Blogs

Nathan's addiction to microcontrollers brings peace and joy to thousands of people with the products, classes and tutorials in the seven years since he started SparkFun Electronics.

CNN Money piece on Nathan: http://money.cnn.com/galleries/2009/smallbusiness/0902/gallery.make_believers.smb/6.html

I wrote down a napkin sketch of an altitude filter a while back and finally got around to testing it in the simulator. I designed it to improve the sensed altitude of the ardupilot. It is based on a fixed gain observer model and shows very promising results. The idea is to use the "lagless" airspeed sensor to give you a less noisy lagless altitude estimate. Enjoy!

K_alt = -0.01;
avg_aoa = 0.52*(pi/180); //alpha = 0.52 deg on the average
gamma = theta - avg_aoa;

alt_est = alt_est + Vair*sin(gamma)*dt;
alt_error = alt_est - GPS_alt;

alt_est += K_alt*alt_error;

The above picture shows the Project Andromeda ground station circuitry. You can also see the DNT900 from RFM. I believe there has been some interest on this radio in the DIY Drones community and once I finish the construction of the autopilot I will be able to give a recount of my experiences with it. So far, however the radio seems to be extremely capable (especially compared to the Aerocomm AC4790 radios that we previously used).

You can find more information related to the ground station and the DNT900 in the full article available at: http://www.projectandromeda.com.au/blog.

Guys,

The revision to the Heineken Robot is now complete and the new system can be seen on YouTube:

https://www.youtube.com/watch?v=WWLcZfeq634

Cheers,

Stephen.

It is fast to get location when power on.(32 sec), but I confused the date of GPS is wrong. Although I just want the location, altitude, direction and speed information. XD

A quick update on Blimpduino: We've temporarily run out of stock at the DIY Drones store but there are plenty at the Maker Shed, where you can buy them at the same price (it's a very cool store--spend some time there!). We've got some components incoming, and I expect to have them back in stock at the DIY Drones store by the end of the month. We'll also be offering the RC and battery + charger option.

We've been recommending the HobbyKing 2.4 Ghz radio for it, but some people have been reporting that Blimpduino doesn't autorecognize RC mode with that radio, due to a slight slower bootup time. So I've modified the code to wait a bit longer for the RC signal and it seems to work fine now.

I've also updated the building manual and operating instructions to make them clearer and easier to use.

All in all, a nice refresh. If you've been wanting to get into UAVs but aren't ready for planes, Blimpduino is a great entry point. Also perfect for winter when you can't fly outside!

We don't talk much about the older commercial autopilots here much, but I was amazed to see the above in my inbox yesterday. The Micropilot 2128g, which is a staple with the university crowd, has only just now upgraded to the 4 Hz uBlox GPS that we in the open source world have been using for years. Weird.

Micropilot's advertising has always bugged me because it's so transparently untrue. Take the below, for example (there are many autopilots MUCH smaller than this; ArduPilot, for example, is 4.5cm by 3 cm):

But Micropilots seem popular with universities, despite the high price. Why is that? It is just a matter of time before the open source IMU-based autopilots, which cost less than 1/10th as much and are closing the gap in performance, take over from these last-gen commercial autopilots in the education world?

Perhaps it's some sort of cruel joke we're not in on but everything I've been able to find on the Internet about tilt-compensated headings from magnetometers leads to this paper [warning, it's a PDF]: http://www.ssec.honeywell.com/position-sensors/datasheets/sae.pdf

In it there is an algorithm for tilt-compensation. It's wrong. Here's what it should be: http://gist.github.com/322555

Ryan Beall is the man.

I thought this was very interesting

http://rcaircraft.blogspot.com/2010/03/wwii-uav-flies-again.html

Another PIC programmer option from Sparkfun, perhaps an alternative to the dubious PICkit III. The $49 Cana Kit says it is "100% compatible with Microchip's MPLAB IDE, and the PICkit 2 interface, and can program all popular PIC 5V microcontrollers including the PIC16F84, PIC16F628, PIC18F458 and PIC16F877."

Connectivity is described this way: "The PIC Programmer offers In-circuit programming through a standard 6-pin ICSP connector as well as a built-in 20-pin ZIF socket for easy programming of any PIC of up to 20-pins right on the programmer. "

Will this work out of the box for the UAVDev Board?