Wednesday, February 26, 2014

Quadcopter Drone - Receiver Wiring & Antennae Mounting

Haven't had a chance to do much in the last two weeks, but I was finally able to sit down for a bit and make some progress on the drone.  First up, going to show what I have done with the Receiver, both connecting it to the flight controller board, and setting up the antennae.  Here is what the receiver looks like out of the box, with the "whip" style antennae.  I have been reading that for the best possible signal reception, the antennae should be mounted at a 90 degree angle from each other, so I will show how I achieved that on my Drone.


The Receiver itself is mounted to the frame using Velcro tape so that if needed, it can be easily removed.  Before attaching it to the Drone, I plugged in the servo leads, and labeled them to make it easier to keep track of which cable is which.

Here are the same leads, again labeled with Roman Numerals, plugged into the Flight Controller.  

Now that the Receiver is mounted to the frame and wired up, its time modify the antenna.  As mentioned before, I wanted the two whips to be set up in a 90 degree angel, so this is what I did to achieve that.  Using some acrylic leftover from my most recent Liquid Cooled PC Mod, I cut a small block and drilled a few holes into it.  I then inserted antennae tubing into the holes, which are set up with the 90 degree angel and the whips can go directly through them.

Here is a close up of the tubing with the whip pulled through and capped off with a rubber end cap.

And here is the setup attached to the frame next to the Receiver.  I used double sided tape and zip ties to secure the antennae mount to the frame.  It is very secure, and I am pleased with how it turned out.  

The next thing I had to do was change out the connector on my batteries.  They came with the "bullet" type connectors, but for use on my Drone, and to charge them, I needed to change it out with a TX60 connector.  Nothing too complicated here, just cut off the bullet connectors, and soldered on the TX60 leads.

Here is the finished connector, with heat-shrink tubing applied. 

And here we have the battery charging with the new connector, hooked up to my Turnigy Accucell.

Now we are going to attache the LED indicator and Speaker to the Flight controller.  Out of the box, the KK2.1 flight controller only comes with the speaker.  The speaker gives audible chirps to notify of status and errors with the flight controller.  This works great up close, but not whey the Drone is more than a few hundred feet away.  So an LED is needed for visual indicators.  

I purchased the LED on eBay, and then modified the wires on the Speaker to match.  Both the Speaker and LED can be plugged into the same port on the flight controller, so to use both at the same time, I made a Y adapter with FST connectors.  I would have done the same twisting wire look with the Y-connector, but I ran out of the wire I needed, so just did a few turns instead.

The speaker is tucked inside the frame and is not visible from this angle.  The LED was attached to the back of the Receiver, which is the "back" of the Drone, so I can see the indicator while in flight.  Going to set things up to that as the battery loses its charge the LED will flash faster and faster to let me know when its time to head back.

Now that everything is plugged into the Flight Controller, I figure its a good time to show a pin layout for the board, along with a bit of explanation at to where things get plugged in.  The leads from the receiver control plug into the left side of the board.  On the right is where the ESCs are connected, and control the motors.  I actuallly have to make one small modification with lead #1 to provide power for the the flight controller, but that will be in a future post.  

Last we have the LED / Speaker indicators that we just went over, and the Voltage Monitor.  The Voltage monitor basically just allows the flight controller to know what the battery level is at, and uses the speaker and LED to show that battery status.  Battery status will also show up on the LCD screen.

Next up I will show what I have done to give my Drone some Directional LEDs for night flying.  Thanks for stopping by.

Sunday, February 16, 2014

Quadcopter Drone - Body Construction & KK2.1 Firmware Flashing

Now that we have have gone through the components that will make up the Drone, its time to start construction!  I figured the best way to show this was by making a video and posting it to YouTube.  This only covers the construction of the body, which consists of some simple soldering, attaching the booms, and at the end modifying an anti-vibration mount for the GoPro.  Check it out here, and hit up the link if you want to watch it in Full screen 720p HD.

Here is a picture of the body fully assembled, and a look at the small modification I had to make for the anti-vibration mount.

And here we have the body again, but this time with the GoPro mounted.  Can't wait to start shooting some aerial videos!

Now that the body is set up, time to add the Flight Controller.  I will be using a HobbyKing KK2.1 flight control board.  There is already a new version of Firmware available, so lets go over flashing it before I install the board onto the Drone.  Here we have the KK2.1 plugged into my Laptop using a USBasp programming tool.  These can be found at various Hobby Stores, and even on Amazon for $5-8.  Be sure to grab one that has a 6pin ribbon adapter, as that is what you will need to interface with the KK2.1 board.  I recommend this one from Amazon, as it comes with everything you will need to get started.

You will need to install the necessary USB drivers for your Windows PC to detect the device, before you can flash any firmware to the control board. First step is to plug in the USBasp device, then open a web browser and download the most current drivers from this website. Once downloaded extract the .zip file to your desktop or an other directory where it will be easy to find later.  While you have your browser open, also download the KKFlashTool from this website. Now that we have the needed drivers and software, navigate to the Device Manager and locate the unrecognized USBasp device under "Other Devices".

Click on images to see a larger version.

Right-click the USBasp device and select "Update Driver Software..." from the menu.  Now browse to the directory where you extracted the downloaded driver to, and hit "Next".

The driver install process will begin, and you will get a prompt saying that "Windows can't verify the publisher of this driver software".  This is safe to ignore for this particular driver, so select "Install this driver software anyway".

You will now see a window showing the drivers for this USB device were installed successfully on your computer.

Back in the Device Manager, refresh the list and you should now see USBasp device is now recognized, and resides under the hardware tree as a normal USB device.

Ok, now unplug the USBasp, and open the KKFlashingTool you downloaded earlier.  Once the screen below pops up, plug back in the USB device and select it from the "Choose your programmer" menu. Then under "Choose your controller", select the KK2.1 from the drop-down menu.  Now select the source for the new Firmware.  There is both an online repository for custom Firmware and the option to select from a local directory.

Once the desired Firmware is selected hit the Green Circle (with the runner inside) and the flashing process will begin.  It will take about 30 seconds, and you should hear a few beeps coming from your KK2.1 if you have the speaker plugged in.  Once complete you should see a dialouge similar to this at the bottom of the KKFlashingTool, telling you the flashing was successful.

If you would like to have a more detailed walkthrough, the website where you download the Flashing took has both manuals and video tutorials to watch.  I am currently using KK2.1 ++ BETA firmware, created by user RC911 over on the RC Groups forum, but there are many options to choose from, including stock v1.6 as of Feb 15, 2014.

Now that my flight controller has the Firmware I want installed, its time to mount it to my Drone.  I used some anti-vibration pads that have adhesive on both sides.  It mounts securely, and is supposed to reduce mico-vibrations from having too much impact on the flight controller's sensors. 

That's all for now.  Next up we will be connecting the ESCs, Receiver, and modifying the antenna whips.  Stay tuned, and thanks for visiting!

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!