Wednesday, November 06, 2013

Review: DJI Phantom Quadcopter

I have always been a fan of remote controlled devices. When I came across the DJI Phantom I was immediately sold. This not too expensive quadcopter can carry a GoPro camera and has built in GPS to make sure your camera returns safely back to you. I already own a GoPro Hero 2 and in combination with the Phantom you can shoot really cool footage.

Assembled Phantom and the rest of the box content.

Features of the Phantom

The Phantom is stable and easy to fly. It will just hover when you release the controls unlike RC helicopters which need constant adjustments during flight to stay in the same spot. That makes it ideal to take pictures and film. Thanks to the GPS it will even counter any wind and won't drift off. The more pro pilots can disable this feature and just have the altitude regulated or can disable any correction features all together and fly it fully manual.

The Phantom has great orientation lights. The Red and green LEDs give you a clear sense of direction, even when flying high up. They also make it possible to fly it at night.

To avoid disaster, the Phantom has some nice failsafes built in. It returns to your lift off location if the connection between your controller and the Phantom fails (provided you have good GPS reception). It also will go in landing mode when the batteries are nearly depleted instead of just dropping out of the sky when the voltage isn't high enough anymore.

A full charge will give you between 10 to 15 minutes of flight depending on the load it is carrying. The maximum speed is about 10 m/s.

What's in the box (or at least in mine)?

  • A quick start manual V1.0
  • The Phantom quadcopter
  • Two legs of landing gear with built in compass
  • A white remote control
  • 4 sets of propellors
  • 2 sets of decals
  • A special mount for the the GoPro camera
  • 1 LyPo battery
  • A balance charger with a set of universal plugs
  • Screws to mount the landing gear
  • A small wrench and 4 nuts to screw on the propellors
  • A USB extension cable
  • A spare USB convertor (USB to Micro USB)
The guys from DJI promise that it takes only minimal effort to assemble and getting the Phantom ready to fly.

Getting the Phantom ready to make its first flight.

The first thing you need to do is to read the manual. Although there is the promise of getting the Phantom quickly into the air, this is by no means a simple device and can become a potential hazard. Fast rotating propellors, even made of plastic, are dangerous. I don't recommend kids flying this thing.

A good source of information next to the quick start guide is the DJI website. You can find extra manuals, video's and the software to calibrate the compass and IMU. The software is unfortunately Windows only.

Before you do the calibration and assembly it is wise to start charging the battery. The charging cycle takes about 1 to 2 hours so it is a good idea to get that underway while you prepare the rest of the Phantom.

Calibration of the IMU

The heart of the Phantom is a NAZA-M + GPS multi-rotor auto pilot system. Part of that system is the IMU. It interprets the built in gyroscopes, accelerometers and the external compass. It is important to calibrate this system because faulty interpretation of the flight data might crash your Phantom.

You need a charged battery to start the calibration process. Always turn on the remote control first and then connect the battery to the Phantom.

The calibration is done by connecting the Phantom with the provided USB cable to the software. It is also wise at this stage to upgrade to the latest firmware and to start out with the standard calibration file which can also be downloaded from the DJI site.

You can also test the response of the remote control and recalibrate it if necessary. When all the updates and calibrations are done it is time to assemble the rest of the parts.

Phantom assembly

There are two plastic legs which need to be mounted on the body with four screws each to form the landing gear. One of the legs has the compass module on it and it needs to be connected with the 5-pin cable so data can be passed onto the IMU. The manual states that this step can be done after IMU calibration but the video shows it is better to screw on the legs and connect the compass before the calibration.

At this stage you can also screw on the connector plate for the GoPro camera if you're planning to film during flights.

The last bits to be assembled are the propellors. There are two different types so it is very important that you screw on the right propellor on the right motor. There are arrow marks on the Phantom and the propellors to make sure you screw on the right one. Make sure they are well tightened. Losing a propellor in mid flight is a fast but fatal way to land the Phantom. 

Calibration of the compass and the first flight

The last step is to calibrate the compass. It is best to do this outside, away from large pieces of metal or magnetic sources. It is one of the steps I neglected a bit and my Phantom wouldn't fly because of it. Remember the process to turn on the remote control first and only then connect the battery to the Phantom. The other way around will give you an error message.

It is possible that the compass is so out of wack that it can't be calibrated with the regular procedure. Through one of the video's I have learned you can get it back straight with a magnet.

Once this is all done you are ready for your first flight.

My personal experience

I am not great with reading manuals. I want to dive in immediately which is actually not a very good idea with a machine as complex as the Phantom. As stated above, read the manual first. I did skip some sections and later on I wondered why the Phantom didn't want to fly.

There was also a bit of confusion concerning the box content. It didn't match the manuals and the video's I have seen online. I did get 2 sets of spare rotor blades instead of 1 but you won't see me complaining about that.

My remote control is also different. It has an extra lever on the back and the throttle control is automatically centered. This was really confusing as one of the important steps for lift off is setting the throttle stick all the way down. This is impossible when a spring centers it. I even opened up the controller to see what was wrong with it. It was only after searching several online forums that I figured out I had the new controller type which they only starting shipping recently. The extra lever on the back is usable as a controller for tilting an optional gimbal.

The last problem I had was the connection between remote control and the Phantom. Although the Phantom itself indicated that there was a connection to the remote control, the software was unable to detect it. The remote control is supposed to be of the PPM type and this is also the default value in the standard calibration file. It was only after changing to D-Bus that it started to work. Again, the forums helped me figure out that this updated controller behaves a bit different. The documentation wasn't updated though which lead to this long search. 

It went all smoothly once I had it into the air. Well, except for landing that is. My first landings were a bit rough and I did cut some grass with the propellors. Once I figured out how to do it, I had no issues whatsoever.

Always check the weather forecasts for the wind speeds. Once it gets too windy, the Phantom really needs to fight it to stay in the same spot, becomes highly unstable and might crash. Since it's maximum speed is 10 m/s I tend not to fly when the wind is blowing faster than 8 m/s.

As you can see, it wasn't a complete walk in the park to get it into the air. Luckily the Phantom is very popular and there are many forums on which you can find a ton of information or ask questions to other Phantom owners. Overall I am very happy with the Phantom. I got mine for 419€.

Flying the Phantom with the GoPro Hero2

Using the GoPro Hero 2 to take pictures. I did some basic grading and removed the lens distortion.

The Phantom is designed to fly with the GoPro Hero3 in mind. That said, it also works with previous models like the Hero2. When checking other people's footage I noticed there was a consensus among all Phantom and GoPro owners that the footage had problems with what they call the jello effect. This is because of micro vibrations that get transferred from the Phantom to the camera during flight. It makes the footage rather unusable for anything professional.

There are a couple of things you can do to avoid this effect.

You can do it the expensive way by getting a gimbal. This is by far the best option and gives extra benefits like camera tilt control. The gimbal is more expensive than the Phantom so it wasn't an option for me (for the time being at least).

Another option is to put some foam or rubber between the Phantom and the connection piece for the camera. This will absorb some of the micro vibrations. This did work for me and it removed them to an acceptable level although not completely.

A last trick is to balance the propellors by sanding off excess weight of one side. There are some handy balancing gizmos on the market which makes it easy enough to get it right. So far I haven't tried this option myself as I was making rough landings which wasn't great for the propellors. Every time you damage your propellors a bit they might become unbalanced again and you have to start all over again.

Some last tips to get better footage and photos.

It is good practice to shoot at 50 (or 60) fps. The footage will look more stable when slowing it down to 25 (or 30) fps during the edit.

It is better to use the camera housing which ships with your GoPro Camera. It protects it from impact should you crash your Phantom.

Another trick to stabilize your footage it to use After Effects Warp Stabilizer. You will loose some resolution but it works like a charm.

The GoPro has quite a bit of lens distortion. This is something you want to get rid of when just shooting still images. Camera Raw which is accessible trough Adobe Bridge has built in lens profiles for the Hero3. Using the Hero3 silver setting also works for the Hero2 camera. This eliminates the lens distortion and is great when shooting panorama's or buildings.


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