charging Crazyflie inductively is almost as old as the copter itself. Last week we received a Palm Touchstone charging kit that we ordered. Like many phone hacks using this inductive charger we dismounted the receiving coil and electronic and attach it to the Crazyflie:

As the Crazyflie has a power-management circuit, any supplied voltage above ~4.5V will make it charge, and as we have made some soldering pads available for things like this it was a simple task. The coil is very thin and light (about 3g) so the flight performance are not affected a lot by the change. The charger is working very well and provides enough current for charging. We charge with a little less then 500mA and we think the Touchstone can supply up to 1A. One possible problem though is that the copter has to be placed exactly in the middle of the charging station to be able to charge. The phone has magnets to align it to the charge station and on top of that the charge station is not straight but tilted. The magnets are way to strong to let the Crazyflie take off so we are trying to find a landing area design that would permit the copter to land in the right spot and still be able to take off again without the magnets, any ideas?

LED hack

  2012-09-17  |     |    3 Comments

When I was shopping for some ink-cartridge at this Swedish accessory store named Kjell&Co I also bought one of these 12V LED lamps. I didn’t buy it to actually use it instead I bought it to have a look inside. I cracked it open when I came home and found, not so surprisingly,  a lot of LEDs and a step up converter with a current sensing mode. Since it was made for 12V AC I removed the rectifier bridge and a large cap to get it as light as possible. Testing it with a power supply reviled that it worked all the way down to 2.2V and at 3.7V it consumed about 0.5A. A bit to much for the Crazyflie so I doubled the current sensor resistors to get it down to 0.25A. Some soldering and some double sided foam tape and we suddenly have  a pretty bright lamp hooked up to the Crazyflie. Now we have a search&rescue device :-) or maybe just an UFO…

Let’s not forget the sensor poll. It’s a very close encounter with 55% wanting the extra sensors. We will keep the poll open until next week to see if it gets any clearer.

Bitcraze turns one year

  2012-09-03  |     |    7 Comments

Last summer we were sitting in a meeting room after office hours discussing how we should react to the fact that a lot of people seemed to want to buy a Crazyflie. After having a bit of down time in the project we finally posted a video, that was already about 6 months old, on Youtube.  It was during the spring 2011 showing us flying the first prototype Crazyflie. After getting picked up by Hackaday it got a lot more attention that we originally thought and a lot of people wanted to buy one which was great! The only problem was that we only had three of them and at this time there where already obsolete components. Another problem was that the motors/propellers were scavenged from toy airplanes (they had a sale and we got them cheep) which was not a scalable sourcing solution.

So sitting in this meeting room we decided to give this project a shot by trying to release a kit that could be sold. Back then the development was funded by Epsilon, the consulting company that we are working for, which was not optimal if we wanted to commercialize the Crazyflie. So we decided (after a lot of discussions) to form a company which became Bitcraze AB (the name came after even more discussions). We needed a company to make manufactures and distributors take us seriously and for import and tax reasons. It is also pretty satisfactory to be on the board of director of our own company :-).

At this time the Crazyflie was already flying but it had to be redesigned, parts sourced and we needed to find someone to manufacture it for us. Since we didn’t (and still don’t) have that much capital this wasn’t something that we could leave our day-jobs for so the development continued on weeknights and weekends. As anyone working with product development (specially if it includes any type of hardware), going from a prototype that is working to a final product requires a lot of work.

A big obstacle for us was sourcing the mechanical parts: Motors, propellers, motor mounts and battery. Some of these can be found and some are harder. And even if you find something that looks good on paper there’s no guarantee that it’s very good or working at all. We got some motors that seemed like they were scavenged from the junkyard (and probably were), we got batteries that didn’t meet the specification and propellers that were unbalanced. All this takes a lot of time. Finally we had to design a motor mount ourselves since we couldn’t find anything that suited our purpose. After a lot of searching/testing we finally found good batteries and motors. The propellers are still a bit hard to find a reliable source for but we think that we have it sorted out.

Even though it’s been very frustrating at times, like when the Invensense gyros we were using went out of production, we have a lot of fun when we work (which you can hear in the videos). Also we have been challenged to learn new stuff and got to try things that we normally would’t do at work. One of the reasons we started the project at all back in the fall of 2009 was that we wanted to do something more challenging and we think that we achieved that :-)

So what’s the plan for the upcoming year? Well, the main plan is to release the kit soon of course! After that there’s a lot of ideas of what we want to do so we will have to see how things go. Also we would like to thank everyone that’s been following our progress and supporting the project!

No, the candle isn’t burning when we are flying…although we did try to…