Common Flight Controller Features

by | Aug 1, 2014 | theory | 0 comments

Flight controllers range in price from $30 to $300 or more and each of the many, many different flight controllers on the market has its own set of features. While many flight controllers, especially those on the higher end of the price range, have proprietary features, like mobile apps, special status LEDs, or plug-and-play GPS modules, there are many common features shared among many flight controllers at a particular price range.

The purpose of this page is to provide an overview of common flight controller features that you will come across often while shopping for and comparing flight controllers.

Common Flight Controller Features

Self-Leveling

The vast majority of flight controllers are equipped with a self-level mode. In self level mode, the flight controller will attempt to keep the level in the air when the pilot releases the pitch/roll stick.

Intelligent Orientation Control

One of the trickiest parts of learning how to fly multirotors is learning how to keep track of which way the multirotor is pointing in the air. In order to steer the multirotor you need to know which way the multirotor will go when you push the pitch stick forward or the roll stick left or right.

Flight controllers equipped with intelligent orientation control (sometimes called “care free” mode), make it much easier to steer by eliminating the need to track which way your multirotor is pointing. In intelligent orientation control mode, when you, for example, push the pitch stick forward, the multirotor will always move in the same direction, regardless of where the front of the multirotor is actually pointing.

Altitude Hold

As discussed in the article “The Physics of Quadcopter Flight,” in order to make our multirotor move around in the air, we adjust the speed of each motor in such a way that the multirotor tilts in some direction. When the multirotor tilts, a portion of the lift produced by the propellers is directed sideways, instead of downward, which pushes the multirotor in some direction.

Now, the consequence of directing a portion of the multirotor’s lift sideways is that there is less lift directed downward to fight the earthly bonds of gravity. Therefore, when we move the quadcopter (which we do pretty much constantly) it has a tendency to lose altitude. It actually loses altitude faster the faster we want the multirotor to move. So, when using flight controllers that lack an altitude hold feature, we as pilots must balance the throttle input with the pitch and roll inputs in order to make the multirotor move without losing altitude.

If this all sounds a bit complex, that’s because it is. The ability to adjust throttle while maneuvering is one of many skills a beginner pilot must master.

That is, unless the flight controller they are using is equipped with altitude hold. In altidude hold mode, the flight controller automatically adjusts the throttle while the pilot maneuvers so that the craft maintains a constant altitude. This certainly makes flying easier, and it also helps establish a more stable platform for aerial photography or videography.

Position Hold

Let’s discuss a much simpler feature: position hold. In position hold mode, as you’ve probably guessed, the flight controller keeps the multirotor in a fixed position in space.

This feature is extremely useful for shooting aerial videos. A pilot can position the multirotor in the air, with the camera pointed at a subject, engage position hold mode, and then perform whatever activity they want to film without having to pilot the multirotor at the same time, because going off a snowboard jump, for example, while piloting a multirotor would be extremely challening to say the least.

Position hold functionality is mostly reserved for flight controllers on the high end of the price range because it requires a GPS reciever to work.

Return Home

Another feature of many high-end, GPS-equipped flight controllers is a return home function. A return home function allows the pilot, typically with a single button press, to summon the multirotor back to the location where it took off.

This feature is mostly used by pilots flying first-person video (FPV) equipped multirotors. Flying in FPV can be a bit disorienting and it is easily possible to get lost in the air. The return home feature lets pilots enjoy the incredible experience that is flying FPV without worrying too much about losing their expensive multirotor.

Now, things can go wrong with the return home feature. As of right now, even the most expensive consumer-grade flight controllers are not capable of detecting obstacles in their flight path. So what if you hit the return home button and there is a tree between you and your multirotor? Well, in that situation, in all likelihood, you are going to have a crash.

Waypoint Navigation

The last common flight controller feature I want to cover on this post (I am sure there are some I missed but this postis pretty long already) is another high-end, GPS-related feature: waypoint navigation.

Waypoint navigation is a semi-autonomous flight mode in which the pilot first programs the flight controller with a series of GPS coordinates and the the flight controller with fly to each of those coordinates all by itself. Neat!

Waypoint navigation is commonly used in races or other competitions, like the SparkFun Electronics Autonomous Vehicle Competition. Pilots can program the layout of the race course in their multirotor’s flight controller via GPS coordinates and the multirotor will fly the course automatically.

Additionally, the pilot can program certain actions for the multirotor to perform at each waypoint, like take a photo for example.

Now, like we discussed in the previous section about return home functionality, flight controllers are not yet capable of detecting obstacles in their flight path.  So, pilots must carefully plan the GPS waypoints to ensure that the multirotor misses any trees, buildings, power cables, or anything else.