The Unmanned Aerial Vehicle (UAV) is a kind of aircraft without a human pilot abroad. It is a flying robot. This aircraft can be remotely controlled through software controlled flight firmware in its embedded systems in cooperation with the onboard sensors and GPS.
How does a Drone work?
A UAV has two parts, the drone itself and the control system. The main part of a drone consists of a lot of sensors and navigational systems. The body of a drone is made up of a material to reduce its weight while increasing its maneuverability. The use of this material helps the drone to fly at high altitudes. Also, these materials are capable of absorbing the vibration which reduces the produced noise.
Different types of Drones
According to different criteria, drones can be classified as follows.
I. Types based on the number of propellers
1) Single rotor drone
These kinds of drones have a single rotor inside. If there is a heavy load that needs a faster flight time with a longer endurance, then a single rotor drone is the best option.
A Tricopter consists of the following parts:
i. Three motors located at each arm of this drone,
ii. Three controls for controlling each of the motors
iii. Four gyros
iv. one servo
A Tricopter lifts the ground and flies like this. Once the gyro gets a signal from the receiver, it orders the controllers for each of the motors and they start working. The main advantage of a Tricopter compared to a hand-controlled drone is that in a Tricopter, stability is automatically achieved.
A drone having four arms with four motors located in each arm is said to be a Quadcopter. The drone uses brushless type DC motors with two of them rotating in an anti-clockwise direction while the other two rotating in a clockwise direction.
It consists of 6 motors where 3 of them rotate in an anticlockwise direction and another 3 rotate in clockwise direction. Because of its more motors, this device has a higher lifting power than a quadcopter.
1) Small drones
These motors have a size ranging from 80 – 100mm. The Nano drones come under this category. They are widely used because of their tiny structure and having a lightweight construction.
Based on its manufacturer, the size of the drones that come under this category differs but the size can be specified as 100-160mm.
3) Mini drones
They have a size larger than micro drones which means their size is between 150mm-300mm. Some other manufacturers define the size of mini-drones as big as 500mm up to 2mm. The ones with a small size need a low power.
4) Medium drones
They are very lighter and smaller than an aircraft yet they can carry the weights up to 200kg and have a flying time capability of 5-10 minutes.
5) Large drones
They have a similar size as that of an aircraft. These kinds of drones are mainly used for surveillance applications.
III. Types based on the range
1) Very close range drones
2) Close range drones
These drones fly up to 50km and having the battery backup of 1-6 hours. They also have applications in surveillance missions.
3) Short Range Drones
They are commonly used for military applications. They can cover up to a maximum distance of 150km. The estimated flight time is 8-12 hours so that they can be used for spy application.
4) Mid-Range Drones
They will cover the distances as long as 650km.They are commonly used for metrological data collection.
It has a flight time of 36 hours and can go up to a maximum height 3000m above the sea level
Things to consider when choosing a drone
1) The weight of the drone
The first criteria for selecting a drone is the overall weight of the drone. By calculating the weight of the individual components, we can get an idea of the average weight of a drone.
It includes all parts, like the battery unit, motor wire, flight controller and frame of the device. Once we find the overall size of the frame, we can find the size of the propeller.
2) Thrust to weight ratio
The motor must be capable to produce 50% higher thrust as compared to the rotor. The motor must have an additional thrust to keep the drone safe.
The efficiency can be calculated by using the formula “thrust/power” in watt. This figure is denoted by g/W rating. It means a motor having a high rate of g/w will have a higher rating and it would be capable of taking the drone to longer flights distances. For normal applications, a motor having an efficiency 7 or above is chosen. When a low-efficiency motor is used, there has to be a compromise between the flight time as well as energy.
The ability of a motor to shift between different RPM values helps to define the torque range. If a motor has a higher torque value, it will give a snappy response leading to less propeller wash and in turn, it will suck more electric current. In case of a lower torque motor for a heavier propeller, it will not achieve the desired RPM value and produce enough torque for spinning. It will rather produce a lower thrust while drawing a lower electric current from the system.
For a high torque motor, it cannot be easily tuned. This kind of motor produces faster response rate and will, therefore, amplify errors that lead to oscillations even at yaw axis.
5) Pole count
There are two options for the pole count of a drone.
- Motors with a higher pole count – such drones produce more torque while demanding more voltage for the operation. Since such motors produce lower RPM, they are normally used with drones with larger blades.
- Motors having a lower pole count – Contrary to the previous motor, such motors produce higher RPM. Due to his property, these motor are used for drones with smaller blades and smaller lifting force.