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New Experiments

Posted by Tom Benedict on 29/03/2014

Because of stuff going on outside of work and hobbies, both work and hobbies have taken something of a back seat in the last month. Typically when this happens I wind up with a backlog of work I need to do as well as a notebook full of hobby ideas I want to take on when the smoke clears and normal life resumes.

The backlog at work happened right on schedule. I’ll be surprised if I dig my way out any time in the next twelve months. And the hobby notebook? I went through the list of ideas and cleared it down to four:

Project 1 – Untaping the Gopro

Pretty simple, really. I’ve been flying my Gopro on my RC airplanes by taping it down with blue painter’s tape. I went this route for a couple of reasons: First, the waterproof case introduces a planar/planar optic in front of a wide-angle lens. This is guaranteed to degrade image quality. Second, the weight of the waterproof case almost doubles the weight of the camera. Unlike kites, airplanes are very touchy about how much weight they can carry. So I went with the “lightweight” mount: blue painter’s tape.

This is a silly thing to do for a number of reasons. If the tape gets wet (which NEVER happens up in the air in the tropics! Gosh!) it starts to fail. A Gopro falling from a couple hundred feet is an injury waiting to happen. Also, it doesn’t offer a lot of options for aiming the camera. So I got a third-party “Frame” case. I’m probably going to stick a 1/4″-20 tripod mount on top of my Phoenix and attach it to that. Lightweight, solid, and I can finally aim the damn thing.

Along with the Frame case I also got a low-profile FPV cable for the Gopro. This lets you power the Gopro from your RC system using a BEC, so you can shave even more weight by leaving out the battery. And the video end of the cable will plug into the video transmitter for both my KAP rig and my planes, so it serves dual purpose.

I’m looking forward to flying the Gopro on my KAP rig with the video cable. As wide as the field of view of the Gopro is, I’ve blown a number of good opportunities to KAP some excellent boogie board action at Hapuna Beach because the subject was off-center in the frame.

Project 2 – OrangeRX Flight Stabilizer Hack

In a thread on the KAP forum, Bill Blake mentioned the OrangeRX RX3S Flight Stabilizer sold by Hobby King. He got one and tested it as a KAP camera stabilizer, but found it to be too slow and notchy in its movements. While poking around for information about the thing I ran across a web site that had a third-party firmware for the RX3S that might solve the notchy problem (improved interrupt handlers), along with some other improvements.

While I was cruising around on that page I saw that the RX3S is basically an Arduino with a 3-axis gyro, three potentiometers, a bank of switches, and headers for servos. Take the idea of it being a flight stabilizer out of the equation and just think of it as a pre-packaged microcontroller with a bunch of cool stuff tacked on, and all of a sudden all sorts of possibilities come to mind.

One I’ve been toying with for a while is an RCKAP / autoKAP switch: In one mode it lets you control pitch, yaw, and shutter. In the other mode the microcontroller acts like an autoKAP controller and moves the camera through a fixed pattern automatically. If the RC receiver it’s plugged into has a failsafe setting on the channel that controls the behavior of the micro, you could have it default to “turn me to autoKAP” when no transmitter signal is detected. Voila! If you leave your radio at home, you get an autoKAP rig. If you bring it you get both RCKAP and autoKAP at the flick of a switch.

So yeah, I got one of these, too. Shipping from Hong Kong being what it is, I expect to see it in a couple of months. Such is life.

Project 3 – KAP / Pole Rig Adapter

This actually ties into another long-term project: building a passively stabilized pendulum KAP rig with an actively stabilized gimbal on the bottom. To do the testing for this, I want to be able to swap rapidly between Picavet and pendulum suspensions on the same rig so I could compare them under similar conditions back-to-back.

As I was going through the sketches and CAD work for the quick-change suspension mount, I realized that a slightly beefier version would mean I could take my KAP rig, flip it upside-down, and attach it to a pole as well. Yay! No more separate rigs!

That’s when it occurred to me that if I was careful about it, I could make a whole set of mating adapters. That way I could carry around one Picavet, one pendulum, one pole, and multiple KAP rigs. Depending on the requirements of the photo I could use a pole or a kite to lift the camera, and put the camera in any of the rigs I have sitting around at the moment. Versatility at its best!

Design work for stuff like this is always something of an iterative process. It needs to be robust, light, and simple to build. Robust is easy: make it in large chunks. Light is easy, too (use small chunks!) but a little harder if you don’t want to jeopardize robustness. And simple to build? Yeah, that’s the kicker. I’m trying to get these down to three setups on no more than two tools. I’m almost there.

Project 4 – A Helmet Camera that Aims!

Years ago I knew a skydiver who later became a photographer and videographer. Even back then (back when film was king) I was fascinated by the hardware the skydiver videographers used. They wore specialized helmets that let them mount video cameras, 35mm cameras, medium format cameras, etc. on their heads, all of which could be triggered using a handheld remote.

That’s all well and good, you might think. No different from a headcam or hatcam mount for a Gopro. Aaaah, but there was one other thing the skydivers had that most head-mounted cameras don’t: a way to aim.

The skydivers all used reflex sights bolted to their helmets to help them aim. The reflex sight projects a dot or crosshair into your field of vision. No matter how you move your eye, the dot’s orientation is preserved. Once all the cameras are aimed to center their frames on that dot, the skydiver only needs to aim the dot at the subject and hit the button on their handheld remote. Bang! All their camera shutters trip, capturing the action.

So I looked up “reflex sight” on Ebay to see what these things cost these days. I was amazed to see they were less than $30US. WOW!

So the last project is to make either a hat or helmet camera mount with a reflex sight over one eye. By bolting a combination of a wide angle camera (Gopro, probably) and a narrow-angle camera (A2200?) on the mount, some neat possibilities open up for slope soaring videos or really any videos that require tracking a moving subject.

Unfortunately I don’t have the shop cash to spring for the reflex sight as well. Not this month, anyway. That project will have to wait.

– Tom

EDIT: I talked to my family’s CFO (aka “my wife”) and she gave me the go-ahead to pick up the reflex sight and rail. Yaaaay! But she cautioned me that if I tack a DSLR with a big bazooka of a lens on the top of my head, she will disown me.

4 Responses to “New Experiments”

  1. Tom,

    That should keep you busy!

    I have a vid clip of the Rx3S ‘working’:

    I don’t know too much about whats possible with the irmware hack but I’ll gladly test out what you can do with it!


    • Tom Benedict said

      Excellent clip! (or clips now, I should say). Thanks for doing those.

      I see two issues that would certainly affect people trying to stabilize a camera: The first is the reversed correction, as you pointed out on the KAP group. The other is the lag. The thing is REALLY slow compared to the period of your suspension.I’d say 90-180 degrees out of phase to what it’s trying to correct.

      As soon as mine gets here and I can be in a position to tinker, I’ll take a look at the open-source code to see what can be done to resolve the reversed correction, and at least start to deal with the lag.

      Thanks again for doing those tests!


      • No problem Tom, ever since I heard Scott was ending production of the GS1 I have thought about a replacement.

        The tillt servo is the one you trash when things go wrong and I have had great benefit from the GS1, I think if a Rx3S hack is possible it would be a real boon to all. I have had a look at the mod site and the re-flashing of the chip seem a bit scary; good job these things are cheap!

        Lets see how the legendary Hobbyking delivery service works out!


  2. […] I wrote New Experiments I’ve accomplished three out of four of my goals: My Gopro has a frame case and a remote […]

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