Scott Berfield's Posts (12)

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Not strictly Drone related, but if the weight and power requirements are manageable, the new Kinect sensor from Microsoft could be pretty amazing as a navigation/obstacle avoidance/3D mapping tool. And it can see in the dark and read your pulse rate.

From Engadget:

The new Kinect for Windows sensor won't be available publicly until some point in 2014, but developers can apply for an early, $400 development kit starting right now (due before July 31st at 9AM PT), Microsoft announced today. In that $400, developers (if accepted) will get early SDK access, a pre-release "alpha" version of the device, a final retail version (at launch), and private access to both APIs and the Kinect for Windows engineering team (in private forums and webcasts). Should you get in, you'll find out more come this August.

Some info on the new Kinect are at this page: Unofficial Kinect Info Page


I have to think a bunch of labs are going to jump on this.

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Google Investing in Drone Tech



Echoing a company belief in autonomous systems, clever algorithms, and replacing fallible humans with smart machines, Google's venture capital arm announced yesterday that it is investing $10.7 million in a company that makes drone brains.


AirWare's osFlexQuad

Full story at Popular Science

And also reported here: TechCrunch

Google has some history with UAVs - presumably for mapping. As well as considerable work in autonomous cars. $10.7M is pretty much a rounding error to Google Ventures, but it is an interesting bet for them.


An MD-200 Quadrotor Two years ago Google purchased one of these quadrotors from German manufacturer Microdrones wikimedia commons

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H-Quad Ready for Tuning

Got everything hooked up except the sonar and i tlooks like a dry weekend coming so hopefully I can get out and do some tuning and flying. Went with 11x4.7 props since the weight is a little higher than I had planned. May swap the arms for wood if flight times are too short.









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H-Quad Part 2


Here's where I am so far on the H I started before the holidays. Ended up trimming the arms and drilling out some of the plates to lessen the weight. Will likely add some CF rods as prop protection during the tuning process.


Using 10x4.7 props for now, though the motors could handle larger. Testing has it hover at just under 50% throttle, so I think I am in a good place. Not tuned yet - that's next when the rain lets up.


The APM is enclosed in a very stylish $0.99 plastic box from Office Depot. The stack sits on a fiberglass plate attached to the body plate with 3M double sided foam squares. The lid of the box is velcroed to the FG plate and the APM is velcroed to the lid. The bottom of the box forms the cover for the stack and clips on.



Still need to rig up battery straps, the external LEDs for GPS and arming indicators, some running lights, a GPS enclosure, and general cleanup.






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New Project - H-Quad


With the non-stop rain around here, I haven't been able to do any flying, so I decided to start a new project. Since I want to do FPV eventually, I went with an H frame layout. Not much to show yet, but all the bits are collected, so it should go together fast.


Decided to make the arms a bit longer than needed to act as prop protectors.

Components right now:

3/4" Square aluminum tubing for arms

1/8" G10 Fiberglass body plates

HobbyWing Quattro 4-in-1 20 Amp ESC

4 x Exceed Optima 850KV motors

APM2 with external GPS (the newer version of the Mediatek from 3DR)

3DR Radio telemetry

FrSky RX


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I am using the APM 2 for both my quads and it is tricky to get the barometer covered to avoid errant airflow since it is below the daughterboard. To solve this, I ended up pretty much filling up my stack cover with breathable foam. But once that was done, I could barely see the on-board LED indicators.

Fortunately, the current code supports remote indicators without too much trouble.

If you look at the pin-out images on the Wiki, you will see that the AN pins are labeled Motor LEDs. They really don’t have a lot to do with the motors – but they do serve as pretty handy indicators.


If you look in the code, you will find defines for these pins as follows:

AN4 – Motor or Aux LED

AN5 – Motor or Beeper

AN6 – Motor or GPS

AN7 – Motor

AN8 – Motor

For my purposes, I focused on AN5 for the Beeper, AN6 for GPS indicator and AN7 as an Armed indicator.

The default seems to be to have the beeper enabled and the LEDs on. That is easy to change however. The different possibilities are set using bit masks to build the LED_mode parameter. A bit mask (if you already know, feel free to skip ahead) is simply a way of packing a bunch of on/off settings into one byte of data. A Byte is 8 bits, so you can have 8 different switches in one byte.  If you look at the following table, you will see a single bit is set to ‘1’ and the rest to ‘0’ in each row. To build the mask, you just add all the rows together and convert to a decimal number (or convert then add).

Bit Number

7              6              5              4              3              2              1              0

0              0              0              0              0              0              0              1      =      1              Motor LEDs On/Off

0              0              0              0              0              0              1              0      =      2              GPS On/Off

0              0              0              0              0              1              0              0      =      4              AUX Function On/Off

0              0              0              0              1              0              0              0      =      8              Beeper On/Off

0              0              0              1              0              0              0              0      =      16            Low Battery Flash – fast/slow

0              0              1              0              0              0              0              0      =      32            Motor LEDs NAV blink On/Off

0              1              0              0              0              0              0              0      =      64            GPS LEDs Nav Blink On/Off

1              0              0              0              0              0              0              0      =      128          Not used


Note that the NAV settings cause the LEDs (either the motor LEDs, the GPS LED, or both) to blink 3 times when you hit a waypoint in AUTO flight.

The low battery flashing defaults to fast flash so setting that bit to 1 will enable slow flash. 


I really only want the beeper, the GPS and the Motor LEDs on, so I set the mode to decimal value 11 (which is binary 00001011). This should equate to: GPS Nav blink off, Motor LED Nav blink off, low battery flash fast, beeper on, AUX off, GPS on, Motor LEDs on..


The way you set this to be the value used is through the Mission Planner.


Establish a connection with the APM and the Mission Planner software. Go to the parameters list and find LED_Mode. It should be set to something like 9. Change that to 170 (or whatever you decide to use) and write the settings to the APM.

The outputs on the APM are 5V, so for most LEDs, you’ll need a resistor on the positive lead (the longer leg of the LED). In my case, the blue LED I was using required a 100 Ohm resistor and the red one required a 150 Ohm resistor (note – not going to explain it here, but there are a ton of online resources and calculators to figure out the resistor values needed for a given LED). I soldered up the resistors and LEDs to leads and cemented them at the edge of my stack cover’s base. For the beeper, I just used a 5V piezo beeper I happened to have lying around. Radio shack sells one that will work, but it isn’t very loud. If you want volume, you may need to shop around,


When you connect to the AN outputs, you need to run the negative lead to the ground pin (the one nearest the edge of the board) and the positive lead goes to the signal pin (the one farthest from the edge of the board). The middle pin is always 5 Volts so if you plugged in there, the LED or beeper would be always on.


Beeper goes to AN5, GPS to AN6 and the ARMED light goes to any other motor LED output, but I chose to just use AN7.


That’s all there is to it. When you turn on the APM, you the LEDs will stay off until it is booted, then will flash the same as the on-board ones. When a GPS lock is achieved, the GPS LED will stay lit. When the bird is armed, the red LED will blink out and once it is fully armed, it will light a solid red. The beeper will beep twice on arming, and once on disarm.


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Gimbal support on APM - dead easy

I wasn't sure what would be involved in getting a simple gimbal (in my case, just a tilt platform really) hooked up and working, but it was dead easy.

My wife recently made me a present of a GoPro Hero 2 and a tilt-mount.


This is a cheap little thing, but it fits the frame I have and it comes with the servo, and it was a gift - so you can't complain.

Took a look at the ArduCopter docs and was a touch intimidated, but as it turns out, it is really easy to get working. Once it was on the frame (took a little sanding and force), all I did was plug the servo into output 11 on the APM2.


If I had something that did roll as well as pitch, I would have plugged the roll servo into output 10 as well.

Where it gets really nice is that the Mission Planer has direct setting support for the gimbal now (as opposed ot what the docs say). I went to Mission Planner->Configuration->Camera Gimbal (duh).

On this screen, you can enable Tilt, Roll, and Pan individually, and can choose which channels to use for each. In my case, I enabled only Pitch, and set it to use "RC11" - this naming convention is a little confusing since RC indicates Radio, but it really is just the output pin number. I left the defaults for the limits. I chose Input channel "RC6" - which actually is a radio input channel.

I have channel 6 on my TX set to a pot for use in tuning, so I chose to use it here. Note - to use Channel 6 for the gimbal, you will want to make sure it is set to CH6_NONE in the ArdiCopter Config screen.

So in theory, channel 6 should set the angle of the mount and then the APM will maintain that angle to counter the pitch of the quad.

As soon as I picked up the quad, the gimbal worked. I could set the angle with the pot and it compensated for pitch as I tipped the quad back and forth. If only everything was this easy.

Once it stops raining in March next year, maybe I'll get to fly it. 

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Finally got around to posting pics

Finally got around to taking pics of my two quads.



The first is my original unit. The frame is an X525 from a kit from GoodLuckBuy. The kit came with everything including a KK board, but I built it with the APM instead. I have since replaced the motors, landing gear, and ESCs. Current setup:


Exceed 1050KV motors

10 x 4.5 CF props

HobbyKing F20 ESCs flashed with SimonK firmware

APM 2.0 with on-board GPS disabled

External MediaTek GPS with backup battery board (JDrones)

3DR 915MHz telemetry

FrSky receiver with voltage monitor

An extremely classy stack cover from a CD tower

and a Ping pong ball "stinger" for orientation

Generally fly on 3S 2500 mAH battery for about 9 minutes flight, but can double up or go with 5000 for app. 15 minutes flight time.


My second one just got in the air today. Put together out of a broken, second hand CF (maybe fake?) BumbleBee frame which I repaired (handy to know how to work with composites).

Exceed 950KV motors

10 x 4.5 CF props

RCTimer 20A ESCs

APM 2.0 with no on-board GPS

External UBLOX Lea-6 GPS

3DR 915MHz telemetry

FrSky receiver with voltage monitor

Another extremely classy stack cover from a CD tower

and a dual Ping pong ball rear end for orientation

Flight times appear to be comparable with other quad so far.


Both fly pretty well, but have very different feels. I think the BumbleBee is going to get a gimbal and a GoPro some day as it appears to be the more stable unit.

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Seattle Police Consider Using Drones

seattle-drone--articleInline.jpgWe had quite a show last week as the Seattle Police held a public meeting to discuss their plans to use small surveillance drones for various purposes. Protesters made the meeting pretty much useless - lots of loud concern over civil liberties. I fear the coverage of offensive weaponized drones combined with a general concern over past misbehaviors by the police here have caused people to be especially suspicious of both the technology and the motives of the department.


The city is planning on spending app. $80,000 for two devices (which seems outrageous to me, but then again, I suspect they are getting a really good warranty).


I believe the ones they are looking at are the Draganflyer units (




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