Basic knowledge of drones

The introduction and utilization of drones in various fields are progressing.In this series, we will explain the basic knowledge of drones six times.The first one is a drone, and explains the difference between the definition of a drone and the conventional wireless pilot (radio control) helicopter, etc., as well as the rules that are indispensable for safe flights and domestic laws related to flights.to introduce.

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1st: What is a drone?

1.What is a drone?

A generation ago, there was an era in which wireless pilots and wireless pilot helicopters were enjoyed as a hobby.Even today, in the agricultural field, pesticides are being sprayed using large wireless piloted helicopters (with power).In recent years, flying wireless pilot devices have become high -performance and automatically piloted, and have been called drones as general names.The Japanese law (Air Law) defines drones as "unmanned aircraft."There is no formal definition of the word drone, and there are wireless pilot devices that are called land drones and underwater drones in addition to those that belong to flying wireless pilots.In this series, we will only explain the drone as a small unmanned unit.

The reason why drones have spread rapidly is that the drone itself has become more performance, and anyone can easily fly, and the price is reasonable and easier to buy.Nowadays, drones as toys (toys) can be purchased for about 10,000 yen.

Another reason the drone has become popular is ...

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2.What is a drone license qualification?

Currently, there is no law on drone licenses under Japanese Japanese law.In other words, there is no system that allows drone flight by obtaining some license.However, there are areas where drone flights are prohibited by the aviation law, and forbidden flight methods such as night flights.If you want to fly a drone in a prohibited area or method, you must be permission or approved by the Ministry of Land, Infrastructure, Transport and Tourism.

Although it is not a legal system, there are skill courses and certifications conducted by private companies and organizations throughout Japan.Drone is getting more high performance, and ...

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3.Related law to consider

There are various laws and rules in drone flights.Mainly, airlines, small unmanned unit of flight prohibition, and radio waves.There are other laws that affect drone operations, but here we will focus on major relevant laws and regulations because it can be introduced so that it can not be introduced.

First, the Aviation Law prohibits drone flights over the area where houses are dense (called the DID district), airspace above the airport, or more than 150m above the ground.I am.In addition, flight methods such as flying at night, flying in places where many people are gathering, and dropping things are also prohibited.Details can be found on the website of the Ministry of Land, Infrastructure, Transport and Tourism Aviation Bureau.

A law similar to the Aviation Law is a prohibition of small unmanned aircraft.This is the law of the National Police Agency, prohibiting drones flights around important facilities in the country or in places where the security of public guests is needed.You can check specific flights on the National Police Agency website.

Next is the radio wave law.For the radio waves used for drones, ...

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4.Introduction of main procedures

So far, we have introduced relevant laws and regulations, but when you actually fly a drone, you are often affected by flights over the DID district in the Aviation Law.In the DID area, flights are prohibited under the aviation law, but you will be able to fly by receiving permission from the Ministry of Land, Infrastructure, Transport and Tourism.Applications for receiving this permission ...

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2nd: Drone flight principle

Last time, I explained the outline of the drone and the relevant laws and regulations to be considered.This time, I will explain the difference between helicopters and multicopters, and what principles the flights are flying.In particular, let's understand the structural difference between a helicopter, which has been powered by the conventional engine, and a multi -comicopter, which is powered by an electric motor that rapidly spreads.In the second half, we will introduce a control method for moving multicopters.

1.A mechanism where drones can fly

There are two factors that float things.One is due to buoyancy generated in fluids such as water and air.The other is due to the power to rise due to the pressure difference of the fluid flowing up and down of the wings, causing lift.

The drone flies the wings called blade at high speed, causing air to the wings (rotating wings) and flies with lift.Many of the commercially available drones rotate the blade using electricity as a power source.The motor part that rotates the blade is called a rotor.By adjusting the current flowing to the rotor, the rotation speed of the blade changes, and the lift changes, so that it can fly in the air freely.

Multicopter -type drones fly by rotating multiple rotors at the same time.The number of this rotor is due to control convenience ...

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2.Difference between helicopter and multicopter

Helicopters and multicopters have some differences in structure.In the case of a helicopter, if the rotor is rotated, the aircraft itself rotates in the opposite direction to the rotation direction of the rotor.To prevent this, there is a mechanism that usually generates a horizontal force in the tail wing (Fig. 2), and prevents the aircraft from rotating unexpectedly.In the case of multicopter, the next rotator of the multiple rotors is turned upside down to cancel the reaction force.

The blade of the rotating wing varies depending on the angle, which is generated in the same rotation speed.The angle of this blade is called a blade pitch (Fig. 3).Almost all multi -copters on the market use a structure called a fixed pitch that cannot change the blade pitch.On the other hand, in the case of a helicopter, the structure (variable pitch) can change the blade pitch during flight by the mechanism called the swash plate attached to the rotor.

In the case of a helicopter, the rotation speed is kept constant and the blade pitch is changed (the larger the blade pitch, the larger the lift, and the smaller the blade pitch, the decrease in the lift) and the lift is adjusted and the flight is flying.I will do it.On the other hand, in the case of multicopter, ...

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3.Moving principle of multicopter

Unlike a car that runs on the ground, airplanes are accompanied by three -dimensional movement, including up and down.The horizontal direction of the aircraft, the angle viewed from the side, and the angle seen from the front are called heading, pitch angle, and bank angle.This adds movements such as rising and descending.

The transfer principle of the multicopter is simple, and in the case of rising, it is realized by increasing the rotation speed of all rotors and increasing the lift.Conversely, if the rotation speed of all rotors is reduced, the lift will decrease and it will fall.When moving forward, the thrust is created by raising only the rotation speed at the back of the aircraft and raising the rear of the aircraft (also called lowering the pitch angle).When retreating, the rotation speed in front of the aircraft is increased and the pitch angle is slightly upward, which creates a backward thrust.

Multicopters can also move horizontally.The principle is ...

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3rd: Cause of drone falling

Last time, I explained the principle of drone flight.This time, I will explain the cause of the drone falling.If you can understand the flight characteristics of the drone, you can pursue the cause of the crash.Understand the difference in flight characteristics between variable pitch blades used in helicopters and commercial fixed pitch propellers used in multicopters.Assuming various crash factors, we aim to ensure safety when operating drones.

1.Fixed pitch merit

Stilling objects (such as cars, trains, etc.) on the ground will continue to stay on the spot unless any power is applied.However, if the drone (if not described hereinafter, multi -copter type), if the rotor is rotated, the lift and gravity created by the blade are balanced, and the lift that is stationary (hovering) in the air may stay in the air.can not.Unlike objects that have contacted the ground, they will fall if nothing is done.The important keyword here is that if you lose lift, it will fall.In other words, even if the rotor is operating normally and the blade is rotating, if you lose lift, it will fall.

The rotating wing, which contains a drone, creates an airflow that taps the air down the rotor by the rotation of the blade.The strong downhill flow created by this blade is called down wash.The heavier the weight of the aircraft (takeoff weight), the more intense the downwash.

If the aircraft in the flight descends rapidly, it will be caught in a strong descent stream that you have created.At this time, the drone is the same as the intense turbulence, often lost control.When the aircraft descends while the rotor is rotating, the phenomenon that it goes into down wash and loses its lift, and falls into down wash again by descending.This phenomenon is called a set ring with power (Fig. 1).When entering the set ring with power, the aircraft often crashes because it loses stability and control.Helicopters that fly on a ride do not descend vertically unless they are in a special situation.In order to prevent entry into the set ring with power, it is important to move in the horizontal direction in consideration of the wind direction.

Down wash is ...

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2.Main crash cause

He mentioned earlier that the crash due to losing power was mainly due to a sudden descent.In addition, there are cases where the battery runs out of power and loses its lift, which leads to a crash.Other than that, it is an accident that collides with other obstacles and breaks the aircraft to crash.Naturally, the pilot needs to ensure the surrounding safety and fly the drone, but in many cases, the pilot loses the aircraft and collides with other properties, or the aircraft and controller (propo).The wireless connection may be broken and lost control may lead to a collision.

In addition, the automatic return function, which is equipped as a convenient function for high -performance drones, sometimes performs an accident, which is sometimes different from the flight route intended by the pilot (Fig. 2).Rarely, ...

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3.Measures for safe flight

In order to fly safely, it is necessary to ensure safety before starting the flight, assuming that there will be trouble.If you are concerned about the impact on non -related people, it is important that the pilot, including the availability of the flight, ensure safety and do not perform unreasonable piloting, such as dying.In addition, in order to prevent falling due to failure of the aircraft ...

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4th: Main aircraft configuration

Last time, I explained the cause of the drone falling.This time, I will explain the main aircraft configuration.A standing actor whose drone has spread rapidly is an automatic posture control device and a drive system.High -performance posture control requires a variety of sensors.I will explain the sensors used for drones while touching on the advantages and disadvantages of each.In addition, we will also introduce the structure of control systems and drive systems that handle large current.

1.A group of sensors that make up a multicopter

Drone (hereinafter, it is limited to multicopter -type drones unless it is noticeable) began to spread rapidly around 2010.Behind its spread is the evolution and high performance of automatic posture control devices.In automatic posture control, it is necessary to accurately and instantly measure what kind of posture the aircraft is currently, what kind of movements accompanied, what position is, and they are.In order to hover the drone in the same position in the air and the same heading (the angle of the drone's head), at least detection of moving to back, back, left and right, detect up and down, yawn (rotate up and down (rotating up and down).) You will need to detect.

The acceleration sensor measures acceleration / deceleration and detects moving to the front, rear, left and right.If you detect acceleration to the left, you will keep the fixed position by moving it to the right as much as you correct it.However, in the case of a drone, the aircraft must be tilted in order to perform intentionally front, rear, left, left and right movements, so in fact, the inclination of the aircraft (the straightforward shadow of each axis of the gravity vector) is actually the value of the acceleration sensor.You need to deduct.If you are performing atth speed exercises in front, back, left and right moving detection, you cannot detect it with the acceleration sensor, so you need to use other sensors for the purpose of supplementing this.GNSS, visible camera, pressure sensor, gyro sensor, etc. play a role.I will explain these four.

Many of today's drones use the GNSS (especially those that use American satellites in GPS) to detect front, back, left and right movements.GNSS can detect the movement even in the equal speed movement.However, the current location measurement by GNSS takes time for each measurement, so it is difficult to detect the movement instantly.Therefore, the acceleration sensor is the main, and it is necessary to use the GNSS signal by supplementing it.

Visual cameras are effective in an environment where GNSS signals cannot be received, such as indoors.Depending on the model of the drone, there is a visible camera that reads the ground pattern on the bottom of the aircraft (Fig. 1), so to speak, the local navigation (the ground pattern is continuously photographed, and the amount of movement is measured by the change in the image.There is something that detects the movement on front, back, left and right by the method (how to do it).However, this visible camera is used only in the role of supplementing the acceleration sensor because the movement cannot be detected on the ground with a uniform pattern.

The barometric sensor is mainly used to detect up and down.If the aircraft rises, the pressure will be lower, and if it descends, the pressure will increase.By analyzing this change, it detects an up and down.However, since environmental pressure changes due to various factors, ...

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2.Control system that realizes stable flight

The important thing in the posture control of the multicopter is to instantly analyze the condition and changes of the aircraft obtained from each sensor, and to immediately correct it when the pilot is unintended.。Especially in the case of drones that fly freely in the air, it is necessary to assume outside disturbance such as wind, radio disorders, and magnetic field disturbances.

FC (Flight Controller) is a central control device that controls the posture of the drone (a fixed pitch multicopter).In the drone control system, it is necessary to manage the remaining battery level and the rotation speed of each rotor.The FC calculates the measurement results of various sensors and the input from the pilot, and controls the posture by determining the rotation speed of each rotor.

ESC (Electric Speed Controller) is ...

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3.A drive system that realizes flight

There are two main types of electric motors used in drone rotors: brushimoters and brushless motors.I will explain these two motors.

A brushimotor is a motor with a brush (electrode).Creating and rotating the current by contacting the brush and the commuter.For this reason, sparks may occur inside the motor, and there are some tasks, such as noise or dust from a contact person.Inexpensive items such as toy drones and lightweight drones of about 100g are mainly brushimotors.It is inexpensive, and the control circuit is simple because it rotates just by flowing the current, and it can be lighter.however,……

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5th: Communication system

Last time, I explained the main aircraft configuration of the drone.This time, we will explain the technology and method of ensuring reliability about the communication system used for drones.In order to achieve remote control, which is the largest characteristic of drones, a communication system that wirelessly connects the pilot (transmitter) and the drone body (receiver) is essential.The reliability of the communication is greatly related to the safety of flight.

1.Communication system that remotely control drones

The characteristics of a drone (unmanned aerial aircraft) and a manned aircraft are, as the name implies, whether or not a pilot will operate on the aircraft.Most of the manned aircraft today is controlled by automatic piloting devices, due to the development of technology.Even in manned aircraft, which is said to have a fatal breakdown only with almost zero probability, sometimes a serious failure occurs.Of course, the automatic pilot may break down.However, if the pilot is on board to operate, even if the automatic pilot device breaks down, the pilot (person) controls the aircraft to continue safe flight.Even if the surrounding environment changes during the flight, even if the automatic pilot device does not break down, and it is necessary to change the flight plan at the time of takeoff, the pilot will change the setting of the automatic pilot in the cabin or the control stick.It can be solved by holding (so Jukan).

What if this is a drone?The drone flight is also ...

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2.Selection of wireless system according to practical work

Drones have two main purposes for using wireless communication.One is a signal exchange that controls the flight (aircraft) using control communication.The other is to transmit a video of a camera mounted on the aircraft using a video transmission communication to a pilot on the ground in real time.Since the amount of data to be transmitted for wireless communication for control signals, the amount of data to be transmitted is small, so it is prioritized for connection stability and hijacking prevention, rather than bandwidth (the amount of radio resources required for wireless communication).On the other hand, wireless communication used for the purpose of video transmission requires a wide range of bandwidth to transmit a clearer video.Radio resources required for wireless communication are limited, so it is necessary to share the communication bands separately.In an environment where radio waves are concentrated and crowded, there is a problem that the video transmission cannot be secured sufficiently, and the transmission of the image is interrupted.

There are several ways to send a signal for control and video transmission by wireless communication (Fig. 1).One is a method of transmitting control signals and video signals by different frequency radio waves.For inexpensive toy drones, it is mainly this method for those that can transmit video in real time.Although the control signal and the video signal are separate communications, it is used in WiFi 2.Exchange signals in the same frequency band of 4GHz.However, in this case, a limited 2.Because the 4GHz band is used in two communications, it is often the case that the surrounding wireless environment occurs, and the video transmission is not interrupted.

The second is to send control signals and video signals in another frequency band....

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3.Legal operation attention

Many of the commercially available drones are also used in WiFi..Because it is communicated in the 4GHz band, anyone can use it without a wireless worker license.However, there is a condition to use radio waves without a license, and the drone must receive a proof of wireless technical standards (commonly known as "skilled").

It is important to note that some of the overseas drones sold on the Internet mail order have no skill, and if you fly without a license, it will be a violation of the Radio Law.For drones that have received skills, the "technical mark" is always displayed, so it is recommended to check when purchasing (Fig. 2).

When using a 5GHz band radio wave called VTX, when using equipment to transmit video ...

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6th: Drone flight stable system

Last time, I explained the communication system.One of the reasons why drones have become rapidly spread is that anyone can easily fly.Depending on the model, those that do not require human control skills at all have begun to spread.These flight stability are realized by various sensors and computers where advanced technology has been combined.In the final episode, we will understand the principle of drone movement and explain how the flight stabilization system is navigating.

1.Mechanism to move drones

The drone creates lift by rotating the propeller (blade) and emerges in the air.So how are horizontal movements such as forward, retreat, and left and right?

First, consider the lift created by the blade.The lift created by the rotation of the blade (the blade pitch is fixed) is only vertical for the rotation surface (Fig. 1).In other words, if the rotor is mounted horizontally on the ground, you can only create a vertical upward.In this case, there is no horizontal force, such as front, back, left and right.

Therefore, by tilting the entire aircraft, the power created by the blade is dispersed in the vertical upward (lifting the force) and the horizontal direction (thrust), and the drone is moved horizontally by creating a horizontal force (Fig. 2).The drone that has begun to move horizontally performs a geomotive exercise, assuming that there is no disturbance.When moving in the horizontal direction, the drone will reduce the inclination and keep the aircraft a horizontal state to continue moving at a constant speed.If you stop the drone while moving horizontally, ...

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2.Main types of stabilization system

Drones can move freely in the air, so there are many factors that require stabilization.One of them is the horizontal movement between the front, rear, left and right similar to the car.A car that runs on the ground can stay in the same position without any control if you stop by stepping on the brake.However, drones floating in the air need to constantly control the aircraft's posture in order to stay in the same position.In many cases, the horizontal movement of the drone is based on one point on the ground.In other words, drones need to calculate how much they have moved based on the coordinates on the ground.

One of them is a method of estimating how much of the aircraft has been moved by accumulating the movement of the aircraft measured by the acceleration sensor.However, it is a low reliable method because the error increases over the passage of flight time.Recently, high -performance drones have become so large that GNSS (especially US satellites are GPS).With GNSS position measurement, you can always measure the position of the aircraft based on one point on the ground regardless of flight time.

However, GNSS uses weak radio waves from the satellite in outer space ...

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3.Navigation system

There are several ways to sail drones.The most typical method is to use a transmitter called a propo to instruct the aircraft's operation.In many cases, fly the drone using two control rods called sticks.Propos and drones are wirelessly connected by radio waves.If the radio communication between the propo and the drone body is disconnected, you will not be able to instruct the drone flight method.This is called a no -control state.For high -performance drones, some models have a function that automatically returns to the pilot using GNSS and the like.

The navigation system is a method of using a propo ...

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