Drones Drones Drones – everyone is writing about them, talking about them and flying them – but only a select few actually know how they work. This article will provide a brief non-technical explanation of the basics that keep a modern Camera Drone in the air.
It really is Magic!
“Any sufficiently advanced technology is indistinguishable from magic.” – Arthur C. Clarke
For our more logical minds, it may help to rename magic to “sensor fusion” which is defined as:
“combining of sensory data or data derived from disparate sources such that the resulting information has less uncertainty than would be possible when these sources were used individually.”
Modern camera quadcopters, such as the Phantom 3 series, need to have control of two systems…the flying machine itself and the camera/gimbal combination. Keeping both steady and under control results in the desired end – butter smooth video and stunning photographs.
Multirotor Flight Control Sensors and Instruments
1. The GPS gathers satellite data in order to determine the position of the Drone – this data is also fed into the main flight controller. Advanced models such as the Phantom 3 Pro read both USA (GPS) and Russian (GLONASS) satellites, resulting in much more accurate positioning than previous models.
2. A Barometer measures the pressure in the air, which help the Phantom know its altitude above the ground.
3. Sonar sensors and a bottom facing camera combine to help advanced models (Phantom 3 Pro, etc.) know where the ground or floor is when it is within 9 feet of the ground. This system is helpful for indoor flight when no GPS is available.
4. Accelerometers inside the Drone sense whether it is moving through the air.
5. A gyroscope helps keep the Drone body level during flight.
6. A compass keeps basic track of which direction the Drone is pointing.
It is the combination of all of these sensors and inputs that results in a flight systems which is extremely robust and reliable.
However, the instruments by themselves are of little good without programming and computing power – that’s where the flight controller (F/C) comes in. This is the central computer of a drone and it performs many thousands of calculations per second.
The Flight Controller and Power System
If you were able to look from above down into your Drone, you’d first see the GPS system which is located in the top center hump of your quadcopter. Underneath that is the flight computer along with the main IMU (Inertial measurement unit) which contains some of the instruments mentioned previously (#2,#4 and #5 in the list). This board also contains the radio receiver and transmitter which help your Drone communicate with the transmitter and smart device back on the ground. Other parts of the main system board contain the “ESCs” (Electronic Speed Controllers) which provide power to the drone motors.
The Battery is usually located below the Flight Controller and provides the energy to power all the electronics and motors of your Phantom. It also contains intelligent circuits which monitor its charge, temperate and other data.
The stabilizer, or gimbal, which keeps the camera steady and vibration-free is a wonder of engineering in itself. We have written a separate article here which explains the operation of brushless camera gimbals. Note that similar electronic components ( IMU, EMS )mentioned in our gimbal article are also used for for stabilizing the main body of the quadcopter (#2,4 and 5 above are EMS – tiny electromechanical devices).
It may be helpful to think of the original Nintendo Wi as well as your Smartphone when trying to understand the gyroscope and accelerometer chips. These low cost Electromechanical Systems (EMS) are what has made drones – as well as fancier video game consoles and smartphones, possible. An EMS (gyroscope) is how your phone knows to switch the display from landscape to portrait. Another EMS (accelerometer) knows how fast you are swinging your bat on a Wii or similar handheld video controller. These amazing devices are a combination of mechanical (moving parts) and electronics all wrapped up in a tiny package. EMS chips are enabling the so-called IOT (internet of things), with wearable and other devices that are able to sense their environment. If you want to learn more about these devices check out Invensense, one of the major manufacturers of these devices.
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