By: Stuti Vyas( ) Drashti Sheth( ) Jay Vala( ) Internal Guide Mr. J. N. Patel

 A quadcopter, also called a quadrotor helicopter, quadrocopter, quadrotor, is a multicopter that is lifted and propelled by four rotors.  Unlike most helicopters, quadcopters generally use symmetrically pitched blades; these can be adjusted as a group, a property known as 'collective', but not individually based upon the blade's position in the rotor disc, which is called 'cyclic‘. Control of vehicle motion is achieved by altering the pitch and/or rotation rate of one or more rotor discs, thereby changing its torque load and thrust/lift characteristics.

 Pitch : Rotation around the side-to-side axis is called pitch.  Roll : Rotation around the front-to-back axis is called roll.  Yaw : Rotation around the vertical axis is called yaw. The following animation will make the understanding of the above terms very clear.

 Each rotor produces both a thrust and torque about its center of rotation, as well as a drag force opposite to the vehicle's direction of flight. If all rotors are spinning at the same angular velocity, with rotors one and three rotating clockwise and rotors two and four counterclockwise, the net aerodynamic torque, and hence the angular acceleration about the yaw axis is exactly zero.

Schematic of reaction torques on each motor of a quadrotor aircraft, due to spinning rotors.

A quadrotor hovers or adjusts its altitude by applying equal thrust to all four rotors.

A quadrotor adjusts its yaw by applying more thrust to rotors rotating in one direction.

A quadrotor adjusts its pitch or roll by applying more thrust to one rotor and less thrust to its diametrically opposite rotor.

Block Diagram (Receiver)

 ESC (Electronic Speed Controller) : The brushless motors are multi-phased, normally 3 phases, so direct supply of DC power will not turn the motors on. That`s where the Electronic Speed Controllers (ESC) comes into play. The ESC generating three high frequency signals with different but controllable phases continually to keep the motor turning. The ESC is also able to source a lot of current as the motors can draw a lot of power.

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 Brushless Motors : They are a bit similar to normal DC motors in the way that coils and magnets are used to drive the shaft. Though the brushless motors do not have a brush on the shaft which takes care of switching the power direction in the coils, and this is why they are called brushless. Instead the brushless motors have three coils on the inner (center) of the motor, which is fixed to the mounting.

Fig : Real view of brushless motor Fig : Block diagram of Brushless motor

 The Inertial Measurement Unit (IMU) is an electronic sensor device that measures the velocity, orientation and gravitational forces of the quadcopter. These measurements allow the controlling electronics to calculate the changes in the motor speeds.  The IMU is a combination of the 3-axis accelerometer and 3-axis gyroscope. Sometimes there is also an additional 3-axis magnetometer for better Yaw stability

 Accelerometer: It is used to measure the orientation with reference to the surface of earth.  Gyroscope: It tells us the rotational movement of the quadcopter.  Magnetometer (optional): The accelerometer cannot sense yaw rotation like it can with roll and pitch, and therefore a magnetometer is sometimes used for better stability. NOTE: These components can be separately mounted.

Fig: IMU i.e. combined Accelerometer, Gyroscope, Magnetometer Fig: Accelerometer Fig: Gyroscope (3 axis) Fig: Magnetometer

 Frame is the structure that holds all the components together. The Frame should be rigid, and be able to minimize the vibrations coming from the motors.  Frame can be made up of several material such as Aluminum, Carbon fiber, Glass fiber, Wood.  It should be light weight. Continued…

 Wireless security cameras are closed-circuit television (CCTV) cameras that transmit a video and audio signal to a wireless receiver through a radio band.

 Research platform: Quadcopters are a useful tool for university researchers to test and evaluate new ideas in a number of different fields, including flight control theory, navigation, real time systems, and robotics.  Military and law enforcement: Quadcopter unmanned aerial vehicles are used for surveillance and reconnaissance by military and law enforcement agencies, as well as search and rescue missions in urban environments. Also can be used in spying. It also can be loaded with light weapons for self defense.

 Commercial : The largest use of quadcopters has been in the field of aerial imagery. Quadcopter UAVs are suitable for this job because of their autonomous nature and huge cost savings. Capturing aerial imagery with a quadcopter is as simple as programming GPS coordinates and hitting the go button. Using on-board cameras, users have the option of being streamed live to the ground.  Other Applications Weather monitoring can be done with quads, installing sensors that monitor weather and sends data to the ground units for real time weather monitoring, also as the quad will be up in the air it can have accurate data.

 GPS modules  Ultrasonic sensors  Barometers  Solar Radiation Sensor.  Water Wind Speed Sensor.  Humidity Sensor.  Temperature Sensor.  Thermal Imaging Camera (For Military Application)

 We have decided the frame which is shown below, it is made up of Glass fiber.

 We will now onwards work on sensors and the programming of the Atmega 32 microcontroller that we are going to use.  We will use Bascom programming language as it is difficult to implement this project in C and Assembly language.  We will then work on assembling all the sensors and we will then add additional sensors for weather monitoring if time permits.