First camera flight tests

In Apis electronica, the drone should eventually be able to navigate pretty much on its own. I’d like to develop a good deal of that functionality using the Crazyflie, but until now I’ve had a difficult time finding a camera and transmitter combination that doesn’t exceed the Crazyflie’s maximal payload.  Last week I experimented a bit with a keychain camera generously donated by my colleague Rüdiger. Here are the results.
The camera is really very small. As you can see, it could easily pass for a car key if you don’t look too closely, especially if it’s the only car key you have on your keychain.

Good to know creepy stuff like this is out there.

The actual “camera” part sticks out of the “bottom” of the keychain, if it’s hanging downwards from the keyring.

The Crazyflie is supposed to be able to lift about 15g, but since I didn’t have a scale at home I decided to just test it by removing the keychain connector, taping it to the Crazyflie and flying around while making a video. It could have gone better, but it could have gone worse too. In my infinite wisdom, I deleted it afterwards, because hey, the video just wasn’t that great.

It was pretty obvious that that wouldn’t work, of course – the thing is just too heavy for the Crazyflie. Plus, the camera housing made it really hard to center the drone’s weight, because it’s a bit curved and oblongly shaped. The flat edge is actually the buttom, so I turned the camera upside down and rotated the video afterwards.

The next step was to take the camera apart. After removing the housing the camera did lose a lot of weight. Here are a few thousand words in pictures:

The keychain camera, carefully pried open with a small screwdriver.

The battery wasn’t securely fastened to the chip and camera – the housing held it together.

Since I didn’t have a small enough screwdriver to get this thing out, I had to do some pretty acrobatic stuff to remove this screw. We won’t get into it.

The camera, completely freed of its housing.

The camera’s mini-USB port.

And a view from the top for scale.

The buttons to turn the thing on and off.

The housing from the inside. Note the padding – it kept the camera positioned properly. Without it, the camera wobbles around. It would have to be fixed in position somehow for good results.

Obviously, if I were to really do any remote sensing with this I’d need to make stabilize the lense somehow, because it’s only attached by that wire and thus kind of wobbles around. But I just wanted to test whether or not the weight was possible for the Crazyflie to carry. I got out my tape roll, attached the camera and battery to the Crazyflie, and took off.

Flying was pretty difficult and I had to change the restrictions I’d set in the PC client quite a bit – allowing more roll and pitch because otherwise I wasn’t able to move quickly at all and turning the maximum thrust up to 99.9%. Why not 100%, by the way? Not possible in the client. I’ll have to take a look at that later.

Obviously, this is not the most elegant way to fly around. The camera has a lot of baggage – the battery, the mini-SD card and the mini-SD card drive make the biggest difference, I believe. It’s also kind of hard to start the video – I completed some test flights but could never really tell if the camera was recording. Guess what? It wasn’t. I only found that out when I got the camera back at the computer. That’s why I don’t have any videos. So in my zeal, I decided to try connecting the camera to the drone’s power supply.

The Crazyflie ready for takeoff! It actually did fly with the camera attached.

This is how it looked from the bottom. The wires were connected to the Crazyflie’s power output behind micro-USB port.

The Crazyflie has a power output for additional devices, but it doesn’t seem to output the same voltage when the drone’s plugged in as when it’s flying. Makes sense. I didn’t know what the camera could or couldn’t handle, so I just cut off the power wires, stripped them and attached them to the Crazyflie.  Plugged in, I even made a video, but the power output was just too low to power the camera during flight. The good news is that weight on that level wasn’t all that hard for the Crazyflie to handle.

The end of the story? The Crazyflie can handle the camera, but the camera can’t handle the Crazyflie 😉

Which puts me back at square 1.5 or so. After trying this out, I’m looking for a camera that can take the Crazyflie’s output voltage *and* is light enough for the Crazyflie to carry. Preferably with a transmitter so I can get the video output live on my PC.

I’ve already found a few links: Here, for example, I could get a keychain camera that would probably be very similar to the other camera. Not a bad price. And this store is incredibly creepy, but might have what I want. And, lastly, the most-likely winning candidate: A store catering directly to drone flight. It seems that the specs match up there. I’ll let you know how it goes.

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About

My name’s Daniel Lee. I’m an enthusiast for open source and sharing. I grew up in the United States and did my doctorate in Germany. I've founded a company for planning solar power. I've worked on analog space suit interfaces, drones and a bunch of other things in my free time. I'm also involved in standards work for meteorological data. I worked for a while German Weather Service on improving forecasts for weather and renewable power production. I later led the team for data ingest there before I started my current job, engineering software and data formats at EUMETSAT.

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