Building Quadcopter Part-1

This is the first blog post in the “Building Quadcopter series” from c2plabs.com which explains different parts of Quadcopter.

Quadcopter generally consists of the following components.

1. BLDC-Motors
2. Propellers
3. ESC (Electronics Speed controllers)
4. Frame
5. Flight Controller
6. Power Distribution Board (PDB)
7. Li-PI Battery

1. Motors: For Quadcopter Brush Less DC (BLDC) motors are commonly used motors. BLDC Motors are of two types Outrunner motors and inrunner motors (Conventional DC Motors). Quadcopter use outrunner motors as they have minimal friction. Propellers are mounted on these motors. When the motors rotating propellers produce thrust which lifts Quadcopter from the ground.   The important rating of the motor is specified in KV rating.KV (rpm/V) is revolutions per minute for a Voltage supplied to the motor. More KV means more thrust. Generally, we get BLDC motors with 1000KV and 1400KV ratings in the hobby drone shops.Current & Voltage ratings of the motor are also essential for selecting appropriate ESC (Electronic Speed Controller).
2. Propellers: Quadcopter uses two clockwise and two counter-clockwise propellers. The propellers are specified with their length and pitch. Length of the propeller is the diameter of the circle made by the propeller when it is rotating. Pitch is the perimeter of the circle.
3. ESC (Electronics Speed controllers): ESC or Electronic Speed Controller is an electronic circuit which supplies a variable voltage to BLDC motors depending on the PWM signal received from Flight Controller.  ESCs are connected to Li-Po battery through Power Distribution Board (PDB).ESCs get their input voltage from Li-Po battery through PDB (power distribution board) and supplies a variable voltage to BLDC motors depending upon the PWM signal received from Flight Controller.
4. Frame: The frame is one of the important parts of Quadcopter. The frame acts as the support structure for mounting all the components like motors, ESC, battery etc. of the Quad.   While building the frame stability of must be ensured after mounting all the components of the drone. I have used off the shelf F450 frame which can be bought from easily in from local hobby shop. Different shapes of frames can be used following are commonly used frame types” + ” Shape.” X” Shape.

   “H” Shape.  Based on the shape we use, the thrust needed for acceleration will be divided.

5. Flight Controller: The heart of Quadcopter is the Flight controller, this controls the motors and provides stabilization to the Quad based on the inputs from the transmitter. I have used Ardupilot (APM 2.6) as the flight controller. APM board is just an Arduino with some additional sensors. But it is always recommended to use APM instead of using Arduino and trying discrete sensors.APM 2.6 includes 3-axis gyros, accelerometer, barometer and provision for connecting the GPS module.
6. Power Distribution Board (PDB): All the Electronic Speed Controllers (ESCs) should be connected to LiPo battery to supply required voltage to BLDC motors. These Motors draw very high current during initial thrust, because of this high current ESCs are connected to the battery through a PCB called as power distribution board (PDB).
7. LiPo Battery: A lithium polymer battery (LiPo) is rechargeable battery using polymer electrolyte instead of liquid electrolyte. LiPo battery is described based on the following factors.a. Voltage:  Most of the DIY Quadcopters use a battery with 12V with 500 to 5000mAH.

b. Number of cells: Battery specifications are specified as 3S or 4S, here 3S means 3 cells and 4 S means 4 cells.

c. Max Current rating (C Rating): C-rating of the LiPo battery is the maximum amount of current a LiPo battery can supply without harming the battery.