Quadcopters : A Comprehensive Glossary of Terms

Quadcopter: A very common category of a Small Unmanned Aircraft System (SUAS)which  has 4 rotors positioned on a horizontal plane like a helicopter. The varying speed of the rotors achieves both the direction of flight and the stability of the vehicle.uadcopters

Hexicopter: A multi-rotor aircraft having six rotors in which the beauty and advantage of the hexicopter is that it can lose any single engine and still maintain control to land.

Drone: This describes any unmanned aerial vehicle.

SUAS – An abbreviation for small unmanned aircrat system, which is a term that generally means a battery powered aircraft (quadcopter) which operates at a very low height and can be picked up by one person.

Autonomous Flight: There are some SUAVs’s that are managed by internal programming that have instructions on where to fly as guided by an onboard GPS system. This is in opposition to steering mechanisms that are operated by radio control from the ground.

GPS: Global Positioning System that is used to track the position of an object in relation to the global spatial plane, track movement, or cause an airborne vehicle such as a quadcoptor to hold position, such as the advanced Dji Phantom.

AP: Acronym for Aerial Photography, as the quadcoptor has that capability of taking photographs of objects on the ground from various elevated positions.

FPV: Acronym for “First Person View.” This is also known as “Remote Person View” (RPV). The FPV is situated on a camera (such as GoPro) and is mounted on the Quadcoptor which allows the operator view exactly what the aerial vehicle is viewing in real time.

Gyroscope: This device measures the angular velocity and helps to maintain the orientation of the quadcopter while in flight. In most cases, quadcopters use a triple-axis gyroscope.

Flight Control System: This is a network of controls that is interconnected and allows the pilot to fly the quadcopter or any other multi-rotor airborne vehicle. NAZA is a flight controller that is used on the DJI Phantom Drones and it does the main control chip, an accelerometer, a gyroscope, and a barometric altimeter.

Brushless Motor: These motors have permanent magnets that rotate around a fixed armature, which eliminates any problems that could be associated with connecting current regarding a moving part. The brushless motors are much more efficient and hardy than brushed motors.

Accelerometer: A device that measures the acceleration forces in a certain direction. These devices are used to stabilize quadcoptors, many times in windy conditions.

Controller: The handheld device that is used by the drone pilot that is used to control the drone and the quadcopter. Controllers are also called transmitters. Here is a picture of a higher end controller.

Gimbal: This is a specialized mount for a camera, giving it the ability to swerve and tilt by utilizing servos. This gives the camera the capability of staying in one position, regardless of the movement of the drone. This allows for a very smooth and stabilized and smooth looking image.

808 Camera: This is a common term for a range of very little spy cameras, which are often sold as keychain cameras. They are extremely lightweight and are used by hobbyists in order to take pictures from from a multi-rotor aircraft.

9X: This is the name of a popular, low cost R/C Transmitter that has been manufactured by different companies over the years. At the present time, the Turnigy brand from Hobbyking is the largest seller.

Arduino: This is a free, open source software project that is centered around a low cost circuit board which allows for the control of objects. It is very easy to program which allows for a lot of experimentation. There are many quadcoptor control boards (FC: Flight Controllers) that are built using this board and its software.

ARA: Almost ready to fly. This is used to describe a Quadcopter or a Drone that you are purchasing and what comes with it. ARA units will many times come without the transmitter, and they may require some assembly.

Balanced Battery Charger: This is a charger or an internal system for Lipo batteries (or different chemistries) which uses smart technology to charge multiple cells properly that are located within the battery and balances them.

Barometric Pressure Sensor: This device used barometric readings to determine the altitude of the aircraft. It can help drones to be able to calculate their height above the ground, along with using combinations of other sensors.

BEC: Battery Eliminator Circuit. This electronic component the single battery on a quadcopter, or other device, to power multiple circuits. For example, using this to power the motors as well as the receiver is a good example. This is utilized for the most part, for the saving of weight. It is designed to give a constant 5V for RC equipment, autopilots, and other installations of onboard electronics.

Bind: This is the process of making the controller (Transmitter)talk to the quadcopter or the drone.

BNF: Bind N Fly. The unit is ready to bind to the transmitter and fly.

Build: A unit that is build at home as opposed to one that is store bought.

CA: Cyanoacrylate adhesive: This is also called SuperGlue. This material along with Gorilla Glue and Liquid Tape, are used often in the building and repair of aerial vehicles.

Camera gimbal: This is actually the holder of the camera used on drones. It can tilt and swerve, thanks to the servos that power it. The gimbal is strong enough to support even large DSLR cameras.

Center of Gravity (CG): This is the point of balance of the unit. It needs to be maintained whenever you add various batteries, mounts, cameras or other accessories to the unit.

CF: Carbon Fiber is a very strong yet lightweight material widely used in aircraft industry and wherever else such materials are required.

DJI: DJI Innovations is one of the most popular multirotor manufacturers. They made the well-known NAZA flight controller among other parts, units and kits.

Flash: to reset the computer code of a chip or controller. It may also mean to add such a code to the chip or controller.

GoPro: a lightweight action sport camera that is often used on multirotors for shooting various landscapes from above.

Hobby Grade: Better than toy grade, these quads can offer a good reliability and operation at a reasonable price tag. RC Logger Extreme Eye One, DL Phantom, Blade 350X QX and AR Drone are a few examples of hobby grade quads.

IMU: The Inertial Measurement Unit is a controller which combines an accelerometer and a gyro, with the purpose of helping with the orientation and stabilization of a quad.

Intervalometer: A feature that enables a camera to take a photo at preset intervals of seconds. It is also known as Interval Shooting.

JPEG: Image file format used in many digital cameras. Smaller than the original RAW format, JPEG images still maintain a good quality of the image.

JST: One of the most popular types of plugs used on quads. There are adapters that can convert between JST and Walkera Connector, the other popular type of plug.

KAP: Kite Aerial Photography means photos taken from a kite.

KK: This is one of the multirotor flight control circuit boards. Developed by Rolf Bakke, these flight controllers are very popular due to their versatility and to their relatively low price.

LHS: Local Hobby Shop – it is the perfect place to find experts in R/C quads to ask them questions.

LOS: Line of Sight – this means you have the drone visible with your naked eyes while in the air.

mAh: milliampere-hour – measure of the current generated by a battery. Quadcopter batteries range from 50 mAh to 5000+ mAh.

Mobius Camera: Popular lightweight camera model which can shoot video in HD and take intervalometer photos. It was developed mainly to be used with RC drones.

mod: modification – Drone addicts modify their machines to integrate new functions or cool features. These changes are usually called mods.

multicopter: Aerial drone with multiple horizontal propellers, also known as rotors. Depending on the number of rotors, we can have tricopters, quadcopters, hexacopters, octocopters and so on.

multiwii: General purpose software which was developed especially for supporting gyros and accelerometers in Nintendo Wii consoles. Many companies use this software today for controlling multirotor aircraft, regardless the name of the company. There are custom models of this software developed to suit quadcopters and used by all manufacturers.

NAZA: One of the most popular flight controllers used on mid:level, including a gyro, an accelerometer and a barometric altimeter besides the main controlled chip. It may also include optional modules such as GPS and compass.

Octocopter: A drone with 8 horizontal propellers or rotors.

Payload: The maximum additional weight a drone is able to lift, besides its own weight and the weight of its batteries.

Pitch: A measure which describes the flight angle along one axis, usually measured from level in case of aerial vehicles.

R/C : Synonym for Radio Controlled.

RAW: image file format that contains all original information from when the shot was taken. This file format is not compressed or processed and it is used in many advanced or mid-level cameras.

RC: Radio Controlled – it refers to drones that can be controlled via radio waves. It’s a shorter way of writing “Radio Controlled”

RTF: Ready to Fly – This means the drone is sold with everything needed in the pack. All you need to do is put it together, add batteries and you are ready to use it. It is possible you may need to buy the batteries separately. This fact is usually mentioned on the box.

rx: Acronym for receiver or receive.

servo: A shorter name for servomotor or servomechanism. Aerial vehicles use servomotors for various functions such as pan cameras and wing flaps adjustments which can be controlled from the ground.

throttle: Control that influences the RPM or the speed of electric motors.

Toy grade: The basic level of quadcopters, usually priced under $100, using relatively cheap components. Not very reliable, toy grade quads can still offer a wide variety of functions. They can be an excellent way to start for beginners, as they can still provide a lot of fun, despite the lack of reliability. when you are ready, you can move on to a hobby grade machine or even or more advanced ones, but you have to be ready to pay a higher price.

tx: Short for transmitter or transmit

Ultrasonic sensor: A sensor that uses the ultra sound wavelength to communicate with a transmitter. In aerial vehicles, ultrasonic sensors are used for calculating the distance to the ground by bouncing sound waves back and forth. They don’t work further than a few meters from the ground.

Waypoint: A set of coordinates which define a point in space. Waypoints are useful in designing various autonomous missions for quadcopters. Mapping out would be impossible without a possibility to define these physical locations.

Wide Open Throttle: WOT.  The throttle stick is on maximum!

YAW: The describes the quadcopter rotation around it’s center axis on a level plane.

2.4 Ghz:  In our applications, this is the frequency that is used by the digital radio communications (spread spectrum), including bluetooth, 2.4Gz RC, and some of the video transmission equipment.  The band is different than the earlier 72 Mhz band used in analog RC communications.  To prevent radio frequency conflict, using 72 Mhz radio equipment is frequently a good idea when using a 2.4 Ghz onboard video transmitter or with 2.4 Ghz RC equipment use 900 Mhz video.

Altitude above ground level: AGL

Altitude Heading Reference System: AHRS.  An IMU along with the code for interpreting the sensors output to establish a plane’s heading and XYZ orientation.

Academy of Model Aeronautics: AMA.  This is the major model aircraft association in the United States.  The AMA and Federal Aviation Administration (FAA) work closely together to establish rules that are reasonable for using amateur UAVs.  Every AMA field and chapter might have policies that are slightly different, however it is possibly to test and fly some technology and air frames on AMA fields without being in violation of the FAA/NAS or association’s rules.

AutoPilot Mega (APM): The Flight Controller provides capabilities for automated mission (or waypoint) path following, position maintenance and stabilized flight.

APM Rotary Wing Copter: APM electronics autopilot software.

APM Fixed Wing Plane: APM electronics autopilot software.

APM Water and Ground: APM electronics autopilot software.

Bootloader: This special software code is stored in non-volatile memory inside a microprocessor.  It interfaces with a PC for downing the user’s program.

Certificate of Authorization: COA.  FAA approval for UAV flight.  For more details, see the DIY Drones Regulatory FAQs and faa.gov website.

Direction Cosine Matrix: DCM.  An algorithm that is the equivalent of Kalman Filer but with less processing.

Eagle File: The PCB design files and schematic (along with related files telling PC fabs how the boards need to be created) generated by the Cadsoft Eagle free program.  In the world of open source hardware, it’s the most common standard in use.  Ironically, however, it isn’t open source software.  This isn’t optimal.  Also, the Eagle software is hard to learn and clumsy.  Hopefully someday an open source alternative will become available.

Electronic Speed Control: ESC.  The device for controlling an electric aircraft’s motor.  It is the connection between the RC receiver and main battery.  It usually includes a Battery Elimination Circuit (BEC), which provides the power for the onboard electronics like an autopilot and the RC system.

Firmware: The sketch or software loaded into the microprocessor based products’ non-volatile memory.  The reason it is referred to as firmware is because it remains in non-volatile memory state even when power is removed.  Therefore, it is non-volatile.  In the autopilots case, it is an application (App for smart phone users) or program that determines how and what the auto pilot does.

FTDI: This standard is used for converting USB into serial communications.  It is available in chip form for board with a USB connector.  It is also available in a cable that connects with breakout pin.  FTDI is short for the term Future Technology Devices International, which is chip manufacturer’s company name.

Ground Control Station: GCS.  This software runs on the ground on a computer.  It receives telemetry information via an airborne UAV.  It displays its status and progress.  This frequently include sensor and video data.  It also can be used for transmitting in-flight commands up to the UAV in the air.

Hard Iron magnetic distortion:  these distortions arise from magnetized metals or magnets on the airframe affecting the compass.  The distortions stay in the same place for all heading orientations relative to the compass.  The distortions mostly can be compensated for through adding constant offsets onto the values that the 3d magnetometer returns.

Hardware in the loop simulation: HIL. A simulation is done where software that is running on a different computer generates data stimulating data that would come from the autopilot sensors. During the simulation, the autopilot is running.  It doesn’t “know” it is simulated data, so it responds in the same way it would if it was real sensor data that it was receiving.  Physical autopilot hardware that is connected to a simulator is used by hardware in the loop, as opposed to also stimulating the autopilot inside the software.  With an open loop simulation, data is fed to the hardware autopilot from the software simulator.  In a closed loop simulation, data is fed back into the software simulator as well from the hardware.

I2C: Several low speed peripherals are allowed by this serial bus, including sensors that get connected onto a microprocessor.

Integrated development environment: IDE.  For example, Arduino serial monitor/downloader/editor software.  A debugger is often included.

Outer loop/Inner loop: Normally used to refer to an autopilot’s navigation and stabilization functions.  The stabilization function needs to run in real time and as frequently as 100 times per second (the inner loop).  The navigation function may run infrequently, as little as once a second.  It can also tolerate interruptions and delays (outer loop).

Inertial Navigation System: INS.  This is a means of calculating position that is based on the initial GPS reading.  This is followed by speed and motion sensor readings that use dead reckoning.  This is useful when the GPS has lots its signal temporarily or is not available.

In Circuit Serial Programmer: ICSP.  This is a way of loading code onto a microprocessor.  Normally this comes in the form of six pin connector  (two rows of three each) on a PCB.  A programmer is needed to use this, like the one using the Serial Peripheral Interface (SPI) standard.

Kalman Filter: This algorithm is relatively complicated.  It is primarily used in our applications for combining gryo and accelerometer data in order to provide accurate descriptions in real time of aircraft movement and attitude.

Lithium Polymer battery: LiPo or LiPoly.  The Lithium Ion battery (Li Ion) is a variant.  Lighter weight and more power is offered by this battery chemistry compared to NiCad and NiMh batteries.

MAVLink: ArduPlane and ArduCopter autopilot lines use this Micro Air Vehicle communication protocol.

Micro Air Vehicle: MAV.  A small UAV.

NMEA is a term that stands for National Marine Electronics Association. This is the standard for GPS info. When people are talking about the NMEA in sentences they are talking about the different ASCII strings that are coming from a GPS module.

Oilpan: This is a style shield in the arduino fashion that is meant to be paired up with the ArduPilotMega. The majority of the sensors (accelerometers, gryos, barometer, etc.) are contained here. These are the sensors that are going to allow the ArduPilotMega to fly on autopilot. These are often superseded by the flight controllers that have the CPU and sensors all on one board.

OSD is a term that stands for on screen display. This is the best way for people to integrate the telemetry and other information into a real time video stream for the aircraft to send back to the ground.

PCB is a term that means printed circuit board. This is a board that is specifically designed and built for a single purpose. This is different than the prototype or breadboard styles which can be changed around for each different project people work on.

A pulse code modulation or PCM is the technique of some of the modern radio control transmitters or receivers to get the information on the various RC channels. This is transmitted in a digital manner and uses are digital code to represent the different channel numbers, the position of the sticks on the transmitter and depending on the level of expertise other information. Some of the modern radio control units are going to provide digital signals that can be used to control the digital servos to specify each manufacturer.

Power Distribution Board is the PDB and is a board that is used on the multicopters to help distribute the power to each of the motors to provide proper stabilization of the unit.

The Pilot in command or the PIC is the FAA requirement that an unmanned aerial vehicle is going to stay under the control of a pilot if the UAV is flying under a recreational COA approval. This is not to be confused with the PIC processor series that is made by Microchip.

Proportional/Integral/Derivative control method or PID. This is a machine controlled algorithm that is going to allow for accurate sensor control over the motion loops.

The point of interest is the area that is going to mark a spot that is going to let the UAV know where it should be pointing its camera at.

PPM does not stand for part per million. Instead, it stands for Pulse Position Modulation. This is the square wave that the pulse train used to transmit the multiple channels of information between some of the radio control receivers and transmitters. Some of these radio control receivers are going to provide a PPM output. This can only be used on the APM  and PX4. Other types of receivers are going to convert the signal and provide on the PWM signals.

The Pulse Width Modulation or the PWM is the square wave signals that are used in RC control to drive the servos and speed controllers. Thers is only a single PWM channel for each PWM. The width of this is going to vary from 1000 to 2000 microseconds.

PX4 is a flight controller system that is going to provide capabilities to help stabilize the flight, the maintenance of the position, and even the waypoints for the controller to follow.

RTL means ready to launch. This is where the aircraft is going to fly back to the location where it took off from.

SiRF III is the type of item that is included in most of the GPS modules and is going to use the binary mode which is a different type of code, but based off of the NMEA standards.

Sketch is the different types of program files that are going to help the drivers and different code that is generated by the Arduinio IDE for a single project.

SVD is the short term for the Subversion version. This is a control repository that is used by the DIY drones and different teams for a source code.

Telemetry system is the two way radio that is going to allow for the flight data to go back and forth between the aircraft and the controller.

Thermopile is the infrared dectector that is used in pairs of UAVs to measure the different types of tilt and pitch they have. Most of the time, unless the models are older these have been replaced by the electronic gyros.

Visual line of sight is the term that is going to control how the pilot can see the aircraft from the ground without the use of artificial vision.

Wide area augmentation system is a system of satellites that is going to provide GPS signal corrections to allow for accurate flight.

Xbee is the commercial name of Zigbee that are the compatible radio modems that are used by most amateur UAVs.

Zigbee is a wireless standard for communications and has a longer range than the bluetooth signals, but uses less power than WiFi.

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