UAV: elementary article first introduction of UAV

UAV: elementary article first introduction of UAV

I have received a lot of private letters from my friends about the basic popularization series for UAVs. In the next few days, I will update the arti

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UAV: elementary article first introduction of UAV

I have received a lot of private letters from my friends about the basic popularization series for UAVs. In the next few days, I will update the articles on the basic technical knowledge of UAVs regularly. You are welcome to keep your eyes open and leave messages.

First, introduction

It is said that every big boy has a flying dream in his heart.  The philosopher said, "some people turn dreams into reality. Some people turn reality into a dream. The point is, what's your dream? What did you do for your dream?"I liked to play with some model plane toys since childhood, but I've been studying since elementary school, and I didn't really work hard for it until I graduated from college and worked for many years. After several years of exploration, learning and practice, finally the UAV control theory has a certain understanding. In this series, we hope to let more friends take fewer detours and bravely enter the field of UAV. Our series is about multi rotor UAVs. Of course, as an amateur, we can't afford to be a real manned aircraft, and in order to realize our dream of flying, UAV is also a great choice.

 



Two. UAV category

In recent years, due to the continuous development of open source UAV flight controllers and automatic aircraft pilots, technology has become mature, tens of thousands of outstanding people around the world contribute code to the open source UAV project. More and more ordinary people can easily enter this field. Usually, UAVs are divided into three categories: fixed wing aircraft, single rotor helicopter and multi rotor helicopter. Fixed-wing aircraft and helicopters dominated the early stage. Over the past decade, multi-rotor theory has become increasingly sophisticated, easy to assemble, and flexible over-control, gradually becoming a favorite UAV. We also focus on multi-rotor UAVs in this series to lead you into the UAV world.
 



Fixed-wing aircraft: Propulsion systems (forward-pulled or backward-thrust propellers) are used to generate forward momentum so that the aircraft can move forward rapidly.  When the airplane gains the forward speed, the upward pull is produced by the action of the airflow on the airplane's wingspan (Bernoulli principle). When the pull is greater than the gravity of the fuselage, the airplane is in the upward flight state. The left and right (roll) balance of the fixed wing is regulated by the sweep angle of the left and right main wings, the front and rear (pitch) balance is regulated by the sweep angle of the tail rudder, and the direction (course) is regulated by the vertical tail rudder. Of course, the course of the fixed wing aircraft is usually accomplished by a combination of roll and pitch, which is not our main research area. No more details here.

Advantages: long endurance and fast speed.

Disadvantages: need runway, vertical take-off and landing.


Single rotor helicopter
 


Single rotor helicopter: single rotor helicopter referred to as a helicopter. There are essential differences in mechanical structure, control principle and flight theory between a single rotor and a multi-rotor as we describe here. Readers should not be confused. The single rotor helicopter (hereafter referred to as the helicopter) has only one large propeller in its active power system. Its main function is to provide the lift power for flight. Therefore, when the lift power is greater than the fuselage gravity, the aircraft is in the ascending state. Because the helicopter has only one active propeller, when the active motor rotates at high speed, the rotation of the propeller will produce a reverse force on the fuselage - reverse torque. Under the action of counter torque, the aircraft will generate spin opposite to the propeller rotation. To solve the problem of helicopter spin, a small horizontal propeller is added to the tail of the helicopter. The pull generated by the small propeller is mainly used to counteract the fuselage spin. When the helicopter needs to change the course, it can also be adjusted by the tail propeller. In addition to the active motor and the tail motor, there are usually three steering gears, used to change the pitch of the active propeller, causing the fuselage to roll and pitch, so that the aircraft flies forward, backward or left, right.

Advantages: vertical take-off and landing, hovering in the air.

Disadvantages: short duration, complicated mechanical structure, difficult control and slow flight speed.

Multi rotor helicopter

Multi rotor helicopter: inorganic consisting of three, four or more propellers. The most typical and the most common one is the four rotor helicopter (hereafter referred to as the four rotor). The Four-rotor has four shafts and four propellers, which can also produce upward pull from the high-speed rotation of the propeller to achieve vertical takeoff and landing. But unlike helicopters, the forward, backward, left and right flight of the multi-rotor depends on the four propellers of different speeds, rather than the helicopter by changing the pitch of the active propeller, because the pitch of the Four-rotor propeller is fixed, the size of the propeller is also fixed. The rotor pitch of the four rotor of the four rotor is usually the same, so its power system is usually symmetrical. Trirotors, hexarotors, octarotors, or other multi-rotor systems differ not only in the scheme of distributing power and torque to multiple propellers, but also in the scheme of Four-rotor systems. It can be said that after learning and mastering the four rotor, you can also know the principle and dynamic system of other multi-rotor.

Advantages: vertical take-off and landing, hovering in the air, simple structure and flexible operation.

Disadvantages: short duration and slow flight speed.

Three, aircraft models and UAVs

Many friends like airplanes and aero models, but they do not have an accurate recognition of UAVs and aero models.


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