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Multi-Rotors, First-Person View, And The Hardware You Need

Flight Controllers: The Processor Behind Every Multi-Rotor Flight

Multi-rotors are unique in the world of R/C hobbyists. Usually, when it comes to controlling a model boat or plane, the pilot has absolute, precise control over the motor. A nudge of the throttle translates to a proportional increase in RPM. The same is true of input to the rudders, ailerons, flaps, and other parts involved in changing speed or direction.

The distinction with multi-rotors, whether or not advantageous, is that no human is capable of controlling the rotational speeds of three or more motors simultaneously with enough precision to balance a craft in the air. This is where flight controllers come into play.

A flight controller (FC) is a small circuit board of varying complexity. Its function is to direct the RPM of each motor in response to input. A command from the pilot for the multi-rotor to move forward is fed into the flight controller, which determines how to manipulate the motors accordingly.

The majority of flight controllers also employ sensors to supplement their calculations. These range from simple gyroscopes for orientation to barometers for automatically holding altitudes. GPS can also be used for auto-pilot or fail-safe purposes. More on that shortly.

With a proper flight controller setup, a pilot’s control inputs should correspond exactly to the behavior of the craft. Flight controllers are configurable and programmable, allowing for adjustments based on varying multi-rotor configurations. Gains or PIDs are used to tune the controller, yielding snappy, locked-in response. Depending on your choice of flight controller, various software is available to write your own settings.

Many flight controllers allow for different flight modes, selectable using a transmitter switch. An example of a three-position setup might be a GPS lock mode, a self-leveling mode, and a manual mode. Different settings can be applied to each profile, achieving varying flight characteristics.

Getting To Know Flight Controllers

DJI, arguably the dominant player in multi-rotors, produces two models. The Naza-M Lite is a high-quality, easy-to-set up unit with GPS and fail-safe capacities. Its Naza-M V2 is virtually identical, but includes a handful of additional features, such as the ability to daisy chain DJI expansions (a Bluetooth module, for example). Also, it allows up to eight motors, rather than six.

DJI Naza Lite flight controller

Multiple flight modes are available: GPS lock, altitude lock, orientation mode (moving forward always happens away from take-off point, regardless of craft rotation), and a non-stabilized manual mode.

The Nazas are the ultimate hobby flight controllers, with a multitude of features, optimized ease of use, and relatively straightforward setup. They may, however, no be the best choice for every multi-rotor. Let's get into why.

  • gio2vanni86
    Great article, and quite an amazing beautiful video shot at the end. Been seeing these around, and have really loved the idea of filming at a elevated level. I actually do hope you guys do more of these. I am bookmarking this for future reference. Thank you.
    Reply
  • Joshua M Below
    I'd really like to see build costs.
    Reply
  • freiss
    Darn it, now you've piqued my interest. :-)
    As stated below, a rundown on build costs would be nice. Hey, you could even do a series of FPV articles akin to the PC builds...budget, mid-range, and enthusiast!
    Reply
  • Steveymoo
    So, how much would the components cost to lift a heavy DSLR with some decent glass? I is pretty curious.
    Reply
  • es0
    It would be awesome if you did build guides for different aircraft. I have begun building different ground based vehicles using arduinos and Pi's and would love to take to the skys next!
    Reply
  • thechief73
    Excellent article, nicely explained. Also glad to see someone in the media make a clarification from drones and multi-copters.

    FYI, DO NOT CALL THESE DRONES: Drones are for military use to kill people. These are, as the authors title states: multi-copters, multi-rotors, or RC model aircraft. By using the word "Drone" you give all the uneducated fear mongers and the law writers canon fodder to regulate this hobby into oblivion before it really gets a chance to take off. Some states and other countries have already passed laws that almost or outright make this hobby a CRIME!

    I have been in the hobby about a year now and I have to say it is so far one of the most fun and rewarding things I have done. I will be doing this until I no longer have the means to do so. I highly recommend anyone that is interested in joining the hobby to buy a Hubsan X4 or one of the many similar RTF mini-quad models. This is widley regarded as the best way to learn how to fly a multi-rotor.

    http://www.youtube.com/user/juz70/videos - not my channel, just really neat.

    So, how much would the components cost to lift a heavy DSLR with some decent glass? I is pretty curious.
    Just a few options: DJI S1000, SkyJib-8 Ti-QR, and CINESTAR-8.
    It would be awesome if you did build guides for different aircraft. I have begun building different ground based vehicles using arduinos and Pi's and would love to take to the skys next!
    Check out youtube, there are thousands of guide videos on the subject.
    Reply
  • HKILLER
    i would highly recommend these 2 for those who that don't want to go through the trouble of the build and already have an smart device such as iphone or android ones...
    http://www.newegg.com/Product/Product.aspx?Item=N82E16886113011&cm_re=parrot-_-86-113-011-_-Product
    and this cheaper model of it....
    http://www.newegg.com/Product/Product.aspx?Item=N82E16814998083&cm_re=parrot-_-14-998-083-_-Product
    Reply
  • rmirwin2
    There is one other regulating authority which is important to keep in mind for those seriously interested. In the US that would be the FCC, since transmission of quality RC and video signals over the available frequencies requires a Technician's class Amateur radio license. Many will find that a relatively easy thing to get that will also maximize the enjoyment of the hobby. Check in with ARRL.org, where you can get everything you need.
    Reply
  • bluescrn
    Great intro to multicopters. But for beginners, it's best not to start out with a serious $500+ quadcopter, as there's a pretty good chance that you'll wreck it on it's first flight...

    Do yourself a favour and get a 'toy grade' mini quadcopter first, such as the Hubsan X4/Q4 Nano or similar. These are cheap, loads of fun, can be flown indoors, are much safer than the big ones, and are a great way to learn to fly a multicopter. Spend a couple of hours playing with one of these, and you'll significantly reduce the time/money spent on crash repairs when you start flying a more serious multicopter.
    Reply
  • bluescrn
    Oh, and if you go down the ready-to-fly route (or even if you self-build), try not to be the next idiot losing control of a DJI Phantom in a location where they shouldn't have been flying at all ( e.g. https://www.youtube.com/watch?v=_U8iHn_2l0U )

    Stick to quiet and safe flying locations, be aware of wind, line-of-sight, and possible sources of RF interference. And don't rely too much on GPS/return-to-home - you might not have a GPS lock when you need it (or it might not have had a lock at take-off, to determine the home position!)
    Reply