In this article, we divide the composition of multi-rotor unmanned aerial vehicle into four systems, namely power system (including power supply system), flight control system, video system and remote control system.
1) power system
At present, the power unit widely used by large, small and light unmanned aerial vehicles is reciprocating engine system. For the sake of cost and convenience of use, electric power system is commonly used in miniature UAV.
1. Propeller: the main component of UAV’s thrust. Common multi-rotor UAV is generally matched with four propellers, two rotating clockwise and two rotating counterclockwise.
About propeller:
Positive paddle: head-down anticlockwise rotation (CCW)
Reverse paddle: clockwise rotation (CW)
2. Motor: Commonly known as motor, it can convert electric energy into mechanical energy and drive propeller to rotate, thus generating thrust.
3. Electronic speed controller: it can not only adjust the motor speed, but also supply steering gear of other channels on the remote control receiver, and can also convert the direct current provided by the battery into a direct drive motor three-phase alternating current.
The speed control system of the power motor is called electrical adjustment, which is all called Electronic speed controller, and Electronic SpedCotoller in English, ESC for short. Different power motors can be divided into brush harmonic brushless electric speed controller. It adjusts the rotation speed of the motor according to the control signal. For their connection in multi-rotor unmanned aerial vehicles, the general situation is as follows:
(1) electrical adjustment input wire is connected to the battery;
(2) electrical adjustment of output cable (with two brushes and three brushless brushes) is connected to the motor;
(3) the signal line of electrical adjustment is connected to the remote control receiver.
In addition, electrical adjustment generally has the power output function (BEC), that is, there is a voltage output of about 5V between the positive and negative poles of the signal line, which supplies power to the receiver and the steering gear through the signal line. Generally, electrical adjustment has the following functions:
1. Rectifier to change the direct current of the power supply into alternating current
2. Voltage stabilization, there is a stable voltage output of about 5V between the positive and negative poles of the signal line
3. Speed regulation, change the speed of the motor by changing the current
4. Check whether the motor is intact and whether there is a remote control signal.
5. Reversing, changing the motor steering
4. Power supply: providing energy for multi-rotor unmanned aerial vehicles is directly related to important indicators such as hover duration, maximum load weight and flight distance of unmanned aerial vehicles.
2) flight control system
1. Main control unit: the core of the flight control system, through which IMU, GPS compass, steering gear, remote control receiver and other equipment are connected to the flight control system to realize the autonomous flight function of the aircraft. In addition to assisting flight control, some main controllers also have the black box function of recording flight data.
2. IMU (inertial measurement unit):
Its function in the aircraft is to sense the change of the aircraft attitude, such as the most basic attitude data such as the current forward or left-right inclination of the aircraft, the direction and height of the nose.
3. GPS compass module: includes GPS module and compass module, which is used to accurately determine the direction, longitude and latitude of the aircraft.
4. LED indicator module: it is used to display the flight status in real time, which is essential in the flight process. It can help pilots understand the flight status in real time.
3) video system
1. Camera: Take pictures on the flight path of UAV.
2. Pan-tilt: two-axis pan-tilt and three-axis pan-tilt are commonly used. As a stabilizing device of a camera or camera, the pan-tilt provides stabilizing control in two or three directions.
3. Image transmission: the image taken by the UAV in the air is transmitted to the ground image transmission remote control receiving Display Terminal in real time and stably for the pilot to watch. UAV image transmission system adopts appropriate video compression technology, signal processing technology, channel coding technology and modulation and demodulation technology, A wireless electronic transmission device that transmits the video captured by the camera carried by the on-site UAV to the rear of the long distance in real time in a wireless way.
If classified by device type, it can be divided into two categories: analog image transmission and digital image transmission. The early image transmission equipment all adopted analog system, which is characterized by that as long as the image transmission transmitter and receiver work in one frequency band, they can receive the picture. Because the video quality and stability transmitted by digital image transmission are far better than analog image transmission system, digital image transmission is usually used in industrial applications.
4) remote control system
There are many ways to control unmanned aerial vehicles. The most traditional one is remote control. In addition, the data transmission radio used in the ground station. In addition, there are not particularly mainstream Bluetooth, wifi, 3G/4G, etc.
Unmanned aerial vehicle remote control is generally sold in pairs, one transmitter and one receiver. They need to be used in pairs. Transmitters and receivers from different manufacturers may not be universal. They need to confirm whether their agreements are consistent when purchasing.
The transmitter is equipped with rocker, knob, switch and other devices. The Flying hand remotely controls the UAV by adjusting these devices on the transmitter. The control command given by the flyer is received by the receiver, and the receiver is connected with the flight control to transmit the signal to the flight control.
Remote control also has an American hand and a Japanese hand. American hand and Japanese hand refer to the control mode of UAV, American hand is left hand throttle, Japanese hand is right hand throttle, corresponding to different layout of throttle Gee pole of different controllers.
American hand: Also called left hand throttle. It is the left rocker of the remote control, which is responsible for the rise and fall of the UAV and the clockwise/counterclockwise rotation in the same place. The shot stick right of the remote control is responsible for the forward and left movement of the UAV in the horizontal position.
Japanese hand: Also called right hand throttle. In fact, the difference with American hands is not big, only in controlling the rise and fall of unmanned aerial vehicles and moving forward and backward. That is, the left rocker is responsible for the forward and backward of the UAV, rotating clockwise/counterclockwise in place; The shot stick right of the remote control is responsible for the rise and fall of the UAV and the left-right movement.
Chinese hand: Some people also call it “anti-American hand”, because it is completely opposite to “American hand”. The left rocker of remote control is responsible for the forward and left movement of unmanned aerial vehicle in the horizontal position; the shot stick right of the remote control is responsible for the rise and fall of the UAV and the clockwise/counterclockwise rotation in place.
There is no difference between good or bad and easy operation methods, but different people have different habits. If you don’t know how to choose, please choose American countries. There are many people using it, and it will be better after elimination.
