Monday, February 3, 2014

Quadcopter Drone - Component Breakdown

I am traveling for work currently, so can't do a lot of actual "building", so until I can get to actually putting things together, I thought I would break down the components that will make up my Drone, and give a bit more detailed information about them.

DJI Flame Wheel F450 Kit
This is the frame or skeleton of the drone. The Main Hub consists of a top and bottom that are attached to the Booms of the drone. The top is also where I will mount the Flight Control Board and a few other avionic and sensory components. The bottom will carry the battery, camera mount, and is also a circuit board acting as the power distribution center for the drone.

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This particular drone is a “Quadrocopter" and therefore has 4 booms which radiate from the central hub. I think am going to go with the Black and White booms, keeping the Red ones as backup in case I break one during a crash. Shorter booms increase maneuverability, while longer booms increase stability. Booms must hold up in a crash while interfering with the prop downdraft as little as possible. These DJI booms are great combination for both maneuverability and stability.

Props, Motors, ESC Units

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The DJI F450 Kit also includes the following components:
  • 4x 10in props (+2 more for backup in case of a crash), and 4x 8in props. The pairs of props spin in different directions. The Standard Props are the same "tractor" propellers used on standard front-engine R/C airplanes. The "pusher" props are contra-rotating and exactly cancel out motor torques during stationary level flight. Opposite pitch gives downdraft.
  • 4x Brushless Electric Motors. There are electrical "outrunner" types, which is more efficient, more reliable, and quieter than a brushed motor.
  • 4x Electronic Speed Controllers (ESC). Converts DC battery power into 3-phase AC for driving brushless motors.

Connectors - Power, Flight Controller, ESCs, LEDs

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Here we have some of the various connectors for the drone. The larger gauge wires are for connecting battery power to the ESCs. The smaller "jumper" type wires are for connecting the ESCs and Receiver to the Fight Control Board. We also have some random Velcro straps to secure the battery and camera during flight. On the far left are two LED strips, green and red.  Supposed to be for orientation during night flying, but I still haven't decied if I am going to use them yet.

Batteries, Charging Unit

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These are the batteries that will be powering the drone during flight. The larger units are for the drone itself (one is a backup for extended flight times), and are 3600mAh capacity. The smaller one powers the handheld radio transmitter. Both are Lithium Polymer (LiPo) and offer the best combination of energy density, power density, and lifetime. Also shown here is the Battery Charging system and the connectors for the batteries. Standard AC/DC transformer is used for the Power System. The output is 15v @ 4A.

Landing Gear, Vibration Reducing Camera Mount, GoPro Hero3
I will be mounting a GoPro Hero3 Black Edition camera to this drone, and have had to obtain a few specialized parts to do so. The underwater protective housing will be attached to an Anti-Vibration Camera mount, which will help stabilize aerial videos. This will allow the drone to carry its "payload" and help reduce the shaking or "jello-effect" that can occur due to high frequency vibrations.

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Since the camera will be mounted as a hanging payload underneath the drone, I had to find a way to get higher ground clearance. There are a lot of skid-style mounts that achieve this, but they look crappy and are add more weight than what I was comfortable with. So I found someone who was manufacturing carbon fiber leg extensions, which give me just enough ground clearance for the camera. Plus it makes the drone look like a flying spider, so I am happy with how they look. I will eventually be going with a gimbal to stabilize the camera level (pitch & roll) in flight, but that is "Phase 2" of this project, along with FPV.

Radio Control System and Receiver

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I will be using a Turnigy 9XR radio transmitter to control my drone. I like that it has a built in display to quickly bounce between menus and settings, or quickly glance at flight status. It operates on the 2.4GHz wireless frequency. The radio receiver is a FrSky combo that also shows flight telemetry. The receiver antenna is a loose wire whip, that I will secure to the side of one of the booms.

KK2.1 Flight Control Board, 3D Printed Protective Casing
I am using a HobbyKing KK2.1Flight Control Board as the "brains" of the craft. The Flight Controller interprets input from the receiver, battery monitor, and onboard sensors. Also regulates motor speeds, via ESCs, to provide steering, as well as triggering cameras or other payloads. Controls autopilot, and other autonomous functions. The USB drive looking device is used to flash new firmware to the flight controller.  On the left is the speaker, and LED status light that is visible during flight.

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I was able to find a guy on RC Forums that uses a 3D printer to create a derelin "housing" to protect the flight controller. Since this will be sitting right on top of my drone, a crash could easily break the board. The housing works and looks great.

KK2.1 Installation

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 Here is a pic of the control board sitting inside the housing. There is also a laser cut acrylic top that protects while allowing access to all of the needed jumper pins and buttons to adjust setting on the board.

KK2.1 Installed, OCD
And here we have to acrylic top installed. I discovered that most of the threads on the drone are the same size and pitch as my various screws that I use when building custom liquid cooled PCs.  So I was able to use there here as I prefer the matte black look over shiny chrome.  As for the storage and labeling... I have been told that I may have a bit of OCD.

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That’s all for now. When I get back from my travels, I will start soldering the power connections to the central hub. Thanks for stopping by!

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