Armageddon421's Hackingblog

From zero to the first FPV flight with my hexacopter

by on Mar.11, 2014, under Multicopter, Projects

It was a long, bumpy road to get this project this far. I’ll tell you a bit about my latest experiences with my custom built hexacopter and another bit about the history of this thing in the last two years because this is my first post about it. Since I made some videos every now and then, I’ll add them in the appropriate places. The latest one can be found at the bottom of this post.

First Verison Hexacopter

First Verison Hexacopter

It all started of with the idea to build a quadcopter. As always, buying finished products is boring. Also: the bigger the better. So I decided to start off with six rotors right away. I clicked myself some parts from hobbyking and started fiddling around. Since I used the cheap 10$ flight control from hobbyking, there was no attitude/auto level mode and it was difficult to hold the height. The frame of the first version consisted of some cheap carbon rods and a 3D-printed center plate to hold it all together. I added some wooden sticks and tons of hot glue to increase sturdiness, but it was still a pain. Watch my first hovering tests!

The decision to remake the frame was really a no brainer. I swapped the meanwhile splinted carbon and wood for some strong aluminium bars from the next hardware store. The other parts are still 3D-printed, but completely redesigned. I did a small sturdiness test by dropping a half-liter glass bottle full of water on it. Watch it!

Shortly after that, I got a request to do some aerial video at an outdoor event. I was excited to do this so I lent a GoPro Hero 2 from a friend (not owning any small camera myself at the time) and replaced that shabby flight control by a DJI Naza. After the first few test flights during the preparations of the event I was so glad everything worked, that I left the hexacopter in my car that was unfortunately parked in direct sunlight the whole afternoon while helping with the preparations for the event. This resulted in all 3D-printed parts melting, rendering the whole thing useless.

Heat-bent hexacopter

Heat-bent hexacopter

The event was the next day, so I had to improvise. There was definitely not enough time to print all the parts again, so I made two decisions: reduce the rotor count to four and improvise the motor mounts. That way I only had to print the now smaller center plate and the landing legs. The motors were mounted directly to the side of the bars, leaving only a gap of about 2mm between motor and bar. Note that the motors have the mounting holes on the same side where the propeller goes. What a mispurchase. After a long night the thing was back in the air and I could fly on the event in medium wind no problem. Because the thing was much lighter and I used the same battery, the flight time increased heavily, too!

A few weeks later I decided I could finally try to fly a flip. I did not know that the Naza has a very limited angular rate at that time, so my attempt to flip the thing resulted in it flying a big arc and crashing into the ground upside down, breaking basically everything.

The next week my hobbyking order arrived. I got some hobbyking donkey motors because they are cheap and sturdy, using ball bearings instead of friction bearings. The frame got a redesign, too. All parts were laser cut from some plastic I found instead of 3D-printed, the bars remained the same. I also discarded the outer ring of bars, drastically reducing weight.

Latest version hexacopter

Latest version hexacopter

That build was stable and powerful enough to easily lift a 1,6kg Teddy Bear, considering the rope was attached to the hexacopter quite a bit off-center. Watch it!

That video was already shot with my GoPro Hero3 black editoion attached to an AlexMos/SimpleBGC controlled brushless gimbal simply screwed to a wooden board. The next step was to mount it to the copter. Have a look!

Buying a wireless video system and the matching camera was the first step to finally flying FPV. But it still took me over half a year to get there. I first mounted the camera system on my RC car and drove around shackspace. Another video…

A while later, being a 3D fanatic anyways, I bought the Zeiss Cinemizer 3D-glasses. Integrated batteries, RCA and HDMI made them the product of my choice, despite the heavy price tag. Now I only had to mount the camera system to the flying thing.

A little 3D-printed frame and a screw was used to hinge the camera to the copter. I turned on the setup, but I could not receive image from the camrea on the other end. Seeing no static noise I concluded the problem must be in the camera, not in the sender. Then I smelled it. Hot electronics. The IC on the back of the camera board was searing hot. After a few retries and wiggling the cables to find any shorts or bad contacts I gave up and ordered a new camera.

When the new camera arrived I removed the old camera from the copter and decided to give it a try on the lab power supply. It still worked! Seems like the ground pin was covered in some goo, directing all the supply current through the video signal pin. That must be what heated up the IC. Luckily it survived! I put it back on the hexacopter and everything worked fine. Off to the first try!

There were a few problems, though.

The camera mount was somehow too weak. Some screws were loosened, probably by vibration, tipping the camera over mid-flight. Seeing only straight down when looking into the VR-glasses, I retreated to normal vision and quickly landed the thing. At the same time I noticed the battery warning flashing like crazy, so the weak screw probably saved the life of the whole copter!

I conclude that one of the next steps would be a HUD or some other way to keep track of battery and system status, possibly using a different flight control.

Charing the battery I noticed only about half its capacity could fit in. I used it quite often so it’s okay it won’t reach its specified capacity anymore, but half is a bit weak. I probably have to tweak the settings for low battery warning and safe landing voltages in the flight control.

That’s it for now. If you have any questions, feel free to ask in the comments here or on any youtube video!

Summary
Article Name
From zero to the first FPV flight with my hexacopter
Author
Description
It was a long, bumpy road to get this project this far. I'll tell you a bit about my latest experiences with my custom built hexacopter and another bit about the history of this thing in the last two years because this is my first post about it.


4 Comments for this entry

Leave a Reply