Demystifying Flight Controllers
Flight Controllers are the heart of a multirotor aircraft. A flight controller, often abbreviated as a FC, stabilizes your multirotor for you and allows you to fly it with ease. It takes input from sensors such as a gyroscope, an accelerometer, a magnetometer, a GPS, and a barometer and then tells how fast each motor should move. Often times, the FC may be the most expensive part of your multirotor build.
The KK Board
At the low end of the FC market is the KK board offered by Hobby King. Costing just over $20, the KK offers basic features for multirotors allowing them to stabilize in the air. It has a LCD screen and pushbuttons for set up and supports multirotor configurations. It does not have advanced features and is not compatible with a GPS.
The 3DR APM 2.6
The APM 2.6 Board is an Arduino based FC and one of the most popular flight controllers on the market. It costs $160 and supports a $80 GPS also sold by 3DR. It supports a variety of flight modes that integrate the GPS to keep multirotors stable in the air. It also supports autonomous missions, where the multirotor travels to predefined waypoints, and also Return to Launch. It has a telemetry port that allows the board to communicate back a ground computer during the flight with a $100 Telemetry Module from 3DR. The project is completely open source (both hardware and software). However, the board is not as user friendly as some of the other boards on the market, such as the Naza.
The 3DR Pixhawk
The Pixhawk is another board by 3DR with more computing power than the APM. In general, it offers mostly the same features as the APM, but has more powerful electronics. The Pixhawk is considered more “future-proof” than the APM and will probably last for several years as much of the computing power it has has not been taken advantage of yet.
It sells for $200 but most people will also need to buy a PPM encoder to convert the channels of a regular RC Receiver to the single PPM port the Pixhawk has. It has a safety switch that must be pressed before the flight controller arms the motors. Like the APM, it supports GPS and a variety of flight modes. It is also completely open source. The large RGB LED displays the status of the flight controller.
As a result of the Pixhawk and APM’s open source nature, very cheap clones of the board have been made, predominantly sold by Chinese companies on RCTimer, Hobbyking, and eBay. APM 2.6 Clones can be found for as little as $50 and Pixhawks can be found for as little as $100.
They often use the same parts as the real thing and are compatible with the firmware released by 3DR. However, the quality and customer support will be nowhere as good as the boards offered by 3DR. Clones may be worth the risk if you are working on a budget build. There are also cheap GPSs (<$20) and Telemetry Modules ($25) available on eBay and from HobbyKing.
The DJI Naza
The DJI Naza is a easy to setup non open-source flight controller. It sells for about $300 with a GPS. It is compatible with other DJI products such as their bluetooth modules or their HD Lightbridge Modules. They are more for beginners than the two 3DR FCs but they lack some of the more advanced features that the 3DR firmware has. In addition, there have been more reports of fly-aways involving the NAZA than the APM 2.6 or the Pixhawk.