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The Flight Controller Nowadays, drones are popular consumerproducts, and one of the most important parts of a drone is the FlightController. The goal of this article is to describe the different components ofthe Flight Controller to give you a better idea about how it works. One of the most important components isthe IMU, or internal measurement unit, which measures the movements of thequadcopter, Roll, Yaw and Pitch, as displayed in the picture below. The IMU unit was not integrated into theflight controllers of early quadcopters. The flight controller mainlycoordinates the rotational speed of each motor, and implements the Roll, Pitchand Yaw movements of the aircraft with only a gyroscope, and motor speed wascontrolled using only gyroscope data.
Due to the use of brushless motors and thelack of ESC (electronic speed control), the motors’ movements in relation toone another could not be controlled. With only a gyroscope, flying a quadcopteris like flying a Phantom in manual mode. If you push the pitch stick forward50%, you must pull the pitch stick back to -50% to keep the drone from driftingforward. As a result, the rotational speeds ofthe four motors had to be adjusted in relation to environmental factors and oneanother to ensure a balanced flight.
Below is an introduction of additional sensorsthat have been added over time:
Complex MotionTracking Sensors: New devices haveboth an accelerometer and a gyroscope. The angular deviation of each axis’direction can be determined with measurements of angular velocities andaccelerations. Deviation data can be obtained through a filtering algorithm.The angular deviation values achieved by the main controller are shown below:
Electronic Compasses: Itsmain application is to confirm flight direction and prevent spinning caused bythe inconsistencies in motor performance. This is important because if youdon’t know which way your drone if facing, it’s easy to crash it.
Barometers: It measures changes in air pressure todetermine the changes in altitude. Normally, changes in air pressure is linearwith the changes in altitude, but the barometer shouldn’t be interfered with bythe airflow. Therefore, barometers integrated into flight controllers aremostly separated by foam pads to avoid airflow interference. But if air pressure changes during flight, will the aircraft continue hoveringat the same altitude? The altitude ofthe aircraft will not change suddenly; the flight controller will ensure itchange slowly.
GPS: GPS technology came from the USA. GPS coordinates are calculated by theradio waves emitted from the several satellites and received by groundinstallations. (In fact the altitude data is also included, but the accuracy istoo inconsistent to be used in most applications.) Most of the GPS measurementsuse the NEMA protocol, which includes time, latitude and longitude, velocity,etc. It is known that the distance between any two points on the earth`ssurface is available for calculation, or a curved line between the two pointscan be approximately described by one or several equations. Therefore the GPScan be used for a number of applications: distance measurement, flight pathplanning, POI (point of interest), Follow Me, and etc.
PID Controllers: PID controllers calculate the differencebetween a given input on the remote controller and the corresponding output.Essentially, it calculates error value. Early flight controllers as KK and MWCrequired PID to be adjusted manually. Nowadays the adjustment of PID parametersis more intelligent, both the APM and Pixhawk have provided a function for configuringthe PID automatically. Hardware: Earlymain controller processors had limitations and couldn’t process complicatedcontrol algorithms. Therefore, it was hard to make significant improvements.Nowadays, flight controllers are mainly use ARM processors, which are widelyused in smartphones. These are a great improvement and has greatly contributedto performance enhancements in recent quadcopters. Black Boxes: the Black Box is a device on theaircraft used for recording the flight data. There is storage device (SD card) configuredin the commercial drone used to record flight data that allows analysis of flightattitude and reduction of accidents. The flight attitude data is saved asfigures or numbers in the storage medium, which allows the reason of the crashof aircraft to be identified. For example, say there is a change in accelerationthat lead to a crash. If there is small fluctuation in acceleration, the causemight be vibration of the aircraft. Analysis of the vibration data allows asuitable PID parameter for the aircraft to be found. Ok, sogood job making it through this! I hope this gave you a better understanding ofyour aircraft’s flight controller.
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