No limits: A helmet camera story. ( I )

A few days after poking around with my F9 camera and finding out there are no new or old firmwares avaliable, nor adjustments for the camera (or anything, for that matter) I decided to start again an old project of mine:

Building a helmet cam from “scratch”

Not from literal scratch tho. Drone camera tech is so advanced that it’s dumb spending time also developing the recording hardware with the enormous amount of options. Not that just developing the casing is easy, but also, what exactly do I want to achieve that no action camera in the market does already?

SO, WHY?

You see, I’m a fashion victim, I admit it. Every time I see a GoPro in a helmet, I get sick.

When I see this:

I think of this:

I know, I know, It’s not like there are lots of types out there. It’s either:

  • Generic Action Camera: GoPro / standard clone.
  • Cube Action Camera: GoPro Session / Runcam 5 / CADDX Orca
  • Tube Camera: Sena Tube / Contour HD / S20W / Cheapo F9.
  • Front facing Action cam: Ghost Drift / Stupid Sena 10C

Not gonna count the mohawk type cameras, albeit cool, because:

  1. Cost: 500€ and upwards to orbit.
  2. Bad helmet compatibility: Top vents, modular helmets and top solar shield sliders pose a problem with those.

And don’t get me started on the mounting solutions. They’re all so large, sometimes as big as the camera you want to mount. And the thing is, our helmets are curved, but none of the avaliable cameras use that to it’s advantage to make them more streamlined, and I’m thinking, why noone makes a wedge shaped camera so it has a lower profile?…

Well, if noone is going to manufacture that, fuck it, I’m gonna build it myself!


First I took out the camera module I had bought some time ago: a CADDX Turtle V2, real 1080p / 60fps (much better than the F9 camera) and just looked at it while brainstorming.

One of the main thoughts I had was:
“If I was ready to carry a powerbank and a cable for the F9 camera, why not remove the whole battery thing altogheter from the camera? (not totally true, but more on that later).
So, I got to work. First I made a simple suport to put all the parts near the helmet so I could visualize what I was dealing with. Be afraid NOT!(yet) this has nothing to do with how I wanted it to look.

With everything in perspective, the first thing I understood is that I wanted the camera to be gimballed, so I could fine tune the angle it pointed out, so, even if the body was not perfectly aligned, the POV would be adjustable.

Implemented:


Frankly it looks more like a ready-to-burst eye, than anything.

With that, I started to devise what kind of shape I wanted it to have, I had very clear in my mind that the camera was to hug the helmet as much as possible. A limiting factor is the control board that measures 29x29mm (the camera body is 19x19mm) so the body itself MUST at least be a bit taller than 30mm. What I definitely didn’t want was the GoPro attachment, so that’s the first thing I removed:

In the helmet:

And compared against the F9.

Looking good, but I had definitely gone overboard with the simplification and volume reduction, and the pcb barely fit, plus the main processor requires heatsinking, so it was not like I could just make a plastic case and call it quits. I would have to add some kind of flat surface where I could embed an aluminium block of sorts.

 

After thinking about it, and some rough modifications later, I got this:

Much better. But that was built over many modifications over the same base design, making the whole Fusion360 file a mess I really didn’t want to work on. Thus, I started from scratch on a new file with more close to real measurements AND most importantly, a clear view of the shape the camera was going to have.

 

 

By advancing the gimbal ball (gimball from now on) holder front face, it was possible to make it look less like a sore eye and more like…well, definitely NOT a sore eye! After some more refining work:

And adding the micro-SD acces port and status light:

That was looking great, altough the camera had started to get bulky at 37x37mm frontal size, and I got worried that the thing was NOT going to be as dramatic as I had hoped. So, I decided to print a simplified body and front cover to fact-check. When you see the first impression, well…it is indeed a bit bulky, altought compared with the F9, it does poke less from the helmet side:

But ah!
When you see it from the side, everything changes! Now the F9 looks humongous against the Nixie-Cam (“official” name, btw):

And without the F9, looks much better:

I went ahead and printed the gim-ball:

Beauty!

Gimbal working:

I literally checked the GoproSession size while writing the post, and it’s 1mm larger on each side!

After that I went ahead and printed the lateral cover. This piece must be made out of aluminium as it will act as heatsink for the main board, there is no way around it.

 

 

The protusion is about the size of the main processor, and the four screws will attach it securely in place. It also serves as port to access inside and make repairs easier than through the camera-ball hole.

 

In place using some micro-screws I had lying around:

But, what about the element exposure? No worries. The ball and lateral cover have o-rings, plus the silicone seal on the micro-SD card.

 

At the very least, the camera should be IP55 rated (dust and water splash resistance) but I bet it will be good up to IP68 (impervious to dust and very heavy rain, BUT NOT underwater-waterproof). This also brings the issue of the controls. This thing would need at least two buttons, ON/OFF and REC/STOP.

The main board has a pushbutton that starts and stops recording, but accessing that as a button from the outside would be a good alignment challenge, so I knew I wanted a separate button for that. For power control, I’d need a switch too, but as much as I looked around, there was no way of finding a momentary and a 2 position waterproof buttons that where absolutely microscopic (so to speak). Smallest I could find was 8mm in diameter and 15mm deep, wich would mess the distribution inside the camera, and waste precious space. After deliberating  for a while, I reached the conclusion that the best option for all that was to seal an opening with a PCB that would act on one side as two buttons (with a rubber cover) and on the inside, as circuit board with a FET latching switch (and two normal connections for the recording button).

The outside, with comprehensible, yet unnecesary operating symbols (the buttons will be operated with the thumb, and facing down, so you can’t really see them. I made it this way because the thing you will operate the most is the SD card, and you definitely don’t want that to fall out, hence it being on top).

And on the inside:

The board size is 24x14mm(corners r3), and the inside area is 11x21mm(corners r2). The plan is to have the vias sit on the pads so after soldering the pushbuttons no hole is left and the board can be simply perimeter sealed to the camera body, ensuring it being waterproof. The board will also probably be conformally coated to prevent corrosion.

This will be the latching circuit, got it from EeVblog. I still have to select the particular components, but this should not be too difficult.

 

 

And now, some prototype beauty shots, because I can:

Some more details:

While making sure I had not forgotten anything important in the camera body files, I realized I had no reference point for aligning the gimball to be horizontal, nor a seal around the camera lens (I was kinda going to glue the camera to the ball with sealant, and be done with it, but that’s a bad idea).

So, I added a pair of horizon marks in the gimball front AND a sealing ring groove:

The camera will be held in place with tight foam and a very tight fitting o-ring, but an impact on the lens (wich do NOT protrude from the ball, so it would require to be a very direct hit) will send it inwards, protecting if from a possible lens break. Just dissasemble and pop out if nothing broke.


POWER

Remember what I mentioned before that this thing being batteryless was not totally true?

In the end, part of the job of this camera is to record in case of emergency/crash. When that happens, the possibilities that the magnetic power cord flies off are very high. and then you would totally miss the aftermath of whatever happened. It is then a good idea to have an emergency power unit inside the camera that can record at least 5 minutes after power is lost. I mean, how are you going to keep crashing for 5 straight minutes?

This brought me to a power supply conundrum that made my head hurt. The camera itself can accept a range of voltages from 5 to 20V, with current going from 600mA@5V to 160mA@12V (got no figures for consumption above that).

I could totally use a normal USB powerbank to drive it but a single lipo could not power the camera directly, so I wondered if modifying a powerbank to output 12V and having 2S LiPo in the camera was possible…but also a bit insane, to be honest. After much wondering and a bit of counsel, I found this tiny little board:

And at first I was going to use it as 5Vin-5Vout, but then I realized, the video board power consumption was not the same! @5V it’s about 3W, whereas @12V is 2W!, that’s a huge difference. So I ordered one that would output 12V. As for the LiPo power, I made a quick sketch to see what kind of space I had avaliable in the camera:

 

 

Bottom rectangle is the video board. Middle rectangle with some protrusions is the DC-DC board, and the rectangle at an angle is about the leftover space I could use to put a battery in there. Volume is about 20x6x32mm, wich is not a huge amount of space.

 

I tried hard to find a battery that would maximise the power I could fit in, but in the end I had to settle down with a meagre 180mAh micro Li-Po. Fun thing tho, when I made the rough calculations as to how much would that last, using a very convervative 80% efficient DC-DC, it gave about 14 minutes of runtime. Given I was aiming for 5 minutes, I am exctatic that it can double that recording time. (I prefer to take that number with a grain of salt and assume it is going to just not be as good, even with the 20% losses. Also, current consumption from the battery should be about 600mA, wich is a discharge of about 3.3C, not a level that should destroy the battery easily.

For details on the magnetic power supply connection, please, refer to this post.


FABRICATION

When building something like this, it’s not always straightforward what should be made in wich way.

When I was designing the camera, I kept telling myself that the shape should be manufacturable using conventional tools, and I kept looking at building the body in halves, so the pieces would be machinable from both sides. But as I continued working, I found myself distancing from that rapidly until I effectively stopped fighting the concept and embraced the truth. I wanted a monocoque body for the camera so it would be easier to seal, and I would need it 3D printed so it could have the shapes I wanted, instead of concessions for ease of manufacturability. It should not matter that much, in the end I’ll be making what, 1 to 5 of these? (various helmets, spares, occasional gift for a friend, tops).

So, I settled on having the body of the camera, frontal clamp/face and camera gimball, 3D printed in SLA resin. Luckily for me, I quickly found someone willing to print those for me at a reasonable price I could afford. The aluminium sideplate I can CNC machine at home with little trouble.

By now, some people might be wondering how is that camera supposed to be attached to the helmet. I did ponder for a while on making it attachable to a GoPro latch, but that would have increased the stickout of the camera by a noticeable margin, negating a good amount of the effort put in making it streamlined. I also considered designing a custom low profile mount, and evaluated a few different approaches, but in the end, I opted for the easiest route, attach the damn thing to the helmet directly. Here’s a list of reasons:

  • Single use: I only own one helmet, it’s not like I’m going to interchange the camera around.
  • Security: with direct attachment there are less points of failure.
  • Non commercial: This is for me, and there are no plans to release this as a product, so I can do whatever I want.

Also, embedded in the thoughts about manufacturing, I considered the effects of the camera during a crash. With a very resistant body and attachment system, you risk them snatching into something while crashing and hurting you more than otherwise not having those stickouts. So this camera is thought as a frangible element. In the event of a helmet collision where the camera is in the middle, the resin body will just shatter and be gone easily. If you crashed hard enough for the microSD card to be destroyed in the process, probably you have greater problems than saving the footage of the crash.

This is the end of part I.
Part II will feature the SLA printed body, control button circuit/PCB, sideplate-heatsink and internal power supply and drive, so, the finished camera, so to speak.

See ya!

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