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Radio Controlled Quadcopter: Construction, Working Principle, and Applications

Written By: 

Ronauk Kumar Maharana

Representational Image of a Radio Controlled Quadcopter

Fig. 1: Representational Image of a Radio Controlled Quadcopter

Aim of the Project:-

To build a remote controlled quadcopter using KK flight control board as the controlling unit.

Materials Required:-

Quadcopter frame

 
4 x 1000 KVA Brushless DC motors
 
4 Electronic speed controller unit
 
4 propellers
 
KK V5.5 flight controller unit
 
4400 mA Li-Po battery with a battery charger
 
6 channel RC Remote with receiver
 

Theory

A quadcopter is a four rotor unmanned aerial drone that operates with the same principle as of a helicopter with slight differences lying within both. It is used for several purposes in the military as well as social fields operating over a wide range of applications. It has become a craze for building a quadcopter among people as it gives a wide variety of benefits as compared to the traditional helicopter such as stability and control. Till date quadcopter has only been used as a drone that is controlled from a distant place.

A general purpose quadcopter is X-type quadcopter with every motor rotating in the anti-spin direction to that of its adjacent motor. The quadcopter works over two principles:
 
(i) Newton’s Third Law of Motion: - In order to create a movement forward, the quad has to push the air backward. Thus for every backward motion of air, there is a forward motion of quadcopter.
 
(ii) Bernoulli’s Principle: - According to Bernoulli’s theorem there is an increase in velocity if there is a decrease in pressure and vice versa. Hence in order to increase the velocity the pressure at that point needs to be decreased.
 
There are four basic movements of the quadcopter viz. throttle, elevator, aileron and rudder. 
 
Throttle is considered when there is an upward and downward motion of the quad. It is used for takeoff and landing of the quad. It is created by rotating all 4 rotors at the same speed.
 
Elevator is considered when there is a forward and backward motion of the quad. In an X-type quad forward motion is created by rotating the 2 rear rotors at greater speed compared to the front rotors whereas for backward motion the front rotors have higher speed than rear rotors.
 
Aileron is considered when there are right and left movements. It is used for changing directions in the moving drone. It is created by rotating the left 2 rotors to rotate at a higher speed than the right rotors for the right turn and vice versa for the left turn.
 
Rudder action is used to create clockwise and anti-clockwise movement of the quadcopter about the central axis. It is achieved by rotating the diagonally situated rotors moving with the same spin to rotate at a greater speed than the other two. 
 
Apart from the above operations, the quad can also use a GPS to track its own location.
 
For small scale building of quadcopters, BLDC motors are best because of their light weight, less friction and high speed. 1000 KVA BLDC motors would be suitable in case of a quad with a dimension of 35 x 35 x 15 cm.
 
Unlike geared DC motors, BLDC motors cannot be used directly in the electrical circuit. To control the movement and speed of the motor an electronic speed controller (ESC) is used that signals the BLDC motor according to the data received by it. For each BLDC motor, there must be one ESC in order to run the motor
 
The flight movements are caused by means of propellers. The size of propeller must be appropriate depending upon the size of the quad in order to create enough thrust to cause the movements.
 
The cheapest and the most efficient flight control board is the KK version 5.5. It is suitable for beginners. For high-level multipurpose applications, various other flight controllers are used. The most widely used flight controller is NAZZA M-Lite manufactured by DJI Company. 
 
The powering unit of the system is a rechargeable lithium polymer battery. It is better suited because of its light weight and high current supply for the quad movements.

Since the quadcopter is an unmanned aerial drone transmission of signals takes place wirelessly via radio frequency transmission system (RFTS).  This is achieved by means of a 6 channel radio control transmitter and receiver.

Construction

The four BLDC motors are mounted on the ends of the quad frame each connected to the flight control board via ESC. The 4 motors are connected in parallel to the supply battery. The ESCs are connected to their respective 4 pins M1, M2, M3 and M4 on the KK board. The receiver is then attached to the KK board. Four channels are used in the receiver for the four different movements and are connected to their respective pins namely the throttle, elevator, aileron and rudder pins. Only one of the pin pair is made in connection to the Vcc and Gnd pins and the remaining three are connected via signal pins. The KK board is an inbuilt microprocessor that gives out the desired output to the motors by receiving the signals for the different movements via the receiver.

Working Principle:-

As discussed earlier there are 4 motions in quadcopter viz. throttle, elevator, aileron and rudder. These motions are controlled by the help on a radio control transmitter.
 
The transmitter transmits the data to the receiver which is placed over the quad.
 
The receiver then sends the data to the flight control board.
 
The flight controller is an inbuilt microprocessor that manipulates the signals received by it and commands the BLDC motors through the ESCs.
After the command is received the motors act according to the signal transmitted by the remote.
 
The throttle is created by rotating all 4 rotors at the same speed.
 
An elevator is created by rotating the 2 rear rotors at greater speed compared to the front rotors whereas for backward motion the front rotors have higher speed than rear rotors.
 
Aileron is created by rotating the left 2 rotors to rotate at a higher speed than the right rotors for the right turn and vice versa for the left turn.
 
Rudder action is created by rotating the diagonally situated rotors moving with the same spin to rotate at a greater speed than the other two.
 

Practical Applications:-

 
A quad possesses a wide range of applications:-
 
It can be used by the military for surveillance purposes as well as used as UAVs.
 
It can be used for home delivery of products.
 
Small scale quadcopters are manufactured as toys for small children.
 
It has become a craze among technocrats to design and built an effective quadcopter.
 
It is such a powerful thing that it can bring war between 2 countries these days.

Like this, it has got many more applications. It is a very essential and productive device for the modern generation of technology.

 

Comments

Construction, Working Principle, and Applications..do you have any video ?