DJI Phantom 3 Versus Custom Built Camera Drone

Anyone reading this blog (does anyone read this blog?) would know that I have built quite a few camera drones - SK450, SK450 Deadcat, S500, S500 Hexacopter.  Most of them used commercial frames, APM or Pixhawk controller, and Gopro or similar cameras.  They all worked, some of the time, and I enjoyed building them.

But I was tempted by a very low price on a DJI refurbished Phantom 3 Standard and bought it.  What was it like getting a pre-assembled and integrated drone working?  In short, very good.

I will not do a full review but just highlight the big differences between a home built drone and the DJI.

Debugging - no debugging needed, just follow the instructions, watch a few Youtube videos, update the firmware and it was ready to fly.  Contrast that with hours and hours trying to get a DIY drone working well.

Features - The DJI has more features than my homebuilts, although I could add more.  Specifically, the DJI came out of the box with failsafes, FPV, full camera control from the ground, auto takeoff and land, as well as full OSD (on screen display).

Flying - I guess DJI has a lot of experience with people crashing their drones and complaining.  The Phantom is easier to fly and has a beginner mode to keep you safe.  The auto takeoff and land also prevent a lot of crashes.

Camera - The DJI camera is pretty good, maybe not quite as good as the Gopro Hero line, but acceptable.

Accessories - Good and bad things here.  Accessories like carrying cases, landing gear extensions, and props are readily available at reasonable prices.  DJI batteries are proprietary and expensive.

So all in all a very good experience with DJI Phantom 3 Standard for about $300 USD.  If you are more into flying and photography than building and debugging, I definitely recommend it.

Short Review: Olympus Air as Drone Camera

As a dedicated Micro 4/3 Mirrorless camera user, I thought it would be great to try the new Olympus Air A01 camera.  This is similar to a product put out by Sony which attached a photo-quality lens to a Smartphone.  However, the unique ability of the Olympus Air is that it will take any interchangeable Micro 4/3 lenses.  Price is low: approximately $299 street price in USA for body only.

Olympus AIR A01

I received the AIR yesterday and rushed to get it charged (about 4 hours) and get it set up.  It is not a perfect product and there are a few warts, some of which could be fixed in future software.  The cylindrical body of the AIR is quite small and light, and it communicates with your IOS or Android device via Bluetooth and Wifi.  This has some issues as you disconnect from your home wifi to access the AIR wifi, as the AIR sets itself up as an access point.  You also have to download the correct Olympus AIR app, and set a few things up.  The normal mode of use is to clip your smartphone to the back of the AIR and use it as a viewfinder and remote control.  I tried this and it works as advertised.

The AIR has the following useful qualities for drones:

• Professional quality sensor (16MP) and lenses, Full HD at 30 fps
• No added functions, buttons, screens, & grips which are normally part of a photo quality camera - you don't have to lift a whole DSLR to get Photo quality
• Tripod mount - invaluable as you can easily adapt it to existing gimbals and mounts
• Interchangeable lenses
• Autofocus, image stabilization, face detection, long list of DSLR type features
• Ability to turn off wireless connections so they do not interfere with drone radio control
• Built-in battery
• Light - I measured 368 gm for the AIR with a Panasonic 14-42mm zoom lens, which is not the lightest 4/3 lens by any means.  The AIR alone is about 150 gm.
• Open API interface so software could be written to control the camera and lens in flight

I rushed to get it installed on my test mule drone, an SK450 Deadcat.  I found a tripod mount that attached to my existing Gopro mount, but it was not ideal as it mounted the AIR too high and too far forward, but it sort of worked (see photos).

There are a few drawbacks to the AIR, which I will list below, mainly concentrating on drone-specific items:

• The setup is complicated, you have to read the instructions carefully and follow them
• The app is not intuitive, some updates needed here
• Wifi video transfer to smartphone takes a long time for some unknown reason, about 10 minutes for a 3 minute video.  I recommend connecting the AIR via USB to your PC where the transfer took about a minute.
• You have to keep your smartphone hooked up to the AIR by wifi and bluetooth, and the smartphone will try to go back to its home network if you turn off the AIR or connection is lost, causing you to have to go back to the setup menu and reselect the right networks again.

Olympus AIR with Panasonic 14-42mm lens

SK450 Deadcat with AIR

Closer View of Not-So-Great Mount

First Successful Quadcopter Autonomous Mission

After all the adjustments to the Deadcat SK450, I took it out to the local "park" (remote muddy field) to try a mission.  It was a simple mission, fly to a few waypoints, circle at one waypoint, return to launch, then land.  It actually worked!  Here is the video:

More Fixes to the SK450

I am plagued by poor loiter on the SK450 and have made further changes to improve things:

1. Fixed the slop or wobble in the GPS mast.  It turns out that the cheap mounts rely on being able to screw down the knurled flange until the mast mount inside is snug.  However, a lot of them cannot be tightened.  I added a plastic washer from an old prop to the mast as shown and the wobble stopped.
2. The APM mount was maybe moving in flight, so I remounted it with the special vibration reducing foam rubber and I secured the USB cable better so it could not move the APM.
3. Added a little foam rubber inside the micro APM case to ensure the barometers were not getting fooled by the prop wash.
4. Wait 5 minutes after power on to get the GPS and all sensors stable before trying a flight.
5. Added some practice golf balls to the landing gear so they do not catch in the grass when taking off or landing.
   
6. I very carefully recalibrated the accelerometers, making sure that the quad was absolutely level during the first stage of calibration.  This made a HUGE difference versus my previous "it looks level" calibrations - the test flight was much beter with much less yaw and pitch on takeoff and during flight.
7. Made a stand out of a medium size plastic storage container as shown:

Pixhawk Versus APM Comparison Review

This blog entry compares two flight controllers from the Ardupilot 3DR-Open-Source stream: the generic APM 2.X controller and the Pixhawk.  I am an intermediate multirotor builder and flyer, so this comparison will focus on functionality and useability, not on advanced features.  Also, this review is based on my experience with 5 different APM modules (none sourced from 3DR) in three different physical forms: standard, mini, and micro (also called mini by some) sourced from Hobbyking and generic Chinese manufacturers.  The Pixhawk is available from multiple domestic and Chinese sources and you should check the reviews to make sure you are getting one with decent build quality.  Each was used with corresponding GPS/Compass units from the same manufacturers.  I built three different quadcopters and used them with different controllers.

Feature/Characteristic	Generic APM 2.X	3DR Pixhawk	Comment
Size/Weight	Small	Larger	APM is available in 35x35x5 mm board.  Pixhawk is 81x50x16 mm
Cost	Low	Higher, about 4X	APM with GPS ~$65
Quality	Variable	Better	Inspect a generic APM after you get it for poor soldering, loose USB..
Support	Good	Good	The best support is from peers on DIYdrones and APM forums
Flight Stability	Good	Good	This is my experience with a well setup APM and Pixhawk, your experience may vary
Accuracy	Good	Better	It does depend on your GPS and its accuracy.  Pixhawk has a more powerful processor and more memory
Onboard indicators	Poor	Good	Pixhawk has multiple LEDs and tones to tell you status, APM has a few LEDs
Ease of Setup	Moderate	Moderate	More components to interconnect on Pixhawk, but well documented. Cables and connectors often an issue with APM and documentation must be found on the Internet.
Ability to fly autonomous missions	Yes	Yes
Mission Planner Ground Station Compatibility	Yes	Yes
Flight logging Capability	Good	Better	Pixhawk logs more information and has a microSD for storage. APM has limited storage of most important variables.
Upgradeability	None	Yes	APM code is now frozen to my knowledge, but Pixhawk software with improvements still being released
Debugging difficulty	Good	More difficult	APMs seem to always work, Pixhawk is more finicky about ESCs, setup, etc.

Overall, both controllers are excellent and have worked well for me.  The APM is a better fit for small quadcopters and is probably better for the beginner builder due to its simpler setup and low cost.  The Pixhawk is very good but it takes more time to set up and it is likely higher quality and performance, so it works well in larger camera quadcopters and similar expensive vehicles.

APM equipped SK450 "Dead Cat" Quadcopter

S500 Quadcopter with Pixhawk

Further Enhancements

After the exciting flight last week, I had to repair the Quadcopter as one of the arms broke in a landing.  So I decide to make a few enhancements:

1. Put in a new APM controller and GPS to fix the Loiter issue.  This did not turn out well as the new controller was defective but the GPS seemed to improve things.  The new GPS is Hobbyking brand, old one was a "no-name" with some mods to make the cable work.
2. Improve power feed to the controller and receiver by using a UBEC (battery eliminator) instead of the power feed from the ESCs.  This is recommended due to the interference from the ESC and I do think  it improved things.
3. Get rid of extra wires in the controller wiring harness.  Done.
4. Install new arm.  Did this, I learned from the dearly departed Flying Flowerpot quadcopter that it is almost impossible to properly fix a quad's arm and they are reasonably cheap.
5. Performed a test flight and analyzed logs.  Seemed to improve things with few glitches on barometer and GPS and more stable flight.  Testing will continue.

Don't Try Auto if You Cannot Loiter

Learned a new lesson yesterday, should not have needed to learn it, because it is obvious.

If your quadcopter cannot LOITER successfully, don't try an AUTO mission.

I headed over to the local "park" - more like a remote muddy field that the county calls a park - to fly my quad.  The plan was to check out AUTO mode with the program shown in the previous blog entry.  I forgot, or ignored the previous tests that showed that LOITER mode did not work well, the copter bobbed up and down and did not hold position.

So I try taking off in AUTO mode with no luck, then do a manual takeoff and flip the switch for Auto mode.  At first, things seemed OK, then the quad headed for the river, gaining altitude.  Before I could react, it was over the Potomac at about 75 feet, then it dipped below the tree line and I could not see it.  I flipped back to manual (Stabilize) control and thought "that quad is gone".  I hit the throttle to try and bring it back up above the trees and it appeared as a little speck in the distance.  I then was able to bring it back with some skillful (lucky) stick work and land it.  Was I ever lucky!

The saving grace is that it took some great video footage while on its semi-controlled mission.  Also, this is why you should not fly near people, as this could happen to you and someone could get hurt.

Here is the video:

Status of the DeadCat SK450

The Deadcat SK450 is working fine.  A few minor modifications:

• packaged up the APM controller and mounted it on anti-vibration foam
• added a LiPo batter monitor
• tidied up some cables

A photo with some details is shown below.

I am also working on a new mission which includes takeoff and landing in the Mission Planner software, see below.

Quanum FPVplus Wide-Angle 1080P HD FPV Camera with 5.8GHz Transmitter Review

I recently purchased this camera from Hobbyking with the intent of using it for video recording on my quadcopter and perhaps FPV operation.  The camera takes still photos, videos, and real time video and incorporates a transmitter so you can use it for FPV flying.  It is an integrated alternative to using an FPV camera and separate 5.8 GHz transmitter and it follows the GoPro form factor to a large extent.

After some use, here are my views on this product.

Positives

1. It uses the Gopro form factor, so it can use Gopro accessories.  It is lightweight.
2. You need to do some work to adapt this to your quadcopter:
1. You have to adapt the supplied cable to provide a 12V supply to the camera.  It has no internal battery so it is useless without power.
2. It has no included mount or tripod threaded hole so you need to adapt a Gopro mount to your purpose.  This can be done with the usual hobby tools.
3. The video is of acceptable quality, quite good in fact, see the video sample below.  This was taken with no gimbal, a shock absorbing mount, and reasonably balanced props, so it still has some shake.
4. Construction seems rugged.
5. With the included transmitter and antenna, it is easy to set up for FPV operation.  I was able to connect the camera to my RX LCD5802 7 inch monitor in about 5 seconds - truly easy.
6. Downloading the videos to a Mac or PC is easy using the microSD card.  Note that the camera will not work without a card.  Also note that the developers seem to have used Huawei phone software as the base for this product - you will see some directories and files that are unusual for a standard digital camera.
7. I recommend always connecting the antenna when the camera is powered up.  Some RF transmitters can burn out if they have no load like an antenna.  Don't know if that is the case here, but better safe than sorry.

Negatives

1. It is difficult to know what mode the camera is in as there is no LCD display and only one LED to provide status.  Spend some time with the very brief instructions on your workbench to familiarize yourself with operation before flying.  Otherwise, you may take off with the camera turned off.
2. The MicroSD card sticks out and can be easily ejected.  You may want to put some tape over it temporarily so you don't eject it at an inopportune time.  You also need to consider this when you adapt the camera to a Gopro accessory.
3. You cannot adapt an onscreen display (OSD) to show quadcopter telemetry on your ground screen as the video to transmitter inteface is within the camera and cannot be accessed to insert an OSD card between camera and transmitter.

In summary, I recommend this camera as a simple to set up FPV camera and transmitter system for quadcopters and other UAV.  It is easy to set up, provides good video, and is rugged.

Rear View

Side View with antenna removed

Side view with MicroSD slot, mode switch, connector

Gopro mount modified to accomodate antenna, cable, switch, etc.

Latest flights - SK450 Deadcat

Got three flights in last week and the quadcopter is still in one piece.  The video from the quad is cleaner than before as there is less vibration, but still a bit of jello.

Balancing a Quadcopter

After a short break, I am back to working on the Deadcat SK450 quad.  One thing I am learning is that balancing the quadcopter is important.

Model aircraft are very sensitive to their point of balance, but I did not realize quadcopters had a similar tendency.

If your quadcopter, properly calibrated with the trims set at 0, tends to go forward or backward slowly after takeoff in Stabilize mode, you are likely nose (forward movement) or tail (backward) heavy.  If your quadcopter is not symmetrically built (left to right across the centerline), you could also see a consistent movement left or right.

The solution is to move equipment to counteract the imbalance.  The battery is usually the easiest thing to move.  The process is like this:

1. Take a short test hop inside or in very calm winds and note which way the quad wanders.
2. Move the battery back if you wander forward, or move the battery forward if you wander backward.  Mark the battery's new position with masking tape.  See figure 2 for battery installation (farthest to rear) on my quadcopter when camera is installed.
3. Try another test hop, see if the quad will hover in one place.  If yes, the balance is OK.
4. If it still wanders, move the battery as in step 2. and also move the tape.   Take a test hop, see if it is fixed.  Repeat until you get a nice stable hover, something like you see in the video below.  My problem was the quad moving forward consistently, which is now fixed, it still moves from side to side due to my clumsy control inputs.
5. Once you have the battery in the right spot, leave the tape in place and mark it so you know where to put the battery next time.  See figure 1.

Figure 1 Tape markings for different quad configurations

Figure 2 Battery installed in camera configuration

You may have to do this for different configurations, like with and without camera, so you would have two markings for where to put the battery.

Don't add weight to get a balance unless you really have to.  Adding weight just decreases flight time and dynamic stability.

Back Up and Running

My Deadcat SK450 is back running and as well as ever, the youtbe proof is above.  The modifications I made:

1. Replaced 3DR Pixhawk and GPS with Hobbyking Micro APM and no-name GPS.
2. Removed 3DR power monitoring module.
3. Used Spektrum DX6i radio and DX610 receiver.
4. New landing gear shock absorbers (see picture).

The finished unit is shown below:

Reconstructed Quad

The other mods are shown in the following pictures:

Deadcat SK450 Test Flight

New Quadcopter Build: SK450 Dead Cat

Now that we are back from Florida and parts have arrived, it is time to start the new build.  I salvaged whatever I could from the Flying Flowerpot (may it rest in peace).  Two motors, the four speed controls, battery, flight control, receiver, and camera were all salvageable.  However, I decided to replace some of these parts and to change the configuration of the quadcopter to "Dead Cat" - a non-square quad setup with more room for cameras.  See the picture below for the basic setup, not fully assembled.

The other changes that I plan to make are:

• New flight control system (Pixhawk) with more accurate GPS (LEA-6H).  I bought the genuine 3DR versions instead of the Chinese clones to ensure quality.  My old APM 2.6 system was a Chinese clone and had limitations and unknown quality.
• New receiver (Spektrum AR610).  This receiver is highly regarded compared to the Orange R615X, which has rumors of range issues.  New Spektrum DX6i transmitter.
• Use of a PCB as a frame to distribute battery power, bought from Hobbyking.
• Dead Cat configuration using a conversion kit from Hobbyking.  I made a mistake and assumed that all I needed was the previously mentioned SK450 Dead Cat PCB, but it turns out that you need this plus the Dead Cat conversion kit.
• Full monitoring of power by the control system.  This was included with the Pixhawk.
• A proper cover instead of a flower pot, sourced from Quadrysteria.com.
• Receiver power from the Pixhawk or separate UBEC, not from the ESC's.  This should be higher quality power with less interference.
• Use of loctite on all screws to reduce the chance of loosening with vibration.
• Carbon fiber props.

The new control and radio system are shown below.

RIP Flying Flowerpot

Pre Flight

The Flying Flowerpot has gone to the great beyond, aka the garbage bin.  It was a great first drone to build, I learned a lot, but it had its share of problems.

For the last flight, I programmed it via Mission Planner to fly a rough polyhedron at 60 feet over the River Mills Park near the Potomac River.  It accomplished this and then loitered.  When I switched it back to Stabilize mode, it somehow became unstable and did a death dive.  This broke the internal frame, two arms, two propellers, one motor, the battery mount, and the flower pot.   The basic electronics are fine, but I will have to get a new frame kit and motor at least.  The video is below.

The new build will take some time, so postings may be sporadic.  Have a Merry Christmas and a Happy New Year and Happy Hannukah.

Flying Flowerpot 2.0 -- SK450 Quadcopter Rebuilt

Flying Flowerpot 2.0

I finished the Flying Flowerpot quadcopter rebuild and had a successful basement test flight in the new configuration.  Changes since the last blog posting:

1. Moved the camera mount again, to the upper level but with a new mounting bracket so the camera is out front between the props.
2. Moved the receiver slightly.
3. Tidied up the wires.

The following photos show the Flying Flowerpot 2.0:

Top view, no flower pot

Note the receiver attached to top level with double sided foam tape

New camera mount

Front view

Rear View

Rebuilding The Flying Flower Pot Quadcopter - The Six Million Dollar Man

Partially Rebuilt Flying Flower Pot (Pot removed for clarity)

One of the advantages of building your own quadcopter is that you know how to fix it if it breaks, and you can make improvements at the same time.  It is kind of like the Six Million Dollar Man TV series:   "We can rebuild him. We have the technology. We can make him better than he was. Better, stronger, faster."  The Flowering Flowerpot, after its last flight and crash (see previous blog post), needs this treatment.

First, I got rid of the battery monitoring module, which might be causing problems and I cannot figure out how to use it.

Second, I rewired the control module (APM) to receiver wiring to get rid of the servo extension cables and labeling.

Rewiring, receiver is on the left

Third, I repaired the damage to the quadcopter - a broken arm and a broken motor mount on the end of another arm using 5 minute epoxy, which smells like crap and gets everywhere.

Broken motor mount

Break in arm

Fourth, I got rid of the structure holding the GPS and compass and mounted them using nylon standoffs on the third level.

GPS remounted

Fifth, I removed the long landing gear and mounted the camera on top.  The long landing gear seem to cause a lot of damage in crashes.

camera mount

I also ordered a bunch of spare parts (arms, motor mounts, landing gear..).  Stay tuned for more updates as we get the Pot ready for its next adventure.

Evaluation of Homebuilt Quadcopter Components

I put together a table with my evaluation of the components I used to build the quadcopter and the rough cost of the quadcopter: $320.

Part	Source	Rating (1=best)	Approx cost	Comments
Hobbyking SK450 Glass Fiber Quadcopter Frame 450mm	Hobbyking	1	$20.00	Well documented, rugged
TURNIGY Plush 25amp Speed Controller	Hobbyking	1	$13.00	Well documented, works well, does not overheat, used 4
Turnigy Multistar 2216-800Kv 14Pole Multi-Rotor Outrunner	Hobbyking	1	$16.00	Works well, used 4 units
Hobby King Quadcopter Power Distribution Board	Hobbyking	2	$5.00	Works well but hard to mount
Extended Landing Skid Set for SK450 Quadcopter Frame	Hobbyking	2	$11.00	Works but a bit too flexible
Slow Fly Electric Prop 1045R SF	Hobbyking	3	$3.00	Works, inexpensive, but prone to breakage
TURNIGY BESC Programming Card	Hobbyking	1	$5.00	Well documented, works well
Turnigy 2200mAh 3S 20C Lipo Pack	Hobbyking	1	$10.00	Good power delivery, good value
OrangeRx R615X DSM2/DSMX Compatible 6Ch 2.4GHz Receiver w/CPPM	Hobbyking	1	$10.00	Works well, good value, compatible with Spektrum DX4i Transmitter
HobbyKing HKPilot Mega Mini Combo Flight Controller GPS and Power Module	Hobbyking	4	$120.00	Flimsy USB, poor documentation
5" (inch) Travel Micro USB Cable, Twin Pack Cables	Amazon	1	$10.00	Great way to protect USB on APM
Hobbypower Top Pin APM2.6 External Compass APM Flight Controller w/ UBLOX NEO-6M GPS	Amazon	2	$70.00	Works great, great value, no documentation
Tenergy 1-4 Cells Li-PO/Li-Fe Balance Airsoft Battery Charger	Amazon	1	$20.00	works great, great value
2 of NEEWER® 3.5mm Gold Plated Bullet Banana Plug Connector for RC Battery 10-Pairs	Amazon	1	$7.00	Works well, used 2 packs
Dowels, screws, glue, velcro, flower pot	Home Depot	1	$25.00	Cheaper than hobby store
Total cost of built unit (not including broken Hobbyking Controller)			$319.00