So just how do you choose a good flight controller for your quadcopter or multi-rotor? Before we get to that, maybe we should discuss what a flight controller does and why your quad needs one. A quadcopter is inherently a very unstable flying machine. You could say stability, when it comes to aircraft, is the ability of the aircraft to return to level and straight flight when you - the pilot - release the controls.
Fixed wing aircraft are designed to be inherently stable - but a quadcopter has no fixed wing. Suppose your quadcopter is hovering at a certain altitude and is stable in mid air. If you touch the controls for just a moment and release, then it will not go back to stable flight all by itself. If one of the propellers were to generate more lift even for a single second, the quad will tilt to one side and will crash to the ground unless you intervene and stabilize it.
Even helicopters are more stable than quadcopters, but then helicopters are more complex - and thus more expensive - because the rotor blades continually have to adjust the pitch while they are spinning. Quads on the other hand use fixed pitch propellers that are directly connected to the motors and so are a lot cheaper to build than similar sized helicopters.
The LCD screen makes it great for beginners. 8 bit controller, very easy to setup.
Professional Aerial Photography or Videography
DJI Naza M V2
This is the best of you want to shoot professional grade video or photos.
In some ways better than DJI's Naza. Firmware is open source.
Hobby FPV Flying
32 bit. Excellent for FPV flying. Good flight characteristics.
32 bit controller, good for FPV.
Drone Racing / Sport
Seriously Pro F3
Lots of features, great for racing and sport.
Another great FC for racing.
But then quads are also less stable - a tradeoff that cannot be avoided. Quadcopters also waste a lot more energy relative to helicopters with the same payload because they use small propellers rotating at a high speed whereas helicopters use large propellers rotating at low speeds. The large propellers in a helicopter also make it more gyroscopically stable.
The flight controller is part of the system that makes it possible for you to fly a quadcopter by keeping it stable. Without it, you will not be able to keep your quad airborne even for a few seconds.
The onboard flight controller - or the flight controller board as it is also called - continuously reads data from the sensors, does a lot of number crunching using sophisticated algorithms - and then makes minute, split second adjustments to each of the four motors. This is what keeps the quadcopter airborne. The only way to keep the quadcopter in flight is to either speed up or slow down the propellers so that propellers on one side do not produce more thrust than the ones on the other side.
Flight controllers have a host of sensors - gyroscopes for stability, accelerometers to measure acceleration, a magnetometer or a compass to measure direction, a barometer for altitude measurement and a GPS incase the auto-pilot feature is to be used.
While most flight controllers have more or less the same kind of hardware, their software can be very, very different. The kind of data they gather may be essentially be the same, but how they interpret the data they receive and what control signals they issue to the ESCs that control the motor speeds can be very, very different. Essentially, their algorithms - or the onboard software, can be so very different that sometimes there can hardly be a comparison between different flight controllers.
The onboard software can be so very different that if you replace your quadcopter's existing flight controller with another one, your quad's flight characteristics can change so much that you may have trouble recognizing your own machine.
Which is why there's no such thing as the "best flight controller" - the one that's right for you depends on what kind of flying you want to do.
And the kind of flying you will be doing depends essentially on your purpose - what you will be using the quadcopter for.
There are three main kinds of flying quads are used for :
This would require a camera capable of capturing high resolution photos and videos to be mounted on a very stable platform so as to produce a really smooth video. With this, you are not looking for maneuverability or speed or agility. Your primary concern would be very low vibration and high stability. And such a quadcopter will have to be able to carry a relatively heavier payload because high resolution cameras suitable for professional videography tend to be heavy.
Being able to fly your quadcopter without manual control opens up a host of exciting possibilities. Having to manually control the quad implies you always have to maintain it within your line of sight at all times and thus limits the range of applications. And piloting a quad manually is pretty hard for beginners as it requires a lot of skill and constant manual supervision. With the appropriate flight controller, you will be able to navigate the quadcopter autonomously - without any supervision on your part - along a preprogrammed trajectory. This is possible because the flight control board already has a host of sensors that can help it to precisely infer its position and the GPS can help it move along the desired trajectory.
Quads used for sports and racing will have to be extremely agile, fast and lightweight. You would not expect them to carry heavy payloads.
As you can see, the flight characteristics for each of these are very different. You would not expect a quadcopter designed for racing to be able to capture professional quality video - and likewise, you would not expect a quadcopter that's designed for capturing professional quality video to be able to do triple flips and aerobatics.
So it would be impossible to design a flight controller that would be best suited for all of these kinds of flying. Simply because the requirements of each are so very different.
So you will need to choose the flight controller depending on the kind of flying you are interested in. There's no one size fits all kind of controller board that you can buy anywhere.
That said, these are the most popular flight controller boards and the kind of flying each is best suited for. You cannot go very wrong if you were to choose one of these ...
If you are just getting started with quadcopters and want to put one together yourself, the best choice for you would be the KK2 controller board. It is inexpensive and really popular.
The main advantage this board offers for beginners is the on board display. This makes it possible to tune the parameters without having to hook it up to a computer. You can do the tuning right on the controller, tuning the parameters using the menu you can see in the display screen.
This controller board does not have any of the advanced features like GPS, altitude hold, go home or autonomous navigation using waypoints. But then, this isn't meant for advanced users. But this is stillpretty good at doing what it is designed to do. If you are a beginner and couldn't care less for the advanced features like autonomous navigation and the like, this would be perfect for you.
If drone racing and sports are what you really are interested in, this would be the ideal choice for you. This flight controller is been designed for FPV racing.
Accelerometers are possibly the most demanding component of the controller board when it comes to racing - and the Tornado F3 has 256K of flash memory and a math coprocessor to handle all of the floating point math that gets thrown at it. Not surprisingly, FinalGlideAUS won the first Drone Nationals in 2015 with a quadcopter using the Tornado F3.
This is a 32 bit flight controller and has a host of features that will appeal to the more advanced users. It comes in two versions - Acro Naze 32 and Full Naze 32. As the name suggests, the Acro Naze 32 ismore suited for users who are interested in sports flying and racing. Full Naze 32 has two additional sensors - a compass and a barometer.
Its main advantage is flight stability. In regard to this particular flight characteristic, its performance exceeds that of many other boards like KK2 controller. And the control response is very good - and you would expect it to be so if you were to use it in a drone meant to perform stunts or race.
That said, since the onboard GPS isn't the best, it is not very well suited to autonomous flying.
So while this is a pretty good board for beginners and intermediate level pilots, if you want to do something like waypoint navigation and autonomous flying, this should not be your first choice.
Verdict : Ideal for intermediate level users and sports quadcopters. But not good enough for advanced users and those looking for autonomous flying.
If capturing professional quality photos and videos is what you want to do, this would be the perfect choice for you. It has possibly every single feature a professional photographer would want.
It is extremely stable, it can Go Home, hold altitude, fly autonomously and more - and all of these are very accurate and reliable. DJI's strength is their user friendliness - their stuff is plug and play and works well, without you having to do a lot of the fine tuning. That's one reason why they are the market leaders when it comes to high end quadcopters - they build quads that are truly plug and play.
It can help you capture the smoothest and highest quality video - with minimal input on your part. It's also a breeze to set up - so if you hate digging into computer code and fiddling with things, you do nothave to worry. And if you take the time and put in a little bit of effort to learn the ropes, you will never have to worry about fly aways with this one.
This is another great choice if telemetry and autonomous flying is what you are really interested in. This is another feature rich flight controller - and the onboard GPS is excellent. This controller board is also used in rc airplanes and rc cars - mainly because the GPS is so very good.
It is also easy to tune and setup. It has a 3 axis gyroscope, a 5 Hz GPS, a 3 axis accelerometer, a barometer and a magnetometer. All of this makes this a great choice for professional videography and telemetry.
This is a flight controller that's very similar to DJI Naza - but works only with quadcopters. This works with only a select few ESCs, so you would want to make sure your ESC is compatible with this if you are planning to buy the bumblebee quadcopter flight controller.
A Word of Caution ...
No piece of hardware is ever designed or built perfectly, and it's all too common to have defects creep in - even in the best hardware. And flight control boards are no exception.
So the very first time you use a flight controller in any multi rotor aircraft, make sure you thoroughly test it in a very safe environment where the quadcopter will not cause any injury or damage in case things get out of control. You certainly do not want to lose control of your quadcopter around people or property.
And always make it a point to read the release notes before your first flight.