Saturday, September 19, 2015

Quadrotor FPV Racer

I needed a new hobby. I just don't have the resources to do the kinds of machining projects I have been doing in the past. I kept seeing a really cool concept pop up on various sites: FPV racing. Basically people are building mini quadrotors (5" diameter propellers) and flying through various found obstacles (forests, abandoned buildings, playgrounds, etc...) or purpose built race courses with gates to fly through. Each racing quad had a small analog video camera and video transmitter. This sends low latency video back to the pilot. The pilot wears video goggles so it feels like sitting in the racing quad.

After watching some videos I knew I had to build one and get into this hobby. There are tons of tutorials online suggesting which parts to get to build one. I figured since I had 0 experience with FPV racing I would go with standard parts and make my own custom one after learning more.

A week after deciding I was getting into the hobby I had this show up at my door! I pretty much went with the standard parts from Lumenier. This wasn't the cheapest option, but I knew the parts were decent and would work together.

The frame was much higher quality than I had expected. The edge surface finish and dimensions were all perfect. I hadn't worked with much carbon fiber before this, so I finally got a chance to feel just how good carbon fiber's stiffness to weight ratio was.

Here's all of the power wiring. There's a nice power distribution board I could use to connect the ESCs. There are also LED boards that let me keep track of the quadrotor when flying without the FPV goggles.

 I made mounts for all of the electronics using 3d printed parts. This was much cleaner looking than the usual hot-glue and tape techniques used in all of the tutorials I saw for building this type of quadrotor.

Here's the final assembly. It looked super clean and was ready for a first flight. The radio mount was pretty heavy, but I needed something to protect it. I also didn't have enough room inside the frame to hold it.

I quickly discovered that my camera needed to be tipped upwards. When trying to fly quickly the quadrotor tips steeply forward. This means you look more at the ground than what you're flying towards. I could only tip the camera 15 degrees, but this made a huge difference for me.

I also made a carrying case for all of my equipment. I had the case lying around in my apartment, but it needed foam. I bought some furniture foam (bad choice: too squishy and hard to cut) and made cutouts for everything I needed for a day of flying.

I managed to find a local group of other FPV racers and finally had people to compete with. Unfortunately my riskier flying led to some hard crashes. The video transmitter mount was shattered in one impact. I need to get a less brittle material for the mount parts (or just make them harder to directly hit).

I also went through a bunch of propellers. Broken parts start to add up and really increase the cost of the hobby. Thankfully I only broke my 3d printed parts or propellers. The pricey electronics, motors, and frame have all held up well.

I also discovered the original FPV camera had some latency. This made flying very difficult. I opted to buy one of the popular "board" cameras.
The new camera left me with more space inside the frame. I was able to sit the video transmitter under the carbon fiber, so I saved a bunch of weight and made the build look significantly sleeker.

Overall FPV racing has been a fantastic new hobby to get into. It take a fair amount of practice to be competitive with the other racers, but the feeling of flight you get is worth all of the effort. It's like a video game, but much more exciting. Crashing has real consequences (breaking expensive parts), which really gives an adrenaline rush. It's also cool being able to see the real world from a new perspective, something you just can't get in a video game. I still need to get a proper recording camera so I can share my best crashes.