How To Build A Quadcopter – Choosing Hardware
In this article I will be talking about quadcopter components and how to choose them. This is part of the tutorial series on how to build a quadcopter. In the next post I will be talking about software, how to go about the algorithm and programming.
If you are planning on building a quadcopter but not sure how, this is the right place for you. Doing research is pretty boring, so I am trying to put together a comprehensive tutorial about quadcopter, hope it helps you as much as it helped me.
If you are a beginner you should also check out this beginner guide.
Building a quadcopter from scratch takes a lot of time and effort. If you are inpatient, afraid of programming/maths and has a good budget, you can just buy a pre-built kit. You could get it assembled within minutes before it’s flying (For example, like this one). But I have to say, you are missing the fun part of building a quadcopter. From choosing the parts, designing the circuits, to programming, you will be involved in every aspect of building a quadcopter, and it’s FUN!
If you have any questions, feel free to ask on this quadcopter message board.
This blog post is divided into a three parts
- What is a Quadcopter and How It Work
- Quadcopter Components Introduction
- Conclusion
What Is A QuadCopter and How It Works
A QuadCopter is a helicopter with four rotors, so it’s also known as quadrotor. Because of its unique design comparing to traditional helicopters, it allows a more stable platform, making quadcopters ideal for tasks such as surveillance and aerial photography. And it is also getting very popular in UAV research in recent years.The Quadcopters exist in many different sizes. From as small as a CD up to something as big as one meter in width.
On a regular helicopter has one big rotor to provide all the lifting power and a little tail rotor to offset the aerodynamic torque generated by the big rotor (without it, the helicopter would spin almost as fast as the propeller)
Unlike a helicopter, a quadrotor has four rotors all work together to produce upward thrust and each rotor lifts only 1/4 of the weight, so we can use less powerful and therefore cheaper motors. The quadcopter’s movement is controlled by varying the relative thrusts of each rotor.
These rotors are aligned in a square, two on opposite sides of the square rotate in clockwise direction and the other two rotate in the opposite direction. If all rotors turn in the same direction, the craft would spin would spin just like the regular helicopter without tail rotor. Yaw is induced by unbalanced aerodynamic torques. The aerodynamic torque of the first rotors pair cancelled out with the torque created by the second pair which rotates in the opposite direction, so if all four rotors apply equal thrust the quadcopter will stay in the same direction.
To maintain balance the quadcopter must be continuously taking
measurements from the sensors, and making adjustments to the speed of
each rotor to keep the body level. Usually these adjustments are done
autonomously by a sophisticated control system on the quadcopter in
order to stay perfectly balanced. A quadcopter has four controllable
degrees of freedom:Yaw, Roll, Pitch, and Altitude. Each degree of
freedom can be controlled by adjusting the thrusts of each rotor.
