Head Tracker (Pan/Tilt) Demonstration

I put together a quick video to show what the setup is like to use with the pan/tilt and the head tracker on the Sabre.

Youtube Link

Sabre Setup Updates

 I fell a bit behind on updates to the Sabre and the ground station setup, so this is a long and detailed post.

Anyway, here is a list of updates since the last post:

1. Up to 50 flights now
2. New FPV camera, the Runcam Eagle 2
3. Ground station UHF control repeater has been refined
4. Head tracker. It causes the pan/tilt function to correspond to my head movements
5. I tried the pan/tilt setup with the Mobius in forward module, looking out the clear "bubble"
6. After limited success of the pan/tilt in the forward module, I updated it to be used on top of the fuselage
7. I've been trying several new antennas

Here are a few pictures that I like from the last time out:

A preparation shot from the last time out with the Sabre.

Ready for Takeoff

Ready for Takeoff

FPV Camera (Runcam Eagle 2):
The Runcam Eagle 2 is considered one of the best FPV cameras currently available. It's a CMOS sensor instead of a CCD, which traditionally, has some bad effects, but this camera has improved those bad effects to the levels of CCD cameras. The dynamic range of this camera is exceptional, resulting in excellent light handling abilities. For example, if the view is facing the sun, the ground doesn't completely black out as a result of the compensation for the bright sun. It is also very customizable, and came with a convenient cable and button setup that plugs into the camera to access its internal settings menus. I'm still working on the settings, but the view is a noticable improvement over my previous camera.

The Runcam Eagle 2 Installed on the Old Pan/Tilt Setup

Ground Station Repeater:
I added a BEC to power the ground station repeater. This device is basically nothing more than a voltage regulator. It has two outputs, so I set the output going to the receiver to 5 volts and the output going to the Dragon Link transmitter to 7.2 volts. The advantage of using the BEC is that I can hook up any 2 cell, 3 cell, or 4 cell battery to the input and it will provide the correct (and stable) voltages. In addition, I will be adding a voltage sensor to the ground station, which will be sent to the DX20 live telemetry screen. This will allow me to monitor the voltage of the ground station battery.

Repeater, Back

Repeater, Front

Head Tracker (Trinity):
I bought the Trinity External Head Tracker from Fat Shark. This device mounts on the Headplay and interfaces with the DX20 through the trainer port. Through some programming and configuring, The head tracker can control the pan and tilt to follow my head movements, for a very immersive FPV experience. It is very fun to use when landing FPV. When I'm flying my downwind and base legs of my approach for landing, it's very useful to be able to look out to the side to look at where I am relative to where I will be landing. Using the levers on the back of the transmitter to control pan/tilt while flying the airplane down low for landing is too risky and cumbersome, so the head tracker really adds to the experience here.

Trinity Head Tracker. It's the black box that says "Fat Shark" on it.

Pan/Tilt Bubble Module:
In addition, I had the head tracker set up to control a new pan/tilt on the plane. The Sabre came with a "module" for the nose that includes a pan/tilt setup. It's designed for the GoPro Hero camera footprint, and it looks downward out of a clear plastic bubble. I modified the mount to accept my Mobius HD camera. The idea is neat, and it looks cool in my opinion, but unfortunately, the views through the bubble were intolerably distorted. There was an obvious rippling effect, and the overall clarity of the video was reduced.

The Mobius on the Pan/Tilt Inside the Bubble

In order to use this pan/tilt in addition to the FPV camera pan/tilt, I had to use 2 additional channels. That means that 4 channels were being consumed by pan and tilt, and the programming got pretty complicated between setting the head tracker up to control the 4 channels correctly.

Pan/Tilt Refinement:
I decided to reduce the complexity by putting both the Eagle 2 and the Mobius on the same pan/tilt. I modified the one that was in the bubble to mount to the location on top of the fuselage where just the Eagle was mounted before. Both the Mobius and the Eagle fit on there reasonably well. The standard size servo for pan is much smoother than the previous setup with the micro servo. Overall, it's a much more robust, and simpler setup. To top it off, it's also lighter weight than the two separate pan/tilt setups. It will also make for much more interesting HD onboard videos because the Mobius will always be pointing where the FPV view is pointing. My intent is to provide a ground video demonstration of the pan/tilt, as well as the head tracker.

New Pan/Tilt Setup, Front

New Pan/Tilt Setup, Side

New Pan/Tilt Setup, Rear

FPV Video Antennas:
I've been experimenting with different video antennas. With all the other changes, it has been difficult to focus on experimenting with the antenna combinations, so it's hard to tell if I have gained any improvement yet. I have the following new antennas, all from Video Aerial Systems:

• Ion (RHCP pair)
• Ion (LHCP)
• Airblade (LHCP pair)
• 3 turn helical (LHCP)
• 10 dBi Crosshair (LHCP)

Video Aerial Systems 5.8 GHz Antenna Assortment

I haven't tried the Crosshair or the LHCP Ion yet, but I have yet to go beyond about 2.1 miles before the video becomes unflyable and I have to turn back. So far, I preferred the pair of Airblades over the pair of Ions, but the flights were done in separate locations on different days, so it's not a good comparison. When flying with the pair of Airblades, I was able to notice better clarity at about 1.5 miles when switching the receiver to the helical. Using the Crosshair should improve on that result further. 

Repeater "Stand"

I finished a quick and somewhat crude stand for my repeater. The main idea was to have a way to keep the Dragon Link transmitter antenna vertical and have it be easily portable.

I made it out of foam board. I used magnets on the bottom so that I can use the heavy ammo can that I always have with me at the field as the base. The Dragon Link transmitter just sits in place, and is held by the rubber band and a dowel, much like how I've done Dragon Link Transmitter mounts for radios.
For now, I will be using one of my 2S 4,000 mAh batteries from my RC monster truck (Traxxas Summit) to power the ground station. That way, I will never have to worry about the amount of battery left, as it is way more than it could consume in a flying session. In the future I will upgrade to a BEC to power the ground station. That way, I can just plug in any battery I want and it will give the correct voltage to the OrangeRX and the Dragon Link transmitter.

The Setup, Front.

The Setup, Back.

The Bottom of the stand, showing the 3 magnets.

New FPV Antennas for the Sabre/Headplay

I had previously been using a really cheap (and bad) set of video antennas on my setup. I just ordered a pair of Video Aerial Systems's (VAS) Ion antennas. One goes on the video transmitter on the plane, and the other goes on the video receiver on the Headplay head set.

The Ion is a very compact omnidirectional antenna, which claims to have the highest gain of any omnidirectional antenna on the market for FPV. This means that the radiation pattern is compressed into more of a disk shape, rather than a sphere. This is ideal for extending my video range because it means the radiation pattern isn't getting wasted in the vertical direction, and instead can extend further horizontally.

The Ion also has a very high standing wave ratio (SWR), which means more energy is sent in the signal that would otherwise be lost to heat due to internal reflections in the antenna.

I may find that they increase the video clarity as well. I'm really looking forward to giving them a try.

The cheap pair of antennas. I couldn't even find any name or
polarization designation on the package.

Headplay SE with the Ion Antenna

The Ion Antenna mounted to the Video Transmitter in the Sabre Wing

Repeater Setup for Dragon Link

I posted a "Mini How-To" on my RCGroups blog, located here.

The Dragon Link UHF transmitter is designed to interface with the trainer port of the radio (in my case, the DX20). The trainer port outputs a PPM data stream, which (I didn't know until I was configuring my DX20) is limited to 8 channels. The solution to be able to use more channels (up to 12) is to use a repeater setup.

To make a repeater setup, I'm using an OrangeRX receiver that can output an SBUS data stream (digital) to the Dragon Link. So now I will be using the Spektrum DSMX protocol of the DX20 to communicate on 2.4 GHz (as designed for normal range aircraft) to the OrangeRx. The OrangeRx's SBUS output is wired to the input of the Dragon Link transmitter, which has been reconfigured from PPM to SBUS. Now I have a separate "repeater" (takes the 2.4 GHs data and repeats it as the output from the Dragon Link transmitter) station on the ground with the OrangeRx and Dragon Link transmitter, rather than having the Dragon Link plugged directly in the DX20.

This means it's a far less bulky setup for moving around at the field while flying. It also means I don't have to remember to try to hold the Dragon Link antenna vertical for maximum signal reception, because the module will be fixed in place to be vertical. I finished the 12 channel setup tonight, and verified that either failsafe condition (2.4 GHz  or Dragon Link failsafe) will trigger the return to home flight mode in the Vector flight controller. I still need to make some kind of stand or container to mount the components to.

Dragon Link Transmitter, OrangeRX Receiver, and 2 Cell Lipo to Power Both

Sabre Flights 44 and 45, Headplay, DX20, Pan/Tilt

All the gear, getting ready. There's a lot of setup that does into
flying with this much equipment!

Flight 44 Onboard Video

Flight 45 Onboard Video

Sunday was another good day with the Sabre, with several firsts:

1. First time flying with the DX20
2. First time flying with pan and tilt on the FPV camera
3. First time flying with the Headplay SE headset
4. First time flying FPV with a DVR for the FPV feed

Overall, having the pan and tilt operating on the FPV camera greatly enhances the FPV experience. It was very enjoyable to be flying in 2D hold mode, while just looking around. It's really neat to be able to look all the way back see either wingtip. Also, looking down while in loiter mode was neat.

The Headplay video monitor was great. I was able to wear it as long as I felt like flying FPV without ever getting uncomfortable. There were no hotspots or areas of discomfort at all. The FPV experience is greatly enhanced as well because the screen is just so much better than what I was using. I was able to see enough detail on the ground to be more confident to land both flights while flying FPV. 

The Headplay came with a DVR so I was able to get some recordings of the flights, which is nice to have, but also is great for peace of mind. If the plane goes down, I should be able to review DVR footage to get an idea of what went wrong and where it went down.

The DX20 was fantastic as expected. The slow operation of the flaps was great to smooth out their application. One unexpected minor annoyance happened though. There are certain functions you do with the Vector that involve rapidly toggling the mode switch a certain number of times. Due to the way I programmed my mode switch, this wasn't working without also toggling my second mode switch. I have since reprogrammed the mode switch mixes in the DX20, and reran the Vector's receiver analysis tool, to be able to access the menus normally.